Electro-hydrometallurgical process for the extraction of base metals and iron

Claim 1

In a continuous hydrometallurgical process for the electrolytic recovery of a selected base metal from ore concentrate in the form of base metal sulphide compounds containing iron, said process utilizing at least a primary and secondary bank of sequentially disposed electrolytic cells, the cells of each bank electrically connected in parallel, or the equivalent thereof, each said cell having separate anode and cathode compartments and each said compartment separated from adjacent said compartments in a bank by a permeable dividing element capable of passing electrolyte between the compartments, the improvement which comprises: continuously withdrawing a first supply of anode solution from the anode compartments of the electrolytic cells in each bank of cells, said anode solution being an aqueous electrolyte including in solution hydrochloric acid and a soluble metal chloride, continuously leaching a first supply of ore concentrate by said first supply of anode solution in at least one leaching vessel to reduce ferric ions to their lowest (ferrous) valence state, separating solids from liquid in the resulting slurry output from the leaching vessel the slurry including solid residue, partially leached concentrate and leaching solution, returning the separated leaching liquid from the slurry output of the leaching vessel to the cathode compartments of both the primary and secondary banks of cells with a first preselected portion of said liquid being returned to the cathode compartments of the secondary bank of cells, continuously withdrawing base metal deposits from a base metal slurry comprising cathode solution and precipitated base metal obtained from the cathode compartments of each bank of cells, returning the separated cathode solution obtained from the base metal slurry to the cathode compartments of both the primary and secondary bank of cells with a second preselected portion of the separated cathode solution being returned to the cathode compartments of the secondary bank of cells, the amounts of said first and second preselected portions being small enough to allow for the establishment in said cathode compartments of base metal impoverished solution areas and the amounts of remaining separated leaching liquid and separated cathode solution returned to the cathode compartments of the primary bank of cells, being large enough to avoid the development of base metal impoverished areas next to the cathode electrodes of the primary bank of cells, continuously withdrawing base metal impoverished cathode solution from the base metal impoverished solution areas of the cathode compartments of the secondary bank of cells, cathodically producing hydrogen gas from the catholyte of the electrolytic cells in each bank of cells, evaporating and crystallizing base metal impoverished cathode solution to yield hydrated ferrous chloride, and reducing the said hydrated ferrous chloride by the hydrogen gas at a selected elevated temperature to produce metallic iron.