Abstract Due to the high heavy and rare element contents, bauxite residue rejects (red mud) are simultaneously an ecological hazard and economic virtue. The abilities of two strains of Aspergillus niger isolated from pistachio husk and grape skin were investigated in the bioleaching of metals from the red mud produced in the Iran Alumina Company. Citric acid secretion (~15 g/l) by both strains was ten times more than oxalic acid (~1.5 g/l) and kinetically obeyed the Luedeking-Piret model. Also, both Gompertz and logistic equations correlated with cell growth and substrate consumption. Considering the best results of the bioleaching experiments, the grape-skin strain extracted about 92% Al, 88% V, 67% Ti, 66% Sr, and 29% Sc from the activated residue; while, the metal recoveries by pistachio-husk strain were 53% Al, 31% V, 67% Ti, 44% Sr, and 38% Sc. Finally, according to the kinetic studies, the shrinking core model could perfectly simulate the process, and the product layer diffusion was determined as the rate-determining step.

中文翻译：

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从开心果壳和葡萄皮中分离的黑曲霉菌株在赤泥中有价值元素的生物浸出中的应用

摘要 由于高重元素和稀有元素含量，铝土矿渣（赤泥）既是一种生态危害，又是一种经济美德。研究了从开心果壳和葡萄皮中分离的两种黑曲霉菌株在从伊朗氧化铝公司生产的赤泥中生物浸出金属的能力。两种菌株的柠檬酸分泌 (~15 g/l) 是草酸 (~1.5 g/l) 的十倍，并且在动力学上遵循 Luedeking-Piret 模型。此外，Gompertz 和逻辑方程都与细胞生长和底物消耗相关。考虑到生物浸出实验的最佳结果，葡萄皮菌株从活化残留物中提取了约92%的Al、88%的V、67%的Ti、66%的Sr和29%的Sc；同时，开心果壳应变的金属回收率为 53% Al、31% V、67% Ti、44% Sr，和 38% Sc。最后，根据动力学研究，收缩核心模型可以完美地模拟该过程，并将产物层扩散确定为决定速率的步骤。