Selenium distillation residue (SDR), inevitably generated in the treatment of refining selenium by vacuum distillation of crude selenium, is a kind of solid residue with low utilization yet massive recycling value. It contains a diverse and complicated component of selenide, telluride, and high-level precious metals. In this study, oxidative acid leaching at atmospheric pressure is adopted to systematically treat SDR to separate selenium, tellurium, copper, and effectively enrich gold and silver. The leaching method in H₂SO₄–H₂O₂ mixed solution under an oxygen atmosphere was employed to investigate the effects of H₂SO₄ concentration, H₂O₂ concentration, oxygen flow rate, liquid–solid ratio, and leaching time on the recovery of Se, Te, and Cu. Under the optimal conditions, the recoveries of Se, Te, and Cu, respectively, achieved 87.96%, 87.02%, and 98.82% while Au, Ag, and Pb were enriched in the leaching residue, the contents were 0.42%, 16.5%, and 24.27%, respectively. Thermodynamic analysis indicated that insoluble Cu₂Se could be oxidized to soluble H₂SeO₃ in the pH range of − 1.5 to 0, and the potential 0.83 V. XRD and EPMA results outline that CuSe, AgSe, CuTe, and AgTe exist in leaching residue resulting in incomplete leaching of Se, Te, and Cu. Besides, the existence of core–shell grain of AgCl@AgSe is another main reason for the incomplete leaching of selenium. Oxygen partial pressure can enhance mass transfer by diffusion and open the envelope phase. The leaching percentages of Se, Te, and Cu at 0.5 MPa are measured as 93.97%, 99.83%, and 97.42%, respectively.

Graphical Abstract

中文翻译：

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硫酸氧化浸取硒蒸馏残渣中有价金属（Se、Te、Cu）的选择性回收

硒蒸馏残渣（SDR）是粗硒真空蒸馏提炼硒处理过程中不可避免产生的一种固体残渣，利用率低，回收价值大。它含有多种复杂的硒化物、碲化物和高级贵金属成分。本研究采用常压氧化酸浸系统处理SDR，分离硒、碲、铜，有效富集金、银。采用氧气氛下H ₂ SO ₄ -H ₂ O ₂混合溶液浸出法考察了H ₂ SO ₄浓度、H ₂ O _{2的影响。}浓度、氧气流量、液固比和浸出时间对硒、碲和铜回收率的影响。优化条件下，Se、Te、Cu的回收率分别达到87.96%、87.02%和98.82%，而Au、Ag和Pb在浸出渣中富集，含量分别为0.42%、16.5%、和 24.27%，分别。热力学分析表明不溶性Cu ₂ Se可以被氧化成可溶性H ₂ SeO ₃在 - 1.5 到 0 的 pH 值范围内，潜在的 0.83 V。XRD 和 EPMA 结果表明，浸出残渣中存在 CuSe、AgSe、CuTe 和 AgTe，导致 Se、Te 和 Cu 的浸出不完全。此外，AgCl@AgSe核壳颗粒的存在是硒浸出不完全的另一个主要原因。氧分压可以通过扩散增强传质并打开包络相。在 0.5 MPa 下，Se、Te 和 Cu 的浸出百分比分别为 93.97%、99.83% 和 97.42%。

图形概要