Abstract There are a number of attempts to release and recover the valuable metals from spent refinery catalysts by bioleaching, and the heat pretreatment is widely used to remove the oil-like compounds for better bioleaching performance. However, the irrational selection of high calcinations temperature of 600–800 °C not only resulted in high energy consumption but also might be cause lower bioleaching efficiencies of metals. In this work, Plackett-Burman design was used to optimize the heat treatment process and recognize the significant control factor. Especially, the mechanisms why low calcinations temperature of 400 °C had the best enhancement on the bioleaching performance of spent catalyst were expounded via microcosmic phase change analysis, biochemical leaching process analysis and bioleaching kinetics analysis. The results showed that the calcinations temperature greatly affected the bioleaching performance and the calcinations of 400 °C witnessed the maximum release efficiencies of 94% for Co and 100% for Mo, respectively; whereas poor bioleaching occurred with 200 or 600 °C. Further studies demonstrated the 400 °C-treatment removed the toxic oil-like compounds, excited the growth of cells, transformed refractory Co/Mo sulfides into tractable Co3O4/MoO3, reduced the percent of residual from, enabled more exposure of Co/Mo oxides at catalyst surface, which caused the best bioleaching performance.

中文翻译：

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通过生物浸出从废钴钼催化剂中同时有效释放钴和钼的热预处理优化及其机制

摘要 有许多尝试通过生物浸出从废弃的炼油厂催化剂中释放和回收有价值的金属，热预处理被广泛用于去除油状化合物以获得更好的生物浸出性能。然而，不合理选择600-800°C的高煅烧温度不仅会导致高能耗，而且可能会导致金属生物浸出效率降低。在这项工作中，Plackett-Burman 设计用于优化热处理工艺并识别重要的控制因素。尤其是通过微观相变分析、生化浸出过程分析和生物浸出动力学分析，阐述了400℃的低煅烧温度对废催化剂生物浸出性能的最佳提高机理。结果表明，煅烧温度对生物浸出性能有很大影响，400℃煅烧的Co最大释放效率分别为94%和100%；而在 200 或 600 °C 时发生较差的生物浸出。进一步的研究表明，400 °C 的处理去除了有毒的油状化合物，刺激了细胞的生长，将难熔的 Co/Mo 硫化物转化为易处理的 Co3O4/MoO3，减少了残留百分比，使 Co/Mo 氧化物的暴露更多在催化剂表面，这导致了最好的生物浸出性能。