Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan.
Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan.
Waste Manag. 2018 Jul;77:195-202. doi: 10.1016/j.wasman.2018.04.039. Epub 2018 May 26.
This paper describes the recovery of gold (Au) from shredder light fraction (SLF) of a recycling plant by flotation and leaching. SLF is typically sent to landfills as waste, but it still contains substantial amounts of Au, and other metals like Cu and Fe. The SLF sample used in this study contains 0.003% of Au, 12% of Cu, and 10% of Fe. Flotation results showed that over 99% of Au and 50% of combustibles were recovered in froth while most of the base metals were recovered in tailing. SEM-EDX of froth products indicates that Au floated via two mechanisms: (1) flotation of Au-plated plastic particles, and (2) agglomeration of fine Au particles together with plastic particles due to kerosene-induced hydrophobic-hydrophobic interactions followed by the flotation of these agglomerated particles. Combustibles in froth/tailing were analyzed by ATR-FTIR, and the results showed that plastics in the froth were mostly sulfonated polystyrene (PS) and acrylonitrile butadiene styrene (ABS) while those in tailing were polyurethane (PU) and polyethylene terephthalate (PET). Contact angle measurements of plastic particles suggest that PS and ABS are more hydrophobic than PU and PET. Most of the base metals in the tailing had either bent or twisted shapes because they were mostly made up of wires. In flotation, these large and heavy particles are unaffected by bubbles and simply sink. Leaching results using ammonium thiosulfate solutions showed that Au extraction increased from 33 to 51% after flotation.
本文介绍了从回收厂的碎料轻组分（SLF）中通过浮选和浸出回收金（Au）的方法。SLF 通常作为废物送往垃圾填埋场，但它仍然含有大量的 Au 以及其他金属，如 Cu 和 Fe。本研究中使用的 SLF 样品含有 0.003%的 Au、12%的 Cu 和 10%的 Fe。浮选结果表明，超过 99%的 Au 和 50%的可燃物在泡沫中回收，而大部分贱金属则在尾矿中回收。泡沫产品的 SEM-EDX 分析表明，Au 通过两种机制浮选：（1）Au 镀覆塑料颗粒的浮选，以及（2）由于煤油诱导的疏水-疏水相互作用，细 Au 颗粒与塑料颗粒团聚，然后浮选这些团聚颗粒。通过 ATR-FTIR 分析泡沫/尾矿中的可燃物，结果表明，泡沫中的塑料主要是磺化聚苯乙烯（PS）和丙烯腈丁二烯苯乙烯（ABS），而尾矿中的塑料主要是聚氨酯（PU）和聚对苯二甲酸乙二醇酯（PET）。塑料颗粒的接触角测量表明，PS 和 ABS 比 PU 和 PET 更疏水。尾矿中大部分贱金属要么弯曲要么扭曲，因为它们主要由金属丝制成。在浮选过程中，这些大而重的颗粒不受气泡影响，只是下沉。使用硫代硫酸铵溶液进行浸出的结果表明，浮选后 Au 的提取率从 33%增加到 51%。
