Systems and methods for continuous electrolytic production of metals

Abstract

An electrochemical cell for converting metal salt or metal oxide to metal comprises: a) a mixture comprising an electrolyte and metal salt or metal oxide; b) an anode submerged in the mixture; c) a cathode partially submerged in the mixture and moveable along a closed loop path; and d) a harvester disposed at an exposed portion of the cathode outside of the mixture, wherein an electrical charge supplied to the electrochemical cell reduces the metal salt or metal oxide to metal at and disposed onto the cathode, and wherein the harvester removes the metal from the exposed portion of the cathode. Methods and systems for converting metal salt or metal oxide to metal are also disclosed including continuous methods and systems.

What is claimed is: 
     
         1 . An electrochemical cell for converting metal salt or metal oxide to metal, comprising:
 a) a mixture comprising an electrolyte and metal salt or metal oxide;   b) an anode submerged in the mixture;   c) a cathode partially submerged in the mixture and moveable along a closed loop path; and   d) a harvester disposed at an exposed portion of the cathode outside of the mixture;   wherein an electrical charge supplied to the electrochemical cell reduces the metal salt or metal oxide to metal at and disposed onto the cathode in form of a plurality of dendritic structures, and wherein the harvester removes the metal from the exposed portion of the cathode.   
     
     
         2 - 8 . (canceled) 
     
     
         9 . The electrochemical cell of  claim 1 , further comprising:
 i) a rinsing unit configured to spray cleaning fluid onto the metal; and   ii) a cartridge to retain the metal removed from the cathode by the harvester.   
     
     
         10 . The electrochemical cell of  claim 1 , wherein: the metal salt or metal oxide is iron oxide; the electrolyte is alkaline electrolyte; and the metal is iron. 
     
     
         11 . A method for converting metal salt or metal oxide into metal, comprising:
 a) providing a metal salt or oxide in an electrolyte in an electrochemical cell to form a mixture, wherein the electrochemical cell includes an anode submerged in the mixture and a cathode partially submerged in the mixture and moveable along a closed loop path;   b) supplying an electrical charge in the electrochemical cell, and reducing the metal salt or metal oxide in the mixture to form the metal at and disposed onto the cathode in form of a plurality of dendritic structures;   c) moving the cathode having the metal disposed thereon from the mixture to provide an exposed portion of the cathode outside of the mixture; and   d) harvesting the metal from the exposed portion of the cathode.   
     
     
         12 - 16 . (canceled) 
     
     
         17 . The electrochemical cell of  claim 1 , wherein the cathode is a cathode assembly comprising a plurality of moveable cathodes. 
     
     
         18 . The electrochemical cell of  claim 1 , wherein the cathode is a cathode assembly comprising a plurality of moveable cathodes and the harvester is a harvester assembly comprising a plurality of harvester units positioned for harvesting metal from the plurality of movable cathodes. 
     
     
         19 . The method of  claim 11 , wherein: the metal salt or metal oxide is iron oxide; the electrolyte is alkaline electrolyte; and the metal is iron. 
     
     
         20 . The method of  claim 19 , further comprising heating the mixture and generating current in the electrochemical cell concurrently with heating the mixture. 
     
     
         21 . The method of  claim 20 , wherein the mixture is heated to a temperature between about 80° C. to about 115° C. 
     
     
         22 . The method of  claim 19 , further comprising stirring the mixture for a period of time to form a stirred suspension. 
     
     
         23 . The method of  claim 22 , wherein the mixture is stirred for a period of time ranging from about 10 minutes to 20 minutes. 
     
     
         24 . The electrochemical cell of  claim 10 , wherein the mixture comprises aqueous sodium hydroxide at a concentration of at least about 5 M; or wherein the metallic iron comprises a purity greater than about 90%; or wherein a mass fraction of iron oxide in the suspension is between about 5% to about 33%. 
     
     
         25 . The electrochemical cell of  claim 10 , the electrochemical cell comprising a faradaic efficiency greater than about 85%. 
     
     
         26 . The electrochemical cell of  claim 10 , wherein the electrochemical cell has an electrical energy consumption of less than 6 kWh/kg iron. 
     
     
         27 . A continuous system for converting metal salt or metal oxide into metal, the system comprising:
 an inlet to receive a mixture comprising a metal salt or metal oxide, an electrolyte, or a combination thereof, where the inlet feeds the mixture to an electrochemical cell;   the electrochemical cell including the mixture, an anode submerged in the mixture, and a cathode partially submerged in the mixture and moveable along a closed loop path, wherein an electrical charge supplied to the electrochemical cell reduces the metal salt or metal oxide to the metal at and disposed onto the cathode in form of a plurality of dendritic structures;   optionally a rinsing unit to spray cleaning fluid onto the metal disposed onto the cathode;   optionally a drying unit to remove moisture from the metal;   a harvester disposed at an exposed portion of the cathode outside of the mixture to remove the metal from the exposed portion of the cathode; and   an outlet to discharge suspension or mixture from the system.   
     
     
         28 . The system of  claim 27 , wherein the metal salt or metal oxide is selected from one or more of FeCl 3 , FeSO 4 , Fe 2 (SO 4 ) 3 , ZnSO 4 , Zn 2 (SO 4 ) 3 , ZnCl 2 , CoCl 2 , CuSO 4 , Fe 2 O 3 , Fe 3 O 4 , FeO, ZnO, CuO, MgO, Co 3 O 4 , and MnO. 
     
     
         29 . The system of  claim 27 , wherein the metal is selected from one or more of Fe, Cu, Ni, Zn, Co, Mn, Ag, Pt, Pd, Au, Ag, Mg, Li, and Pb. 
     
     
         30 . (canceled) 
     
     
         31 . The system of  claim 27 , wherein the cathode comprises a disc. 
     
     
         32 . The system of  claim 27 , wherein the cathode comprises a connected looping structure. 
     
     
         33 . The system of  claim 27 , wherein the harvester comprises a mechanical harvester, a magnetic harvester, or combinations thereof. 
     
     
         34 . (canceled) 
     
     
         35 . (canceled)