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Abstract

A novel process for refining high or low impurity blister copper containing S, As, Sb, Pb, Ni, Bi, Se, and/or Te to anode quality by means of a solution containing sulphates and alkali oxides is provided. More specifically, the process comprises the steps of (1) injecting air/O.sub.2 gas mixtures in the presence of an alkali source, over a period of time sufficient to complete the sulphur removal stage, with the innovation of removing the SO.sub.2 in situ, thereby forming an effective amount of a molten alkali sulphate on top of the copper bath, the temperature in the bath being maintained between 1100-1300.degree. C.; (2) adding and/or injecting molten or solid alkali sulphates together with basic oxides or carbonates into the copper bath to promote the in situ scrubbing of As and Sb into a solution containing sulphates, while the dissolved oxygen in copper increases from 0.1 to 0.6 wt %; (3) increasing the level of oxygen in the copper to remove the remaining impurities into a molten solution of Cu.sub.2 O and/or Cu.sub.2 O--CaO, while the molten sulphate and oxide phases co-exist as two immiscible liquid layers of slag; and (4) skimming both the sulphate and oxide slag layers prior to commencing de-oxidation.

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