Abstract

Insufficient recycling of a continuously increasing amount of liquid crystal display (LCD) waste leads to the waste of potentially recyclable materials, especially rare and critical indium. Moreover, landfilling of LCD waste increases the potential for environmental risk. This paper describes a recycling process combining membrane filtration unit processes to hydrometallurgical indium recovery process. The LCD panels were crushed and leached with 1 M H₂SO₄. 97.4% yields on average were obtained, and a novel finding was made about fast kinetics (2 min for the maximum indium yield). Ultrafiltration was used to remove the dissolved organic material from the leachate, which was concentrated with nanofiltration before liquid–liquid extraction for indium purification. The results showed that commercial polymeric membranes removed more than 90% (from over 3000 mg/L to under 200 mg/L) of the dissolved organic compounds, thus potentially significantly diminishing the detriments caused by these compounds in the liquid–liquid extraction step. The concentration of the leachate with nanofiltration enables the use of smaller processing equipment and to save chemicals in the further steps of the process. The indium content in the leachate was more than five times higher after nanofiltration than after leaching (126 mg/L vs. 677 mg/L). In liquid–liquid extraction, the phase separation took place in only 34 s with the membrane-treated leachate, while with the untreated leachate it remained incomplete even after three hours. The purity of indium was increased from 10 to 74%. From the obtained HCl solution, a 95.5% pure indium product with 69.3% yield was obtained by cementation.

Graphical Abstract

中文翻译：

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废LCD面板膜过滤增强铟的湿法冶金回收工艺。

摘要

不断增加数量的液晶显示器（LCD）废料回收不足，会导致潜在可回收材料的浪费，尤其是稀有和重要的铟。此外，LCD垃圾的填埋会增加潜在的环境风险。本文介绍了将膜过滤装置工艺与湿法冶金铟回收工艺相结合的回收工艺。将LCD面板压碎并用1 MH ₂ SO ₄浸出。平均获得了97.4％的产率，并且关于快速动力学（最大铟产率为2分钟）做出了新发现。超滤用于从渗滤液中去除溶解的有机物，渗滤液经纳滤浓缩后再进行液-液萃取以提纯铟。结果表明，商用聚合物膜可去除90％以上的溶解有机化合物（从3000毫克/升以上至200毫克/升以下），从而有可能显着减少这些化合物在液-液萃取步骤中造成的损害。通过纳滤浓缩渗滤液可以使用较小的加工设备，并在该工艺的其他步骤中节省化学药品。纳滤后浸出液中的铟含量比浸出后高出五倍（126 mg / L对677 mg / L）。在液-液萃取中，膜处理的渗滤液仅在34 s内就发生了相分离，而未经处理的渗滤液甚至在3小时后仍不完全。铟的纯度从10％增加到74％。从所得到的HCl溶液中，通过胶结获得了具有99.3％产率的95.5％纯铟产物。

图形概要