Electrochemical reactor and method for reducing iron from an iron-containing feedstock

Abstract

An electrochemical reactor, including a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream includes an electrolyte and an iron-containing feedstock; an anode and a cathode positioned in contact with the channel; and a source of a magnetic field positioned in proximity to the cathode, wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in a magnetic field of the source, and wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.

What is claimed is: 
     
         1 . An electrochemical reactor, comprising:
 a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream comprises an electrolyte and an iron-containing feedstock;   an anode and a cathode positioned in contact with the channel; and   a source of a magnetic field positioned in proximity to the cathode,   wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and   wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.   
     
     
         2 . The electrochemical reactor of  claim 1 , wherein the iron metal comprises an iron metal powder. 
     
     
         3 . The electrochemical reactor of  claim 1 , wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof. 
     
     
         4 . The electrochemical reactor of  claim 1 , wherein the iron-containing feedstock comprises magnetite or hematite. 
     
     
         5 . The electrochemical reactor of  claim 1 , wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source. 
     
     
         6 . The electrochemical reactor of  claim 1 , wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof. 
     
     
         7 . The electrochemical reactor of  claim 1 , wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 weight percent, based on a total weight of the electrolyte. 
     
     
         8 . The electrochemical reactor of  claim 1 , wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C. 
     
     
         9 . The electrochemical reactor of  claim 1 , wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock. 
     
     
         10 . The electrochemical reactor of  claim 1 , wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream. 
     
     
         11 . The electrochemical reactor of  claim 1 , wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof. 
     
     
         12 . The electrochemical reactor of  claim 1 , wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream. 
     
     
         13 . The electrochemical reactor of  claim 1 , wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream. 
     
     
         14 . The electrochemical reactor of  claim 1 , wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof; or
 wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof; or   a combination thereof.   
     
     
         15 . The electrochemical reactor of  claim 1 , wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode. 
     
     
         16 . The electrochemical reactor of  claim 1 , wherein the channel is arranged vertically. 
     
     
         17 . The electrochemical reactor of  claim 1 , further comprising a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream. 
     
     
         18 . An electrochemical reactor, comprising:
 a channel for containing and directing flow of an electrolyte stream, wherein the electrolyte stream comprises an electrolyte and an iron-containing feedstock;   an anode and a cathode positioned in contact with the channel; and   a source of a magnetic field positioned in proximity to the cathode,   wherein the electrochemical reactor electrochemically reduces at least a portion of the iron-containing feedstock to an iron metal at a surface of the cathode and in the magnetic field of the source, and   wherein the iron-containing feedstock comprises magnetite or hematite.   
     
     
         19 . The electrochemical reactor of  claim 18 , wherein the iron-containing feedstock is not subjected to electrochemical reduction before the electrochemical reduction in the magnetic field. 
     
     
         20 . The electrochemical reactor of  claim 18 , wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. 
     
     
         21 . The electrochemical reactor of  claim 18 ,
 i) wherein the iron metal comprises an iron metal powder;   ii) wherein the iron-containing feedstock further comprises maghemite, goethite, limonite, pyrite, red mud, or a combination thereof;   iii) wherein the iron-containing feedstock consists essentially of magnetite or hematite;   iv) wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the source;   v) wherein the electrolyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;   vi) wherein the alkali hydroxide, the organic hydroxide, or the combination thereof is present in the aqueous solution in an amount from 20 to 50 weight percent, based on a total weight of the electrolyte;   vii) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;   viii) wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream;   ix) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;   x) wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream;   xi) wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream;   xii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;   xiii) wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;   xiv) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;   xv) wherein the channel is arranged vertically;   xvi) wherein the electrochemical reactor further comprises a separation unit disposed downstream of the channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the electrolyte stream;   xvii) wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock;   xviii) wherein the electrochemical reactor is configured to continuously flow an electrolyte stream through the channel; or   xix) a combination thereof.   
     
     
         22 . An electrochemical reactor, comprising:
 a catholyte channel for containing and directing flow of a catholyte stream, wherein the catholyte stream comprises a catholyte and an iron-containing feedstock;   an anolyte channel for containing and directing flow of an anolyte stream;   a cathode positioned in contact with the catholyte channel;   an anode positioned in contact with the anolyte channel;   a source of a magnetic field positioned in proximity to the cathode; and   a separator disposed between the catholyte channel and the anolyte channel,   wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to iron metal at a surface of the cathode and in the magnetic field of the source, and   wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to the iron metal at a current efficiency ratio of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.   
     
     
         23 . The electrochemical reactor of  claim 22 ,
 i) wherein the iron metal comprises an iron metal powder;   ii) wherein the electrochemical reactor is configured to provide continuous flow of the electrolyte stream;   iii) wherein the electrochemical reactor is configured to flow an electrolyte stream through the channel in a unidirectional flow from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode during electrochemical reduction of the iron-containing feedstock;   iv) wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof;   v) wherein the iron-containing feedstock comprises magnetite or hematite;   vi) wherein the iron-containing feedstock consists essentially of magnetite or hematite;   vii) wherein the electrochemical reactor reduces at least a portion of the iron-containing feedstock to an iron metal powder at the surface of the cathode and in the magnetic field of the magnet;   viii) wherein the catholyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;   ix) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;   x) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;   xi) wherein the source is positioned external to the catholyte channel comprising the catholyte stream, wherein the source does not contact the catholyte stream;   xii) wherein at least a portion of the source is positioned within the catholyte channel comprising the catholyte stream;   xiii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;   xiv) wherein the anode comprises carbon, titanium, platinum, iridium, ruthenium, titanium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, tin, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;   xv) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;   xvi) wherein catholyte channel is arranged vertically;   xvii) wherein the electrochemical reactor further comprises a separation unit disposed downstream of the catholyte channel, wherein the separation unit is configured to separate at least a portion of the iron metal from the catholyte stream; or   xviii) a combination thereof.   
     
     
         24 . The electrochemical reactor of  claim 22 , wherein the anolyte comprises an aqueous solution comprising:
 a strong acid; and   optionally a supporting electrolyte compound.   
     
     
         25 . The electrochemical reactor of  claim 22 , wherein the separator comprises an anion exchange membrane, a cation exchange membrane, a zwitterionic membrane, a porous membrane having an average pore diameter of less than 10 nanometers, a polybenzimidazole-containing membrane, a polysulfone-containing membrane, a polycarboxylic-containing membrane, a polyetherketone-containing membrane, a membrane comprising a polymer of intrinsic microporosity, or a combination thereof. 
     
     
         26 . The electrochemical reactor of  claim 22 , wherein the catholyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the catholyte stream. 
     
     
         27 . A method of processing an iron-containing feedstock to produce iron metal, the method comprising:
 flowing an electrolyte stream comprising the iron-containing feedstock through a channel of an electrochemical cell, the electrochemical cell comprising an anode and a cathode disposed in the channel;   applying a magnetic field at the cathode of the electrochemical cell;   electrochemically reducing at least a portion of the iron-containing feedstock to produce the iron metal on a surface of the cathode while the magnetic field is applied at the cathode; and   collecting the iron metal from the surface of the cathode using the electrolyte stream,   wherein the electrochemically reducing is at a current efficiency of at least 0.75, wherein the current efficiency is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode.   
     
     
         28 . The method of  claim 27 , wherein the step of collecting further comprises stopping the electrochemical reduction of the iron-containing feedstock, releasing or partially releasing the magnetic field from the cathode, and flushing the iron metal from the surface of the cathode using the electrolyte stream. 
     
     
         29 . The method of  claim 27 , wherein the iron-containing feedstock is not electrochemically reduced before the magnetic field is applied at the cathode. 
     
     
         30 . The method of  claim 27 , wherein the iron metal comprises an iron metal powder. 
     
     
         31 . The method of  claim 27 , wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof,
 wherein the iron-containing feedstock comprises magnetite or hematite, or   wherein the iron-containing feedstock consists essentially of magnetite or hematite.   
     
     
         32 . The method of  claim 27 , wherein at least a portion of the iron-containing feedstock is substantially reduced on the surface of the cathode while the magnetic field is applied to the cathode. 
     
     
         33 . The method of  claim 27 ,
 i) wherein the flowing the electrolyte stream is unidirectional from a region of the channel upstream of the cathode and the anode to a region of the channel downstream of the cathode and the anode;   ii) wherein the catholyte comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof;   iii) wherein the electrochemical reactor is operated at a temperature of 50° C. to 140° C.;   iv) wherein the electrolyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, based on a total weight of the electrolyte stream;   v) wherein the source comprises an electromagnet, a permanent magnet, an electropermanent magnet, or a combination thereof;   vi) wherein the source is positioned external to the channel comprising the electrolyte stream, wherein the source does not contact the electrolyte stream or wherein at least a portion of the source is positioned within the channel comprising the electrolyte stream;   vii) wherein at least a portion of the magnet is positioned within the channel comprising the electrolyte stream;   viii) wherein the cathode comprises aluminum, carbon, molybdenum, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof;   ix) wherein the anode comprises carbon, titanium, lead, nickel, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, cobalt, antimony, tungsten, an alloy thereof, an oxide thereof, or a combination thereof;   x) wherein a current density at the cathode for the reduction of the iron-containing feedstock is from 40 to 5,000 milliamperes per square centimeter, based on a total area of the cathode;   xi) wherein the channel is arranged vertically; or   xii) a combination thereof.   
     
     
         34 . The method of  claim 27 , further comprising:
 transporting the electrolyte stream to a separation unit located downstream of the channel; and   separating at least a portion of the iron metal from the electrolyte stream.   
     
     
         35 . The method of  claim 27 , further comprising:
 transporting the electrolyte stream to a separation unit located downstream of the channel;   separating at least a portion of the iron metal from the electrolyte stream; and   recirculating the electrolyte stream to an upstream region of the channel.   
     
     
         36 . The method of  claim 27 , wherein the iron metal has
 i) a specific total embedded emissions of less than 0.8 tons of CO 2  per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism;   ii) a carbon emission intensity of less than 1100 kilograms of CO 2  per ton of the iron metal, when determined according to ISO 14404;   iii) a carbon emission intensity of less than 800 kilograms of CO 2  per ton of the iron metal, when determined according to the Intergovernmental Panel on Climate Change Methodology 2006 Guidelines for National Greenhouse Gas Inventories;   iv) a carbon emission intensity of less than 1500 kilograms of CO 2  per ton of the iron metal, when determined according to the 2017 World Steel Life Cycle Inventory Methodology;   v) a carbon emission intensity of less than 1300 kilograms of CO 2  per ton of the iron metal, when determined according to the 2008 World Resource Institute Iron and Steel Greenhouse Gas Protocol;   vi) a carbon emission intensity of less than 750 kilograms of CO 2  per ton of the iron metal, when determined according to European Union Commission Implementing Regulation 2018/2066;   vii) a specific total embedded emissions of less than 0 tons of CO 2  per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism; or   viii) a combination thereof.   
     
     
         37 . An iron metal produced by the method of  claim 27 , wherein the iron metal is a powder having an average particle size of less than or equal to 200 micrometers.