Abstract：
Ion adsorption rare earth ore nearly satisfy global market demand for heavy rare earth elements (HREEs). Bio-leaching has important potential for the clean and efficient extraction of ion-adsorption rare earth ore. However, the complexities of in-situ mining restrict the use of contact/direct bio-leaching, and non-contact/indirect bio-leaching would be the best choice. This study explore the potential of fermentation broths prepared by Yarrowia lipolytica (ATCC 30162) for the bio-leaching of ion-adsorption rare earth ore, and three typical metabolites (potassium citrate (K3Cit), sodium citrate (Na3Cit) and ammonium citrate ((NH4)3Cit) of Yarrowia lipolytica were further evaluated in simulated bioleaching (non-contact bioleaching) of ion-adsorption rare earth ore, including leaching behavior, seepage rule and rare earth elements (REEs) morphological transformation. The column leaching experiments shown that direct leaching of REEs using fermentation broths results in incomplete leaching of REEs due to the influence of impurities. Using the purified and prepared metabolites as lixiviant, REEs can be effectively extracted (leaching efficiency >90%) at cation concentration was only 10 % of the commonly used ammonium sulfate concentration (45 mM). Cation type had less effect on leaching efficiency. During the ion-adsorption rare earth ore leaching process, rare earth ions form a variety of complex chelates with citrate, thus transferring rare earth elements from the mineral surface to the leachate. Experimental results showed that pH and concentration together determined the type and form of rare earth chelates, which in turn affect the leaching behavior of REEs and solution seepage rule. This study helps to provide a theoretical basis for the regulation and enhancement of ion-adsorption rare earth ore non-contact bioleaching process.
摘要：
离子吸附稀土矿石几乎满足了全球市场对重稀土元素(HREEs)的需求。生物浸出在离子吸附型稀土矿石的清洁高效提取中具有重要的潜力。然而,现场开采的复杂性限制了接触/直接生物浸出的使用，非接触/间接生物浸出将是最佳选择。本研究探索了用Yarrowialipolytica（ATCC30162）制备的发酵液用于生物浸出离子吸附稀土矿石的潜力，和三种典型的代谢物(柠檬酸钾(K3Cit)，在模拟生物浸出（非接触生物浸出）中，进一步评估了亚氏酵母的柠檬酸钠（Na3Cit）和柠檬酸铵（（NH4）3Cit）对离子吸附的稀土矿石，包括浸出行为，渗流规律和稀土元素(REE)形态转化。柱浸出实验表明，由于杂质的影响，使用发酵液直接浸出稀土元素会导致稀土元素的浸出不完全。使用纯化和制备的代谢物作为浸提剂，在阳离子浓度仅为常用硫酸铵浓度的10%(45mM)时,可有效提取稀土元素(浸出效率>90%)。阳离子类型对浸出效率的影响较小。在稀土矿石离子吸附浸出过程中,稀土离子与柠檬酸盐形成多种络合螯合物,从而将稀土元素从矿物表面转移到渗滤液中。实验结果表明,pH和浓度共同决定了稀土螯合物的种类和形态,进而影响稀土元素的浸出行为和溶液渗流规律。该研究有助于为离子吸附型稀土矿石非接触生物浸出过程的调控和强化提供理论依据。
