Direct electrochemical reduction of metal-oxides
First Claim
1. A method of controlling the direct electrolytic reduction of a metal oxide ormixtures of metal oxides to the corresponding metal or metals comprising establishing a non-consumable anode and a cathode in contact with a molten salt electrolyte having mobile oxygen ions and reductant metal ions, providing a first reference electrode near the non-consumable anode and a second reference electrode near the cathode, establishing a substantially constant voltage across the anode and cathode or passing a substantially constant current between the anode and the cathode to reduce the metal oxide or oxide mixtures to the corresponding metal or metals while producing oxygen gas, and monitoring the anode potential compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and monitoring the cathode potential compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.
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Abstract
A method of controlling the direct electrolytic reduction of a metal oxide or mixtures of metal oxides to the corresponding metal or metals. A non-consumable anode and a cathode and a salt electrolyte with a first reference electrode near the non-consumable anode and a second reference electrode near the cathode are used. Oxygen gas is produced and removed from the cell. The anode potential is compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and the cathode potential is compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.
77 Citations
27 Claims
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1. A method of controlling the direct electrolytic reduction of a metal oxide or
mixtures of metal oxides to the corresponding metal or metals comprising establishing a non-consumable anode and a cathode in contact with a molten salt electrolyte having mobile oxygen ions and reductant metal ions, providing a first reference electrode near the non-consumable anode and a second reference electrode near the cathode, establishing a substantially constant voltage across the anode and cathode or passing a substantially constant current between the anode and the cathode to reduce the metal oxide or oxide mixtures to the corresponding metal or metals while producing oxygen gas, and monitoring the anode potential compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and monitoring the cathode potential compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.
- 23. A method of electrochemically reducing metal oxide comprising establishing a molten chloride or fluoride electrolyte having mobile oxide ions and reductant metal ions therein under an inert atmosphere, positioning an oxygen stable anode assembly surrounded by a shroud of substantially oxygen impervious material and a first reference electrode in the molten electrolyte, positioning a cathode assembly including a porous container for the metal oxide and a second reference electrode in the molten electrolyte, establishing a substantially constant potential across the anode assembly and the cathode assembly or passing a substantially constant current between the anode assembly and the cathode assembly to reduce metal oxide or oxide to metal or metals at the cathode while producing oxygen gas at the anode, periodically interrupting the electrolytic process to determine the anode potential relaxation with respect to the first reference electrode and to determine the cathode potential relaxation with respect to the second electrode and adjusting the potential across the anode assembly and the cathode assembly or the current to prevent anode dissolution or production of reductant metal from its ions in the electrolyte and to maintain the reductant metal production such that the reductant metal is being consumed in a chemical reaction with the oxide to be reduced at about the same overall rate as the reductant metal is being produced.
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