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Selective Water Leaching of Sulfated Rare Earth Ore and Impurity Removal from a Rare Earth Sulfuric Liquor
Mining, Metallurgy & Exploration ( IF 1.9 ) Pub Date : 2020-01-15 , DOI: 10.1007/s42461-020-00179-9
Ruberlan Gomes Silva , Carlos Antonio Morais , Éder Domingos Oliveira

The objective of this work was to assess the influence of parameters such as residence time, solid content, and temperature in a process route towards purified rare earth liquor which could be adequate to produce marketable rare earth products. The steps of the process route proposed in this study comprised water leaching of a sulfated rare earth ore and removal of impurities through the purification of the rare earth sulfuric liquor, which is the product of the water leaching step. The sample used in the water leaching experiments was a sulfated rare earth ore produced by the reaction of a beneficiated rare earth ore with sulfuric acid followed by roasting at 700 °C for 2 h in a muffle furnace and cooling at 20 °C. The water leaching experiments showed that the best condition comprised a residence time of 30 min, temperature of 20 °C, and solid content of 10% w/w, resulting in a recovery of 71.3% of the rare earth elements (REE) and a lower impurity extraction, e.g., only 15.0% of Fe, representing the main impurity in the rare earth ore. Even when presenting low amounts of impurities, the rare earth sulfuric liquor still needed to be purified before it can be used in the production of marketable rare earth products. In the study, the rare earth sulfuric liquors were purified in two consecutive neutralization steps, first by dosing the limestone pulp to pH up to 3.5 and secondly by adding the lime pulp to raise the pH from 3.5 to 5.0. The application of two consecutive purification steps at 20 °C resulted in the highest overall REE recoveries (65.4%) throughout all the steps of the process, being 71.3% in the water leaching, 99.6% in the partial purification with limestone pulp, and 92.1% in the purification with lime pulp at 20 °C. Under this condition, there was a total elimination of Fe, P, and Th and a significant reduction in the Al, U, and sulfate concentrations in the purified rare earth liquor. The purified rare earth liquor attained through the experiment is expected to be amenable to be used in the production of marketable products due to the lower impurities/REO mass ratios. Graphical Abstract

中文翻译:

硫酸化稀土矿的选择性水浸及稀土硫液中的杂质去除

这项工作的目的是评估工艺路线中诸如停留时间、固体含量和温度等参数对纯化稀土液体的影响,这些液体足以生产可销售的稀土产品。本研究中提出的工艺路线的步骤包括硫酸化稀土矿的水浸和通过纯化稀土硫酸液去除杂质,这是水浸步骤的产物。水浸实验中使用的样品是硫酸化稀土矿石,其通过选矿后的稀土矿石与硫酸反应,然后在马弗炉中在 700 °C 下焙烧 2 h 并在 20 °C 下冷却而产生。水浸实验表明,最佳条件包括停留时间为 30 min,温度为 20 °C,固含量为10% w/w,稀土元素(REE)的回收率为71.3%,杂质提取率较低,如仅15.0%的Fe,代表稀土矿中的主要杂质。即使在杂质含量较低的情况下,稀土硫酸液仍需经过提纯处理,才能用于生产适销对路的稀土产品。在该研究中,稀土硫酸液在两个连续的中和步骤中进行纯化,首先将石灰石浆的 pH 值加到 3.5,然后添加石灰浆将 pH 值从 3.5 提高到 5.0。在 20 °C 下应用两个连续的纯化步骤导致整个过程的所有步骤的 REE 总回收率最高 (65.4%),水浸为 71.3%,石灰石浆部分纯化为 99.6%,92.1% 用石灰浆在 20°C 提纯。在此条件下,纯化的稀土溶液中的 Fe、P 和 Th 完全消除,Al、U 和硫酸盐浓度显着降低。由于较低的杂质/REO质量比,预计通过实验获得的纯化稀土溶液可用于生产适销产品。图形概要
更新日期:2020-01-15
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