Electrolytic method, apparatus and product

A method for removing a substance from batches of a feedstock comprising a solid metal, containing the substance in solid solution, or a metal compound comprising the substance and a metal, to produce batches of a product comprising the metal, comprising the steps of:

• (A) producing a batch of the product by;
• providing a fused-salt melt comprising a fused salt, a reactive-metal compound and a reactive metal, the fused salt comprising an anion species which is different from the substance, the reactive-metal compound comprising the reactive metal and the substance, and the reactive metal being capable of reaction to remove at least a portion of the substance from the feedstock;
• contacting the melt with a cathode;
• contacting the cathode and the melt with a batch of the feedstock such that the batch feedstock is cathodically connected;
• contacting the melt with an anode;
• and
• applying a current between the cathode and the anode to remove at least a portion of the substance from the cathodically-connected batch of feedstock so as to produce the product;
• in which a portion of the applied current during step (A) is carried by a reaction in which the reactive metal in the melt is oxidized at the anode;
• and
• in which a quantity of the reactive metal in the melt is sufficient to prevent oxidation of the anion species at the anode when the current is initially applied and at all times during step (A);
• and then
• (B) applying the current between the cathode and the anode for a further period of time, during which time the product remains cathodically connected in the melt, to decompose a portion of the reactive-metal compound in the melt and so increase the quantity of the reactive metal in the melt;
• in which steps (A) and (B) are carried out under current control;
• (C) removing the batch of product from the melt;
• and
• (D) re-using the melt to process a further batch of feedstock as defined in steps (A) to (C).