Electrochemical cell and process for producing metal and chlorine gas

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 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 is operated at a current density of from 20 mA cm −2 to 500 mA cm −2 ; or

(iii) the electrochemical cell is operated at a temperature from 25° C. to 150° C.; or

(iv) any combination of (i), (ii), and (iii).