Vanadium(II) reductive upgrading of copper sulfide concentrates via Iron leaching to facilitate stagewise oxidative copper leaching at room temperature

Abstract

Over this coming decade, copper demand in the United States is projected to increase significantly because of the energy transition to carbon-free sources. Compared to traditional hydrometallurgical processes involving oxidation, reductive leaching of copper mineral concentrates has been shown to yield significant advantages. For example, reductive leaching of chalcopyrite can be performed at ambient temperatures without intensive grinding. This could achieve high yields, reduced processing costs, all while minimizing environmental impacts.

This work explores vanadium reductive leaching of other copper mineral concentrates by measuring leaching kinetics and yields. Over 90 % of the copper was successfully extracted from copper concentrates obtained from three active mines, each with different mineral compositions, after reacting in VSO₄, H₂SO₄ solution at room temperature for 60 min. It was shown that the addition of FeSO₄ enhanced the leaching yields of copper from chalcocite (Cu₂S), from 55.1 % to 100 % in concentrates having moderate iron concentrations and from 62.7 % to 82.2 % in low-iron concentrates. The copper recovery in low-iron concentrates could be increased to 99 % after leaching a second time, suggesting a staged operation may be favored. Results show that similar yields may be achieved when leaching occurs in a continuous flow reactor with residence times between 10 and 20 min. For example, 85.2 % - 100 % of iron was leached from Source 2 concentrates, and 87.7 % - 95.3 % of iron was leached from Source 3 concentrates in continuous flow leaching. The processing rate using the continuous flow reactor was 87 g/L h⁻¹, a rate competitive with existing processing methods.