还原-磨选法从汽车尾气失效催化剂中富集铂族金属

Enrichment of PGMs by Reduction Grinding-Separation Method from Spent Automobile Catalyst

针对废催化剂，以铁作为补集剂，提出了低温还原．磨选一酸浸的工艺路线来富集废催化剂中的贵金属。重点研究了残渣与捕集剂配比、还原温度、还原时间、添加剂配比、还原剂配比、磨矿细度对指标的影响。通过实验，确定了最佳工艺参数：残渣与捕集剂配比为1．0：1．5，还原温度为1220℃，还原时间为6h，添加剂配比为捕集剂重量比的10％，煤粉配比为捕集剂重量比的9％，球磨时间45min。采用扫描电镜（SEM）和x射线衍射物相分析（XRD）对还原产物进行了分析，结果表明，在还原过程中加入添加剂可促进铁晶粒聚集长大并能够有效捕集铂族金属，经还原后铁晶粒大小范围为50～150μm，并与渣相呈现物理镶嵌分布，有利于后续磨选分离。通过磨选，获得含铂族金属还原铁粉，采用x射线衍射物相分析（XRD）对铁粉进行分析，分析表明其物相主要为金属铁，实现了金属铁与脉石分离，为后续酸溶富集铂族金属奠定基础。在确定的工艺条件下，得到铂族金属富集物，其中：Pt47495．3g.t-1；Pdl2756．8g.t-1；Rh23145．5g．t-1，从原料到酸溶，铂钯铑富集比分别为551．30，512．73，545．90，回收率分别为98．16％，91．22％，97．35％。通过实验可知，金属铁可有效富集催化剂中的铂族金属，该工艺具有操作简单、环境友好、高富集率和实用性强等优点，可为铂族金属二次资源富集技术的提供参考。

For the spent automobile catalyst, iron as the capturing agent, the process route of low temperature reduction-grinding and separation-acid leaching was proposed to enrich the PGMs. The effects of the residue and capturing agent ratio, reduction temperature, reduction time, additive ratio, reducing agent ratio and grinding fineness were studied. Through the experiments, the reasonable exper- iment parameters and conditions were determined as follows ： the residue and iron capturing agent ratio of 1.0： 1.5, reduction tempera- ture of 1220 ℃, reduction time of 6 h, the weight of additive of 10% of the capturing agent, the the weight of coal of 9% of the captu- ring agent, milling time of 45 min. The reduction product was analyzed by scanning electron microscope （SEM） and X-ray diffraction （XRD） , the results showed that it promoted the iron grain aggregation and growth and the PGMs was effectively captured when addi- tives were added. The range of iron grain size was from 50 to 150μm after reduction, it was physic mosaic distribution with the slag phase and beneficial to the follow-up grinding-separation process. The iron powder containing rich PGMs was obtained after grinding- separation process and the main phase was iron by XRD analysis, this process achieved the separation of iron and gangue and laid thefoundation for the follow-up acid leaching and enrichment of PGMs. Under the determining condition, PGMs concentrate was obtained （Pt 47495.3 g.t-1, Pd 12756.8 g.t -1 , Rh 23145.5 g.t-1 ）, the enrichment ratios of Pt, Pd and Rh were 551.30, 512.73 and 545.90, respectively, and the recovery rates of Pt, Pd and Rh were 98. 16% , 91.22% and 97.35% , respectively. The experiments showed that iron could effectively enrich PGMs from the spent catalyst. This process had advantages like a simple process, environ- ment-friendly characteristic, good applicability for raw materials and high enrichment ratio of precious metals. It could provide a refer- ence for other PGMs secondary resources.