Sulfuric acid leaching of a complex zinc sulfide concentrate with high copper and lead concentrations under oxygen pressure

ABSTRACT

This paper presents the use of an oxygen pressure-based acid leaching process for the selective extraction of basic metals from a complex zinc ore containing high concentrations of lead (6.00%) and copper (2.47%). The effects of leaching temperature, ore particle size distribution, leaching time, liquid-to-solid ratio, and oxygen partial pressure on the leaching efficiencies of zinc and copper were investigated, and the phase transformation behaviour of lead compounds was studied. Under the optimal conditions that is, a particle size of −48/+40 μm, initial sulfuric acid concentration of 150 g/L, liquid-to-solid ratio of 6:1, leaching time of 150 min, leaching temperature of 150°C, and oxygen partial pressure of 0.8 MPa – the leaching efficiencies of zinc, copper, and iron were 98.85%, 82.69%, and 33%, respectively. The leaching residue showed that almost all of the zinc sulfide was dissolved as ZnSO₄, and most of the negatively charged bivalent sulfur was converted to zero-valent element sulfur. Through the pressure leaching reaction, galena in the concentrate was converted to lead jarosite (PbFe₆(SO₄)₄(OH)₁₂) and elemental sulfur. The formation of lead jarosite facilitated the removal of a significant portion of iron during leaching, reducing the subsequent purification burden.

KEYWORDS:

• Zinc sulfide concentrate
• pressure acid leaching
• zinc and copper extraction
• iron removal
• lead jarosite

Acknowledgements

This research was financially supported by the National Natural Science Foundation of China (Grant Nos. 51964029, 51804146), Applied Basic Research Project of Yunnan Province of China (Grant Nos. 202001AT070079), for which the authors are sincerely grateful, and we gratefully acknowledge many helpful comments and suggestions from anonymous reviews.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number: 51964029]; National Natural Science Foundation of China [grant number: 51804146]; Applied Basic Research Project of Yunnan Province of China [grant number: 202001AT070079].