沉铂钯后液中碲铋的分离与回收工艺

Separation and recovery process of tellurium and bismuth from precipitating platinum and palladium solution

以铜阳极泥处理中的沉铂钯后液为原料,经过氢氧化钠沉淀、酸浸沉淀渣、SO_2还原后,得到碲粉和还原碲后液,在还原碲后液中加入氢氧化钠沉淀后过滤得到氯氧铋,在氯氧铋中加入氢氧化钠溶液脱氯制得氧化铋。结果表明:加入氢氧化钠调节沉铂钯后液pH为6、反应温度20~25℃、反应时间为1 h时,沉铂钯后液中碲和铋沉淀率分别达到99.91%和99.96%;沉铂钯后液得到的沉淀渣混酸浸出适宜条件是3 mol/L盐酸和1.5 mol/L硫酸体积比为2:1,H^+浓度为3 mol/L,反应温度为50℃,反应时间为2 h,铋和碲的浸出率分别为99.93%和98.21%;在富集碲铋的浸出液中通入SO_2还原,当SO_2流量为0.25 L/min、反应温度为70℃、反应时间为50 min时,碲的还原率为96.59%,还原碲粉中碲含量达到79.45%,砷和铋含量仅为0.003%和0.067%(质量分数);在SO_2还原碲后液中加入氢氧化钠调节溶液pH值为2,过滤后得到氯氧铋;在氯氧铋中加入6 mol/L氢氧化钠溶液,当液固比为3:1、反应温度为80℃、反应时间为2 h时,所得氧化铋产物中氧化铋含量达到93.80%。

Tellurium powder and tellurium reduction liquid were obtained through a sets of steps including precipitation process of NaOH,HCl leaching process of slag producing in the previous process,and the reduction process of SO2.The BiOCl was obtained after reduction tellurium liquid was precipitated using sodium hydroxide and then the slurry was filtered.The Bi2O3 was obtained by using NaOH to remove chlorine from BiOCl.The results show that the precipitation rates of Te and Bi are 99.91%and 99.96%,respectively,using NaOH as pH regulator,when the pH value is 6,temperature is 20-25℃and the reaction time is 1 h.The leaching rates of Te and Bi are 98.21%and 99.93%,respectively,when the volume ratio of 3 mol/L HCl to 1.5 mol/L H2SO4 is 2：1,the concentration of H~＋is 3 mol/L,the reaction temperature is 50℃and the reaction time is 2 h.The reduction rate of Te is 96.59%,and the contents of Te,As and Bi in the tellurium powder are 79.45%,0.003%and 0.067%（mass fraction）,respectively.The BiOCl is obtained by filtering when the pH of Te reduction solution is 2.Finally,the Bismuth content reaches 93.80%after adding 6 mol/L NaOH to the BiOCl when the ratio of liquid to solid is 3：1,the reaction temperature is 80℃and the reaction time is 2 h.