Industrial Development of a Novel Sulfate System for Copper Pyro-Refi ning

This article presents the results of a series of industrial-scale tests conducted at the Noranda Horne smelter, focusing on a novel molten sulfate salt used for the copper pyro-refining process. The objective was to test a new technology that addresses the increasing levels of deleterious impurities in copper concentrates. Methodologically, 116 industrial-scale tests were performed, where variations in the amount of sulfate and lime added, as well as the CaSO4-Na2SO4 ratio in the molten sulfate phase, were systematically assessed. The results indicated a complex interaction between the molten oxide layer and the molten sulfate layer, affecting the refining capabilities and minor element distribution between copper, oxides, and sulfate phases. This study suggests that fine-tuning the sulfate salt composition and understanding the thermodynamic principles governing the system can enhance copper purification efficiency, presenting significant implications for the competitiveness of copper smelters. The findings point towards promising pathways for the optimization of copper pyro-refining technologies in the face of environmental and operational challenges.