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<p>The efficient recovery of copper (Cu) and cobalt (Co) from complex sulfide concentrates, particularly those from the Democratic Republic of Congo (DRC), remains a significant metallurgical challenge. This study investigates a flotation sulfide concentrate (Cu: 22.7%, Co: 3.44%) derived from the acid leaching residue of oxide ores. A systematic investigation of atmospheric oxygen enhanced acid leach was conducted, examining the effects of particle size, temperature, acid concentration, pulp density, and time. Under selected conditions (90&#xa0;°C, 333–400&#xa0;g/L H<sub>2</sub>SO<sub>4</sub>, 12&#xa0;h), a maximum Cu leaching efficiency of 92.8% was achieved. However, Co extraction was consistently poor (below 35%), remaining the process bottleneck. Pilot-scale continuous trials (11 days, 200.5&#xa0;kg dry ore) confirmed these findings, achieving an average Cu extraction of 89.6%, limited by residual flotation reagents increasing pulp viscosity. Comprehensive mineralogical analysis of the leach residue revealed that the primary Cu loss was in covellite, while the majority of Co was locked in a refractory carrollite (CuCo<sub>2</sub>S<sub>4</sub>) phase, which was resistant to atmospheric leaching. Various attempts to enhance Co leaching, including oxidative/reductive leaching with persulfate/metabisulfite, chloride addition (up to 50&#xa0;g/L Cl<sup>−</sup>), and two-stage leaching, proved ineffective. In contrast, pressure oxidation leaching (POX) at 200&#xa0;°C with an oxygen overpressure of 0.5&#xa0;MPa achieved remarkable extractions of over 97.8% for Cu and 98.8% for Co in just 2&#xa0;h. This study conclusively demonstrates that while atmospheric oxygen-enriched leaching is an effective and economically viable process for Cu recovery from this material, it is incapable of extracting Co. The refractory nature of the Co-bearing mineral necessitates a high-temperature, high-pressure oxidative environment, such as that provided by POX, to achieve commercially viable Co recovery.</p>

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Processing of a complex copper-cobalt sulfide concentrate from DRC: a comparative study of atmospheric and pressure oxidative leaching

  • 期刊论文

  • 发表日期：

    2026年7月7日

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  • Qifan Zhou,
  • Feng Xie,
  • Hao Ma,
  • Haibei Wang

摘要

The efficient recovery of copper (Cu) and cobalt (Co) from complex sulfide concentrates, particularly those from the Democratic Republic of Congo (DRC), remains a significant metallurgical challenge. This study investigates a flotation sulfide concentrate (Cu: 22.7%, Co: 3.44%) derived from the acid leaching residue of oxide ores. A systematic investigation of atmospheric oxygen enhanced acid leach was conducted, examining the effects of particle size, temperature, acid concentration, pulp density, and time. Under selected conditions (90 °C, 333–400 g/L H2SO4, 12 h), a maximum Cu leaching efficiency of 92.8% was achieved. However, Co extraction was consistently poor (below 35%), remaining the process bottleneck. Pilot-scale continuous trials (11 days, 200.5 kg dry ore) confirmed these findings, achieving an average Cu extraction of 89.6%, limited by residual flotation reagents increasing pulp viscosity. Comprehensive mineralogical analysis of the leach residue revealed that the primary Cu loss was in covellite, while the majority of Co was locked in a refractory carrollite (CuCo2S4) phase, which was resistant to atmospheric leaching. Various attempts to enhance Co leaching, including oxidative/reductive leaching with persulfate/metabisulfite, chloride addition (up to 50 g/L Cl−), and two-stage leaching, proved ineffective. In contrast, pressure oxidation leaching (POX) at 200 °C with an oxygen overpressure of 0.5 MPa achieved remarkable extractions of over 97.8% for Cu and 98.8% for Co in just 2 h. This study conclusively demonstrates that while atmospheric oxygen-enriched leaching is an effective and economically viable process for Cu recovery from this material, it is incapable of extracting Co. The refractory nature of the Co-bearing mineral necessitates a high-temperature, high-pressure oxidative environment, such as that provided by POX, to achieve commercially viable Co recovery.