SEM study of a lead-iron slag flotation process

Abstract Companies producing lead-acid batteries are required by law to recycle their battery scrap. The recycling can be performed by a pyrometallurgical process resulting in slags containing mainly lead and iron. A study was carried out with the aim of recovering the lead contained in this slag. This work has economic and environmental implications. Slag characterization was performed by X-ray diffraction, X-ray fluorescence and scanning electron microscopy (SEM). A laboratory-scale mechanical cell was used for flotation tests. The results showed that Pb-Fe selectivity is possible using ethyl xanthate as collector. The coke floats together decreasing concentrate grade. However, this is no problem because coke participates in the metallurgical process for the production of lead. A concentrate containing 22.9% Pb was obtained from a slag with 2.2% Pb. The process removes more than 99.6% of the iron contained. However, the recovery was only 19.0 %. Analyses from scanning electron microscopy detected the presence of lead inside the iron particles, limiting the possibility of lead recovery.

摘要 生产铅酸蓄电池的企业依法需回收其产生的电池废料。该回收过程可通过火法冶金工艺完成，最终得到主要成分为铅与铁的炉渣。本研究旨在回收该炉渣中的铅，此项工作兼具经济与环境双重意义。研究通过X射线衍射、X射线荧光光谱法及扫描电子显微镜（SEM）对炉渣进行了表征，并采用实验室规模的机械浮选槽开展浮选试验。结果表明，以乙基黄原酸盐作为捕收剂时，可实现铅与铁的选择性分离。但焦炭会随之上浮，导致精矿品位降低；不过这一问题并无大碍，因为焦炭可参与铅冶炼的冶金流程。最终从铅含量为2.2%的炉渣中，得到了铅品位达22.9%的精矿。该工艺可脱除炉渣中99.6%以上的铁，但铅的回收率仅为19.0%。扫描电子显微镜分析发现，铅赋存于铁颗粒内部，这限制了铅的回收效率。