从铜转炉烟尘中制备高纯氯氧化铋工艺研究

Abstract

本文采用“稀硫酸浸出–氧化剂 + 稀硫酸浸出–固相预脱铅–氯盐浸出–浸铋液中除铅砷–沉铋”工艺处理铜转炉烟尘制备氯氧化铋。首先，前两步浸出，均在L/S = 2: 1，t = 1 h，T = 60℃的条件下水浴浸出，使大部分可溶解元素如Cu、Zn、Sn等进入溶液，Pb、Bi等留在渣中。其次，在L/S为5:1，室温下使用pH值为4.5的缓冲溶液，处理二次浸铜渣，进行固相预脱铅；再次，用改性试剂处理浸铋液，去除铅砷。结果表明，室温条件下，盐酸浓度为1 mol∙L−1，氯化钠浓度为2.5 mol∙L−1，液固比为5:1时，铋的平均浸出率达到92%，而浸出液浓度为0.20~0.30 mol∙L−1。用质量分数为1.66%的Na2CO3溶液调节酸浸液的pH值由0.5至3.0左右，沉铋。综上几步，此工艺能将有价金属元素铜、铋有效回收利用，铜的浸出率由原来的40%提高到70%以上；砷在氯氧化铋的含量从3.80%降到0.03%，去除率达到99.21%；铅在氯氧化铋的含量从3.46%降到0.189%；去除率达到96.39%；最后，沉铋后的氯盐溶液返回处理二次浸铜渣。 The process of “dilute sulphuric acid leaching-oxidant + dilute sulphuric acid leaching-initial delead from solid phase-chloride leaching-removal of lead and arsenic from dip bismuth solution- bismuth precipitation-dearsenication” was used for preparation of high-purity bismuth oxychloride from copper converter flue dusts. Firstly, dilute acid and manganese dioxide + dilute acid mixture were used as leaching agent, under the condition of 60˚C water bath, the liquid-solid ratio 2:1, leaching 1 h respectively, so that most solubility elements such as Cu, Zn, Sn could enter solution and lead, and bismuth stays in slag. Secondly, the configured solution is used with pH = 4.5 at room temperature. Under the condition of solid-liquid ratio of 5:1, treated with secondary leaching of copper residue, the purpose is to take off the lead for solid phase. Thirdly, bismuth leaching liquid was treated with modified reagents, in order to reduce metal elements of lead and arsenic content in the solution. The results showed that acid leaching under the condition of the room temperature, 1 mol∙L−1 HCl, 2.5 mol∙L−1 NaCl, and the liquid-solid ratio 5:1, was feasible, and the average extraction rate of bismuth reached 92%, while the leaching solution concentration of bismuth was 0.20 - 0.30 mol∙L−1. The pH value of leaching solution was adjusted with the sodium carbonate solution with the mass fraction of 1.66%. With the addition of sodium carbonate solution, the pH value increased from 0.5 to 3. The purpose is to deposit bismuth. In a comprehensive view, through this process, copper and bismuth as the valuable metals get an effective recycling. The leaching rate of copper was increased from 40% to 70%. This process can effectively separate the Bi from other elements. The content of arsenic in bismuth oxide decreased from 3.80% to 0.03%, and the removal rate reached 99.21%. The content of lead in bismuth oxide decreased from 3.46% to 0.189%, and the removal rate reached 96.39%. Finally, solution after Bi precipitation is treated with hydrochloric acid and sodium chloride mixed solution, and the solution is returned to leaching bismuth.