Comparison of Heterotrophic Bioleaching and Ammonium Sulfate Ion Exchange Leaching of Rare Earth Elements from a Madagascan Ion-Adsorption Clay
Comparison of Heterotrophic Bioleaching and Ammonium Sulfate Ion Exchange Leaching of Rare Earth Elements from a Madagascan Ion-Adsorption Clay
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DOI：
10.3390/min8060236
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发表时间：
2018-06-01
期刊：
影响因子：
2.5
通讯作者：
Gregory, Simon P.
中科院分区：
文献类型：
--
作者：
Barnett, Megan J.;Palumbo-Roe, Barbara;Gregory, Simon P.
稀土元素（REE）被认为是一种关键资源，因为它们在绿色能源应用中的重要性以及对中国进口的过度依赖。富稀土离子吸附型矿床是富稀土火成岩热带风化作用的产物。使用盐溶液，通过离子交换机制从IAD中浸出商业稀土元素。将曲霉菌或芽孢杆菌对IAD的生物浸出与未接种的对照和盐浸出（0.5 M硫酸铵）进行了60天的比较。盐浸效果最好，其次是曲霉菌，芽孢杆菌，未接种对照。大部分的稀土元素和常量元素的释放发生在第3天之前。生物淋滤，稀土元素和常量元素的释放随时间的推移而增加，并有较大的重轻稀土比。盐浸和曲霉菌的重稀土释放总量相似（分别为73.1%和70.7%）。在生物浸出实验中，pH值呈负相关与稀土元素的释放（R-2 = 0.947 Lu），表明微生物产生的酸浸出。这些实验显示了从IAD中生物浸出REE的潜力，但是不期望的元素的溶解可能在下游处理中引起问题。进一步了解生物淋滤机理，可以优化稀土元素的回收。
Rare earth elements (REE) are considered to be a critical resource, because of their importance in green energy applications and the overdependence on Chinese imports. REE rich ion-adsorption deposits (IAD) result from tropical weathering of REE enriched igneous rocks. Commercial REE leaching from IAD, using salt solutions occurs via an ion-exchange mechanism. Bioleaching of IAD by Aspergillus or Bacillus, was compared to Uninoculated Control and Salt leaching (0.5 M ammonium sulfate) over 60 days. Salt leaching was most effective, followed by Aspergillus, Bacillus then Uninoculated Control. Most of the REE and major elements released by Salt leaching occurred before day 3. With bioleaching, REE and major elements release increased with time and had a greater heavy to light REE ratio. Similar total heavy REE release was observed in Salt leaching and Aspergillus (73.1% and 70.7% Lu respectively). In bioleaching experiments, pH was inversely correlated with REE release (R-2 = 0.947 for Lu) indicating leaching by microbially produced acids. These experiments show the potential for bioleaching of REE from IAD, but dissolution of undesirable elements could cause problems in downstream processing. Further understanding of the bioleaching mechanisms could lead to optimization of REE recovery.