从碲渣中选择性分离与回收碲的新工艺

摘要

以粗铋碱性精炼过程中产生的碲渣为研究对象,采用 Na2S 浸出?Na2SO3还原的新工艺选择性分离回收碲.考察Na2S浓度、浸出温度、浸出时间和液固比等工艺参数对碲浸出率的影响,以及Na2SO3过量系数、反应温度和反应时间等因素对碲还原率的影响.结果表明:在Na2S浓度40 g/L、浸出温度50 ℃、浸出时间1 h、液固比8的条件下,碲的浸出率达87.77%;在Na2SO3过量系数2.0,反应温度30 ℃,反应时间30 min条件下,碲还原率达98.84%,还原产物中碲含量达97.34%,XRD结果显示其为单质态碲.Na2S浸出?Na2SO3还原新工艺可以有效地分离回收碲渣中碲,实验过程简单、清洁,生产成本低,具有产业化前景.%A novel process, including sodium sulfide leaching and sodium sulfite reduction, was proposed to selectively separate and recover tellurium from tellurium slag, which came from basic refining of bismuth crude. The effects of Na2S concentration, leaching temperature and time, liquid to solid ratio on leaching efficiency of tellurium, and Na2SO3 multiple of stoichiometric, reacting temperature and time on reduction efficiency of tellurium were investigated. The results show that the leaching efficiency of tellurium reaches 87.77% under the conditions of Na2S concentration 40 g/L, leaching temperature 50 ℃, leaching time 1 h, L/S 8, and the reduction efficiency of tellurium reaches 98.51% under the conditions of Na2SO3multiple of stoichiometric 2.0, reacting temperature 30 ℃, reacting time 30 min. The content of tellurium in the reduction product reaches 97.34%, and the XRD results show that reduction product is a single Te element phase. Tellurium can be effectively extracted and recovered from tellurium slag by sodium sulfide leaching and sodium sulfite reduction. The process is simple, clean and low cost, which is promising for industrialization in the future.