Process

Abstract

The present invention relates to a process for electrochemical extraction of a metal (M) from a metal (M) oxide, to a conducting electrode and to an electrolytic cell comprising the conducting electrode.

1 .- 27 . (canceled) 
     
     
         28 . A process for electrochemical extraction of a metal (M) from a metal (M) oxide comprising:
 applying a voltage between a cathode comprising or in contact with the metal (M) oxide and an anode in an oxygen-dissolving molten electrolyte in the presence of an alkali metal (M a ) oxide whereby to form an alkali metal (M a ) metallate (M) phase,   wherein the alkali metal (M a ) oxide forms the alkali metal (M a ) metallate (M) phase from a reaction of the alkali metal (M a ) oxide with a metal (M″) metallate (M) phase.   
     
     
         29 . A process as claimed in  claim 28 , wherein the alkali metal (M a ) oxide is potassium oxide. 
     
     
         30 . A process as claimed in  claim 28 , wherein the metal (M″) metallate (M) phase is a perovskite (or perovskite-type) phase. 
     
     
         31 . A process as claimed in  claim 28 , wherein the diffusivity of oxygen in the alkali metal (M a ) metallate (M) phase is higher than the diffusivity of oxygen in the metal (M″) metallate (M) phase. 
     
     
         32 . A process as claimed in  claim 28 , wherein the alkali metal (M a ) metallate (M) phase is a liquid. 
     
     
         33 . A process as claimed in  claim 28 , wherein the alkali metal (M a ) metallate (M) phase is M a   4 MO 4 . 
     
     
         34 . A process as claimed in  claim 28 , wherein the alkali metal (M a ) oxide is in admixture with the metal (M) oxide in or in contact with the cathode. 
     
     
         35 . A process as claimed in  claim 28 , further comprising: mixing the alkali metal (M a ) oxide and the metal (M) oxide and forming the mixture of alkali metal (M a ) oxide and metal (M) oxide into a self-supporting mixture. 
     
     
         36 . A process as claimed in  claim 28 , wherein the alkali metal (M a ) oxide is formed in situ by decomposition of a decomposable alkali metal (M a ) salt, wherein the decomposable alkali metal (M a ) salt is in admixture with the metal (M) oxide in or in contact with the cathode. 
     
     
         37 . A process as claimed in  claim 36 , further comprising: mixing the decomposable alkali metal (M a ) salt and the metal (M) oxide and forming the mixture of decomposable alkali metal (M a ) salt and metal (M) oxide into a self-supporting mixture. 
     
     
         38 . A process as claimed in  claim 36 , wherein the decomposable alkali metal (M a ) salt is an alkali metal (M a ) bicarbonate. 
     
     
         39 . A process as claimed in  claim 36 , wherein the metal (M) is one or more metals selected from the group consisting of Ti, Nb, Ta, U, Th, Cr, Fe, steel and Zr. 
     
     
         40 . A process as claimed in  claim 28 , wherein the metal (M) is one or more metals selected from the group consisting of Ti, Nb, Ta and Zr. 
     
     
         41 . A process as claimed in  claim 28 , comprising: applying a voltage between a cathode comprising TiO 2  in admixture with an alkali metal (M a ) salt decomposable into the alkali metal (M a ) oxide and an anode in an oxygen-dissolving molten CaCl 2 -containing electrolyte whereby to form a liquid alkali metal (M a ) titanate phase. 
     
     
         42 . A conducting electrode comprising a metal (M) oxide and either an alkali metal (M a ) oxide capable of forming an alkali metal (M a ) metallate (M) phase or an alkali metal (M a ) salt decomposable into an alkali metal (M a ) oxide capable of forming an alkali metal (M a ) metallate (M) phase. 
     
     
         43 . An electrolytic cell comprising a cathode which comprises or is in contact with a metal (M) oxide and one or more inert anodes in contact with a fusible or fused oxygen-dissolving electrolyte in the presence of an alkali metal (M a ) oxide. 
     
     
         44 . An electrolytic cell as claimed in  claim 43 , comprising a single inert anode, wherein the cathode is a cathodic basket in which is carried the metal (M) oxide. 
     
     
         45 . An electrolytic cell as claimed in  claim 43 , wherein the cathode is a cathodic vessel which is adapted to facilitate in use continuous flow of the fused oxygen-dissolving electrolyte between a feeder end into which the fused oxygen-dissolving electrolyte is feedable and a discharge end from which the fused electrolyte is dischargeable, wherein the electrolytic cell comprises a plurality of inert anodes housed in the cathodic vessel between the feeder end and the discharge end. 
     
     
         46 . An electrolytic cell as claimed in  claim 43 , comprising a plurality of inert anodes housed in a vessel which contains the fused oxygen-dissolving electrolyte, wherein a mixture of the alkali metal (M a ) oxide and metal (M) oxide in contact with a cathode is present in the form of a plurality of self-supporting elements conveyable in use through the fused oxygen-dissolving electrolyte. 
     
     
         47 . An electrolytic cell as claimed in  claim 43 , comprising a plurality of inert anodes housed in a vessel which contains the fused oxygen-dissolving electrolyte, wherein the alkali metal (M a ) oxide and metal (M) oxide are present in the oxygen-dissolving electrolyte in contact with a plurality of cathodic elements conveyable in use through the fused oxygen-dissolving electrolyte. 
     
     
         48 . An electrolytic cell as claimed in  claim 43 , wherein the cathode is a metal crucible containing the alkali metal (M a ) oxide and metal (M) oxide in molten admixture, wherein the metal crucible is suspended in the fused oxygen-dissolving electrolyte.