Abstract:
The iron and steel industry has a history of environmental consciousness, and efforts are continually made to reduce energy consumption and CO 2  emissions. However, the carbothermic process has approached limits on the further reduction of greenhouse gas emissions, and only marginal improvements can be expected. Low temperature electrolysis using a dispersion medium to efficiently distribute charge throughout a colloid mixture including iron oxide provides an environmentally friendly method for performing an electrochemical reduction of Fe 2 O 3  to produce granular Fe. An electrical-ionic conductive colloidal electrode containing the electrochemically active species (Fe 2 O 3  particles), the liquid electrolyte (NaOH solution), and a percolating electrical conductor (carbon network) is utilized to produce Fe. The resulting simultaneous percolation of electrons and ions effectively increases the area of the current collector, and enables the process to function at higher currents and rate of charge transfer than static electrolysis.

Description:
RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent App. No. 62/037,723, filed Aug. 15, 2014, entitled “ELECTROLYSIS BASED STEEL FABRICATION,” incorporated by reference in entirety. 
     
    
     BACKGROUND 
       [0002]    Iron (Fe) is the most widely used metal, and currently nearly all crude Fe is produced by reducing Fe ores with coke in a blast furnace at a temperature of 2000 degrees Celsius. This carbothermic reduction process directly produces liquid metal, however it generates two metric tons of CO 2  per metric ton of crude Fe produced. In addition to carbon emissions from the blast furnace, the iron and steel industry contributes greenhouse gas (GHG) in several ways, including coke production emissions, the use of carbonate flux during calcination, and emissions from the carbon electrodes in electric arc furnaces. 
       SUMMARY 
       [0003]    Configurations herein are based, in part, on the observation that iron production produced by conventional carbothermic processes (Fe 2 O 3 +C=Fe+CO 2 ) using high temperature blast furnaces for heating required to generate the desired reaction. Unfortunately, conventional approaches suffer from the shortcoming that the carbothermic approach generates large quantities of carbon dioxide and other so-called “greenhouse gases” that are environmentally detrimental. Accordingly, configurations herein substantially overcome the above described shortcomings by providing a low temperature electrolysis (LTE) approach that generates iron powder from an electrochemical reaction in a fluidic substance, and avoids the high temperature reaction and resulting volume of carbon dioxide. 
         [0004]    Conventional attempts to generate low temperature electrolysis based iron have encountered difficulty with volume and throughput because the electrical current, or electrons, are limited to the contact point of the electrode, and further that the iron particles have the tendency to adhere to the electrode once the reaction is complete. 
         [0005]    These major challenges have prevent the LTE process from being adopted in commercial plants. Conventional electroextraction of metal is normally achieved from dissolved species, which are transported by electromigration and diffusion. The solubility of reactant and liquid-to-surface mass-transfer control can be the main limitation for productivity. In the current alkaline LTE process, one way is Fe 2 O 3  particles suspend in alkaline solution and Fe 2 O 3  particles also need to diffuse to the electrode surface for the electrochemical reaction to occur, which lowers the reaction rate. Kinetically, the diffusion of solid Fe 2 O 3  particles to the electrode surface can be the limiting step, and the point, or single, electrode area limits the reaction rate. Fe is deposited on the electrode surface, and therefore the electrode must be removed in order to collect Fe, which could interrupt the production process. The other way is Fe 2 O 3  particles are pressed to a pellet under very high pressure. The pellet is treated as cathode in alkaline electrolyte. Due to the very poor electronic conductivity of Fe 2 O 3 , the reaction rate is also very slow. 
         [0006]    In order to overcome above challenges associated with the LTE process, configurations herein introduce a process where the electrons and ions can percolate into the liquid mixture, referred to as a colloid, and this mixture contains the iron oxide or other target substance that can be extracted easily from the electrolysis, which significantly increases the reaction rate and allow the production continuously. The fluidic substance defining a conductive Fe 2 O 3  colloidal electrode flows into an electrochemical cell, for continuous electrolysis, from an input reservoir. Fe is collected in an extraction reservoir, which facilitates the collection of the reduced Fe. An electronic-ionic conductive colloidal electrode, which contains the electrochemically active species (Fe 2 O 3  particles), the liquid electrolyte (NaOH solution), SDBS and a percolating electronic conductor (carbon network) is utilized to overcome the diffusion limitation of Fe 2 O 3  electrolysis associated with 2-dimensional reaction area and the poor electronic conductivity of Fe 2 O 3 . A formed 3-dimensional network with mixed conductivity significantly increases the reaction area and electrolysis current. Fe 2 O 3  particles then do not need to diffuse to the electrode surface for the effective electrochemical reaction to occur and percolated carbon network increases electronic conductivity effectively. 
         [0007]    In further detail, the method for low temperature electrolysis (LTE), as disclosed herein includes circulating a fluidic substance between opposed electrodes, in which the fluidic substance is defined by a colloid including a reactant, an electrolyte, and a disbursement medium, the colloid responsive to an electric charge for producing a target reaction. A flow pump or other flow process agitates the fluidic substance for disposing the fluidic substance between the opposed electrodes, and an electrical source applies an electric charge to the opposed electrodes for electrolytically causing the target reaction. Outflow from the pumped fluidic substance is directed to a reservoir for receiving the circulated fluidic substance, which now includes a precipitate or result of the target reaction for separating a desired substance from the fluidic substance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0009]      FIG. 1   a  shows the dispersement medium in the fluidic substance including the reactant; 
           [0010]      FIG. 1   b  shows a graphing of an increase in electrical charge resulting from the dispersement medium of  FIG. 1   a;    
           [0011]      FIG. 2  shows a flow electrolysis design for agitating the fluidic substance between the opposed electrodes for facilitating electrolysis using the dispersement medium of  FIG. 1   b ; and 
           [0012]      FIGS. 3   a - 3   c  show promoting or shifting the electrochemical reaction rate away from undesired substances such as hydrogen gas. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Configurations discussed below depict an example arrangement of the disclosed approach. The fluidic substance defining the colloid circulates through a flow vessel or other containment for agitating the fluidic substance in communication with electrodes. 
         [0014]    The fluidic substance flows between a source and collection reservoir. The source reservoir contains a mixture defining the colloid including the iron oxide or other reactant, the electrolyte, typically an alkaline substance, and the dispersement medium for facilitating charge conductivity through the fluidic substance, such as a carbon network resulting from carbon powder. The colloid mixture including the disbursement medium (carbon) therefore defines a colloid electrode because the liquid substance itself conducts the electrical charge to the Fe 2 O 3  particles. Following electrolysis in the flow vessel, the fluidic substance flows to the collection reservoir where iron particles (Fe) or other result of the electrolysis are gathered and extracted by a magnetic, filtration or other separation approach. 
         [0015]      FIG. 1   a  shows the dispersement medium in the fluidic substance including the Fe 2 O 3  reactant. Referring to  FIG. 1   a , in a fluidic substance  100 , a dispersement medium  110  such as carbon powder percolates throughout the fluidic substance  100  to form a carbon network  112 . An electron flow  114  from an electrode  116  transports electrons to a reactant  120  such as iron oxide (Fe 2 O 3 ). A resulting electrolysis (electrochemical reaction) generates iron particles (Fe) as the desired substance  130 , which is then physically extracted or filtered out as the fluidic substance  100  is pumped into a containment reservoir. In the example approach, the electrolysis reaction is given by: 
         [0000]      Cathode: Fe 2 O 3 (s)+3H 2 O+6e − →2Fe(s)+60H − 
 
         [0000]      Anode: 60H − →3/2O 2 (g)+3H 2 O+6e − 
 
         [0016]      FIG. 1   b  shows a graphing of an increase in electrical charge resulting from the dispersement medium of  FIG. 1   a . Referring to  FIGS. 1   a  and  1   b , the electrode  116  provides voltage resulting in a current to an opposed electrode through the fluidic substance  100 . In a suspension without the dispersement medium  110 , electrical flow is limited as current encounters resistance, as shown by line  140 . In a colloid defined by the reactant mixed with the dispersement medium  110 , current flow is facilitated as electrons may pass between particles of the particles (i.e. carbon atoms) of the dispersement medium  110 , as shown by line  142 . The disclosed colloids may include gels, sols, and emulsions, such that the particles do not settle and are difficult to separate out by ordinary filtering or centrifuging as in a suspension. In the example configuration, the fluidic substance  100  is defined by a colloid mixture defining a colloidal electrode, which contains the electrochemically active species (Fe 2 O 3  particles), the liquid electrolyte (NaOH solution), and a  3 D percolating electrical conductor (C network). The simultaneous percolation of electrons and ions effectively increases the area of the current collector, and enables the process to function at high currents rates such as those in  FIG. 1   b.    
         [0017]    In the example configuration, the iron oxide defines a reactant responsive to electrolysis for generating iron particles and oxygen as a by-product, rather than CO 2  as in conventional approaches. Alternate configurations may employ other reactants, in which the reactant is form of the desired substance in a molecular form responsive to the electric charge to result in a desired substance as a result of the target reaction. A fluidic substance  100  including the reactant generates the desired substance from electrolysis of the reactant resulting in an alternate molecular form of the reactant, such as the disclosed Fe 2 O 3  to Fe as in the reaction above. 
         [0018]    Other forms of the reactant may also benefit from the approach herein in addition to iron oxide. For example, the reactant may include forms of other metals such as Fe, Ag, Ni, Cu, and rare earth elements for extraction as the desired substance. 
         [0019]      FIG. 2  shows a flow electrolysis design for agitating the fluidic substance  100  between the opposed electrodes for facilitating electrolysis using the dispersement medium of  FIG. 1   b . Referring to  FIGS. 1   a ,  1   b  and  2 , a flow vessel  150  may include an electrochemical cell fluidically coupled between a colloid reservoir  152 , or source, and an output reservoir  154 . A pump  156  drives and agitates the fluidic substance  100  from the reservoir  152  through the flow vessel  150  where the fluidic substance  150  is in communication with opposed electrodes, including a titanium plate cathode  160  and a platinum foil anode  162  connected to a voltage source  164  such as a potentiostat. The electrodes are not limited to titanium and platinum. Other metals/alloys and materials can also be utilized as the electrodes. A series of parallel opposed plates  160 -N and  162 -N define the electrodes and enhance the surface area of the electrodes for transfer of electrons to the fluidic substance  100 , and the resulting iron particles contained in an outflow liquid  100 ′ in the output reservoir  154 . 
         [0020]    The pump  156  operation and a resulting flow rate of the fluidic substance  100  across the electrodes may be altered to conform to a desired reaction rate in the flow vessel. The reaction rate may depend on such factors as the electrical plate size, the fluid vessel size, the capacity of the pump, and other factors which affect the speed with which electrolysis occurs in the flow vessel. Flow may be altered according to static and continuous modes, and circulating the fluidic substance based on intervals of static containment of the fluidic substance and resuming a fluidic flow of the fluidic substance across the opposed electrodes following the interval. A continuous mode may also be employed for circulating the fluidic substance in a continuous flow across the electrodes and collecting the continuous flow in a reservoir for extracting the desired substance. 
         [0021]    The dispersement medium  110  percolates throughout the fluidic substance  100  permits electrolysis even when the Fe 2 O 3  particles are not in contact with an electrode  160 ,  162  as the electrons  114  are dispersed throughout the fluidic substance  100  by the carbon particles in the dispersement medium  110  which conducts charge. The electrode  160 ,  162  plates disperse an electric charge throughout the fluidic substance from conductivity of the dispersement medium for transporting electrons from at least one of the opposed electrodes  160 ,  162  to the reactant via the dispersement medium  110 . Thus, the dispersement medium  110  defines a percolating electrical conductor dispersed in the fluidic substance  100  and conducive to conducting electrical charges throughout the fluidic substance  100  for providing electrons to the target reaction. 
         [0022]    In operation, the pump  156  draws the fluidic substance from the colloid reservoir  152  to propel the fluidic substance  110  through the flow vessel  150  for agitating the fluidic substance  100  to disposing the fluidic substance between the opposed electrodes. Movement of the fluidic substance, in combination with the dispersement medium, allows electrical communication between the reactant particles as electrons flow to the reactant for generating the desired substance through electrolysis. In this manner, the flow vessel  150  circulates the fluidic substance between the opposed electrodes  160 ,  162 , such that the fluidic substance  100  is defined by a colloid including a reactant, an electrolyte, and a disbursement medium, in which the colloid includes the reactant responsive to an electric charge for producing a target reaction. The reactant flowing through the flow vessel  150  generates an electrolytic reaction from a colloidal electrode, in which the colloidal electrode is defined by the combination of the dispersement medium  110  and the reactant for transporting electrons to reactant molecules distant from a charge surface, and the electrolytic reaction results in the desired substance through electrolysis of the reactant, Fe 2 O 3  in the example shown. While the disclosed examples exhibit an example reactant as iron oxide (Fe 2 O 3 ) and the dispersement medium as carbon for resulting in iron particles (Fe) as the desired substance, other reactants responsive to electrolysis may also be employed in the colloidal electrode. 
         [0023]    In the example arrangement, the opposed electrodes include a colloid electrode  160  defined by a titanium plate, and a counter electrode  162  defined by a platinum foil, and the flow vessel  150  employs a plurality of titanium plates  160 -N and opposed planar platinum foil  162 -N electrodes arranged in a series of parallel planes, typically opposed pairs, in the flow vessel  150  for transporting the fluidic substance  100  between the opposed electrodes for collection in the reservoir  154 . 
         [0024]    Since the disclosed fluid substance  100  depicts a colloidal electrode that possesses both electrically and ionically conductive properties, hematite particles don&#39;t need to diffuse from bulk solution to the surface of the electrode for electrolyzing, and the conversion rate from Fe 2 O 3  to Fe is not limited by the residence time of the particle adsorbing on electrode surface. The carbon network can conduct the electrons, which forms a 3D reaction network, significantly increasing reaction area and reaction rate. The disclosed approach demonstrates the use of electrolysis in a colloidal electrode for LTE to avoid generation of greenhouse gases resulting from high temperature reactions. A further consideration includes ensuring that the electrochemical reaction does not generate undesirable by-products, such as hydrogen gas.  FIGS. 3   a - 3   c  show promoting or shifting the electrochemical reaction (rate) potential away from undesired substances such as hydrogen gas. Selection of a particular electrolyte provides an alkaline substance that shifts the reaction to avoid generation of undesirable or harmful precipitants. In  FIG. 3   a , the potential  170  at which iron electrolysis occurs is very close to the potential at which hydrogen is produced (2H + →H 2 ), and the current peak of reducing Fe 2+  to Fe is merged with the current of H 2  evolution. Selection of the proper type and percentage of electrolyte mitigates such an undesirable result. As shown in  FIG. 3   b , addition of sodium sulfide shifts the potential of the iron reaction  170 ′ well above that of hydrogen production.  FIG. 3   c  shows the reduction charge  180  and the potential  182  for the electrochemical reaction with sodium sulfide  184  and without  186 . 
         [0025]    The colloid therefore benefits by defining the fluid substance  100  based on selecting the electrolyte based on an electrochemical reaction rate for shifting electrolysis towards reactions resulting in the generation of the desired substance and away from reactions resulting in hydrogen gas (H 2 ). In the example arrangement, the electrolyte may be an alkaline substance selected from the group consisting of sodium hydroxide (NaOH) and sodium sulfide (Na 2 S). 
         [0026]    In the examples discussed above, the dispersement medium demonstrates how carbon affects the electronic conductivity and viscosity of the colloidal electrodes under static condition. Alternate configurations systematically determine the electronic conductivity, viscosity and stability of the colloidal electrodes, by changing the content of the disbursement medium and electrolyte before and after flow. It is desirable to have a high concentration of carbon, to increase electronic conductivity, and a high concentration of Fe 2 O 3  to get a high current density, although at a certain point the colloidal electrodes may become excessively viscous and unusable in flow electrolysis. The electronic conductivity and viscosity will be measured with different compositions of the colloidal electrodes. Correlations may then link the viscosity with the electronic conductivity to determine the effects of the rheology on the conductivity. For example, it may be revealed that colloidal electrodes with the same amount of C and different viscosity possibly possess different electronic conductivity and electrolysis currents. 
         [0027]    While the system and methods defined herein have been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.