Abstract:
A system [ 100 ′] and process [ 100 ] for the continuous recovery of metals is disclosed. The system [ 100 ′] comprises a continuous acid wash system [ 10 ′], a holding tank [ 60 ], a continuous elution system [ 20 ′], a continuous electrowinning system [ 40 ′], a carbon regeneration system [ 30 ′], and a continuous carbon loading/adsorption system [ 70 ′]. The systems and methods disclosed overcome the disadvantages associated with current systems and processes which utilize batch process steps and equipment designed for batch processes. The systems [ 10′, 20′, 30 ′] are each configured to receive a continuous inflow of a solution or slurry and deliver a continuous outflow of a solution or slurry, without interruptions which are common with conventional metal recovery systems [ 9000′].

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to mining and metallurgical refining and more particularly to systems and processes for solvent extraction and electroextraction of metals. 
         [0002]    To this end, there are generally two main processes available for precious metal concentration and recovery: zinc precipitation, and electrowinning. Zinc precipitation involves crushing and grinding ore containing the precious metal (e.g., gold), and then combining the ground ore with a water and caustic cyanide solution. The resulting mud-like pulp is moved to a settling tank where the coarser gold-laden solids move to the bottom via gravity, and a lighter first pregnant solution of water, gold, and cyanide moves to the top and is removed for further processing. The gold-laden solids are agitated and aerated in a separate agitated leach process where oxygen reacts to leach the gold into the caustic water and cyanide forming a second pregnant solution. The second pregnant solution passes through a drum filter which further separates remaining solids. The first and second pregnant solutions are combined with zinc to precipitate out the dissolved gold. The resulting precipitated gold concentrate may then be smelted to produce refined gold bar. 
         [0003]    Electrowinning typically involves extracting a precious metal such as gold from an electrolyte. First, activated carbon is combined with a pregnant solution in a batch process step. The activated carbon adsorbs the precious metal contained within the pregnant solution, and becomes “loaded” with the precious metal. The loaded carbon is then descaled by sequentially washing it in three batch process steps to remove ore residue. First, the loaded carbon is moved to a washing tank and then the tank is filled with a dilute acid solution. The washing tank is then drained and the used dilute acid solution is pumped away and disposed of. The same washing tank is then filled with water to rinse remaining acid from the loaded carbon. The water becomes slightly acidic during this process. In a similar fashion to the dilute acid, the used slightly acidic rinse water is also drained from the washing tank, pumped away, and disposed of. Lastly, the tank is filled with a caustic solution, and the activated carbon is washed in the caustic solution. The used caustic solution is then drained from the tank, pumped away, and disposed of. An optional final water rinse step may be performed by again, filling the washing tank with rinse water or pH-neutral solution, rinsing caustic residue from the loaded carbon, and then draining the tank of the used rinse water/solution so that it may be pumped away for disposal. 
         [0004]    After washing, the loaded carbon is removed from the washing tank and then added to a strip solution comprising water, a caustic substance, and cyanide to form a strip solution/loaded carbon slurry. The strip solution/loaded carbon slurry goes through an elution process where high temperatures and pressures are used to “re-leach” gold from the loaded carbon into the caustic strip solution to form an electrolyte solution. The electrolyte solution is then moved to a batch electrolytic cell where wire (e.g., reticulated) or plate cathodes collect deposited gold concentrate during electrolysis. After the batch electrowinning process, the cathodes are manually removed from the cell for cleaning, so that gold concentrate deposited thereon can be removed from the cathodes and readied for smelting. After cleaning, the cathodes are then manually replaced within the electrolytic cell, and the entire sequence of batch washing, elution, and electrowinning processes is repeated. Some cathodes (e.g., wire cathodes, due to their small interstices) are not re-useable and must be recycled after processing, thereby increasing overhead/operational costs. 
         [0005]      FIG. 27  schematically illustrates a conventional metal recovery process  9000  as described above. Activated or reactivated carbon  9560  is suspended within a pregnant solution in a conventional batch carbon loading step  9700 . The pregnant solution is generally formed by percolating a dilute cyanide solution through a heap leach pad of crushed mineral-laden ore (e.g., by way of a drip or spray irrigation having a concentration of about 0.5 to 1 pound of sodium cyanide, potassium cyanide, or calcium cyanide per ton of solution). Once the active carbon adsorbs the desired material (e.g., gold, silver, platinum, lead, copper, aluminum, platinum, uranium, cobalt, manganese) from the pregnant solution, it becomes “loaded” carbon  9570  and enters a batch acid wash process  9100  configured for descaling the loaded carbon  9570  as previously discussed. 
         [0006]      FIG. 28  shows one example of a conventional batch acid washing system  9100 ′. Loaded carbon  9570  enters an acid wash vessel  9120  which receives dilute acid from a dilute acid tank  9140  via a pump  9132 . Dilute acid overflow is captured by a sump pump  9150  which moves the overflow to a neutralizing tank  9160 . Contents of the neutralizing tank  9160  may be moved to a secondary holding tank via a pump  9136 . The conventional batch acid wash process  9100  continues by draining the acid wash vessel  9120  of dilute acid solution, and then filling the vessel  9120  with an aqueous rinse solution. Overflow of aqueous rinse solution is captured by sump pump  9150  which moves the overflow to a neutralizing tank  9160  and/or a holding tank. The process  9100  may continue by draining the vessel  9120  of aqueous rinse solution, and then filling the vessel  9120  with a caustic rinsing agent. Overflow of the caustic rinse may likewise be captured by sump pump  9150  and moved to a neutralizing tank  9160  and/or a holding tank (not shown). 
         [0007]    After the loaded carbon  9570  is descaled, it leaves the batch acid washing process  9100  (via carbon transfer pump  9134 ) and enters a conventional batch (e.g. Zadra strip) elution process  9200 . As shown in  FIG. 29 , a conventional batch elution process  9200  typically involves feeding descaled loaded carbon  9500  and/or loaded carbon directly from an adsorption system  9700  into a strip vessel  9240 . Strip vessel  9240  is generally a large cylindrical tank of material suitable for holding reagents at an elevated pressure and temperature (e.g., 138 degrees C.-148 degrees C.). The descaled loaded carbon  9500  is maintained within the strip vessel  9240  at high temperatures and pressure in the presence of a caustic aqueous strip solution comprising cyanide. After a period of time, spent carbon  9550  is removed from the strip vessel  9240  (e.g., via carbon transfer pump  9232 ), and is moved to a carbon handling system or carbon regeneration system  9300 ′ or process  9300 . Hot electrolyte solution  9421  is formed within the strip vessel  9240  as material previously adsorbed onto the loaded carbon leaches into the strip solution. The hot electrolyte solution  9421  is also removed from the strip vessel  9240  and passes through a heating skid  9250  or equivalent heat exchanger for cooling before entering a conventional batch electrowinning system  9400 ′ or process  9400 . Cooling of hot electrolyte solution  9421  to form a lower temperature electrolyte solution  9530  is generally necessary to reduce the risk of flashing within a conventional batch electrolytic metal recovery cell  9420 . The heating skid  9250  also serves to recycle energy by warming cooler barren solution  9540  which exits the electrolytic metal recovery cell  9420  (e.g., at about 66 degrees C.) and/or barren solution  9237  which exits the barren solution storing tank  9220  before re-entering the strip vessel  9240  to serve once again as a strip solution re-leaching agent. Warming of the cooler barren solution  9237 ,  9540  to form a hot barren solution  9239  may also be done using a heater in addition to, or in lieu of said heating skid  9250 . One or more pumps  9234 ,  9236  are generally used to transfer barren solution back to the strip vessel  9240 . Additional reagent from a reagent handling system and/or more pregnant solution may be added to barren solution tank  9220  as needed. 
         [0008]    As shown in  FIG. 30 , electrolyte solution  9530  enters a conventional batch electrolytic metal recovery cell  9420  which operates in batch cycles. A series of parallel plate cathodes are placed within close proximity and the electrolyte solution  9530  is pumped in and agitated around the cathodes. Body portions of the cell  9420  carry an opposing charge with respect to the cathodes, and by virtue of electrolysis, ions contained in the electrolyte solution  9530  are subsequently deposited on the cathodes as a cathode sludge concentrate of the recovery metal or as a solid cathode plating. In operation, cathodes are typically removed simultaneously from the cell  9420  in a batch process step in order to collect the recovered metal. In instances where plate cathodes are used, the cathode may be flexed to delaminate and remove the hard cathode plating from the cathode. In other instances where higher deposition wire mesh (i.e., “reticulated”) cathodes are employed, the concentrate is separated from the cathode in a subsequent process and the cathodes are then recycled. Sludge concentrate may collect at the bottom of the cell  9420  and may be removed periodically. An electrowinning pump box  9440  and pump  9430  may be employed to temporarily store spent electrolyte (i.e., barren solution) which is removed from the cell  9420  between batches. 
         [0009]    Problems associated with the abovementioned conventional acid wash systems  9100 ′ and processes  9100  are numerous. For instance, the systems utilize independent, non-continuous, “batch” process steps which require constant manpower, downtime, and energy (e.g, continually draining and refilling the same acid wash vessel  9120  with different rinsing agents). Moreover, such conventional batch acid wash processes  9100  typically discard expensive acid, caustic, and/or other reagents after each use. This increases overhead (e.g., purchasing costs, disposal costs) and creates unnecessary harm to the environment. Furthermore, every time a conventional acid wash vessel  9120  is drained and re-filled with a different rinsing solution, carbon (and precious minerals/metals attached thereto) may not be recovered due to system inefficiencies caused by heat, friction, increased pump residence time and exposure, an increased number of pipe elbows and valves, and the frequent discarding of spent rinsing solution which may still contain small amounts of loaded carbon and precious metal. In other instances (not shown), if separate vessels are used for each rinse step of the acid wash process, as many as four tanks and ten pumps may be required. This increases both initial plant overhead costs and overall plant footprint. 
         [0010]    Problems associated with the described conventional batch elution process  9200  are also numerous. For instance, the process  9200  employs batch process steps which require constant manpower and energy (e.g., continually draining and refilling the strip vessel  9240  with new strip solution, hot barren solution  9239 , and loaded carbon  9500  each time more electrolyte solution  9530  is needed for electrowinning  9400 ). This increases overhead costs (e.g., labor, maintenance), complicates production scheduling, and may cause harm to the environment. Furthermore, conventional metal recovery systems  9000 ′ are bulky and require large plant layout footprints as demonstrated by  FIG. 23 , when compared to a system  100 ′ for the continuous recovery of metals according to the invention ( FIG. 22 ) which will be described hereinafter. Moreover, conventional elution systems have limited operating flow rates, temperatures, and pressures which drive up radiation losses and power consumption. Additionally, the electroextraction of metals using the conventional “batch” electrowinning processes  9400  described above requires intervals of non-production downtime of the electrowinning cell  9420  and significant physical labor, which may contribute to premature cathode wear and wasted electrolyte solution  9530 . 
         [0011]    The process of using zinc to precipitate precious metals out of pregnant solutions is also costly, may be less efficient for large-scale operations, works for only certain metals, and may result in less precious metal recovery. 
       OBJECTS OF THE INVENTION 
       [0012]    It is, therefore, an object of the invention to provide an improved metal recovery system which is configured for continuous carbon loading/adsorption, continuous washing and stripping of loaded carbon, continuous electrolyte formation, continuous electrowinning, and continuous regeneration/re-activation, thereby avoiding the aforementioned problems associated with conventional batch metal recovery processes. 
         [0013]    Another object of the invention is to improve the efficiency of a metal recovery process (e.g., by minimizing radiation losses, reducing power consumption, minimizing reagent consumption, and preventing carbon breakdown and electrolyte loss). 
         [0014]    Yet another object of the invention is to prevent or minimize carbon loss and reagent waste. 
         [0015]    Another object of the invention is to maximize total metal recovery. 
         [0016]    Another object of the invention is to provide a metal recovery system which is configured to cost less and have a smaller footprint area than conventional metal recovery systems. 
         [0017]    Another object of the invention is to provide a system and process for the recovery of metals which is configured to operate at higher flow rates, temperatures, and/or pressures than conventional processes. 
         [0018]    Yet even another object of the invention is to reduce the percentage by weight of unrecovered metal present in spent electrolyte/barren solution. 
         [0019]    These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the objects of the invention. 
       SUMMARY OF THE INVENTION 
       [0020]    A system for the continuous recovery of metals is provided. The system comprises, in accordance with some embodiments of the invention, at least one of a continuous acid wash system configured for receiving a continuous, uninterrupted inflow of loaded carbonaceous particulate and delivering a continuous, uninterrupted outflow of descaled loaded carbonaceous particulate; a continuous elution system configured for receiving a continuous, uninterrupted inflow of a strip solution containing a descaled loaded carbonaceous particulate and delivering a continuous, uninterrupted outflow of electrolyte solution; and a continuous electrowinning system configured for receiving a continuous, uninterrupted inflow of electrolyte solution, delivering a continuous uninterrupted outflow of a barren solution, and continuously and uninterruptedly forming a cathode sludge concentrate. Each of the continuous acid wash system, the continuous elution system, and the continuous electrowinning system are generally configured to operate simultaneously without periodic interruptions which are common with conventional batch metal recovery processes. 
         [0021]    In some embodiments, the system may comprise an integrated carbon regeneration system operatively connected to the continuous elution system. A continuous carbon loading/adsorpsion system may be operatively connected to and upstream of the continuous acid wash system. The continuous acid wash system may be operatively connected to the continuous elution system; for example, via a holding tank between said continuous acid wash system and said continuous elution system. One or more pumps may be provided to facilitate the transportation of slurry and solids within the system. In preferred embodiments, the continuous elution system is operatively connected to the continuous electrowinning system and comprises one or more screens or filters configured to prevent carbonaceous particulate from passing to the continuous electrowinning system. 
         [0022]    The continuous acid wash system may comprise a chamber adapted for retaining a fluidization medium; an inlet adapted for receiving a feed containing loaded carbonaceous particulate; a fluidized bed distribution panel or other means adapted for fluidizing the loaded carbonaceous particulate in the presence of said fluidization medium; an opening adapted to pass loaded carbonaceous particulate and fluidization medium from the chamber; and a screen adapted to filter loaded carbonaceous particulate from a fluidization medium. The continuous elution system may comprise a splash vessel, a continuous elution vessel, and a flash vessel, wherein the splash vessel is operatively connected to the continuous elution vessel in series, the continuous elution vessel is operatively connected to the flash vessel in series, and the splash vessel is operatively connected to the flash vessel in parallel. The continuous electrowinning system comprises an electrolytic cell having a cell body configured to maintain electrolyte solution at a high pressure and/or temperature; at least one anode; at least one cathode; an inlet configured for receiving a continuous, uninterrupted influent stream of electrolyte solution; a first outlet configured for discharging a continuous, uninterrupted effluent stream of spent electrolyte solution; a second outlet configured for removing cathode sludge concentrate; and a residence chamber configured to continuously transfer electrolyte solution from said inlet to said first outlet and increase residence time of said electrolyte solution between said at least one anode and said at least one cathode. The residence chamber may comprise one or more channels which are configured to provide a forced flow of electrolyte solution therein which is strong enough to continuously dislodge and/or transport cathode sludge concentrate along said one or more channels and eventually out of said residence chamber. 
         [0023]    The continuous elution vessel may comprise an influent manifold and an effluent manifold which communicate with the first outlet and inlet of the electrolytic cell, respectively, and may further comprise a fluidized bed and/or one or more internal baffles which are configured to torture flow paths and increase a residence time of loaded carbonaceous particulate therein. A valve configured to flash solution leaving the continuous elution vessel and entering the flash vessel may also be provided. 
         [0024]    The continuous acid wash system may comprise at least one of an acid solution, an aqueous solution, and a caustic solution. The continuous elution system may comprise a solution containing at least one of a carbonaceous particulate loaded with a precious metal, an electrolyte solution, spent carbonaceous particulate, a caustic, an aqueous component, and cyanide. The continuous electrowinning system may comprise an electrolyte solution or cathode sludge concentrate. Each of the continuous acid wash system, the continuous elution system, and the continuous electrowinning system may be configured to increase a residence time, pressure, or temperature of solutions or slurries contained therein and may comprise a screen or filter element. 
         [0025]    In some embodiments, the continuous acid wash system may comprise multiple washing vessels, each washing vessel comprising a chamber adapted for retaining a fluidization medium; an inlet adapted for receiving a feed containing a loaded carbonaceous particulate; a fluidized bed distribution panel or other means adapted for fluidizing and cleaning the loaded carbonaceous particulate with said fluidization medium; an opening adapted to pass loaded carbonaceous particulate and fluidization medium from the chamber; and a screen adapted to filter loaded carbonaceous particulate from fluidization medium. For instance, in some embodiments, the continuous acid wash system may comprise an acid wash tank containing an acidic fluidization medium, an aqueous rinse tank containing a substantially pH-neutral aqueous solution, and a caustic rinse tank containing an alkaline fluidization medium. 
         [0026]    In some embodiments, the continuous acid wash system may comprise one or more recirculation tanks for collecting spent fluidization medium, and one or more weirs, channels, valves, or drains for capturing spent fluidization medium. The continuous electrowinning system may be configured for continuous and uninterrupted collection and removal of said cathode sludge concentrate and may comprise one or more channels defined between a cathode, an anode, and an insulator. The one or more channels may comprise portions of a helix, spiral, coil, compound curve, 3D-spline curve, figure-8, or serpentine shape and the cathode and anode may be formed as sleeves or tubes which are separated by said insulator. In some embodiments, the carbon regeneration system is operatively connected to both the continuous elution system and the continuous carbon loading/adsorpsion system, and the continuous carbon loading/adsorpsion system is operatively connected to said continuous acid wash system. 
         [0027]    A process for the continuous recovery of a metal is also disclosed. The process, comprises, in accordance with some embodiments, continuously feeding a continuous wash system with particulate loaded with a metal; continuously washing said loaded particulate within the continuous wash system to descale the loaded particulate; continuously removing descaled loaded particulate from said continuous wash system; continuously loading a continuous elution system with said descaled loaded particulate; continuously removing electrolyte solution from said continuous elution system; continuously feeding a continuous electrowinning system with said electrolyte solution; continuously removing spent electrolyte solution from said continuous electrowinning system; and, continuously delivering said spent electrolyte solution to said continuous elution system; wherein each of the continuous wash system, the continuous elution system, and the continuous electrowinning system are configured to allow the above steps to be performed simultaneously, without the periodic interruptions required for conventional batch processes. 
         [0028]    The process may further comprise continuously removing spent particulate from the continuous elution system; continuously feeding said spent particulate to a carbon regeneration system; continuously removing cathode sludge concentrate from the continuous electrowinning system; and/or forming said loaded particulate by continuously adsorbing metal onto said particulate in a continuous carbon loading/adsorption system which is similar to or identical to said continuous wash system. The particulate may be one of a carbonaceous particulate, a polymeric adsorbent, or an ion-exchange resin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIGS. 1 and 2  schematically illustrate a system and method for the continuous recovery of metals according to some embodiments; 
           [0030]      FIG. 3  is a flowchart of a three-sequence continuous acid wash operation according to some embodiments; 
           [0031]      FIGS. 4 and 5  outline steps of a continuous acid washing process according to some embodiments; 
           [0032]      FIGS. 6 and 7  depict a washing tank which may be used in the acid wash process shown in  FIGS. 1-5 ; 
           [0033]      FIG. 8  shows an acid wash system comprising a plurality of the washing tanks depicted in  FIGS. 6 and 7 ; 
           [0034]      FIGS. 9 and 12  schematically illustrate a system and method of continuous elution according to some embodiments; 
           [0035]      FIG. 10  is an isometric view of a continuous elution system according to some embodiments; 
           [0036]      FIG. 11  shows a side cutaway view of the continuous elution system of  FIG. 10 ;  FIGS. 13 and 19  schematically illustrate a system and method of continuous electrowinning according to some embodiments; 
           [0037]      FIG. 14  shows a top plan view of a continuous electrowinning system according to some embodiments; 
           [0038]      FIGS. 15 and 16  are vertical and isometric cutaway views, respectively, of a continuous electrowinning system taken on line XV-XV in  FIG. 14 ; 
           [0039]      FIG. 17  is a detailed view of  FIG. 15 , showing the particulars of an inlet according to some embodiments; 
           [0040]      FIG. 18  is a transverse cutaway view of an electrowinning cell along line XVIII-XVIII in  FIG. 14 ; 
           [0041]      FIG. 20  shows a process for regenerating/reactivating spent carbon according to some embodiments; 
           [0042]      FIGS. 21 and 22  show a system for the continuous recovery of metals; 
           [0043]      FIG. 23  shows a conventional batch system for the recovery of metals; 
           [0044]      FIG. 24  shows an alternative to the washing tank shown in  FIGS. 6-8  or an apparatus to be used for continuous carbon loading/adsorption; 
           [0045]      FIG. 25  shows a detailed isometric view of the chamber shown in  FIG. 24 ; 
           [0046]      FIG. 26  is a cutaway view of the chamber shown in  FIG. 25 ; 
           [0047]      FIG. 27  shows a conventional system for the recovery of metals. 
           [0048]      FIG. 28  shows a conventional acid wash process; 
           [0049]      FIG. 29  shows a conventional batch elution process; and, 
           [0050]      FIG. 30  shows a conventional batch electrowinning process. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]    As shown in  FIGS. 1 and 2 , a plant system  100 ′ or process  100  for the continuous recovery of a metal from mined ore may comprise, in accordance with some embodiments of the invention, a continuous acid wash system  10 ′ or process  10 , a continuous elution system  20 ′ or process  20 , a continuous electrowinning system  40 ′ or process  40 , a continuous carbon regeneration system  30 ′ or process  30 , and a continuous carbon loading/adsorption system  70 ′ or process  70 . Activated/reactivated carbon  56  (which may be derived for example, from coconut shells or charcoal), or alternatively, an equivalent particulate substance such as loaded polymeric adsorbent or loaded ion-exchange resin, is subjected to a continuous carbon adsorption process  70  where it spends a time of residence suspended in a pregnant solution which contains a dissolved target recovery metal such as gold, silver, copper, aluminum, platinum, uranium, chromium, zinc, cobalt, manganese, or lead. The continuous carbon loading/adsorption system  70 ′ or process  70  may comprise, for example, an apparatus as shown in  FIGS. 6 and 7  or  FIGS. 24-26  which serves to fluidize the activated/reactivated carbon  56  within the pregnant solution. Once the carbon  56  becomes loaded with the target recovery metal, it undergoes a continuous acid wash process  10 . Descaled loaded carbon  50  leaving the continuous acid wash process  10  enters a holding tank  60  filled with a strip solution containing one or more reagents (e.g., water, caustic, and cyanide) to form a slurry  51  of strip solution and descaled loaded carbon  50 . The slurry  51  enters a continuous elution process  20  where the temperature and/or the pressure of the slurry  51  is increased and the target recovery metal previously adsorbed by the carbon is re-leached into the strip solution thereby forming an electrolyte solution  53  which may be used for a continuous electrowinning process  40 . Barren solution (i.e., spent electrolyte)  54  leaving the continuous electrowinning process  40  is returned to the continuous elution process  20  and/or the holding tank  60  for re-use. A solids fraction  55  of spent carbon, depleted of its target recovery metal via the continuous elution process  20 , moves to a carbon regeneration process  30  for reactivation before being re-used in the continuous carbon loading/adsorption process  70 . 
         [0052]    As shown in  FIGS. 2-5 , a continuous acid wash process  10  may generally comprise the steps of: feeding  1004  loaded carbon  57  into a continuous acid wash system  10 ′, fluidizing  1006  incoming loaded carbon  57  in a dilute acid solution within a first acid wash tank  12 , extracting  1008  loaded carbon from the acid wash tank  12 , screening  1010  the extracted loaded carbon to remove the dilute acid solution, capturing  1012  dilute acid solution  57   c  separated from the loaded carbon, optionally processing  1014  the captured dilute acid solution  57   c  (e.g., filtering, additives, pH adjust), and recycling the dilute acid solution  57   c  by feeding  1016  the dilute acid solution  57   c  back into the acid wash tank  12 . Acid-rinsed loaded carbon  57   a  which has undergone an acid bath in acid wash tank  12  is fed  1018  into a second aqueous rinse tank  14  containing water or another pH-neutral aqueous rinse solution  57   d , and then fluidized  1020  in said aqueous rinse tank  14 . The process  10  further comprises extracting  1022  rinsed loaded carbon  57   b  from the aqueous rinse tank  14 , screening  1024  the extracted rinsed loaded carbon  57   b  to remove aqueous rinse solution  57   d , capturing  1026  separated aqueous rinse solution  57   d  separated from the rinsed loaded carbon  57   b , optionally processing  1028  the captured aqueous rinse solution  57   d  (e.g., filtering, additives, pH adjust), and recycling the aqueous rinse solution  57   d  by feeding  1030  the aqueous rinse solution  57   d  back into the aqueous rinse tank  14 . Rinsed loaded carbon  57   b  which has undergone washing in aqueous rinse tank  14  is fed  1032  into a third caustic rinse tank  16  containing a caustic rinse solution  57   e , and is then fluidized  1034  in said caustic rinse tank  16 . The continuous acid wash process  10  further comprises extracting  1036  descaled loaded carbon  50  from the caustic rinse tank  16 , screening  1038  the extracted descaled loaded carbon  50  to remove caustic rinse solution  57   e , capturing  1040  caustic rinse solution  57   e  separated from the descaled loaded carbon  50 , optionally processing  1042  the captured caustic rinse solution  57   e  (e.g., by filtering, providing additives, or adjusting pH), and recycling the caustic rinse solution  57   e  by feeding  1044  the solution  57   e  back into the caustic rinse tank  16 . The continuous acid wash process  10  may comprise the step of providing one or more pumps  13   a ,  13   b  for re-circulating the rinsing solutions in each of the aforementioned tanks  12 ,  14 ,  16 . Optionally, a fourth aqueous rinse cycle (not shown) may be provided, and one of ordinary skill in the art would acknowledge that any one or more of the aforementioned washing steps may be repeated or alternated. 
         [0053]    Turning now to  FIGS. 6 and 7 , an acid wash tank  200  for cleaning and descaling a loaded particulate material may be employed for any portion of the continuous acid wash process  10 . The loaded particulate material washed within said acid wash tank  200  may be of any particle size, shape, and density which can be fluidized by or suspended within a cleaning fluidization medium. The acid wash tank  200  is advantageously configured to descale active carbon particulate which has been loaded with a target metal, in preparation for creating an electrolyte for electrowinning. In such instances, the acid wash tank  200  may be filled with a fluidization medium comprising acid. Similar tanks  200 ′,  200 ″ may be used with fluidization mediums comprising water or caustic soda. Moreover, similar tanks may be used in yet other processes such as a continuous carbon loading/absorption process  70 , wherein the particulate comprises activated/reactivated carbon  56 , and the fluidization medium comprises a pregnant solution formed by percolating cyanide and/or other reagents through a heap leach pad of crushed ore containing a target metal or mineral. 
         [0054]    According to some embodiments, acid wash tank  200  may comprise an acid wash tank having a first chamber  220 , a first fluidized bed distribution panel  221 , a first inlet  222 , a first recirculation inlet  223   a , a first recirculation outlet  223   b , a first weir  224 , a first screen  226 , a first overflow outlet  227 , a first discharge outlet  228 , a first recirculation tank  229 , a bottom wall  260 , an inner tubular wall  266 , an outer tubular wall  268 , and a first channel  282  defined between the inner tubular wall  266  and outer tubular wall  268  adjacent the first weir  224 . The first screen  226  serves to filter an incoming feed by separating its liquid fraction (e.g., spent pregnant solution, fluidization medium, or transport fluid) from its solid particulate fraction (metal-laden loaded or reloaded carbon). The liquid fraction drained from the particulate is maintained in the first recirculation tank  229  and may be removed through first recirculation outlet  223   b . The first recirculation outlet  223   b  may be sealed during operation, coupled to a holding tank, coupled to a drain, coupled to a sump pump, or otherwise configured to feed an upstream or downstream process. 
         [0055]    In some embodiments, as shown in  FIG. 8 , a continuous acid wash system  10 ′ may comprise one or more separate washing tanks  200 ,  200 ′,  200 ″ connected in series in order to provide flexibility in customizing plant layout and/or reduce overall footprint. In some instances, the tanks  200 ,  200 ′,  200 ″ may comprise similar or identical design characteristics, each containing different fluidization mediums. For example, in some embodiments, a first tank  200  may comprise an acid wash tank containing a strong or dilute acid solution  57   c , whereas second  200 ′ and third  200 ″ tanks may comprise aqueous and caustic rinsing tanks containing aqueous  57   d  and caustic  57   e  rinsing agents, respectively. While not required, tanks  200 ,  200 ′, and  200 ″ may be constructed as “universal” or “interchangeable” tanks. Moreover, tanks  200 ,  200 ′,  200 ″ may be configured with tubular (e.g., cylindrical pipe or prismatic extrusion) shapes as shown in order to reduce manufacturing costs. Any one or more of tanks  200 ,  200 ′, and  200 ″ may be replaced with a tank of dissimilar scale or a tank  2000  as shown in  FIGS. 24-26 , which will be described hereinafter. 
         [0056]    A first fluidization medium comprising a dilute acid or anti-scaling agent solution may occupy the first acid wash tank  200 . In some embodiments, the first fluidization medium may comprise a solution of 1-10% vol/vol mineral acid, such as nitric acid or hydrochloric acid configured to dissolve carbonate scale. In use, incoming loaded/reloaded carbon  57  moves over the first screen  226  and flows into the first chamber  220  of the first acid wash tank  200  via the first inlet  222 . Fluid which may be present with the incoming loaded/reloaded carbon  57  is drained and enters the first recirculation tank  229 . The screened loaded carbon subsequently falls downwardly along the first screen  226  and towards the first fluidized bed distribution panel  221  and is fluidized by the first fluidization medium. The first fluidization medium enters the first recirculation inlet  223   a  and passes through distribution panel  221 . Clarified first fluidization medium rises above the highest suspended level of loaded carbon within the first acid wash tank  200  and pours over the first weir  224  and into the first channel  282 . Thereafter, clarified first fluidization medium exits the first acid wash tank  200  via outlet  227  and optionally feeds the first recirculation inlet  223   a  and first fluidized bed distribution panel  221 . One or more pumps  13   a  may be provided between outlet  227  and inlet  223   a.    
         [0057]    A slurry of acid-rinsed loaded carbon  57   a  and residual first fluidization medium exits the first acid wash tank  200  through the first discharge opening  228  and enters a second aqueous rinse tank  200 ′ through a second inlet  232 . The acid-rinsed loaded carbon  57   a  may be conveyed to the tank  200 ′ using only gravitational forces, or the acid-rinsed loaded carbon  57   a  may be conveyed to the tank  200 ′ using one or more slurry pumps (not shown). A second fluidization medium such as a substantially pH-neutral aqueous scrubbing solution or a hot water may occupy the second aqueous rinse tank  200 ′. In use, the acid-rinsed loaded carbon  57   a  and first fluidization medium moves over a second screen  236  or equivalent filter and then flows into the second chamber  230  for pre-soak. The second screen  236  serves to separate residual first fluidization medium liquid from the acid-rinsed loaded carbon  57   a , wherein drained first fluidization medium is maintained in a second recirculation tank  239  and may be removed through second recirculation outlet. The second recirculation outlet  233   b  may be coupled to a holding tank, a filtering apparatus, or an upstream or downstream process. For instance, as schematically indicated by the dotted line path of dilute acid solution  57   c ′, the second recirculation outlet  233   b  may be operatively connected to the first recirculation inlet  223   a  to fluidize loaded/reloaded carbon  57  within the first washing tank  200 . Though not shown, one or more pumps may be disposed between the outlet  233   b  and inlet  223   a.    
         [0058]    After passing over the second screen  236 , acid-rinsed loaded carbon  57   a  subsequently falls towards a second fluidized bed distribution panel  231  and is fluidized within the second chamber  230  by a flow of second fluidization medium entering the second recirculation inlet  233   a  and passing upwards through panel  231 . Clarified second fluidization medium free of loaded carbon particulate rises above a suspended level of acid-washed loaded carbon and pours over a second weir  234  and into a second channel  284 , where it exits the second aqueous rinse tank  200 ′ via outlet  237  and optionally feeds the second recirculation inlet  233   a  and second fluidized bed distribution panel  231  as schematically illustrated by dotted line path taken by aqueous rinse solution  57   d.    
         [0059]    A slurry of rinsed loaded carbon  57   b  and second fluidization medium exits the second washing tank  200 ′ through second discharge opening  238  and enters a third washing tank  200 ″ through a third inlet  242 . The rinsed loaded carbon  57   b  may be conveyed to the third caustic rinse tank  200 ″ using only gravitational forces, or the rinsed loaded carbon  57   b  may be conveyed to the tank  200 ″ using one or more pumps (not shown). A third fluidization medium such as a caustic rinse solution may occupy the third washing tank  200 ″. For example, the third fluidization medium may comprise an amount of sodium hydroxide (NaOH) or potassium hydroxide (KOH) between 0.5% and 5% wt, for instance 1% wt. The third fluidization medium may comprise other reagents, for instance 1-10% wt sodium cyanide (NaCN). The third fluidization medium may be heated (e.g., 20-100 degrees C.). In use, a slurry of rinsed loaded carbon  57   b  and second fluidization medium flows over a third screen  246  or equivalent filter and into the third chamber  240 . The third screen  246  serves to filter the slurry by separating its second fluidization medium liquid fraction from its rinsed loaded carbon  57   b  solid fraction. The separated second fluidization medium is maintained in a third recirculation tank  249 . The second fluidization medium may be removed from the tank  249  via a third recirculation outlet  243   b  which may be coupled to a holding tank, filtering apparatus, or one or more upstream or downstream processes. For instance, as schematically indicated by path taken by aqueous rinse solution  57   d ′, the third recirculation outlet  243   b  may be operatively connected to the second recirculation inlet  233   a  in order to help fluidize particulate within the second washing tank  200 ′. Though not shown, one or more pumps may be disposed between the outlet  243   b  and inlet  233   a . In some instances, outlet  243   b  and inlet  233   a  may be operatively connected to a plant water system. 
         [0060]    After passing over third screen  246 , twice-rinsed loaded carbon particulate subsequently falls towards a third fluidized bed distribution panel  241  and is fluidized within the third chamber  240  by a flow of third fluidization medium entering the third recirculation inlet  243   a  and passing through the panel  241 . Clarified third fluidization medium rises above the highest level of suspension of the loaded carbon fluidized within the tank  200 ″ and pours over a third weir  244  and into a third channel  286 , where it exits the caustic rinse tank  200 ″ via outlet  247  and optionally feeds the third recirculation inlet  243   a  as indicated by the dotted line path taken by caustic rinse solution  57   e.    
         [0061]    A slurry of caustic-rinsed, descaled loaded carbon  50  and third fluidization medium exits the third caustic rinse tank  200 ″ through third discharge opening  248  and may be subsequently screened or filtered for further processing. After leaving the tank  200 ″, de-scaled loaded carbon  50  within the slurry may be separated from the third fluidization medium liquid fraction by a screen or filter (not shown) and then added to a strip solution of water, caustic, and cyanide in a holding tank  60  for use in downstream continuous elution  20  and electrowinning  40  processes. 
         [0062]    The continuous acid wash system  10 ′ shown and described, when used, reduces or eliminates the need to continually purchase and replace lost quantities of carbon particulate, water, caustic, acid, and/or other anti-scaling agents. System  10 ′ also significantly reduces the amount of spent solution and carbon requiring disposal and reduces the potential for environmental harm. 
         [0063]    It should be known that the particular features and suggested uses of the continuous acid wash system  10 ′ described herein are exemplary in nature and should not limit the scope of the invention. For example, fluidized bed portions  221 ,  231 ,  241  may be replaced with, or used in combination with one or more mechanical or forced air agitators (not shown) to suspend loaded carbon particulate in fluidization medium. Moreover, the number of chambers  220 ,  230 ,  240  per system  10 ′ may be greater or less than what is shown. In some embodiments, the relative sizes, dimensions and/or volumes of chambers  220 ,  230 ,  240  may vary. In other embodiments, the chambers  220 ,  230 ,  240  may be dimensioned and proportioned similarly. Additionally, one or more tanks  200 ,  200 ′,  200 ″ may be placed in parallel with others in order to increase throughput. For example, a third caustic rinse tank  200 ″ of a system  10 ′ may be directly or indirectly coupled to a plurality of upstream aqueous rinse tanks  200 ′. Multiple tanks  200  may replace any one of the single tanks  200 ,  200 ′,  200 ″ in system  10 ′ by splitting inlets  222 ,  223   a ;  232 ,  233   a ;  242 ,  243   a  and/or outlets  223   b ,  227 ;  233   b ,  237 ;  243   b ,  247 . Moreover, any one chamber  220 ,  230 ,  240  may be compartmentalized into multiple chambers. As previously stated, the system  10 ′ or portions thereof may be used to continuously load activated carbon in a continuous carbon loading/adsorption process  70 . For example, infeed particulate may comprise activated or reactivated carbon and the first, second, and third fluidization mediums may comprise a pregnant solution (e.g., sodium cyanide (NaCN) solution containing a dissolved precious metal). 
         [0064]      FIG. 9  illustrates a continuous elution process  20  according to some embodiments. A feed slurry  51  of strip solution and descaled loaded carbon  50  is moved to a splash vessel  22  via gravity or one or more pumps  23 . The splash vessel  22  increases the temperature and/or pressure of incoming slurry  51  and delivers the hot pressurized slurry  51   a  to a continuous elution vessel  24 . In the continuous elution vessel  24 , target metal previously adsorbed onto the loaded carbon is leached into the strip solution to form an electrolyte solution  53 . The electrolyte solution  53  is filtered by one or more screens to remove spent carbon and non-stripped loaded carbon from the electrolyte solution  53 , before it is moved to a continuous electrowinning process  40 . Electrolyte solution  53  may be conveyed to the continuous electrowinning process via an effluent manifold  28   b  provided on the continuous elution vessel  24 . Spent slurry  51   c  of strip solution and spent carbon is flashed by a valve  29  and enters into a flash vessel  25  where steam is captured and returned to the splash vessel  22  via a steam return  21  to help heat and pressurize the splash vessel  22  in an efficient manner. The resulting concentrated spent slurry  51   d  is separated into solid  55  and liquid  52  fractions using a dewatering screen  26 . The liquid fraction  52  of concentrated spent slurry  51   d  may be returned to holding tank  60 , and the solids fraction  55  of the concentrated spent slurry  51   d  (i.e., spent de-watered carbon) may be sent to a carbon regeneration process  30  for reactivation. Barren solution  54  returning from a continuous electrowinning process  40  is generally heated with an immersion heater  27  and then sent back to the continuous elution vessel  24  via one or more pumps  23  and an influent manifold  28   a.    
         [0065]      FIG. 10  shows a continuous elution system  20 ′ according to some embodiments. The continuous elution system  20 ′ generally comprises a first splash vessel  22 , a second continuous elution vessel  24 , and a third flash vessel  25  connected in series via piping sections, and a steam return  21  extending between the splash  22  and flash  25  vessels in parallel. One or more pumps  23  may be provided at various portions of the system  20 ′ in order to facilitate flows to, from, and between the vessels  22 ,  24 ,  25 , other parts of the system  20 ′, and/or other portions  10 ′,  30 ′,  40 ′ within a system  100 ′ for the continuous recovery of metals. 
         [0066]    As shown in  FIG. 11 , the continuous elution vessel  24  comprises a fluidized bed distribution panel  320  which separates a residence chamber  340  from a fluidizing chamber  350 . One or more baffles  318  may be provided within the residence chamber  340  in various configurations (e.g., number, angle, spacing, geometry), in order to increase the residence time of incoming hot pressurized slurry  51   a  within the continuous elution vessel  24 . The one or more baffles  318  may be parallel and staggered to create a serpentine flow path  51   b  of hot pressurized slurry  51   a . The baffles  318  may be parallel, non-parallel, staggered at a single predetermined angle, or disposed in alternating fashion with each baffle oriented in a different predetermined angle. It should be understood that other baffle patterns and arrangements may be used without limitation, and that the shapes, porosities, and/or textures of baffles  318  may differ from what is shown. For example, any one or more of the baffles  318  may comprise folds, bends, curves, corrugations, openings, lattice structures, or the like. 
         [0067]    Slurry flowing within the continuous elution vessel  24  may contain incoming hot pressurized slurry  51   a  and barren solution  54  leaving a continuous electrowinning system  40 ′ or process  40 . Fluidizing chamber  350  may be fed by an influent manifold  28   a  connected to the continuous elution vessel  24  via one or more influent ports  326  having influent port mounts  322 . Alternatively, the influent manifold  28   a  may instead be connected directly to the one or more sidewalls  310  of the continuous elution vessel  24 . A stream of barren solution  54  flows into the continuous elution vessel  24  via the influent manifold  28   a . The stream enters and fills the fluidizing chamber  350  and flows through fluidized bed  320  to help fluidize and suspend carbon particulate within the residence chamber  340  as it travels along the serpentine flow path  51   b.    
         [0068]    An effluent manifold  28   b  is also provided to the continuous elution vessel  24  to extract an electrolyte solution  53  from the residence chamber  340  and deliver said electrolyte solution  53  to a continuous electrowinning system  40 ′ or process  40 . Effluent manifold  28   b  comprises one or more effluent manifold ports, which may be provided with effluent manifold port mounts for ease of connection to the continuous elution vessel  24 . Similarly to the influent manifold  28   a , the effluent manifold  28   b  may be connected directly to the one or more sidewalls  310  of the continuous elution vessel  24 , or may be connected to the vessel  24  via one or more effluent ports  316  having effluent port mounts  312 . 
         [0069]    While in the residence chamber  340  of the continuous elution vessel  24 , loaded carbon is exposed to strip solution reagents under high temperature and high pressure conditions. The reagents in the strip solution act to strip the loaded carbon of its previously adsorbed metal contents (e.g., gold), and “re-leach” it into the solution to form an electrolyte solution. One or more screens or filters  324  may be provided between the residence chamber  340  and the effluent manifold  28   b  in order to extract a clarified stream of electrolyte solution  53  from the continuous elution vessel  24  and/or prevent carbon particulate from passing downstream of the effluent manifold  28   b . In some embodiments, as shown, the placement of said screens or filters  324  may be at the interface between the effluent ports and the one or more sidewalls  310  of the continuous elution vessel  24 . However, the screens or filters  324  may be provided in other locations without limitation, for instance: within the effluent manifold  28   b , within the continuous elution vessel  24 , at the interface between the effluent manifold  28   b  and mounts  312 , or downstream of said effluent manifold  28   b . It should be known that one or more seals or gaskets (not shown) may be placed between the influent  28   a  or effluent  28   b  manifolds and the continuous elution vessel  24 . 
         [0070]    Fluidized carbon and solution within residence chamber  340  continues to move along the serpentine flow path  51   b  until it is either removed through effluent manifold  28   b  to be used as electrolyte, or passes through outlet  328 . The outlet  328  may comprise an outlet mount  330  and/or an outlet seal  329  for connecting to a valve  29 . The valve  29  may be of any sort known in the art, such as a ball or cone valve without limitation, and one would appreciate that the valve may be separately coupled to, or formed integrally with either one or both of the continuous elution vessel  24  and the flash vessel  25 . Moreover, additional piping sections may be added between the second outlet  328  and the valve  29  if the distance between the continuous elution vessel  24  and the flash vessel  25  is large. 
         [0071]    The stream of hot pressurized spent slurry  51   c  exiting the continuous elution vessel  24  “flashes” as it passes through the valve  29 . The resulting mixture of gas vapors, fluids, and solids enters the lower pressure flash vessel  25 , where heated steam is diverted back to the splash vessel  22  via steam return piping  21 . Unvaporized spent solution and spent carbon leave the flash vessel  25  in a stream of concentrated spent slurry  51   d . The concentrated spent slurry  51   d  may comprise a barren solution liquid fraction  52 , and a solids fraction  55  of spent carbon substantially-free of previously-adsorbed precious metal (e.g., gold). As previously mentioned, the stream of concentrated spent slurry  51   d  may be subsequently screened or filtered by a dewatering screen  26 . 
         [0072]    In the embodiment shown, a liquid fraction  52  of the concentrated spent slurry  51   d  is separated from the solid fraction  55  by dewatering screen  26  and returned to the holding tank  60  for re-use as strip solution. One or more pumps (not shown) may be provided to move the liquid fraction  52  to the holding tank  60 . The solids fraction  55  of dewatered spent carbon is sent to a carbon regeneration process  30  comprising a regeneration kiln  35  or other means for reactivating the carbon. Dewatering screen  26  may be provided as a two-stage screen, wherein a first stage removes a majority of the liquid fraction  52  from the spent carbon solids fraction  55 , and a second stage removes residual caustic and/or cyanide from the solids fraction  55  of spent carbon before it enters a regeneration kiln  35  or wash vessel. Accordingly, equipment in the carbon regeneration system  30 ′ is not damaged. 
         [0073]      FIG. 12  schematically illustrates a continuous elution process  20  according to some embodiments. First, a slurry  51  of descaled loaded carbon  50  and a caustic strip solution comprising water and cyanide is produced  1048 . The slurry  51  may be formed and stored in a holding tank  60 . The slurry  51  is then pumped  1050  into the splash vessel  22  which is configured to elevate the temperature and/or pressure of the descaled loaded carbon/strip solution slurry  51 . After increasing the temperature and/or pressure  1052  of the slurry  51  in the splash vessel  22 , a hot pressurized slurry  51   a  of loaded carbon/strip solution is formed and moved  1054  from the splash vessel  22  to the continuous elution vessel  24 . The hot pressurized slurry  51   a  is kept within the vessel  24  for an increased residence time  1056 , for instance, by providing a fluidized bed  320  alone or in combination with a plurality of baffles  318  in order to elongate the physical travel path of the hot pressurized slurry  51   a  between the inlet  304  of the vessel  24  and the outlet  328 . The physical travel path may be for instance, a serpentine flow path  51   b  as shown. 
         [0074]    During its time of residence within the continuous elution vessel  24 , the loaded carbon in the hot pressurized slurry  51   a  is stripped of its adsorbed precious metal by reagents in the caustic strip solution. Accordingly, the caustic strip solution dissolves the precious metal into itself thereby forming an electrolyte solution  53 . The electrolyte solution  53  is screened to remove carbon particulate therefrom and is extracted  1064  from the continuous elution vessel  24 . Subsequently, the electrolyte solution  53  is fed  1066  to a continuous electrowinning system  40 ′ (e.g., into a continuous electrolytic metal extraction cell  42 ) for precious metal recovery. During the electrowinning process  1068  (see  FIG. 19 ), barren solution  54  is continuously removed  1070  from the continuous electrowinning system  40 ′ and pumped  1072  back into the continuous elution vessel  24  either directly, or indirectly (e.g., via a barren solution holding tank (not shown) or immersion heater  27 ). 
         [0075]    Solution and carbon are continuously removed from the continuous elution vessel  24 , and the liquid fraction of the solution “flashed” or at least partially vaporized  1058  with a valve  29  before entering the flash vessel  25 . The process  20  further comprises recovering  1060  heated steam from the rapid evaporation of exiting spent slurry  51   c , and piping  1062  the steam back to the splash vessel  22  in order to efficiently increase  1052  the temperature and/or pressure of the first vessel  22 . Concentrated spent slurry  51   d  is removed  1074  from the flash vessel  25 , and then dewatered  1076  to separate the spent liquid fraction  52  from the spent solids fraction  55 . The solids fraction  55  comprises dewatered carbon which is sent  1078  to a carbon regeneration system  30 ′, and the spent liquid fraction  52  of the concentrated spent slurry  51   d  is sent  1080  to the holding tank  60  for re-use. 
         [0076]    It should be known that the particular features and suggested uses of the continuous elution systems  20 ′ and processes  20  shown and described herein are exemplary in nature and should not limit the scope of the invention. For example, fluidized bed  320  may be replaced with, or used in combination with one or more mechanical agitators (not shown) to suspend loaded carbon particulate. Moreover, the number of baffles  318  in the continuous elution vessel  24  may be greater or less than what is shown, in order to provide the residence times and flow rates required for a particular process. Additionally, one or more additional vessels  22 ,  24 ,  25  may be added to a continuous elution system  20 ′ and placed in series or parallel with other vessels  22 ,  24 ,  25  to increase throughput. For example, two or three continuous elution vessels  24  may be directly or indirectly coupled to each other in parallel, and placed in series between a single splash vessel  22  and a single flash vessel  25 . 
         [0077]      FIG. 13  shows a continuous electrowinning process  40  according to some embodiments. The process  40  comprises continuously providing an electrolyte solution  53 , continuously feeding the electrolyte solution  53  to a continuous electrolytic metal extraction cell  42 , extracting cathode sludge concentrate  53   f  from the cell  42  in a sludge removal stream  53   g , continuously extracting barren solution  54  from the cell  42  and using said barren solution  54  to feed a continuous elution vessel  24  within a continuous elution process  20 . 
         [0078]    As shown in  FIGS. 14-18 , the continuous electrowinning system  40 ′ largely comprises a continuous electrolytic metal extraction cell  42  comprising a cell body  406  having a first end  440 , a second end  480 , one or more sidewalls  482  extending therebetween, a base  404  having one or more mounts  402 , at least one inlet  410  for receiving a continuous influent stream of a precious metal-containing electrolyte solution  53 , at least one first outlet  420  for providing continuous egress of a spent electrolyte stream  53   d  and barren solution  54  contained therein, and at least one second outlet  430  for providing egress of cathode sludge concentrate  53   f  collected within the cell  42 . The second outlet  430  may be configured for continuous egress of collected cathode sludge concentrate  53   f , or the second outlet  430  may be configured for intermittent egress of said collected cathode sludge concentrate  53   f . Within the cell body  406  is provided a first chamber  405 , a second chamber  407 , a third chamber  408 , and a residence chamber  460  comprising one or more elongated channels  462 . The channels  462  are configured to increase residence time of the electrolyte solution  53  and provide a forced flow electrolyte stream  53   b  of electrolyte solution  53  therein which is strong enough to dislodge and/or displace cathodic sludge concentrate which forms and builds up within the channels  462 . The one or more channels  462  may comprise, for example, a portion of a helix, double-helix, coil, spiral, serpentine, spline, compound curve, and may extend in curvilinear paths. In some embodiments, as shown, the residence chamber  460  may be concentrically situated between the first chamber  405  and the third chamber  408 . The first chamber  405  may be configured to be devoid of electrolyte and/or cathodic sludge concentrate during operation, and may generally serve as a space-filler bounded between first end  440 , inner anode  477 , and baffle  450 . The space filling first chamber  405  generally provides channels  462  within the residence chamber  460  with a larger radius, thereby increasing the overall effective length and total surface area of the channels  462  exposed to forced flow electrolyte streams  53   b  contained therewithin. The third chamber  408  serves to temporarily hold and/or transport spent electrolyte streams  53   d  from within the cell  42  to one or more first outlets  420 . In some embodiments, to reduce material costs, the first end  440  may be configured as an annular panel having a central opening exposing the first chamber  405 , rather than as a solid continuous circular panel as shown. The one or more first outlets  420  may be provided at an upper portion of the cell  42  where overflow is likely to be more clarified and free from cathode sludge concentrate. 
         [0079]    Each channel  462  may be defined between at least one anode  474 , at least one cathode  472 , and one or more insulators  476  extending therebetween. In the particular embodiment shown, one or more anodes  474  and one or more cathodes  472  are provided as sleeve portions which alternate concentrically between an outer anode  479  and an inner anode  477  with each sleeve portion having a different radius. The anodes  474  and cathodes  472  are radially separated and maintain a uniform spacing by one or more spacing protuberances  473  projecting from said one or more cathodes  472 . It should be understood, that while not shown, the one or more protuberances  473  may alternatively extend from the anodes  474  alone, or may extend from both anodes  474  and cathodes  472  without limitation. However, by providing protuberances  473  on the one or more cathodes  472 , a small amount of extra cathodic surface area is provided for precipitating cathodic sludge concentrate out of the forced flow electrolyte stream  53   b  during electrolysis. The one or more insulators  476  prevent short circuit between the negatively charged anodes  474  and positively charged cathodes  472  and may serve as flexible, tolerance-compensating gaskets which delineate the cross-sectional boundary of each channel  462  and build/concentrate the forced flow electrolyte stream  53   b  within each channel  462 . 
         [0080]    As shown in  FIG. 18 , each anode  474  may communicate with one or more anode terminals  442 . Anode terminals  442  may comprise, for example and without limitation, a fastener  442   a  such as a pin or screw, a clamping member  442   b  such as a nut, flange, or head, a terminal lead  442   c  connected to a ground or power source, a conductive washer  442   d  or other clamping member, an insulative bushing  442   e  to prevent electrical currents from passing to surrounding portions of the cell  42 , a thread or equivalent securing feature  442   f  provided on said fastener  442   a , a conductive support  442   h  comprising a complimentary thread or equivalent securing feature  442   g  for communicating with said thread or equivalent securing feature  442   f , and a receiving portion  442   i  provided within the conductive support  442   h  for engaging and supporting one or more anodes  474 . In the particular embodiment shown, anodes  474  are generally tubular cylindrical sleeves and therefore, receiving portions  442   i  may be provided as small straight or generally arcuate slits. However, other equivalent interfaces are envisaged, particularly for non-cylindrical or non-tubular anodes  474  and cathodes  472 . For example, instead of slits, receiving portion  442   i  may comprise a plurality of conductive clamps, spring clips, or pegs extending from the support  442   h  which straddle and secure an anode  474  thereto. 
         [0081]    In some embodiments, the continuous electrowinning system  40 ′ may be provided with a cylindrical cell body  406 , a flat circular upper first end  440 , and a generally frustoconical lower second end  480 . The frustoconical shape of the lower second end  480  generally aids in channeling collected heavy cathode sludge concentrate  53   f  to the second outlet  430  for removal. The first end  440  may be secured to the cell body  406  via an annular flange  445  which may be electrically neutral or positively charged with the rest of cathodic cell body  406 . The first end  440  may comprise a series of sandwiched panels, such as one or more ground or electrically-neutral panels  447 , one or more anodic panels  444 , and one or more insulative panels  446 . In some embodiments the one or more insulative panels  446  may comprise a gasket, such as a polytetrafluoroethylene (PTFE) insulating gasket. One or more fasteners  441  or adhesives may be provided to secure the first end  440  to the body  406  and/or to secure sandwiched panels  444 ,  446 ,  447  together. For example, a series of fasteners  441  may be provided around a perimeter of the first end  440  to secure the first end  440  to the flange  445 . The fasteners  441  may be insulated, for example, with a sheath, coating, bushing, or washer of non-conductive material such as high molecular weight polyethylene (HMWPE), polyvinylidene fluoride (PVDF), polypropylene, or polyvinylchloride (PVC). Moreover, the fasteners  441  may serve the dual purpose of securing the first end  440  to the body  406  and also securing sandwiched panels  444 ,  446 ,  447  together. 
         [0082]    In use, an influent stream of electrolyte solution  53  at a higher-than-ambient pressure and temperature continuously enters the cell  42  via inlet  410 . The electrolyte solution  53  may contain metal ions of copper, gold, silver, platinum, lead, zinc, cobalt, manganese, aluminum, or uranium, without limitation. The continuous electrowinning system  40 ′ is preferably maintained at a higher-than-ambient temperature (e.g., around 88 degrees Celsius) and/or pressure. The influent stream of electrolyte solution  53  may come from an upstream electrolyte holding tank (not shown), a continuous elution system  20 ′, or a combination thereof. In some embodiments, the inlet  410  may be formed from a portion of a pipe or tubing having one or more sidewalls  412  and may further comprise an inlet mount  414  having a flange, seal, valve, pipe fitting, or equivalent connector for integration with the continuous elution system  20 ′. Inlet  410  comprises one or more openings  413  (e.g., through said one or more sidewalls  412 ), which are configured to feed said one or more channels  462  of the residence chamber  460  with incoming electrolyte solution  53 . Though not shown, a plurality of openings  413  may be provided per channel  462 . In the event multiple channels  462  and a single inlet  410  is employed as shown, the influent stream of electrolyte solution  53  may be split into a plurality of dispersed influent streams  53   a , each entering different channels  462 . Alternatively, while not shown, a separate inlet  410  may be provided for each channel  462 . The openings  413  may be configured to provide uniform or non-uniform flow rates across each channel  462  or provide similar electrolyte residence times for each channel  462 . As clearly shown in  FIG. 17 , one or more insulators  417  (e.g., an insulation pad) may be placed between one or more sidewalls  412  of the inlet  410  and the first end  440  of the cell body  460 . The one or more insulators  417  may encircle the one or more openings  413  to ensure that incoming electrolyte solution  53  from dispersed influent streams  53   a  does not form, plate, or sludge within the openings  413 , particularly adjacent cathodes  472 . 
         [0083]    In some embodiments, channels  462  may be configured to allow the dispersed influent streams  53   a  of electrolyte solution  53  to flow forcedly through the channels  462  in a forced flow electrolyte stream  53   b  which follows a uniform helical or spiral path as shown. However, while not shown, the channels  462  may also be configured to direct the dispersed influent streams  53   a  along straight paths, serpentine paths, compound curve paths, or complex 3D-spline curve paths so long as they can support a forced flow electrolyte stream  53   b  therein and provide a sufficient residence time of electrolyte between an anode  474  and cathode  472 . 
         [0084]    Channels  462  may shrink or grow in circumference or change in overall or cross-sectional shape and/or size as they extend within the residence chamber  460 ; however, it is preferred that channels  462  remain uniform in cross-section, direction, and/or anode-cathode spacing throughout their entire length. While not shown, since channels  462  located at greater radial distances from the center of the cell  42  are longer and will generally have higher residence times than inner channels  462 , the number of turns of inner channels  462  (e.g., channels adjacent inner anode  477  and first chamber  405 ) may be adjusted to be greater than the number of turns for outer channels  462  (e.g., channels more proximate the outer anode  479  and third chamber  408 ). In other words, while not shown, inner portions of residence chamber  460  may be greater in height than outer portions of residence chamber  460 , in order to lengthen the effective length of inner channels  462  (adjacent the first chamber  405 ). Portions of baffle  450  adjacent the residence chamber  460  and third chamber  408  are generally open so as to allow channels  462  to continuously deliver spent electrolyte streams  53   d  to the third chamber  408  and collected cathode sludge concentrate  53   f  formed in the channels  462  to the second chamber  407 . 
         [0085]    As shown in  FIG. 16 , baffle  450  may comprise an anodic layer  452 , a middle electrically-neutral insulator  454  to support said one or more anodes  474  and cathodes  472 , and a support structure  456  for supporting the insulator  454  and anodic layer  452 . The insulator  454  may be made of a chemically-robust material such as ultra-high molecular weight polyethylene (UHMWPE) and may be cruciform in shape as shown. A plurality of receiving portions  458  such as notches may be provided to the insulator  454  to hold, space, insulate, and support the one or more anodes  474  and cathodes  472 ; however, other holding means such as pegs, spring clips, or clamps may be provided. The insulator  454  may be connected to the support structure  456  with one or more fasteners, adhesives, or other connecting means, and the support structure  456  may be connected to the body  406  by conventional means such as bolting, forming, adhering, welding, or supporting on a flange or shelf. The anodic layer  452  may serve to close off the first chamber  405  and prevent electrolyte  53  in the forced flow electrolyte stream  53   b  from entering said first chamber  405 . In some embodiments, the support structure  456  may be a lattice structure such as a mesh screen or supporting member such as a crossbar which spans a width of the cell body  406 . Support structure  456  is generally configured not to inhibit electrolyte flowing from the channels  462  to the third chamber  408 , or inhibit the passage of cathode sludge concentrate  53   f  to the second chamber  407 . 
         [0086]    As electrolyte solution  53  forcibly flows through the one or more channels  462  in the residence chamber  460 , a large electric potential is placed between the one or more anodes  474  and one or more cathodes  472  in order to effectively “plate-out” sludge concentrate onto the one or more cathodes  472 . However, by varying operating parameters such as residence time, electric current, electrolyte flow rate, temperature, pressure, electrolyte concentration/composition, and/or smoothness/material/coating of each cathode(s)  472 , the channels  462  may be configured such that cathodic sludge concentrate initially forms on or adjacent to the one or more cathodes  472 , but will not actually bond or “plate” to the cathodes  472  and will instead flush down the channels  462  and/or become suspended in the forced flow electrolyte streams  53   b . Any sludge concentrate that may settle to bottom of a channel  462  may also be washed down and eventually swept out of the channels  462  and into second chamber  407  by the forced flow electrolyte streams  53   b . Sludge concentrate may be flushed out of the one or more channels  462  by virtue of: gravitational forces acting on inclined surfaces, high flow rates of forced flow electrolyte streams  53   b  passing through the one or more channels  462 , increased turbulence within each channel  462 , and/or by virtue of small cross-sectional areas provided to each channel  462 . 
         [0087]    After the forced flow electrolyte streams  53   b  pass through the one or more channels  462 , the outflow  53   c  of the residence chamber  460  will generally comprise a liquid carrier component of barren solution  54  which is substantially-free of dissolved precious metal, and a solid precipitate component comprising cathodic sludge concentrate which has been discharged from the channels  462  by the forced flow electrolyte stream  53   b . The heavier solids may follow a sludge precipitate stream  53   e  before settling in a mass of collected cathode sludge concentrate  53   f  within the second chamber  407  adjacent the second end  480 . Barren solution  54  travels via spent electrolyte stream  53   d  into the third chamber  408  and continuously leaves the cell  42  through outlet  420 . In embodiments where the cell body  406  is cathodic, some residual plating or cathodic sludge concentrate formation may occur within the third chamber  408  (for example, on or around inner portions of cathodic sidewall(s)  482 ). However, any cathode sludge concentrate  53   f  formed within the third chamber  408  will typically settle and eventually end up in second chamber  407  with the rest of the collected cathode sludge concentrate  53   f.    
         [0088]    The first outlet  420  may be formed from a portion of a pipe or tubing having one or more sidewalls  422  and may further comprise a first outlet mount  424  having a flange, seal, valve, pipe fitting, or equivalent connector for integration with a continuous elution system  20 ′. When in use, an effluent stream of barren solution  54  continuously leaves the cell body  406  through said first outlet  420  at which point it may enter a barren solution holding tank (not shown), be discarded, return to a continuous elution system  20 ′, or undergo further processing. 
         [0089]    Captured cathode sludge concentrate  53   f  may be removed from the cell  42  intermittently or continuously via second outlet  430 . The underflow, or sludge removal stream  53   g  of cathode sludge concentrate  53   f  may proceed to a holding tank, be pumped away for further refining, or may be dumped into a container and transported to a smelter. In some embodiments, the second outlet  430  may be formed from a portion of a pipe or tube having one or more sidewalls  432  and may further comprise a second outlet mount  434  having a flange, seal, valve, pipe fitting, nozzle, tap, or equivalent connector for integration with a holding tank or smelting apparatus. 
         [0090]    The cross-section of residence chamber  460  may vary, so long as one or more channels  462  therein are formed between at least one anode  474  and at least one cathode  472  which are separated from each other by one or more insulators  476 . Channels may extend linearly (resembling an elongated pipe), helically, in a cascade of connected, horizontally-arranged, and vertically-displaced “figure-8s”, or in any continuous path in 3-D space which is configured to provide a “forced flow” of electrolyte solution. In order to assist with outgassing of air which could get caught in the channels  462  and also prevent the backup of precipitated sludge concentrate within the channels, it is preferred that the continuous path the channels follow in 3-D space be free of sharp bends, abrupt turns, overhangs, high spots, and/or tightly wound corners which may be prone to air capture and clogging. In some embodiments, a residence chamber  460  may comprise one or more channels  462  therein which simply extend as long straight pipe sections tilted at an angle with respect to horizontal. 
         [0091]      FIG. 19  schematically illustrates a continuous electrowinning process  40  according to some embodiments. The process  40  comprises providing  1082  an electrolyte solution  53  having an elevated temperature or pressure with respect to ambient conditions. The electrolyte solution  53  may be produced from a continuous elution process  20  and may comprise water, cyanide, caustic, and a dissolved metal (e.g., gold, copper, silver, platinum, aluminum, lead, zinc, cobalt, manganese, or uranium) therein. The electrolyte solution  53  is continuously fed  1084  (e.g., at a predetermined flow rate) into a continuous electrolytic metal recovery cell  42  which is preferably maintained  1086  at a higher-than-ambient temperature and/or pressure. In some embodiments, the cell  42  may comprise a series of nested anode sleeves  474  and cathode sleeves  472 , wherein adjacent sleeves have a different electrical potential or charge. In a preferred embodiment, the sleeves are spaced concentrically and radially evenly with respect to each other so that any two neighboring sleeves hold an opposite charge  1088 . One or more insulators  476  may be placed between the anodes  474  and cathodes  472  to define a plurality of channels  462  (e.g., helical channels) and simultaneously prevent arcing between the anodes and cathodes. The process  40  further comprises subjecting  1090  the electrolyte solution  53  to a longer residence time within a continuous electrolytic metal recovery cell  42 . This may be achieved by providing one or more elongated channels  462  between the anode  474  and cathode  472  sleeves, which extend in smooth, continuous, and uninterrupted helical paths. It should be known that residence time may also be increased by alternatively employing long tubular straight channels. Electrolyte solution  53  maintained within the channels  462  is forced through the channels  462  and walls thereof by small pressure differentials between the inlet  110  and the first  120  outlet and/or small pressure differentials between the inlet  110  and the second  130  outlet. As the electrolyte solution  53  moves through the channels  462 , cathodic sludge concentrate precipitates out of the electrolyte solution  53  until the solution becomes weaker in concentration and eventually substantially-free of precious material  1092 . Precipitating concentrate from the sludge precipitate stream  53   e  is continuously collected  1094  within second chamber  407 , and collected cathode sludge concentrate  53   f  may be extracted  1098  continuously or intermittently or a combination thereof. A stream of barren solution  54  (which is substantially devoid of precious metal) is continuously extracted  1096  from the cell  42  via outlet  420 , and may be fed to a continuous elution vessel  24  within a continuous elution process  20 . 
         [0092]      FIG. 20  shows a carbon regeneration process  30  according to some embodiments. A solids fraction  55  of concentrated spent slurry  51   d  comprising spent de-watered carbon is sifted with a screen  32  to separate out spent carbon fines  55   b . The spent carbon fines  55   b  are placed in a carbon fines holding tank  34 . The remaining course spent carbon  55   a  is sent to a regeneration kiln  35  (or other means for regeneration such as a chemical, steam, or biological process). Hot reactivated carbon  55   c  is removed from the regeneration kiln  35  and quenched in a carbon quench tank  36 . A slurry of cooled regenerated carbon and fluid moves to a dewatering screen  37  via pump  33 . After passing through dewatering screen  37 , dewatered activated/reactivated carbon  56  is moved to a continuous carbon loading/adsorption process  70 . The fluid underflow, which comprises cool reactivated carbon slurry  55   d , is moved to the carbon fines holding tank  34 . 
         [0093]      FIG. 21  shows a continuous metal recovery system  100 ′ according to some embodiments of the invention comprising a continuous acid wash system  10 ′, a continuous elution system  20 ′, a continuous electrowinning system  40 ′, and a carbon regeneration system  30 ′.  FIGS. 22 and 23  serve to compare scale plant layouts and overall footprints.  FIG. 22  shows the system  100 ′ for the continuous recovery of metals according to  FIG. 21  and  FIG. 23  comprises a conventional system  9000 ′ for the batch recovery of metals using “batch” process steps. As can be seen from  FIGS. 22 and 23 , the system  100 ′ according to the invention is smaller in size than the conventional system  9000 ′ depicted in  FIG. 23 . In addition to smaller size, system  100 ′ is also more efficient and environmentally-friendly. 
         [0094]      FIG. 24  shows an alternative to the washing tanks  200 ,  200 ′,  200 ″ shown in  FIGS. 6-8 . In the embodiment shown, an acid wash tank  2000  is provided, which may replace acid wash tank  200 . Acid wash tank  2000  comprises a wash chamber  2020  having a fluidized bed panel  2021  spanning the length of the wash chamber  2020  with pore sizes smaller than the mean particle size of loaded/reloaded carbon, one or more adjustable mounts  2007 ,  2009  which may be individually raised, lowered, or pivoted on a rack or linkage (not shown for clarity) to change the inclination angle of the chamber  2020  with respect to a skid  2002 , a recirculation inlet  2023   a  provided below the fluidized bed panel  2021 , and a recirculation outlet  2023   b  provided above the fluidized bed panel  2021 . Recirculation outlet  2023   b  comprises one or more overflow outlets  2027 , each provided with at least one washable/replaceable recycle screen  2008 , which maintains loaded/reloaded carbon  57  within the chamber  2020  and filters exiting dilute acid solution  57   c . Recycle screens  2008  may be conveniently provided between bolted flange members of the overflow outlets  2027  and may comprise built-in peripheral gaskets.  FIGS. 25 and 26  show more detailed views of the chamber  2020  shown in  FIG. 24 . 
         [0095]    Recirculation inlet  2023   a  may comprise one or more adjustable nozzles  2011  which serve to fluidize loaded/reloaded carbon  57 . The nozzles  2011  may be individually or collectively angularly adjusted and “set” to a fixed angle, in order to: compensate for various inclinations of the chamber  2020 , prevent buildup of loaded/reloaded carbon  57 , and counteract backflow within the chamber  2020  caused by eddy currents surrounding interior baffles  2018 . Chamber  2020  may, as shown, be constructed in clamshell form, with a number of fasteners  2004  connecting upper and lower clamshell portions together. One or more additional gaskets may be employed between the upper and lower clamshell portions to form a seal, or the fluidized bed panel  2021  itself may be provided with peripheral gasketing material properties to provide a seal between the upper and lower clamshell portions. 
         [0096]    A first filter  2001  is provided at an inlet  2022  to the acid wash tank  2000 . The first filter  2001  comprises a housing  2003  which serves to collects influent loaded/reloaded carbon slurry  57 ′, a first screen  2026  which serves to separate loaded/reloaded carbon  57  from carrier fluid  57   f  present in the slurry  57 ′, a first filter outlet  2006  which serves to transfer strained loaded/reloaded carbon  57  from within the upper housing  2003  to the wash chamber  2020 , a recirculation tank  2029  which collects carrier fluid  57   f  separated from the liquid fraction of the influent slurry  57 ′, and one or more clamps  2005  which removably attach the housing  2003  to the recirculation tank  2029  with the first screen  2026  extending therebetween, thereby allowing periodic cleaning and/or replacing of the first screen  2026 . Recirculation tank  2029  may be configured to continuously redistribute carrier fluid  57   f  to a holding tank (not shown) or may simply comprise a valve for batch removal of the collected carrier fluid  57   f.    
         [0097]    A second filter  2024 , similar to the first filter  2001 , is provided adjacent a first channel  2082  extending from the fluidized bed panel  2021  to an outside portion of the wash chamber  2020 . First channel  2082  is configured to provide egress of acid-rinsed loaded carbon  57   a  resting on/around/above fluidized bed panel  2021  after it has undergone a predetermined residence time of acid washing within the chamber  2020 . The acid-rinsed loaded carbon  57   a  is filtered by a second screen  2036 , and the strained solids fraction of the acid-rinsed loaded carbon  57   a  exits a discharge outlet  2028 . The acid-rinsed loaded carbon exiting the discharge outlet  2028  may be captured and contained by a holding tank  2060  and subsequently transported (via pump  2030 ) to a downstream process (e.g., aqueous rinse cycle). Alternatively, the acid-rinsed loaded carbon exiting the discharge outlet  2028  may directly enter a downstream process (e.g., pour into another aqueous rinse tank  200 ′ without an intermediate holding tank  2060  and pump  2023 ). Holding tank  2060  advantageously serves as a buffer which maintains a level of process control and prevents too much carbon feed to downstream processes. 
         [0098]    In use, replenished dilute acid solution  57   c ′ (obtained by filtering acid-rinsed loaded carbon  57   a  with second screen  2036 ) enters recirculation tank  2039  and is pumped to chamber  2020  via a pump  2030 . The replenished dilute acid solution  57   c ′ enters the recirculation inlet  2023   a  and then passes upwards through fluidized bed panel  2021  via nozzles  2011 . The replenished dilute acid solution  57   c ′ suspends incoming loaded/reloaded carbon  57 , and moves the loaded/reloaded carbon  57  through the chamber  2020  and around baffles  2011  for a predetermined residence time. The replenished dilute acid solution  57   c ′ passes through recycle screens  2008  and filtered dilute acid solution  57   c  re-enters the recirculation tank  2039  via recirculation outlet  2033   b . Residence time of the loaded/reloaded carbon  57  may be increased or decreased by adjusting the inclination angle of the chamber  2020  and/or adjusting the angular orientation of nozzles  2011 . For a fixed, non-variable metal extraction process, the inclination angle of chamber  2020  and angular positions of nozzles may be preset by the manufacturer and permanently fixed in the optimum configuration to yield the most efficient residence time for said process. 
       Example 1 
       [0099]    A water-based, loaded carbon slurry  57  comprising approximately 30-300 oz/ton gold and approximately 30% wt/wt, activated coconut shell carbon is delivered to a continuous acid wash system  10 ′. First, inorganic components, namely calcium and magnesium carbonate, are removed from the loaded carbon by fluidizing a bed of loaded active carbon with a dilute aqueous acid solution comprising approximately 1-5 wt % hydrogen chloride (HCl) and/or nitric acid (HNO 3 ) in an acid wash tank  12 ,  200 . The loaded active carbon is continuously transferred from the acid wash tank to an aqueous rinse tank  14 ,  200 ′ where the loaded active carbon is fluidized and cleaned with water. The loaded carbon is subsequently continuously transferred from the aqueous rinse tank  14 ,  200 ′ to a caustic rinse tank  16 ,  200 ″. The pH of the loaded active carbon delivered to the caustic rinse tank is raised above 10 by a caustic solution comprising approximately 1-3 wt % sodium hydroxide. 
         [0100]    The basic descaled loaded carbon  50  is fed continuously to a splash vessel  22  within a continuous elution system  20 ′ via a transfer medium of caustic strip solution comprising approximately 1 wt % caustic (NaOH) and 0.1 wt % cyanide (NaCN). The splash vessel  22  is generally held at an operating temperature between approximately 100 and 200 degrees Fahrenheit (° F.), and at a pressure of approximately atmospheric level. The loaded carbon is transferred from the splash vessel  22  to the continuous elution vessel  24 , where the gold is removed from the carbon (i.e., gold dissolution). The continuous elution vessel  24  operates at roughly 300 degrees Fahrenheit (° F.), which temperature is achievable by elevating the strip solution pressure to roughly 70 psi (gauge). The continuous elution vessel  24  continuously discharges into a lower pressure flash vessel  25 . A drop in pressure between the continuous elution vessel  24  and flash vessel  25  causes rapid flash vaporization of a portion of the effluent caustic strip solution. Steam generated is channeled to the splash vessel  22 , thereby simultaneously heating the splash vessel  22  and cooling the flash vessel  25 . Spent carbon, (e.g., comprising less than 1 oz/ton gold), is continuously moved out of the continuous elution system  20 ′ and into a regeneration process  30 . 
         [0101]    The approximately 300° F. pressurized caustic strip solution is filtered by one or more screens or filters  324  to remove barren carbon particulate and form electrolyte solution  53 , which is then passed through a continuous electrolytic metal extraction (i.e., electrowinning) cell  42 . The electrolyte solution  53  is forced (via the increased pressure provided by the continuous elution vessel  24 ) through at least one channel  462  having a fixed helical path between a cylindrical sleeve anode  474  and a cylindrical sleeve cathode  472 . A voltage between approximately 2 and 4 volts is passed between the anode  474  through the electrolyte solution  53  and the cathode  472 , thereby depositing cathode sludge concentrate  53   f  on surfaces of the cathode  472 . The velocity of the electrolyte solution  53  creates a forced flow electrolyte stream  53   b  within the channel  462  which continuously washes the collected cathode sludge concentrate  53   f  which may form and collect on the cathode&#39;s surfaces to the conical bottom of the cell  42 , where it may be removed at the operator&#39;s leisure or continuously via a control valve. 
         [0102]    A contractor or other entity may provide a system  100 ′ or process  100  for the continuous recover of metals in part or in whole as shown and described. For instance, the contractor may receive a bid request for a project related to designing a continuous metal recovery system  100 ′ or process  100 , or the contractor may offer to design such a system  100 ′ or a process  100  for a client. The contractor may then provide, for example, any one or more of the devices or features thereof shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer. The contractor may subcontract the fabrication, delivery, sale, or installation of a component of the devices or of other devices used to provide such devices. The contractor may also survey a site and design or designate one or more storage areas for stacking the material used to manufacture the devices. The contractor may also maintain, modify, or upgrade the provided devices. The contractor may provide such maintenance or modifications by subcontracting such services or by directly providing those services or components needed for said maintenance or modifications, and in some cases, the contractor may modify an existing metal recovery process  9000  or system  9000 ′ with a “retrofit kit” to arrive at a modified process or system comprising one or more method steps, devices, or features of the systems  100 ′ and processes  100  discussed herein. 
         [0103]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. For example, particulates and carriers other than carbon (e.g., polymers or ion exchange resins) may be used with the disclosed systems and processes. Moreover, reagents other than water, cyanide, and caustic may be used to wash, descale, or strip the particulates. Furthermore, the disclosed systems and processes may be used to recover numerous types of materials including, but not limited to copper, gold, silver, platinum, uranium, lead, zinc, aluminum, chromium, cobalt, manganese, rare-earth and alkali metals, etc. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Reference numeral identifiers 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  10 
                 Continuous acid wash process 
               
               
                  10′ 
                 Continuous acid wash system 
               
               
                  12 
                 Acid wash tank 
               
               
                  13 
                 Pump 
               
               
                  14 
                 Aqueous rinse tank 
               
               
                  16 
                 Caustic rinse tank 
               
               
                  20 
                 Continuous elution process 
               
               
                  20′ 
                 Continuous elution system 
               
               
                  21 
                 Steam return 
               
               
                  22 
                 Splash vessel 
               
               
                  23 
                 Pump 
               
               
                  24 
                 Continuous elution vessel 
               
               
                  25 
                 Flash vessel 
               
               
                  26 
                 Dewatering screen 
               
               
                  27 
                 Immersion heater 
               
               
                  28a 
                 Influent manifold 
               
               
                  28b 
                 Effluent manifold 
               
               
                  29 
                 Valve 
               
               
                  30 
                 Carbon regeneration process 
               
               
                  30′ 
                 Carbon regeneration system 
               
               
                  32 
                 Screen 
               
               
                  33 
                 Pump 
               
               
                  34 
                 Carbon fines holding tank 
               
               
                  35 
                 Regeneration kiln 
               
               
                  36 
                 Carbon quench tank 
               
               
                  37 
                 Dewatering screen 
               
               
                  40 
                 Continuous electrowinning process 
               
               
                  40′ 
                 Continuous electrowinning system 
               
               
                  42 
                 Continuous electrolytic metal extraction cell 
               
               
                  50 
                 Descaled loaded carbon (or caustic/basic slurry thereof) 
               
               
                  51 
                 Slurry of strip solution and descaled loaded carbon 
               
               
                  51a 
                 Heated and/or pressurized slurry 
               
               
                  51b 
                 Serpentine flow path of slurry 
               
               
                  51c 
                 Spent slurry 
               
               
                  51d 
                 Concentrated spent slurry 
               
               
                  52 
                 Liquid fraction of concentrated spent slurry 
               
               
                  53 
                 Electrolyte solution 
               
               
                  53a 
                 Dispersed influent stream 
               
               
                  53b 
                 Forced flow electrolyte stream 
               
               
                  53c 
                 Residence chamber outflow 
               
               
                  53d 
                 Spent electrolyte stream 
               
               
                  53e 
                 Sludge precipitate stream 
               
               
                  53f 
                 Cathode sludge concentrate 
               
               
                  53g 
                 Sludge removal stream 
               
               
                  54 
                 Barren solution (i.e., spent electrolyte) 
               
               
                  55 
                 Solids fraction of concentrated spent slurry (e.g., de-water 
               
               
                  55a 
                 Course spent carbon 
               
               
                  55b 
                 Spent carbon fines 
               
               
                  55c 
                 Hot reactivated carbon 
               
               
                  55d 
                 Cool reactivated carbon slurry 
               
               
                  56 
                 Activated/reactivated carbon 
               
               
                  57′ 
                 Loaded/reloaded carbon slurry 
               
               
                  57 
                 Loaded/reloaded carbon 
               
               
                  57a 
                 Acid-rinsed loaded carbon 
               
               
                  57b 
                 Rinsed loaded carbon 
               
               
                  57c, 57c′ 
                 Dilute acid solution 
               
               
                  57d, 57d′ 
                 Aqueous rinse solution 
               
               
                  57e 
                 Caustic rinse solution 
               
               
                  57f 
                 Carrier fluid 
               
               
                  60 
                 Holding tank 
               
               
                  70 
                 Continuous carbon loading/adsorption process 
               
               
                  70′ 
                 Continuous carbon loading/adsorption system 
               
               
                  100 
                 Process for the continuous recovery of metals 
               
               
                  100′ 
                 System for the continuous recovery of metals 
               
               
                  200 
                 Acid wash tank 
               
               
                  200′ 
                 Aqueous rinse tank 
               
               
                  200″ 
                 Caustic rinse tank 
               
               
                  220 
                 First chamber 
               
               
                  221 
                 First fluidized bed panel 
               
               
                  222 
                 First inlet 
               
               
                  223a 
                 First recirculation inlet 
               
               
                  223b 
                 First recirculation outlet 
               
               
                  224 
                 First weir 
               
               
                  226 
                 First screen 
               
               
                  227 
                 First overflow outlet 
               
               
                  228 
                 First discharge outlet 
               
               
                  229 
                 First recirculation tank 
               
               
                  230 
                 Second chamber 
               
               
                  231 
                 Second fluidized bed panel 
               
               
                  232 
                 Second inlet 
               
               
                  233a 
                 Second recirculation inlet 
               
               
                  233b 
                 Second recirculation outlet 
               
               
                  234 
                 Second weir 
               
               
                  236 
                 Second screen 
               
               
                  237 
                 Second overflow outlet 
               
               
                  238 
                 Second discharge outlet 
               
               
                  239 
                 Second recirculation tank 
               
               
                  240 
                 Third chamber 
               
               
                  241 
                 Third fluidized bed panel 
               
               
                  242 
                 Third inlet 
               
               
                  243a 
                 Third recirculation inlet 
               
               
                  243b 
                 Third recirculation outlet 
               
               
                  244 
                 Third weir 
               
               
                  246 
                 Third screen 
               
               
                  247 
                 Third overflow outlet 
               
               
                  248 
                 Third discharge outlet 
               
               
                  249 
                 Third recirculation tank 
               
               
                  251 
                 Acid overflow 
               
               
                  253 
                 Drained acid return 
               
               
                  254 
                 Rinse water overflow 
               
               
                  256 
                 Drained rinse water return 
               
               
                  257 
                 Caustic rinse overflow 
               
               
                  260 
                 Bottom wall 
               
               
                  266 
                 Inner tubular wall 
               
               
                  268 
                 Outer tubular wall 
               
               
                  282 
                 First channel 
               
               
                  284 
                 Second channel 
               
               
                  286 
                 Third channel 
               
               
                  301 
                 Inlet seal 
               
               
                  302 
                 Inlet mount 
               
               
                  304 
                 Inlet 
               
               
                  306 
                 First end 
               
               
                  308 
                 Second end 
               
               
                  310 
                 One or more sidewalls 
               
               
                  312 
                 Effluent port mount 
               
               
                  314 
                 Mounting member 
               
               
                  316 
                 Effluent port 
               
               
                  318 
                 One or more baffles 
               
               
                  320 
                 Fluidized bed panel 
               
               
                  322 
                 Influent port mount 
               
               
                  324 
                 Filter (e.g., disk screen) 
               
               
                  326 
                 Influent port 
               
               
                  328 
                 Outlet 
               
               
                  329 
                 Outlet seal 
               
               
                  330 
                 Outlet mount 
               
               
                  340 
                 Residence chamber 
               
               
                  350 
                 Fluidizing chamber 
               
               
                  402 
                 Mount 
               
               
                  404 
                 Base 
               
               
                  405 
                 First chamber 
               
               
                  406 
                 Cell body 
               
               
                  407 
                 Second chamber 
               
               
                  408 
                 Third chamber 
               
               
                  410 
                 Inlet 
               
               
                  412 
                 One or more inlet sidewalls 
               
               
                  413 
                 One or more openings 
               
               
                  414 
                 Inlet mount 
               
               
                  417 
                 One or more insulators 
               
               
                  420 
                 First outlet 
               
               
                  422 
                 One or more first outlet sidewalls 
               
               
                  424 
                 First outlet mount 
               
               
                  430 
                 Second outlet 
               
               
                  432 
                 One or more second outlet sidewalls 
               
               
                  434 
                 Second outlet mount 
               
               
                  440 
                 First end 
               
               
                  441 
                 Fastener 
               
               
                  442 
                 Anode terminal 
               
               
                  442a 
                 Fastener 
               
               
                  442b 
                 Clamp 
               
               
                  442c 
                 Terminal lead 
               
               
                  442d 
                 Conductive washer 
               
               
                  442e 
                 Insulative bushing 
               
               
                  442f 
                 Thread or equivalent securing feature 
               
               
                  442g 
                 Complimentary thread or securing feature 
               
               
                  442h 
                 Conductive support 
               
               
                  442i 
                 Receiving portion 
               
               
                  444 
                 Anodic panel 
               
               
                  445 
                 Cathodic flange 
               
               
                  446 
                 Insulative panel 
               
               
                  447 
                 Anodic panel 
               
               
                  450 
                 Baffle 
               
               
                  452 
                 Anodic panel 
               
               
                  454 
                 Anode/Cathode insulator 
               
               
                  456 
                 Anode/Cathode insulator support 
               
               
                  458 
                 One or more receiving portions 
               
               
                  460 
                 Residence chamber 
               
               
                  462 
                 One or more channels 
               
               
                  472 
                 Cathode 
               
               
                  473 
                 One or more protuberances 
               
               
                  474 
                 Anode 
               
               
                  476 
                 One or more insulators 
               
               
                  477 
                 Inner anode 
               
               
                  479 
                 Outer anode 
               
               
                  480 
                 Second end 
               
               
                  482 
                 One or more sidewalls 
               
               
                 1000 
                 Process for the continuous recovery of metals 
               
               
                 1002-1046 
                 Continuous acid wash steps 
               
               
                 1048-1080 
                 Continuous elution steps 
               
               
                 1082-1100 
                 Continuous electrowinning steps 
               
               
                 2000 
                 Acid wash tank 
               
               
                 2001 
                 First filter 
               
               
                 2002 
                 Skid 
               
               
                 2003 
                 Housing 
               
               
                 2004 
                 Fastener 
               
               
                 2005 
                 Clamp 
               
               
                 2006 
                 First filter outlet 
               
               
                 2007 
                 First adjustable mount 
               
               
                 2008 
                 Recycle screen 
               
               
                 2009 
                 Second adjustable mount 
               
               
                 2011 
                 Nozzle 
               
               
                 2018 
                 Baffle 
               
               
                 2020 
                 Chamber 
               
               
                 2021 
                 Fluidized bed panel 
               
               
                 2022 
                 Inlet 
               
               
                 2023 
                 Pump 
               
               
                 2023a 
                 Recirculation inlet 
               
               
                 2023b 
                 Recirculation outlet 
               
               
                 2024 
                 Second filter 
               
               
                 2026 
                 First screen 
               
               
                 2027 
                 Overflow outlet 
               
               
                 2028 
                 Discharge outlet 
               
               
                 2029 
                 Recirculation tank 
               
               
                 2033b 
                 Recirculation outlet 
               
               
                 2036 
                 Second screen 
               
               
                 2039 
                 Recirculation tank 
               
               
                 2060 
                 Holding tank 
               
               
                 2082 
                 First channel 
               
               
                 9000 
                 Conventional batch metal recovery process 
               
               
                 9000′ 
                 Conventional batch metal recovery system 
               
               
                 9100 
                 Conventional batch acid wash process 
               
               
                 9100′ 
                 Conventional batch acid wash system 
               
               
                 9120 
                 Acid wash vessel 
               
               
                 9132 
                 Pump 
               
               
                 9134 
                 Carbon transfer pump 
               
               
                 9136 
                 Pump 
               
               
                 9140 
                 Dilute acid tank 
               
               
                 9150 
                 Sump pump 
               
               
                 9160 
                 Neutralizing tank 
               
               
                 9200 
                 Conventional batch (Zadra strip) elution process 
               
               
                 9200′ 
                 Conventional batch (Zadra strip) elution system 
               
               
                 9220 
                 Barren solution tank 
               
               
                 9232 
                 Carbon transfer pump 
               
               
                 9234 
                 Barren solution backup pump 
               
               
                 9236 
                 Barren solution pump 
               
               
                 9237 
                 Barren solution 
               
               
                 9239 
                 Hot barren solution 
               
               
                 9240 
                 Strip vessel 
               
               
                 9250 
                 Heating skid or equivalent heat exchanger 
               
               
                 9300 
                 Carbon regeneration process 
               
               
                 9400 
                 Conventional batch electowinning process 
               
               
                 9400′ 
                 Conventional batch electowinning system 
               
               
                 9420 
                 Batch electrolytic metal recovery cell 
               
               
                   
                 (e.g., removable plate cathodes) 
               
               
                 9421 
                 Hot electrolyte solution 
               
               
                 9430 
                 Pump 
               
               
                 9440 
                 Electrowinning pump box 
               
               
                 9500 
                 Descaled loaded carbon 
               
               
                 9530 
                 Electrolyte solution 
               
               
                 9540 
                 Barren solution 
               
               
                 9550 
                 Spent carbon 
               
               
                 9560 
                 Activated/reactivated carbon 
               
               
                 9570 
                 Loaded or reloaded carbon 
               
               
                 9700 
                 Conventional batch carbon loading process