This article presents the behavior of black copper minerals in reducing acid leaching using FeSO₄ as reducing agent. The original sample, which was a blend of green and black copper minerals, was treated first by an oxidizing acid leach using O₃ to dissolve the soluble phase (green copper oxides). The residue (mainly black copper) was evaluated by agitated leaching under three different solution potentials, with respect to the standard hydrogen electrode (SHE) (450, 500, and 600 mV (SHE)) at 25 °C. The original sample and the leach residue were characterized by scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The O₃ leach residue was 1.43% copper, with 50% of the insoluble phase associated with copper pitch, copper limonites, and unreacted chrysocolla. The results of leaching using FeSO₄ demonstrate that it is possible to obtain 90% copper extraction using a solution with a potential of 450 mV, while leaching at 600 mV resulted in 65% copper extraction. Acid consumption was 40 kg/t in the test at 450 mV, followed by 30 kg/t in the 500 mV test, and finally 25 kg/t in the 600 mV test, showing that reactivity decreases with increased solution potential. The results show that retreatment of a leaching residue is possible, considering the presence of copper pitch, copper limonites, and chrysocolla as the main copper contributing minerals. Modeling of copper extraction with nonlinear regression is proposed. The retreatment of residues resulting from conventional acid leaching can be an alternative to make use of the treatment capacity of hydrometallurgical plants.

中文翻译：

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从浸出残渣中溶解黑色氧化铜

本文介绍了以FeSO ₄为还原剂的黑铜矿物质在减少酸浸中的行为。原始样品是绿色和黑色铜矿物的混合物，首先通过使用O ₃氧化酸浸法处理以溶解可溶相（绿色氧化铜）进行处理。通过在25°C下相对于标准氢电极（SHE）（450、500和600 mV（SHE））在三种不同的溶液电势下通过浸出来评估残留物（主要是黑铜）。通过扫描电子显微镜（SEM）和电感耦合等离子体原子发射光谱（ICP-AES）对原始样品和浸出残留物进行表征。O ₃浸出残渣为1.43％的铜，其中50％的不溶相与铜沥青，褐铁矿和未反应的金相胶相关。用FeSO ₄浸出的结果证明了使用电位为450 mV的溶液可以提取90％的铜，而以600 mV的浸出率可以提取65％的铜。在450 mV的测试中，酸消耗为40 kg / t，随后在500 mV的测试中为30 kg / t，最后在600 mV的测试中为25 kg / t，表明反应性随溶液电位的增加而降低。结果表明，考虑到铜沥青，铜褐铁矿和温石棉是主要的促铜矿物，存在浸出残渣的再处理是可能的。提出了利用非线性回归对铜提取进行建模的方法。对常规酸浸所产生的残留物进行再处理可以作为利用湿法冶金设备的处理能力的替代方法。