Association characteristic study and preliminary recovery investigation of rare earth elements from Fire Clay seam coal middlings
Association characteristic study and preliminary recovery investigation of rare earth elements from Fire Clay seam coal middlings
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DOI：
10.1016/j.fuel.2017.11.075
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发表时间：
2018-03
期刊：
影响因子：
7.4
通讯作者：
Wencai Zhang;Xin-an Yang;R. Honaker
中科院分区：
文献类型：
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作者：
Wencai Zhang;Xin-an Yang;R. Honaker
由于对全球供应的担忧，使用物理和/或化学方法从煤和煤副产品中回收稀土元素（REE）一直是最近研究的焦点。本文系统地研究了某火泥煤层煤中稀土元素的赋存特征及从有机组分和无机组分中回收稀土的方法。煤样在搅拌球磨机中研磨，并通过泡沫浮选分阶段处理，以获得洁净煤精矿和尾矿样品。将来自第一阶段的洁净煤精矿重新研磨以释放更多的微分散矿物质，然后进行浮选。经过6个研磨和回收阶段，累积研磨时间为110 min，使粒度从90%通过84.3 μm降至4.5 μm。对各阶段尾矿样品的分析表明，稀土元素与微分散高岭石有很强的相关性。尾矿材料中的稀土元素含量以灰分计从约580 ppm增加到1200 ppm。在两个洁净煤精矿和尾矿样品的重，轻稀土元素的比例增加，这表明更强的亲和力之间的重稀土元素和有机基质中的最细的矿物质颗粒。在此基础上，进行了泡沫浮选、磁选和酸浸富集稀土试验。使用间歇式WHIMS装置从含有500 ppm RE的进料获得含有近7000 ppm RE的产物。稀土元素含量分析表明，精矿中稀土矿物主要为独居石。浸出的高灰分含量的馏分产生的顺序研磨和浮选步骤，使用1 M硝酸导致回收超过80%的总稀土元素的钪除外。钪的回收率较低，表明相对于其他稀土元素，钪与矿物质有着独特的联系。
Rare earth element (REE) recovery from coal and coal byproducts using physical and/or chemical methods has been the focus of recent investigations due to concerns over worldwide supply. In the current study, the association characteristics of REEs and the recovery of REEs from the organic and inorganic components were systematically studied for a Fire Clay seam coal source. The coal sample was ground in a stirred ball mill and treated by froth flotation in stages to obtain clean coal concentrates and tailing samples. The clean coal concentrate from the first stage was re-ground to liberate more micro-dispersed mineral matter followed by flotation. After six grinding and recovery stages, the cumulative grinding time was 110 min, which reduced the particle size from 90% passing 84.3 μm to 4.5 μm. Analyses conducted on the tailing samples collected from each stage revealed that the REEs have a strong association with micro-dispersed kaolinite. The REE content in the tailings material increased from around 580 ppm to 1200 ppm on an ash basis. The ratio of heavy-to-light REEs in both the clean coal concentrates and tailing samples increased, which indicated a stronger affinity between the heavy REEs and the finest mineral matter grains in the organic matrix. Based on these findings, REE concentration tests were performed using froth flotation, magnetic separation and acid leaching. A product containing nearly 7000 ppm of REEs was achieved from a feed containing 500 ppm REEs using a batch WHIMS unit. The elemental content indicated that the rare earth mineral in the concentrate was primarily monazite. Leaching the high ash content fractions generated from the sequential grinding and flotation steps using 1 M nitric acid resulted in recovering more than 80% of total REEs with the exception of scandium. A lower recovery value obtained for scandium indicated a unique association with the mineral matter relative to the other REEs.