Electrochemical cell and process for producing metal and chlorine gas

Patent metadata

Field	Value
Publication number	US-2023392272-A1
Application number	US-202318329849-A
Country	US
Kind code	A1
Filing date	Jun 6, 2023
Priority date	Jun 7, 2022
Publication date	Dec 7, 2023
Grant date	—

Abstract

An electrochemical cell for producing metal and chlorine from metal ore and a metal chloride includes a cathode, an anode, and a separator. A catholyte includes (i) water, (ii) a metal hydroxide comprising Q, where Q is an alkali metal, an alkaline earth metal, or a combination thereof, and (iii) suspended metal ore particles comprising M x O y where M is a metal and x and y are integers. An anolyte includes (i) water and (ii) a metal chloride comprising Q. An electrowinning process for producing metal and chlorine includes applying a voltage across the electrochemical cell to effect reduction of the M x O y in the cathode compartment to provide the metal M and oxidation of chloride ions in the anode compartment to form Cl 2 gas.

First claim

We claim:

1 . An electrowinning process for producing metal and chlorine, comprising:
providing an electrochemical cell comprising (i) a cathode comprising low-carbon steel, copper, iron, graphite, vitreous carbon, or titanium, (ii) an anode comprising an oxide coating comprising Ru, Pt, Ir, or any combination thereof, on a conducting substrate, (iii) a separator between the cathode and the anode, the separator comprising a porous composite or a cation-selective membrane, and (iv) a voltage source electrically connected to the cathode and the anode; providing a catholyte comprising (i) water, (ii) a metal hydroxide comprising Q, where Q is an alkali metal, an alkaline earth metal, or a combination thereof, and (iii) suspended metal ore particles comprising M x O y where M is a metal and x and y are integers; providing an anolyte comprising water and a metal chloride comprising Q; and applying a voltage across the electrochemical cell to effect reduction of the M x O y in the catholyte to provide the metal M and oxidation of chloride ions in the anolyte to form Cl 2 gas.

2 . The electrowinning process of claim 1 , wherein:
(i) M is Fe, Mn, Ni, Cr, Co, Zn, or any combination thereof; or (ii) Q is Na, K, Li, Mg, Ca, or any combination thereof; or (iii) both (i) and (ii).

3 . The electrowinning process of claim 1 , wherein:
(i) the metal ore particles comprise Fe 2 O 3 ; or (ii) Q is Na; or (iii) both (i) and (ii).

4 . The electrowinning process of claim 1 , wherein
(i) the catholyte comprises from 50 g/L to 500 g/L of the suspended metal ore particles prior to applying the voltage; or (ii) the catholyte comprises from 10 wt % to 50 wt % of the metal hydroxide prior to applying the voltage; or (iii) the anolyte comprises from 10 wt % to 50 wt % of the metal chloride prior to applying the voltage; or (iv) any combination of two or more of (i), (ii), and (iii).

5 . The electrowinning process of claim 1 , further comprising:
continuously or periodically removing Cl 2 generated in the anolyte; and periodically removing at least a portion of the metal M from the cathode.

6 . The electrowinning process of claim 5 , wherein the metal M is magnetic and is deposited onto a surface of the cathode, and periodically removing at least a portion of the metal M comprises:
passing a magnet over the surface of the cathode or over an opposing surface of the cathode; and removing the magnet from the electrochemical cell, whereby the metal M deposited onto the surface of the cathode is transferred to the magnet as the magnet is removed.

7 . The electrowinning process of claim 1 , further comprising:
(i) periodically adding a quantity of the metal ore particles to the catholyte; or (ii) periodically adding a quantity of the metal chloride to the anolyte; or (iii) both (i) and (ii).

8 . The electrowinning process of claim 1 , wherein the metal ore particles are obtained from a metal ore feedstock further comprising aluminates, silicates, or aluminates and silicates, the method further comprising leaching at least a portion of the aluminates, silicates, or aluminates and silicates from the metal ore feedstock by contacting the metal ore feedstock with a hydroxide solution to provide the metal ore particles.

9 . The electrowinning process of claim 8 , wherein the hydroxide solution is a spent catholyte obtained from the electrochemical cell after applying the voltage across the electrochemical cell.

10 . The electrowinning process of claim 1 , wherein the anolyte comprises concentrated seawater having a metal chloride concentration of from 10 wt % to 50 wt %.

11 . The electrowinning process of claim 1 , wherein:
providing the electrochemical cell further comprises providing a cell stack comprising
(i) a number n of the electrochemical cells, a cathode electrical connector connecting cathodes of each of the electrochemical cells in parallel, an anode electrical connector connecting anodes of each of the electrochemical cells in parallel, and a voltage source electrically connected to the cathode electrical connector and the anode electrical connector, or
(ii) a number n of the electrochemical cells, a number n−1 of conductive bipolar plates wherein a conductive bipolar plate is positioned between each adjacent pair of electrochemical cells, a cathode electrical connector connected to a cathode of a first electrochemical cell in the series, an anode electrical connector connected to an anode of a last electrochemical cell in the series, and a voltage source electrically connected to the cathode electrical connector and the anode electrical connector;
providing the catholyte further comprises providing the catholyte within each electrochemical cell of the cell stack; providing the anolyte within the anode compartment further comprises providing the anolyte within each electrochemical cell of the cell stack; and applying a voltage across the electrochemical cell further comprises applying the voltage across the cell stack to effect reduction of the M x O y in each cathode compartment to provide the metal M and formation of Cl 2 gas in each anode compartment.

12 . The electrowinning process of claim 1 , wherein:
(i) the voltage applied is from 2 V to 5 V per electrochemical cell; or (ii) the electrochemical cell or cell stack is operated at a current density of from 20 mA cm −2 to 500 mA cm −2 ; or (iii) the electrochemical cell or cell stack is operated at a temperature from 25° C. to 150° C.; or (iv) any combination of (i), (ii), and (iii).

13 . An electrochemical cell, comprising:
a cathode comprising low-carbon steel, copper, iron, graphite, vitreous carbon, or titanium; an anode comprising an oxide coating comprising Ru, Pt, Ir, or any combination thereof, on a conducting substrate; and a separator between the cathode and the anode, the separator comprising a porous composite or a cation-selective membrane.

14 . The electrochemical cell of claim 13 , wherein the separator comprises:
a porous composite comprising a polymer and metal oxide nanoparticles; or a cation-selective membrane that is permeable to alkali metal cations, alkaline earth metal cations, or a combination thereof.

15 . The electrochemical cell of claim 14 , wherein the separator comprises:
a porous composite comprising polysulfone and ZrO 2 nanoparticles; or a cation-selective membrane comprising fluorinated polyethylene chains with side groups comprising fluorinated sulfonic acids; or a cation-selective membrane comprising perfluorosulfonic acid on a polytetrafluoroethylene (PTFE) substrate; or a cation-selective membrane comprising zirconium oxide on a polyphenylene sulfide substrate.

16 . The electrochemical cell of claim 13 , further comprising:
(i) gas collecting means for collecting gas generated at the anode; or (ii) a magnet operable to be passed over a surface of the cathode; or (iii) a catholyte mixing means and an anolyte mixing means; or (iv) comprising a voltage source electrically connected to the cathode and the anode; or (v) any combination of two or more of (i), (ii), (iii), and (iv).

17 . The electrochemical cell of claim 13 , further comprising:
a catholyte comprising (i) water, (ii) a metal hydroxide comprising Q, where Q is an alkali metal, an alkaline earth metal, or a combination thereof, and (iii) suspended metal ore particles comprising M x O y where M is a metal and x and y are integers; and an anolyte comprising water and a metal chloride comprising Q.

18 . A cell stack,

Assignees

• Univ Oregon

Inventors

• Kempler Paul
• Boettcher Shannon W
• Noble Berkley B

Classifications

• C25C1/06 Primary

  or iron group metals, refractory metals or manganese · CPC title

• C25C7/04

  Diaphragms; Spacing elements · CPC title

• C25C7/02 Primary

  Electrodes (consumable anodes for the refining the metals C25C1/00 - C25C5/00); Connections thereof · CPC title

• C25C7/08

  Separating of deposited metals from the cathode · CPC title

• C25B1/26

  Chlorine; Compounds thereof (by simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine C25B1/34) · CPC title