Abstract:
The present invention provides for a method for the separation of a mixture of differing particulate types comprising the steps of: a) selecting a coating material; b) coating said coating material onto at least two different particulate types in said mixture of differing particulate types for forming a mixture of coated particulate types; c) measuring the fracture strength of at least one coated particulate types in said mixture of coated particulate types under at least one applied stress subjected at a controlled rate; d) applying at least one substantially uniform stress on at least one coated particulate type in said mixture of coated particulate types at a controlled rate for fracturing at least one coated particulate type in said mixture of coated to a greater degree than for at least one other particulate type in said mixture of coated particulate types for forming a mixture of differentially fractured types; e) separating said mixture of differentially fractured types for separating said mixture of differing particulate types.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a process for the recovery of mineral particles from gangue by differential fracture techniques. More particularly, this invention relates to a process for the separation and recovery of mineral particles from gangue utilizing differential fracture techniques operating in conjunction with specified separation and recovery means.  
           [0002]    Industrial nations are constantly increasing their metal consumption and the known supply of metal, and particularly copper, lead and zinc, is shrinking. In a few years, the metal industry may not be able to supply the world needs. Similarly, the supply of previous metals and minerals is shrinking. There are, however, still large quantities of minerals and metals in very low grade ore that have been heretofore untouched because of the difficulty in recovering the valuable minerals and metals from the other solid materials, referred to as gangue, which are of little value.  
           [0003]    In the low grade ore, the desired minerals many times appear only as just a few specks mixed with other minerals and solids, and a great amount of material must be handled to recover the small amount of desired mineral or metal. Any process for recovery of the desired minerals from low grade ore should involve as few handling steps as possible. In addition, there has been difficulty in developing processes that can detect or select the small amount of mineral from the large amount of solids of little value generally termed gangue. This operation known as ore dressing or concentration generally involves comminution or fragmentation of the ore to small size to permit easy separation of the different kinds of solids, followed by one or more sorting operations designed to distinguish and separate the valuable mineral particles from the rest. In the past, the sorting has generally been accomplished by techniques, such as, for example, those based on gravity, magnetism, chemical attraction or reaction.  
           [0004]    The gravity separation processes depend upon the different rates of fall through water and are patterned after the simple panning technique where the particles are swirled with water in a shallow conical dish with the effect that the dense particles stratify in the bottom while the lighter mineral, being more buoyant, remain partly suspended and can be decanted with water from time to time. The modern successors to the panning technique use more complicated steps and equipment, but the process is still limited by difficulty of obtaining particles of the right size, interference with walls and bottom of the containing vessels, and the like.  
           [0005]    The magnetic separation process can be used for separating only a few minerals. The most obvious case is that of the ferromagnetic magnetite and minerals that can be chemically altered to become magnetic. Such separators work efficiently only if the material is presented in rather a thin layer only a few particles deep. Consequently, the design of a high capacity plant for use with fine material at reasonable cost is scarcely practicable.  
           [0006]    Froth flotation is probably the more desirable of the sorting processes as it operates through the sensitive surface properties of the individual minerals. It is generally applicable to very fine concentrates and can distinguish, not only ore mineral from gangue, but one mineral from another. Briefly, conditions are arranged so that when a mixture is agitated and air bubbles are blown through it, certain minerals attach themselves to the bubbles and are floated out of a froth which is skimmed off and discharged of its mineral burden. In many cases, the surface properties of the ore and gangue minerals vary within too narrow a range to be useful for effective separation, and, as a result, certain organic compounds called collectors are added to bring about more selective adsorbtion. The main type of collectors are organic acids, their salts, organic bases and oils, such as kerosene, creosotes, diesel or fuel oils. To be effective, these processes generally require strict control over particle size, of pH and the addition of many additives, such as conditioners, wetting agents, frothing agents, which add greatly to the cost, particularly when treating large quantities of ore. In addition, the technique requires that the minerals be ground to very fine particles before an effective separation can be accomplished.  
         OBJECTS OF THE INVENTION  
         [0007]    It is an object of the present invention to provide a fracture process for extracting metals and minerals from mixtures containing them.  
           [0008]    It is a further object of the invention to provide a process for sorting or extracting valuable metals and minerals from gangue by a fracture technique, which can be effectively operated on large quantities of ore with few operational steps, is operative with particles of great variety of size, is dependent upon very few process variables and can be made effective for the separation of a great variety of different metals and mineral ores.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides for a method for the separation of a mixture of differing particulate types. The differing particulate types can be in the form of crushed ores or minerals, dirty coal or a mixture of spent and fresh catalytic materials. The method comprises the steps of first selecting a coating material for coating at least two different particulate types in the mixture of differing particulate types for forming a mixture of coated particulate types. In one form of the invention, the coating material is selected for forming a mixture of coated particulate types having different fracture strengths. The fracture strength of at least one coated particulate type is then measured under at least one applied stress which is applied at a controlled rate for finding the fracture threshold for at least one coated particulate type in the mixture of coated particulate types. The mixture is then differentially fractured for forming a mixture of fractured types. In one form of the present invention, the differential fracturing is accomplished by applying at least one substantially uniform stress which is at least as great as the lowest fracture threshold to the mixture of coated particulate types at a uniform rate for fracturing at least one coated particulate types to a greater degree than for at least one other particulate type for forming a mixture of differentially fractured types. The mixture of differentially fractured types are then separated for separating the mixture of differing particulate types.  
           [0010]    In one form of the invention, the stress is applied for forming a mixture of differentially fractured types having differing bulk properties such as size, shape, density, heat conductivities, and ability to be magnetically manipulated. The differing bulk properties of the fractured mixture is then used to separate the differing particulate types by such methods as screening, gravitational, magnetic separation, aerodynamic sizing and differential bouncing.  
           [0011]    In another form of the present invention, the stress is applied for forming a mixture of differentially fractured types having differing surface properties such as refractive index, luminosity, fluorescence, optical absorbency, catalytic nature, electrical conductivities, ability to become electrostatically charged, and hydrophobic nature. The differing surface properties of the fractured mixture is then used to separate the differing particulate types by “hand picking” separation techniques, electrostatic separation and floatation.  
           [0012]    In another form of the present invention, heat is applied to the mixture of coated particulate types from at least one heating source for forming a mixture of differentially strained coated particulate types having different fracture strengths. The fracture strength of at least one coated particulate types in the mixture of differentially strained types is then measured for finding the fracture threshold for at least one coated particulate types. At least one stress, which is at least as great as the fracture threshold for at least one coated particulate type is uniformly applied to the differentially strained coated particulate types for fracturing at least one coated particulate type in said mixture of differentially strained coated particulate types to a greater extent than for at least one other coated particulate types for forming a mixture of differentially fractured types.  
           [0013]    In yet another form of the invention for forming a mixture of differentially fractured types, the mixture of coated particulate types is exposed to a fluid which can be either a gas or a liquid while the fracturing stress is applied for changing the fracture strength of at least one coated particulate type to a geater extent than for at least one other coated particulate type for forming a mixture of differentially fractured types.  
           [0014]    In another form of the invention, a stress is applied to a mixture of coated particulate types for fracturing at least one coated particulate type in said mixture for forming a mixture of differentially fractured types that are also differentially electrostatically charged. The differentially electrostatically charged types are then electrostatically separated.  
           [0015]    The present invention also provides for an additional method for the separation of a mixture of differing particulate types comprising the steps of first forming a mixture of differentially coated particulate types having differing fracture strengths. The differentially coated particulate types are than selectively fractured for forming a mixture of differentially fractured types which are then separated for separating the differing particulate types.  
           [0016]    The present invention provides for three methods for forming differentially coated particulate types. In the first, the method comprises the steps of first selectively coating with a first coating material at least one particulate type in a mixture of particulate types. The mixture is then coated with a second coating material for forming a mixture of differentially double coated particulate types having differing fracture strengths. The first coating material can comprise a solid or a fluid which can be in the form of individual particles or in the form of a continuous layer.  
           [0017]    In the second form of the invention, the method for forming differentially coated particulate types comprises the steps of selecting a coating material for selectively reacting with at least one particulate type in a mixture of particulate types to a greater extent or in a different way than for at least one other particulate type. The coating material is then applied under conditions for selectively reacting the coating material for forming a mixture of differentially coated particulate types having differing fracture strengths.  
           [0018]    In the third form of the invention for differentially coating particulate types includes the steps of: (a) coating a mixture of differing particulate types with a coating material for forming a mixture of coated particulate types and then (b) holding said mixture of coated particulate types at a substantially uniform temperature for forming a fluid layer at the interface of at least one coated particulate type to a greater extent than for at least one other coated particulate type for forming said mixture of differentially coated particulate types.  
           [0019]    The present invention also provides for a third method for the separation of a mixture of differing particulate types. The third method comprises the steps of: (a) selecting a coating material; (b) coating said coating material onto at least two different particulate types in said mixture of differing particulate types for forming a mixture of coated particulate types at least one of said coated particulate types having at least one boundary layer; (c) applying a stress to said mixture of coated particulate types for separating matter at a boundary layer for forming a mixture of differentially bounded particulate types; and (d) separating the differentially bounded particulate types for separating said mixture of differing particulate types.  
           [0020]    The present invention also provides for several methods for the separation of a mixture of differing particles. In one form of the invention, the differing particle types can be in the form of differing particulate types such as crushed minerals or ores, dirty coal or a mixture of spent and fresh catalytic materials. In another form of the invention, the differing particle types can be in the form of differing biological cells such as but not limited to bacteria or human cells.  
           [0021]    In one form of the invention, the method for the separation of particles comprises the steps of first selecting a coating material for coating at least two different particles in the mixture of differing particles for forming a mixture of coated particles. An energizing field is then applied to the mixture of coated particles for forming a mixture of particles having different strains or different fracture strengths. The mixture is then differentially fractured for forming a mixture of fractured types. In one form of the present invention, the differential fracturing is accomplished by applying at least one substantially uniform stress to the energized mixture for forming a mixture of differentially fractured types. The mixture of differentially fractured types are then separated for separating the mixture of differing particles.  
           [0022]    The above method can also comprise the steps of measuring the fracture strength of at least one of the coated particles in the energized mixture for forming the fracture threshold for at least one coated particle type in the mixture of coated particles. A stress is then applied which is at least as great as the lowest fracture threshold for the mixture of coated particles for forming the mixture of differentially fractured types.  
           [0023]    In one form of the invention, the stress is applied for forming a mixture of differentially fractured types having differing bulk properties such as size, shape, density, heat conductivities, and ability to be magnetically manipulated. The differing bulk properties of the fractured mixture is then used to separate the differing particulate types by such methods as screening, gravitational, magnetic separation, aerodynamic sizing and differential bouncing.  
           [0024]    In another form of the present invention, the stress is applied for forming a mixture of differentially fractured types having differing surface properties such as refractive index, luminosity, fluorescence, optical absorbency, catalytic nature, electrical conductivities, ability to become electrostatically charged, and hydrophobic nature. The differing surface properties of the fractured mixture is then used to separate the differing particulate types by “hand picking” separation techniques, electrostatic separation and floatation.  
           [0025]    In another form of the invention, a stress is applied to a mixture of energized coated particles for fracturing at least one coated particle type in said mixture for forming a mixture of differentially fractured types that are also differentially electrostatically charged. The differentially electrostatically charged types are then electrostatically separated.  
           [0026]    The present invention also provides for an additional method for the separation of a mixture of differing particles comprising the steps of first forming a mixture of differentially coated particles. The mixture of differentially coated particles is then energized by an energizing field for forming a mixture of differentially strained particles. The mixture of differentially strained particles are than subject to at least one applied stress for forming a mixture of differentially fractured types which are then separated for separating the differing particle types.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a schematic of a method for the separation of particles by using differences in the adherence properties of the particles to coating matter.  
         [0028]    [0028]FIG. 2 shows a schematic of a method for altering the adhesion of a mixture of differing particle types that are in the form of ores, minerals, or coal to a coating material.  
         [0029]    [0029]FIG. 3 shows a method and apparatus for forming differentially coated particles and their separation.  
         [0030]    [0030]FIG. 4 shows a method and apparatus for forming differentially coated particles and separating them using a thermal expander/separator.  
         [0031]    [0031]FIG. 5 shows a method and apparatus for forming differentially coated particles and separating them using a heat stress/separator.  
         [0032]    [0032]FIG. 6 shows a method and apparatus for forming differentially coated particles and separating using an electromagnetic separator.  
         [0033]    [0033]FIG. 7 shows a method and apparatus for forming differentially coated particles and separating using a magnetic heater/separator.  
         [0034]    [0034]FIG. 8 shows a method and apparatus for forming differentially coated particles and separating using an electric field heater/separator.  
         [0035]    [0035]FIG. 9 shows a method and apparatus for coating particles by condensation.  
         [0036]    [0036]FIG. 10 shows a method and apparatus for coating a mixture of particles with differing thicknesses.  
         [0037]    [0037]FIG. 11 shows a method and apparatus for forming differentially coated particles and separating them using an electromagnetic heater/separator.  
         [0038]    [0038]FIG. 12 shows a method and apparatus for forming differentially coated particles and separating them using an microwave heater/separator.  
         [0039]    [0039]FIG. 13 shows a method and apparatus for forming differentially coated particles and separating them using an electromagnetic conduction heater/separator.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]    Now referring to FIG. 1, there is shown a schematic of a method for the separation of particles by using differences in the adherence properties of the particles to coating matter. The method is a selective shedding process for the separation of particles and is generally indicated by the numeral  10 .  
         [0041]    The selective shedding process  10  operates as follows. A mixture, generally indicated by the numeral  12 , to be separated is selected. Mixture  12  can be selected to be in the form of crushed ores, minerals, coal and the like, or mixture  12  can be selected to be a mixture of fresh [good] and spent [bad] catalytic materials or mixture  12  can be selected to be a plurality of differing biological cell types. Mixture  12  is comprised of a plurality of particle types generally indicated by the numeral  14  having either (1) naturally occurring differences in their adhesion strength (adherence) to a material coating or (2) are imparted with such differences in accordance with the teachings of the present invention.  
         [0042]    Mixture  12  is then passed through a coating device  50  for coating at least two particle types contained in mixture  12  with at least one coating material  52  for forming a mixture of coated particle types generally indicated by the numeral  54  having differing pressure and/or abrasion sensitivities. In particular, mixture  12  is passed through device  50  for coating mixture  12  for forming a mixture of coated particle types  54  comprised of one more coated particle types  56  [not shown] having a low pressure and/or abrasion sensitivity and one or more particle types  58  [not shown] having a higher pressure or abrasion sensitivity. Coating device  50  can be any type well known in the art for coating particles, particulates, granules, or fine matter.  
         [0043]    The mixture of coated particles is then imparted with energy one or more times by at least one energy imparting device  60 . Device  60  can be of a type for imparting a substantially equal amount of energy to each coated particle type for removing more matter from particles  58  then from particles  56  for forming a mixture of differentially coated particles generally indicated by the numeral  62  comprised of one or more more coated particle types  64  and one or more less coated particle types  66 . Device  60  can be any known device(s) for applying energy to matter or can be one in accordance with the teachings of the present invention.  
         [0044]    Mixture  62  is then passed through one or more separators  70  for separating particles  64  from particles  66  for separating the differing particle into at least two separate streams generally indicated by the arrows  74  and  76  for separating particle types  14  from each other. Separator  70  can be any known means for separating particles. In the preferred form of the invention, separator  70  is of a type for separating mixture  62  in a more efficient manner than for separating mixture  12 . Separator  70  can be for example and not limiting the present invention to, an electrostatic separator, a floatation separator, a filtering device, inertial separator, other known physical separator or a separator in accordance with the teachings of the present invention.  
         [0045]    In the preferred form of the invention, the stress sensitivity of at least one particle type in the mixture of coated particles is determined by a tester  80  for determining the stress sensitivity of at least one particle type in the mixture for determining the amount of applied energy by the energy imparting device.  
         [0046]    The present invention also provides for a method for the determination of the kind and degree of coating removal by use of an acoustic emission detector for detecting the level and kind of acoustic emission occurring during the impartation or transmission of energy process. In the preferred form of the invention, the detector is in the form of a microphone located in or near the region of imparted energy for detecting acoustic waves and producing a signal. The signal is then sent to an acoustic analyzer of a type well known in the art for analyzing the signal and for directing an appropriate response in the decoating process, such as but not limited to, the amount and rate of energy applied by the stressing device.  
         [0047]    The present invention also provides for a method for the determination of the kind and degree of coating removal by use of a temperature detector for detecting the level temperature of the coated particles during the applied stress process. In the preferred form of the invention, the detector is in the form of a thermocouple located in or near the region of imparted energy for detecting the temperature and producing a signal. The signal is then sent to an analyzer (a computer connected with the acoustic detector) of a type well known in the art for analyzing the signal and for directing an appropriate response in the decoating process such as but not limited to the amount and rate of energy applied by the stressing device.  
         [0048]    The present invention also provides for another method for the determination of the kind and degree of coating removal in the form of a fine particle detector for measuring the amount and kinds of fines generated during the decoating process. In one form of the invention, the fine particle detector is in the form of a filter for collecting an measuring the amount of fines created. In another form of the invention, the fine particle detector is in the form of a blower for blowing a fluid through a pile processed coated particles for determining the degree of fines generated by measuring the amount of fluid passed through the batch of processed coated particles in a given time.  
         [0049]    Major New Invention  
         [0050]    The present invention also provides for yet another method for the determination of the kind and degree of coating removal by measuring the vibrational energy imparted to the particles by the imparting device.  
         [0051]    In another form of the invention, the mixture of coated particles is sized by a sizer before being passed through the stressing device for forming a mixture of substantially uniformly sized coated particles and thereby increase the selectivity of the coating removal process.  
         [0052]    The present invention provides for three general methods for selectively altering the pressure and/or abrasion sensitivities of one or more coated particle types in the mixture of coated particles for increasing the efficiency of the separation process. These three general methods are (1) selecting mixture  12  having differing particle types having differing adhesion strengths or adherences to the coating material, (2) pretreating the mixture of particles before the coating step for increasing the differnces in the adhesion strengths or adherences to the coating for one or more particle types to a greater extent than for at least one other particle type, or (3) coating the mixture of particles in such a way to bring about increased differences in adhesion strengths or adherences of one or more particle types to the coating material than for at least one other particle type.  
         [0053]    I. Selecting the Mixture of Particles for Having Differing Particle Types Having Differing Adhesion Strengths or Adherences to the Coating Material by:  
         [0054]    1. Selecting a mixture  12  for containing particles  14  that differ in one or more of the following properties: composition, crystalline structure or particle morphologies for creating a plurality of substantially uniformly coated particle types  22  having differing pressure or abrasion sensitivities.  
         [0055]    2. Selecting a mixture  12  for containing particles  14  that differ in wetting ability to one or more coating material(s) for creating a plurality of coated particle types  22  having differing pressure or abrasion sensitivities.  
         [0056]    3. Selecting a mixture  12  for containing particles that differ in their ability to form solid matter at the coating-particle interface at a set temperature for creating a plurality of coated particle types having differing pressure or abrasion sensitivities due to the presence of a fluid at the interface for at least one particle type while one other particle type has a solid layer at that temperature. For example around −13 C. ice forms at the interface around some particle types and for others is forms a liquid layer between the particle and the ice.  
         [0057]    4. Selecting a mixture  12  for containing particles that differ in their surface energies for creating a plurality of coated particle types having differing pressure or abrasion sensitivities. 5. Selecting a mixture  12  for containing particles that differ in their ability to form compounds with coating material for creating a plurality of coated particle types having differing pressure or abrasion sensitivities. In another form of the invention, mixture  12  is selected for containing particles  14  at least one of which is capable of forming compounds with coating material for creating a mixture of coated particles having differing adherences.  
         [0058]    6. Selecting a mixture  12  for containing particles at least one of which is capable of interacting with a fluid while being imparted with energy for removing more coating material from those surfaces.  
         [0059]    7. Selecting a mixture  12  for containing particles that have differing pressure or abrasion sensitivities at different rates of imparting energy for forming a mixture of differentially coated particles to be separated.  
         [0060]    II. Coating the Mixture of Particles in Such a Way to Bring About Increased Differences in their Adhesion Strengths or Adherences to the Coating Material for One or More Particle Types to a Greater Extent than for at Least One Other Particle Type by  
         [0061]    1. A) Selecting a mixture  12  for containing particles that differ in their ability to cure coating material (b)two or more particle types in mixture  12  are then coated and then after a selected time interval one or more particle types are decoated. This form of the invention is particularly useful when applied to coating forming electrostatic bonds with the particles.  
         [0062]    2. Selecting a coating material for forming a coating comprising one or more discrete layers with little or no compound formation. This may be accomplished by selecting a coating material that is chemically inert to the mixture of particles. In particular, a chemically inert coating material can be selected for forming a discrete layer on the particles that is held thereon by one or more of the following forces  
         [0063]    1) electrostatic attraction  
         [0064]    2) polar bonds  
         [0065]    3) ionic bonds or  
         [0066]    4) Van der Waals forces.  
         [0067]    This method of separation by selective removal of a discrete layer or layers of coating material is particularly useful in the separation of particles having differences in one or more of the following properties  
         [0068]    A) particle composition,  
         [0069]    B) crystalline structure or  
         [0070]    C) particle morphologies  
         [0071]    such that the differing particle types form different types or degrees of binding forces for forming a mixture of coated particle types having differing adhesive strengths.  
         [0072]    Another advantage of forming a discrete layer of coating material is that the material can be recovered at the end of the separation process and recycled.  
         [0073]    3. Selecting a coating material for selectively interdiffusing with at least one type of particle in the mixture of particles for forming an interdiffused layer at the coating-particle interface. The mixture of particles is then coated for forming an interdiffused layer on selected particle types for creating a mixture of coated particles having differing pressure and/or abrasion sensitivities.  
         [0074]    4. Selecting a coating material for coating the mixture of particles by evaporation for forming a mixture of coated particle types having differing pressure or abrasion sensitivities. In particular, selecting a coating material for coating a mixture of particles having differing porosities for forming a mixture of coated particles having differing pressure or abrasion sensitivities.  
         [0075]    III. Pretreating the Mixture of Particles Before the Coating Step for Increasing the Differences in the Adhesion Strengths or Adherences to the Coating  
         [0076]    The present invention provides for several method and apparatuses for imparting energy to the coated particles for forming a mixture of differentially coated particles. These methods and apparatuses can be used separately or in combination for effectually achieving differentially coated particles. In one form of the invention, the energy is imparted to the coated particles by an energy imparting device in the form of a mechanical impactor for imparting energy by impaction. In this form of the invention, the coated mixture of particles are physcially moved about in such a manner by the mechanical impactor that the coated particles come into contact with each other, or other objects for imparting energy thereto. The contacting or impacting can be of a singe type or can be comprised of a number of impacts. In the preferred form of the invention, the number of impacts and the amount of energy imparted to each of the coated particle types is substantially the same for removing a greater amount of coating material from particle types having a low pressure or abrasion sensitivity. The impacts can be in the form of, but are not limited to, one or more of the following: striking, shearing and or frictional forces.  
         [0077]    In another form of the invention, the energy is imparted to the mixture of coated particles by an energy imparting device in the form of an expansion device for imparting energy in the form of pressure at the particle-coating interface. In this form of the invention the mixture of particles  12  is coated with one or more coating materials in a fluid under pressure; the mixture of coated particles is then brought to a region of lower pressure by such an expansion device as an expansion nozzle for imparting energy in the form of built up pressure at the particle-coating interface. In the preferred of the invention, the coating material is comprised of an inner layer of more volatile material than that of an out coating material. The inner coating material can be in the form of a fluid. This form of the invention can be easily coupled with an additional energy imparting device in the form of a mechanical for both imparting energy in the form of built up pressure and in the form of mechanical energy.  
         [0078]    In still another form of the invention, the energy is imparted to the mixture of coated particles by an energy imparting device in the form of a heater. The mixture of coated particles can be either (1) heated uniformly (or nearly uniformly) or (2) heated nonuniformly.  
         [0079]    In another form of the invention, the energy is imparted to the mixture of coated particles by an energy imparting device in the form of an electromagnetic radiator for selectively heating one or more particle types to a greater extent than for at least one other particle type.  
         [0080]    In the preferred form of the invention, the differences in the adherences or binding energies of the differing particles to the coating is great enough such that they can be differentially decoated in kind or degree by the use of a controlled amount of imparted energy. In addition to these energy requirements, it is preferred that the overall energy used in the decoating process be low for reducing the cost of processing. The present invention therefore provides for several methods for forming coated particles having differing adherences while having at least one particle type having a coating that is easy to remove.  
         [0081]    In one form of the invention, the coating material is selected for forming a frangible or cleavable coating for easily splitting of matter when imparted with energy. In this form of the invention, the coating material can be selected from but not limited to the group comprised of ice, gas hydrates, an inorganic salt or a mixture of such salts, such as but not limited to nitrates, carbonates, bicarbonates, phosphates, silicates and chlorides, especially alkali metal salts and alkaline earth metal salt, and minerals which liberate molecularly bound water or water of crystallization upon heating.  
         [0082]    In another form of the invention, the coating material is comprised of organic matter which can be in the form of polymers. In either case, the coating material can be applied in the form of a gas, liquid, semiliquid or solid. For liquids and semiliquids, after expose to the liquids or semiliquids material is allowed to set. The set may result form evaporation, solidification, deemulification, crosslink formation or other method for setting liquids well known in the art of coating.  
         [0083]    The coating may be carried out by any conventional coating process, e.g. by contacting the particles with a solution under vaporizing conditions in a rotating inclined disk, a rotary drum, or in a fluidized bed.  
         [0084]    The choice of apparatus in which to carry out the coating process is not critical. Thus it may be for example, a rotating inclined disk, or a rotary drum. Other similar equipment may also be used. A particularly preferred apparatus is a fluidised bed, operated conventionally so that the particles are fluidised by an upward-flowing inert gas such as air or nitrogen and are contacted with a solution, the solvent of which evaporates off depositing a coating on the particles. The solution may be injected directly into the bed, srayed onto the bed or dispersed in the upward-flowing inert gas. The process may be operated batchwise, or continuously by using a compartmented bed. The exit of the coated particles may be obtained by a simple overflow device or by elutriation via an outlet located at any desired level in the bed.  
         [0085]    Whichever apparatus employed it is preferable that the particles should be contacted with solution at a temperature sufficiently high to result in rapid evaporation of solvent from the solutions. Clearly, the preferred temperature will depend upon the solvent used and for water should be of the order of 60° C. or more.  
         [0086]    In the preferred form of the invention, the fines generated by the coating removal process are separatly withdrawn from the decoater (energy impacting device).  
         [0087]    Now referring to FIG. 2, there is shown a schematic of a method for altering the adhesion of a mixture of differing particle types that are in the form of ores, minerals, or coal to a coating material. The method is an ore, mineral or coal pretreatment process generally indicated by the numeral  110  for altering the degree of adherences of at least one particle type to a coating material.  
         [0088]    The ore, mineral, or coal pretreatment process operates as follow. A mixture of particles generally indicated by the numeral  111  in a bulk  109  are passed through a reducing device  113  for liberating particles  11  for forming a mixture generally indicated by the numeral  115  of free particles generally indicated by the numeral  117 . Reducing device  113  can be any known type of reducer for liberating particles form ores, minerals or coal.  
         [0089]    The mixture  115  of free particles  117  is then passed through a sizer  119  for forming a mixture generally indicated by the numeral  121  of substantially uniformly sized particles  123 . Sizer  119  can be any known sizer, such as but not limited to a screening separator of a type well known in the art.  
         [0090]    Mixture  121  is then passed through a washer  125  for removing contaminates therefrom for forming a mixture  131  comprised of substantially uniformly sized, and substantially clean particles  133 .  
         [0091]    Mixture  131  is then passed through a dyer  135  for dying mixture  131  of particles  133  for forming a mixture generally indicated by the numeral  41  comprised of substantially uniformly sized substantially cleaned and substantially dried particles  143  having a well defined adhesion strength for each particular particle type. After this pretreatment the mixture of particles is then ready for separation in accordance with the teachings of the present invention.  
         [0092]    In another form of the invention, mixture  141  is then passed through and additional pretreater  171  for forming a mixture generally indicated by the numeral  173  of particles  175  having a higher degree of differences in their pressure or abrasion sensitivities. Pretreater  171  can be an oxidzer for oxidizing particles  143 , a reducer for reducing particles  143 , a water exposer for forming a layer of water on at least one particle type or be of a type in accordance with the teachings of the present invention.  
         [0093]    Now referring to FIG. 3 there is shown a method and apparatus for forming differentially coated particles and their separation. The apparatus is a decoating particle separator generally indicated by the numeral  210 .  
         [0094]    The decoating particle separator  210  operates as follows. A mixture generally indicated by the numeral  212  of two or more coated particle types is accelerated by a flow of air in a direction generally indicated by the numeral  214  through an expansion nozzle or tube  216 . The accelerated mixture of coated particles generally indicated by the numeral  218  is exposed to an energy imparting device in the form of a contact surface  220  for imparting energy to the mixture of coated for removing matter from at least one particle type  224  having a greater pressure or abrasion sensitivity to a greater extent than for at least one other particle type  226  having a lower pressure or abrasion sensitivity for forming a mixture of differentially coated particles generally indicated by the numeral  228 . Mixture  228  is then allowed to fall in the direction indicated by the arrow  230  and into a screen shaker  232  for separating particle types  224  and  226  from each other for separating the differing types of particles.  
         [0095]    Now referring to FIG. 4, there is shown another method and apparatus for forming differentially coated particles and their separation. The apparatus is a thermal expander/separator generally indicated by the numeral  310 .  
         [0096]    The thermal expander/separator  310  operates as follows. A mixture generally indicated by the numeral  310  of two or more coated particle types is passed into an expansion nozzle or tube  316 . Tube  316  in in intamate contact with a heat exchanger for either heating or cooling the mixture of coated particles  312  for imparting or removing energy therefrom for thermally stressing to at least one particle type to a greater extent than for at least one other particle type for forming a mixture generally indicated by the numeral  315  of differentially thermally stressed particle types. The thermal stress may be in the form of a thermal expansion or contraction of the particles contained in the coated particles  312 . Mixture  315  is is then exposed to an additional energy imparting device  320  for imparting energy to the mixture of coated particles for removing matter form at least one coated particle type  324  to a greater extent than at least one other particle type  326  for forming a mixture of differentially coated particles generally indicated by the numeral  328 . Energy imparting device  320  is of a type for apply a force to the mixture of coated particles. In the preferred form of the invention, energy imparting device  320  is of a type for applying a impact force, or a pulling force or a vibrating force or combination thereof. Mixture  528  falls in the direction indicated by the arrow  330  and into a screen shakeer  332  for separating particle types  324  and  326  from each other for separating the differing types of particles.  
         [0097]    Now referring to FIG. 5, there is shown another form of the invention for forming differentially coated particles and their separation. The apparatus is a heat stress/separator generally indicated by the numeral  410 .  
         [0098]    The heat stress/separator  410  operates as follows. A mixture generally indicated by the numeral  412  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  214  through a tube  416 . The accelerated mixture of coated particles generally indicated by the numeral  218  is passed through a energy imparting device in the form of a flame for thermally stressing at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  425  of differentially thermally stressed coated particles. The thermal stress can be due but is not limited to differences in the thermal conductivities of the differing particle type to be separated. Mixture  425  is then exposed to an additional energy imparting device in the form of a contact surface  420  for imparting energy to mixture  425  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  424  to a greater extent than for at least one other particle type  426  for forming a mixture of differentially coated particles generally indicated by the numeral  428 . Mixture  428  falls in the direction indicated by the arrow  430  and into a screen shaker  432  for separating particle types  424  and  426  from each other for separating the differing types of particles.  
         [0099]    Now referring to FIG. 6 there is shown a yet another method and apparatus for forming differentially coated particles and their separation. The apparatus is a electromagnetic separator generally indicated by the numeral  510 .  
         [0100]    The electromagnetic separator  510  operates as follows. A mixture generally indicated by the numeral  512  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  514  through a tube  516 . The accelerated mixture of coated particles generally indicated by the numeral  518  is passed through a energy imparting device in the form of an electromagnetic wave  417  generated by an electromagnetic wave generator  427  for thermally stressing at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  525  of differentially thermally stressed coated particles. Electromagnetic wave generator  527  can be a microwave source, an rf heater, a light source for emitting light in the ir, near ir, visible or uv spectrum such as a laser. In the preferred form of the invention for minerals the light generator  527  is a tungsten filament with a polished aluminum reflector for forming imparting energy to the interface with visible light. One or more filters can be used to filter the light from the tungsten filament for imparting visible light in a narrow spectrum region. The thermal stress generated in one or more particles can be due but is not limited to difference in the absorption characteristics of the differing particle types to be separated. Mixture  525  is then exposed to an additional energy imparting device in the form of a contact surface  520  for imparting energy to mixture  525  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  524  to a greater extent than for at least one other particle type  526  for forming a mixture of differentially coated particles generally indicated by the numeral  528 . Mixture  528  falls in the direction indicated by the arrow  530  and into a screen shaker  532  for separating particle types  524  and  526  from each other for separating the differing types of particles.  
         [0101]    Now referring to FIG. 7 there is shown a still yet another method and apparatus for forming differentially coated particles and their separation. The apparatus is a magnetic heater/separator generally indicated by the numeral  610 .  
         [0102]    The magnetic heater/separator  610  operates as follows. A mixture generally indicated by the numeral  612  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  614  through a tube  616 . Mixture  612  contains one or more particle types that are capable of being heated by to a greater degree by an high frequency magnetic field than for at least one other particle in the mixture of coated particles. The accelerated mixture of coated particles generally indicated by the numeral  618  is passed through a energy imparting device in the form of an high frequency magnetic field  517  generated by an magnetic generator  627 , of a type well known in the art, for thermally stressing at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  625  of differentially thermally stressed coated particles. In the preferred form of the invention, high frequency magnetic field  617  is between 50 Hz to 100 Ghz for differentially heating differing particle types due to differences in hysteresis losses or Joule heating. Mixture  625  is then exposed to an additional energy imparting device in the form of a contact surface  620  for imparting energy to mixture  625  of differentially thermally stressed coated particles for removing matter from at least one coated particle type  624  to a greater extent than for at least one other particle type  626  for forming a mixture of differentially coated particles generally indicated by the numeral  628 . Mixture  628  falls in the direction indicated by the arrow  630  and into a screen shaker  632  for separating particle types  624  and  626  from each other for separating the differing types of particles.  
         [0103]    Now referring to FIG. 8 there is shown a another method and apparatus for forming differentially coated particles and their separation. The apparatus is a electric field heater/separator generally indicated by the numeral  710 .  
         [0104]    The electric field heater/separator  710  operates as follows. A mixture generally indicated by the numeral  712  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  714  through a tube  716 . Mixture  712  contains one or more particles having a dielectric constant such that they are capable of being heated by to a greater degree by an high frequency electric field than for at least one other particle in the mixture of coated particles. The accelerated mixture of coated particles generally indicated by the numeral  718  is passed through a energy imparting device in the form of an high frequency electric field  717  generated by an electric field generator  727 , of a type well known in the art, for thermally stressing [heating] at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  725  of differentially thermally stressed coated particles. In the preferred form of the invention, high frequency electric field  717  is between 50 Hz to 100 Ghz for differentially heating differing particle types due to differences in dielectric loss. Field  717  can be either continuously or intermittently applied to the coated particles. Mixture  725  is then exposed to an additional energy imparting device in the form of a contact surface  720  for imparting energy to mixture  725  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  724  to a greater extent than for at least one other particle type  726  for forming a mixture of differentially coated particles generally indicated by the numeral  728 . Mixture  728  falls in the direction indicated by the arrow  730  and into a screen shaker  732  for separating particle types  724  and  726  from each other for separating the differing types of particles.  
         [0105]    In another form of the invention, the particles are selectively heated by a combination of both high frequency magnetic and electric fields for selectively thermally stressing the coated particles.  
         [0106]    Now referring to FIG. 9, there is shown a method and apparatus for coating particles by condensation. The apparatus is a particle coating apparatus generally indicated by the numeral  810 .  
         [0107]    The particle coating apparatus  810  operates as follows. A mixture of particles  812  is passed into a tube or channel  814  by a flow of gas generally indicated by the numeral  816 . Tube  814  is in thermal contact with a exchanger  818  for lowering the temperature of the mixture of temperature  812  to just above the dew temperature of gas  816 . The gas can be comprised of water or water and a gas for forming ice or a gas hydrate. The mixture of gas  816  and particles  812  is then passed through an expansion nozzle  820  for expanding the mixture for forming coated particles  822  by condensation processes. The coated particles can be in the form of ice or gas hydrate covered particles that are at least partially transparent to visible light and selected wwavelenghts of micowaves.  
         [0108]    Now referring to FIG. 10, there is shown a method and apparatus for coating a mixture of particles with differing thicknesses. The apparatus is a particle cooling/condensation apparatus generally indicated by the numeral  910 .  
         [0109]    The particle cooling/condensation apparatus  910  operates as follows. A mixture of particles  912  is passed into a tube  914  by a flow of gas  916 . Tube  914  is in thermal contact with a heat exchanger  918  for heating the mixture of particles to a temperature at least 5 degrees C above the dew point of gas  916 . The mixture of gas  916  and particles  912  is then passed through an expansion nozzle  920  for condensating a greater amount of gas  916  onto particles having a higher thermal conductivity or lower specific heat than for other particle types having a higher specific heat for forming a mixture of particle types having differing thicknesses.  
         [0110]    Now referring to FIG. 11 there is shown a another method and apparatus for forming differentially coated particles and their separation. The apparatus is an electromagnetic heater/separator generally indicated by the numeral  1010 .  
         [0111]    The electromagnetic heater/separator  1010  operates as follows. A mixture generally indicated by the numeral  1012  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  1014  through a tube  1016 . Mixture  1012  contains one or more particles having differing absorption characteristics such that they are capable of being heated by to a greater degree by an electromagnetic radiation of a selected wavelength(s) than for at least one other particle in the mixture of coated particles. The accelerated mixture of coated particles generally indicated by the numeral  1018  is passed through a energy imparting device in the form of an intense electromagnetic radiation  10110  generated by an electromagnetic radiation generator  1027 , of a type well known in the art, for thermally stressing [heating] at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  1025  of differentially thermally stressed coated particles. In one form of the invention, the electromagnetic radiation is in the visible range of the spectrum [from 300 to 700 nanometers] for differentially heating different particle types that are colored differently. In this form of the invention, it is preferred that the coating be at least partially transparent to the selected wavelength of light. For this purpose the coating can be made of, for example and limiting the invention to, ice or a gas hydrate. The electromagnetic radiation  1017  can be either continuously or intermittently applied to the coated particles. Mixture  1025  is then exposed to an additional energy imparting device in the form of a contact surface  1020  for imparting energy to mixture  1025  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  1024  to a greater extent than for at least one other particle type  1026  for forming a mixture of differentially coated particles generally indicated by the numeral  1028 . Mixture  1028  falls in the direction indicated by the arrow  1030  and into a screen shaker  1032  for separating particle types  1024  and  1026  from each other for separating the differing types of particles.  
         [0112]    Now referring to FIG. 12, there is shown a another method and apparatus for forming differentially coated particles and their separation. The apparatus is an microwave heater/separator generally indicated by the numeral  1110 .  
         [0113]    The microwave heater/separator  1110  operates as follows. A mixture generally indicated by the numeral  1112  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  1114  through a tube  1116 . Mixture  1112  contains two or more particle types having different induction heating characteristics (i.e, distinct thermal, dielectric strength and/or loss tangent characteristics such that at leat one particle type is capable of being heated by to a greater degree by an microwave radiation of a selected wavelengths than for at least one other particle in the mixture of coated particles. The accelerated mixture of coated particles generally indicated by the numeral  1118  is passed through a energy imparting device in the form of an microwave radiation  1110  generated by an microwave generator  1127 , of a type well known in the art, for thermally stressing [heating] at least one particle type to a greater extent than for at least one other particle type in the mixture for forming a mixture generally indicated by the numeral  1125  of differentially thermally stressed coated particles. In one form of the invention, the microwave frequency is held at 10 Ghz for passing through a water and/or ice coating. The microwave radiation  1117  can be either continuously or intermittently applied to the coated particles. Mixture  1125  is then exposed to an additional energy imparting device in the form of a contact surface  1120  for imparting energy to mixture  1125  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  1124  to a greater extent than for at least one other particle type  1126  for forming a mixture of differentially coated particles generally indicated by the numeral  1128 . Mixture  1128  falls in the direction indicated by the arrow  1130  and into a screen shaker  1032  for separating particle types  1124  and  1126  from each other for separating the differing types of particles.  
         [0114]    Now referring to FIG. 13 there is shown a another method and apparatus for forming differentially coated particles and their separation. The apparatus is an electromagnetic conduction heater/separator generally indicated by the numeral  1210 .  
         [0115]    The electromagnetic heater/separator  1210  operates as follows. A mixture generally indicated by the numeral  1212  of two or more coated particle types is accelerated by a flow of air generally indicated by the arrow  1214  through a tube  1216 . Mixture  1212  contains one or more particles having differing absorption characteristics and/or thermal conductivities such that they are capable of being heated by to a greater degree by an electromagnetic radiation of a selected wavelength(s) than for at least one other particle in the mixture of coated particles. The accelerated mixture of coated particles generally indicated by the numeral  1218  is passed through a energy imparting device in the form of an non-intense electromagnetic radiation  1210  generated by an electromagnetic radiation generator  1227  for a time sufficient for at least one particles type to transfer heat away from the interface for heating that particle type to a lessor extent than for at least one other type for forming a mixture generally indicated by the numeral  1225  of differentially thermally stressed coated particles. In this form of the invention, it is preferred that the coating be at least partially transparent to the selected wavelength of light. The electromagnetic radiation  1217  can be either continuously or intermittently applied to the coated particles. Mixture  1225  is then exposed to an additional energy imparting device in the form of a contact surface  1220  for imparting energy to mixture  1225  of differentially thermally stressed coated particles for removing matter form at least one coated particle type  1224  to a greater extent than for at least one other particle type  1226  for forming a mixture of differentially coated particles generally indicated by the numeral  1228 . Mixture  1228  falls in the direction indicated by the arrow  1230  and into a screen shaker  1232  for separating particle types  1224  and  1226  from each other for separating the differing types of particles.