In one of the keynote presentations at ALTA 2016 this May, Ken Baxter, VP Technology, SNC-Lavalin, Australia, asks Are we any closer to hydromet overtaking smelting for copper sulphide concentrates? The abstract follows.

Where primary copper concentrates contain little in the way of deleterious elements and transport or government royalties for export of untreated concentrates do not present significant commercial issues, smelting of primary copper concentrates remains the route of choice. Opportunities for technically viable hydrometallurgical treatment routes ultimately turn on commercial viability and an assessment of risk for hydrometallurgical options.

While pyrometallurgical treatment of concentrates is capital intensive and has stringent environmental controls, smelting technology also continues to evolve to address these issues, so it is unlikely that primary sulphide concentrate treatment will move significantly away from smelting unless concentrate compositions change significantly. However, increases in the proportion of concentrates produced with high levels of impurities will increasingly open opportunities for hydrometallurgical flowsheets to be considered.

Most primary hydrometallurgical options for treating both clean and dirty primary copper concentrates remain commercially unproven, although there are an increasing number of process plants treating primary and secondary copper concentrates where the hydrometallurgical process can add value to the project that cannot be achieved via a concentrate smelting route.

For secondary copper concentrates, the alternatives are much more open, with a significant number of hydrometallurgical plants in operation treating both concentrates and run of mine ores ROM. Whole ore treatment is prevalent as a result of difficulties in obtaining good flotation recoveries.

This paper will explore the basis of flowsheet selection, in cases where alternatives other than smelting have been considered for copper sulphide concentrate treatment.