Ammoniacal leaching solutions have been considered as an effective lixiviant for the oxidative dissolution of chalcopyrite. However, compared with the extensive studies of acidic chalcopyrite dissolution, the dissolution mechanism of chalcopyrite in ammoniacal solutions needs further understanding. In this study, the oxidative dissolution of chalcopyrite in ammonium chloride solutions under room temperature and pH 8.5 was studied by X-ray absorption near-edge spectroscopy (XANES), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). Both batch leaching experiments and electrochemical studies showed that Cu(II) ions were more efficient than dissolved oxygen for chalcopyrite oxidation in ammonium chloride solutions. Leaching kinetics analysis showed that without the initial addition of Cu(II), chalcopyrite dissolution rate was controlled by two different stoichiometric chemical reactions: the initial and slow leaching stage controlled by dissolved oxygen; then predominated by Cu(II) rather than dissolved oxygen with a fast leaching rate when copper concentration exceeded a certain level (>0.12 g/L). Thiosulfate (S₂O₃²⁻) rather than sulfate (SO₄²⁻) was confirmed as the primary soluble sulfur species produced during chalcopyrite dissolution. Decomposition of S₂O₃²⁻ in the presence of both O₂ and Cu(II) resulted in the final stable product SO₄²⁻ accompanied by the formation of other sulfur intermediate species, including S₄O₆²⁻ and SO₃²⁻. No evidence was found for the formation of elemental sulfur. Amorphous hematite (Fe₂O₃) and six-line ferrihydrite (5Fe₂O₃·9H₂O) were the major components residing on the chalcopyrite surface, which were responsible for the slow dissolution rate at late stage. According to the present work, a model for the chalcopyrite dissolution mechanism in alkaline ammonium chloride solutions under ambient conditions is provided.

氨浸出液被认为是黄铜矿氧化溶解的有效浸出剂。然而，与酸性黄铜矿溶解的广泛研究相比，黄铜矿在氨溶液中的溶解机理需要进一步了解。在这项研究中，黄铜矿在室温和 pH 8.5 条件下在氯化铵溶液中的氧化溶解通过 X 射线吸收近边光谱 (XANES)、拉曼光谱和电化学阻抗光谱 (EIS) 进行了研究。批量浸出实验和电化学研究均表明，在氯化铵溶液中，Cu(II) 离子比溶解氧更有效地氧化黄铜矿。浸出动力学分析表明，在没有初始添加 Cu(II) 的情况下，黄铜矿的溶解速率由两种不同的化学计量化学反应控制：由溶解氧控制的初始和缓慢浸出阶段；当铜浓度超过一定水平（> 0.12 g / L）时，以Cu（II）而不是溶解氧为主，具有快速浸出率。硫代硫酸盐 (S₂ O ₃ ^2- ) 而不是硫酸盐 (SO ₄ ^2- ) 被确认为黄铜矿溶解过程中产生的主要可溶性硫物质。在 O ₂和 Cu(II)存在下S ₂ O ₃ ^{2- 的}分解导致最终稳定的产物 SO ₄ ^2-伴随着其他硫中间体物种的形成，包括 S ₄ O ₆ ^2-和 SO ₃ ^2-。没有发现元素硫形成的证据。无定形赤铁矿（Fe ₂ O ₃）和六线水铁矿（5Fe ₂O ₃ ·9H ₂ O)是黄铜矿表面的主要成分，是后期溶解速度缓慢的原因。根据目前的工作，提供了环境条件下碱性氯化铵溶液中黄铜矿溶解机制的模型。