Abstract Sulfuric acid leaching of phosphogypsum (PG) waste and leachate treatment in sulfate-reducing bioreactor was studied, in order to recover rare earth elements (REE) and remove sulfate from the residual solution. The challenge was to balance efficient REE extraction from PG while maintaining suitable leach solution acidity and sulfate concentration for the microorganisms in the bioreactor. Stirred tank reactor experiments were conducted for PG leaching to form the scope for suitable sulfuric acid concentration and REE leaching efficiency. According to these experiments, moderate REE leaching started already at 0.01 M H2SO4 concentration (yield 6–15%), and increased steadily when increasing H2SO4 concentration to 0.05 M (yield 34–62%). Different leachates were treated in sulfate-reducing bioreactor to understand the limits of acidity and sulfate concentration for the biological system. It was shown that bioreactor requires rather a mild leachate (

中文翻译：

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用于稀土回收的磷石膏酸浸和生物硫酸盐综合还原

摘要 为回收稀土元素（REE），去除残留溶液中的硫酸盐，研究了硫酸浸出磷石膏（PG）废物和硫酸盐还原生物反应器中渗滤液的处理。面临的挑战是平衡从 PG 中有效提取 REE 的同时保持合适的浸出液酸度和生物反应器中微生物的硫酸盐浓度。对PG浸出进行搅拌釜反应器实验，形成合适的硫​​酸浓度和REE浸出效率的范围。根据这些实验，中等 REE 浸出在 0.01 M H2SO4 浓度（产率 6-15%）时已经开始，并且当 H2SO4 浓度增加到 0.05 M（产率 34-62%）时稳定增加。在硫酸盐还原生物反应器中处理不同的渗滤液，以了解生物系统的酸度和硫酸盐浓度限制。结果表明，生物反应器需要相当温和的渗滤液（