Abstract The exploitation of massive rare-earth element (REE) deposits is frequently contested because of the pollution generated by the heavy mining operations and REE extractive metallurgy operations. In an effort to minimise the environmental footprint of the REE production and meet the increasing demand for these elements, mine wastes and extractive metallurgy tailings are attracting attention as alternative primary sources. However, these residues frequently contain small amounts of monazite [(Ce,La,Nd)PO4] in silicate-rich gangues, rendering the efficient and selective recovery via current flotation routes difficult. Herein, we investigated the use of LaCl3 as an activator to promote the selective adsorption of fatty acid collectors on the surface of phosphate minerals, thus improving the monazite flotation performance. Bench-scale flotation tests were performed on a low monazite-grade, silicate-rich residue and revealed that a low LaCl3 dosage (about 1 g t−1) selectively enhanced the floatability of monazite and gangue phosphate minerals. We found that the influence of LaCl3 on the monazite flotation performance depends on the LaCl3 dosage, collector dosage, and method of addition of these reagents to the pulp. The mineral composition of the flotation products was determined by mineral liberation analysis (MLA), which indicated that higher concentrations of lanthanum ions promote the adsorption of the collector on rutile and aluminium-rich minerals, thus reducing the selectivity of the monazite flotation separation. This study is a stepping stone towards the development of a new practice of monazite flotation with environmentally friendly collectors and may render low REE-grade residues a commodity.

中文翻译：

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使用镧盐作为选择性磷酸盐活化剂，使用脂肪酸捕收剂从富含硅酸盐的尾矿中高效浮选独居石

摘要 由于重采作业和稀土元素提取冶金作业产生的污染，大块稀土元素（REE）矿床的开采经常受到争议。为了尽量减少 REE 生产的环境足迹并满足对这些元素日益增长的需求，矿山废料和冶炼尾矿作为替代的主要来源正在引起人们的关注。然而，这些残留物在富含硅酸盐的脉石中经常含有少量的独居石 [(Ce,La,Nd)PO4]，这使得通过目前的浮选路线进行高效和选择性回收变得困难。在此，我们研究了使用 LaCl3 作为活化剂来促进脂肪酸捕收剂在磷酸盐矿物表面的选择性吸附，从而提高独居石浮选性能。对低独居石品位、富含硅酸盐的残渣进行了实验室规模的浮选试验，结果表明低 LaCl3 剂量（约 1 g t-1）选择性地提高了独居石和脉石磷酸盐矿物的可浮性。我们发现 LaCl3 对独居石浮选性能的影响取决于 LaCl3 用量、捕收剂用量和这些试剂加入矿浆的方法。浮选产物的矿物组成由矿物释放分析（MLA）确定，表明较高浓度的镧离子促进捕收剂对金红石和富铝矿物的吸附，从而降低独居石浮选分离的选择性。