废催化剂中铂族金属回收现状与研究进展

Status and research progress on recovery of platinum group metals from spent catalysts

  • 摘要: 我国铂族金属(Platinum group metals, PGMs)储量少,消费量大,对外依存度高,PGMs二次资源的回收利用是缓解我国PGMs短缺最重要的途径。废催化剂是PGMs最主要的来源,其回收成为研究的热点。本文详细介绍了PGMs消费结构与回收现状,全球PGMs回收量约占原矿产量的20%~30%,且将保持持续增长的趋势。样品的精准分析对PGMs回收有至关重要的作用,同时还原、焙烧、机械球磨等预处理能提高PGMs回收率。相对于传统氰化法和王水溶解,近年来开发出氯化浸出法、超临界萃取法、载体溶解法等较环保的浸出工艺。尽管部分湿法浸出工艺已经产业化应用,但存在废水量大、产生有毒气体及回收率低(特别是Rh)的问题。火法富集是以铅、铜、铁、镍锍为捕集剂,与PGMs形成合金富集,载体熔化造渣。本文对上述富集方法进行了综述并总结了优缺点,基于现有技术存在的污染严重、PGMs回收率不高等问题,展望了PGMs绿色高效回收技术,如活化预处理、协同提取有价金属和载体利用、贱金属协同冶炼和铁捕集–电解等,为从事该领域的科研工作者提供了良好的参考。

     

    Abstract: In China, the reserves of platinum group metals (PGMs) are scarce, but the consumption of PGMs is enormous, which has resulted in a high external dependence. As more than 90% of PGMs are used by the catalyst industry, spent catalysts are the most important secondary source. Therefore, recycling PGMs from spent catalysts is the most significant strategy for relieving the risk of shortage in the PGMs supply. In this review, the consumption distribution of PGMs and their recycling status were introduced and recycling technologies were discussed in detail. The volume of recycled PGMs has been estimated to be approximately 20%–30% of the global mine production and this trend is increasing. Sample analysis is considered to be crucial for determining the recovery efficiency of PGMs. Extensive studies have shown that pretreatment methods such as reduction, calcination, and mechanical milling can improve the efficiency of PGMs recovery. Compared with traditional cyanide leaching and aqua regia dissolution, more environmentally friendly leaching methods have been developed in recent years, including chlorination leaching, supercritical fluids extraction, and substrates leaching. However, although some hydrometallurgical processes have been industrialized, their disadvantages include the generation of wastewater, emission of hazardous gases, and low recovery efficiency of Rh, which must be carefully evaluated. Pyrometallurgical methods have been widely used to concentrate PGMs due to the generally low PGMs content in spent catalysts. Lead, copper, iron, and matte are good PGMs collectors, whereby the PGMs form alloys with the collector metals and supporting materials, then enter the slag phase. These melting collection methods were reviewed and their advantages and disadvantages were summarized. Based on the serious environmental problems and low recovery efficiency of PGMs by current technologies, future trends for PGMs recycling have been proposed, including activation pretreatments, co-recovery of valuable metals and carrier materials, base metals synergistic smelting, iron melting capture, and electrolysis. These recycling technologies may indicate the development directions and can serve as effective references for further research in this field.

     

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