火法铋捕集废汽车催化剂中Pt、Pd、Rh的机理

Mechanism of bismuth capture Pt,Pd and Rh from spent auto-catalysts by pyrometallurgical process

废汽车催化剂中铂族金属的绿色高效富集一直是制约二次资源综合利用的关键问题。本文对铋捕集铂族金属的熔炼渣型和还原热力学进行了模拟计算,实验考察了多种因素对铂族金属回收率的影响,重点对单铂族金属贵铋进行微观表征。结果表明:通过控制Na_(2)B_(4)O_(7)·10H_(2)O和Na_(2)CO_(3)用量,可形成Na_(2)O-B_(2)O_(3)-SiO_(2)-(15%)Al_(2)O_(3)四元渣系,得到具有低熔点的NaAl_(8)O_(14)和Na_(2)Al_(12)O_(18)渣相,在优化条件下Pt、Pd、Rh的回收率分别为96.63%、95.71%、95.70%,贵铋的XRD分析结果表明,Bi与单独的Pt、Pd、Rh可分别形成Bi_(2)Pt、Bi_(2)Pd、Bi_(2)Rh物相,XPS表征结果显示Bi为0和+3价,Bi-Pt贵铋中Pt^(2+)、Pt^(4+)的比例分别为76.89%、23.11%,Bi-Pd贵铋中Pd^(2+)、Pd^(3+)所占比例分别为79.19%、20.81%,Bi-Rh贵铋中Rh~0、Rh^(3+)所占比例分别为62.50%、37.50%。本研究结果可为火法熔炼金属捕集铂族金属的理论体系提供一定的有益补充。

The green and efficient enrichment of platinum group metals from spent auto-catalysts has been a key problem restricting the comprehensive utilization of secondary resources.The smelting slag constitution and reduction thermodynamics of bismuth capture platinum group metals were calculated.The effects of various factors on the recovery efficiency of platinum group metals were investigated,the microscopic characterization of noble bismuth was carried out.The results indicate that by controlling the amounts of Na_2B_4O_7·10H_(2O) and Na_2CO_3,a Na_2O-B_2O_3-SiO_2-(15%)Al_2O_(3) quaternary slag system can be formed,resulting in low melting point NaAl_8O_(14) and Na_2Al_(12)O_(18) slag phases.Under the optimized conditions,the recovery efficiency of Pt,Pd and Rh are 96.63%,95.71%and 95.70%,respectively.The XRD analysis of precious bismuth shows that Bi and individual Pt,Pd and Rh can form Bi_2Pt,Bi_(2Pd) and Bi_(2Rh) phases,respectively.XPS characterization shows that Bi is 0 and+3 valence.Pt~(2+)and Pt~(4+)accounted for 76.89%and 23.11%in Bi-Pt precious bismuth,Pd~(2+)and Pd~(3+)accounted for 79.19%and 20.81%in Bi-Pd precious bismuth,Rh~0 and Rh~(3+)accounted for 62.50%and 37.50%in Bi-Rh precious bismuth.The results of this research can provide a useful supplement to the theoretical system of capturing platinum group metals.