System and methods for separation of electrolytic iron from iron-containing feedstock

Abstract

An electrochemical reactor system includes: an electrochemical cell, having: an anode; a cathode; an electrolyte stream including an electrolyte and an iron-containing feedstock containing feedstock particles; and a channel that contains the electrolyte stream; and a magnetic field source positioned to provide a magnetic field at the surface of the cathode. The electrochemical cell electrochemically reduces the iron-containing feedstock to form iron particles at a surface of the cathode and in the magnetic field. The feedstock particles have an average particle size in at least one dimension of 10 micrometers or less, and the iron particles have an average particle size in at least one dimension of 50 to 1,000 micrometers, or the feedstock particles have an average particle size in at least one dimension of 25 micrometers or greater, and the iron particles have an average particle size in at least one dimension of 0.1 to 20 micrometers.

1 . An electrochemical reactor system, comprising:
 an electrochemical cell, comprising:
 an anode; 
 a cathode disposed opposite the anode; 
 an electrolyte stream contacting the cathode, the electrolyte stream comprising an electrolyte and an iron-containing feedstock comprising feedstock particles; and 
 a channel that contains the electrolyte stream within the electrochemical cell; and 
   a magnetic field source positioned to provide a magnetic field of at least one gauss, preferably 25 to 10,000 gauss, more preferably 300 to 3,000 gauss to the cathode, or to provide a magnetic field of 0.0025 to 1 Tesla, preferably 0.03 to 1 Tesla, more preferably 0.03 to 0.3 Tesla at the surface of the cathode, or a combination thereof, and   wherein the electrochemical cell is configured to electrochemically reduce at least a portion of the iron-containing feedstock to form iron particles comprising iron metal at a surface of the cathode and in the magnetic field, and   wherein the feedstock particles have an average particle size in at least one dimension of 10 micrometers or less, preferably 0.1 to 10 micrometers, and the iron particles have an average particle size in at least one dimension of 50 to 1,000 micrometers, preferably 50 to 200 micrometers, or   wherein the feedstock particles have an average particle size in at least one dimension of 25 micrometers or greater, preferably 25 to 500 micrometers, and the iron particles have an average particle size in at least one dimension of 0.1 to 20 micrometers, preferably 0.1 to 10 micrometers.   
     
     
         2 . (canceled) 
     
     
         3 . The electrochemical reactor system of  claim 1 , further comprising a separator disposed between the anode and the cathode, wherein
 the channel comprises a catholyte channel and an anolyte channel, and the separator is disposed between the catholyte channel and the anolyte channel;   the catholyte channel contains the electrolyte stream;   the anolyte channel is configured to contain an anolyte stream;   the cathode is positioned in the catholyte channel; and   the anode is position in the anolyte channel.   
     
     
         4 . The electrochemical reactor system of  claim 3 , further comprising the anolyte stream in the anolyte channel, wherein the cathode contacts the electrolyte stream and the anode contacts the anolyte stream, wherein the analyte stream comprises an acid having a pKa of 2 or less; and optionally a supporting electrolyte compound. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The electrochemical reactor system of  claim 1 , wherein the channel or the catholyte channel has an inlet for receiving the electrolyte stream and an outlet for discharging an electrolyte product stream after at least a portion of the iron-containing feedstock is reduced to form iron particles comprising iron metal at the surface of the cathode and in the magnetic field; and wherein the electrochemical rector system is configured to flow the electrolyte stream through the channel channel in a unidirectional flow from the inlet to the outlet of the channel. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . The electrochemical reactor system of  claim 1 , further comprising a separation unit disposed downstream of the channel or the catholyte channel, wherein the separation unit is configured to separate at least a portion of the iron particles from the electrolyte product stream, wherein the electrolyte product stream comprises the iron particles and a residual feedstock comprising the feedstock particles that are not reduced in the electrochemical cell, and the separation unit is configured to separate the iron particles from the residual feedstock in the electrolyte product stream based on a particle size difference between the iron particles and the residual feedstock to provide an iron product, and optionally wherein the iron product comprises less than 10 wt % of the residual feedstock based on a total weight of the iron product. 
     
     
         11 . The electrochemical reactor system of  claim 10 , wherein the separation unit comprises a sieve, a filter, a screen, a hydrocyclone, a centrifuge, or a combination thereof. 
     
     
         12 . The electrochemical reactor system of  claim 10 , wherein the separation unit has two subunits, the first subunit is configured to separate the iron particles from the electrolyte product stream, generating a first stream comprising the residual feedstock and a liquid, and a second stream comprising the iron particles, and the second subunit is configured to separate the residual feedstock from the liquid in the first stream, and optionally wherein the first subunit is a sieve, a filter, a screen, a hydrocyclone, or a centrifuge, and the second subunit is a magnetic separator or a physical separator. 
     
     
         13 . The electrochemical reactor system of  claim 10 , wherein the separation unit has two subunits, the first subunit is configured to separate the residual feedstock from the electrolyte product stream, generating a first stream comprising the iron particles and a liquid, and a second stream comprising the residual feedstock, and the second subunit is configured to separate the iron particles from the liquid in the first stream, and optionally wherein the first subunit is a sieve, a filter, a screen, a hydrocyclone, or a centrifuge, and the second subunit is a magnetic separator or a physical separator. 
     
     
         14 . The electrochemical reactor system of  claim 10 , wherein
 the feedstock particles have an average particle size in at least one dimension of 10 micrometers or less, and   the separation unit is configured to separate the residual feedstock in the electrolyte product stream from the iron particles having an average particle size in at least one dimension of 50 to 1000 micrometers.   
     
     
         15 . The electrochemical reactor system of  claim 14 , wherein the separation unit comprises a sieve or screening having openings with a diameter less than the average particle size of the iron particles in at least one dimension but greater than the average particle size of the feedstock particles in at least one dimension. 
     
     
         16 . The electrochemical reactor system of  claim 15 , wherein the sieve or screen has openings with a diameter of 15 micrometers to 45 micrometers. 
     
     
         17 . The electrochemical reactor system of  claim 10 , wherein
 the feedstock particles have an average particle size in at least one dimension of 25 micrometers or greater, and   the separation unit is configured to separate the residual feedstock in the electrolyte product stream from iron particles having an average particle size in at least one dimension of 0.1 to 20 micrometers.   
     
     
         18 . The electrochemical reactor system of any one of the preceding claims, wherein the electrolyte stream contained within the electrochemical cell comprises from 0.1 to 30 wt % of the iron-containing feedstock, based on a total weight of the electrolyte stream contained within the electrochemical cell, wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, or a combination thereof, wherein the iron particles comprise greater than 90 wt % of iron metal, or a combination thereof. 
     
     
         19 . (canceled) 
     
     
         20 . The electrochemical reactor system of  claim 1 , wherein:
 (i) the electrolyte stream comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof; or   (ii) the electrolyte stream comprises an aqueous solution of an alkali hydroxide, an organic hydroxide, or a combination thereof, and 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 stream.   
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . The electrochemical reactor system of  claim 1 , wherein wherein the magnetic field source comprises a permanent magnet, an electromagnet, or an electropermanent magnet, wherein the magnetic field source is positioned external to the channel or the catholyte channel, and the magnetic field source does not contact the electrolyte stream, or a combination thereof. 
     
     
         24 . The electrochemical reactor system of any one of claims  1  to  22 , wherein the magnetic field source comprises a permanent magnet, an electromagnet, or an electropermanent magnet, wherein at least a portion of the magnetic field source is positioned within the channel or the catholyte channel, or a combination thereof. 
     
     
         25 . The electrochemical reactor system of  claim 1 , wherein:
 (i) the cathode comprises aluminum, carbon, molybdenum, nickel, copper, titanium, iron, chromium, an alloy thereof, or a combination thereof;   (ii) The electrochemical reactor system of any one of the preceding claims, 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   (iii) a combination thereof.   
     
     
         26 . The electrochemical reactor system of any one of the preceding claims, 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, wherein the at least a portion of the iron-containing feedstock is electrochemically reduced to form the iron particles at a current efficiency of at least 0.6, 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, or a combination thereof. 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . A method of processing an iron-containing feedstock to produce iron particle, the method comprising:
 providing an electrochemical rector system  claim 1 ;   flowing the electrolyte stream through the channel or the catholyte channel of the electrochemical cell;   applying the magnetic field to the cathode; and   electrochemically reducing at least a portion of the iron-containing feedstock in the magnetic field to produce the iron particles at the surface of the cathode.   
     
     
         30 . The method of  claim 29 , wherein the method further comprises maintaining a temperature of the electrolyte stream contained within the electrochemical cell at a temperature of 50° C. to 140° C. when at least a portion of the iron-containing feedstock in the magnetic field is electrochemically reducing to produce the iron particles at the surface of the cathode and in the magnetic field, wherein the electrolyte stream is flowed unidirectionally from a region of the channel or the catholyte channel upstream of the cathode and the anode to a region of the channel or the catholyte channel downstream of the cathode and the anode, or a combination thereof. 
     
     
         31 . (canceled) 
     
     
         32 . The method of  claim 29 , wherein the method further comprises collecting the iron particles at the surface of the cathode using the electrolyte stream, wherein the method further comprises separating the iron particles from a residual feedstock comprising the feedstock particles that are not reduced in the electrochemical cell based on particle, or a combination thereof. 
     
     
         33 . (canceled) 
     
     
         34 . The method of  claim 29 , further comprising
 collecting the iron particles at the surface of the cathode using the electrolyte stream, generating an electrolyte product stream comprising the iron particles and a residual feedstock comprising the feedstock particles that are not reduced;   flowing the electrolyte product stream out of the electrochemical cell;   separating the iron particles from the residual feedstock in the electrolyte product stream at a separation unit comprising a sieve, a filter, a screen, a hydrocyclone, a centrifuge, or a combination thereof based on a size difference of the iron particles and the feedstock particles that are not reduced.   
     
     
         35 . An iron metal powder produced using the method of  claim 29 , 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.