氧化协同浸出复杂铜碲铋渣中的碲及有价金属

以铜、铅阳极泥火法处理产生的铜碲铋渣为原料，采用中性浸出-氧化协同浸出-草酸沉铜-水解沉铋-亚硫酸钠还原碲工艺分离回收铜碲铋渣中的碲及有价金属。研究了硫酸浓度、双氧水用量、NaCl浓度、浸出时间、浸出温度、液固比对协同浸出铜、碲、铋浸出率的影响，草酸过量系数对沉铜效果的影响，终点pH值对铋沉淀率的影响以及Cl-浓度对碲还原率的影响。结果表明: 在硫酸浓度4 mol/L、双氧水用量0.6 mL/g、NaCl浓度2.5 mol/L、浸出时间1 h、浸出温度80 ℃、液固比3 mL/g时，铜、碲、铋浸出率分别达到98.2%、90.1%和99.3%; 草酸用量为理论量的1倍时，沉铜率达99.2%; 在终点pH=2时，铋沉淀率达97.72%; Cl-浓度0.8 mol/L，碲还原率达95.6%。铜以草酸铜形式回收，铋以氯氧铋形式回收，碲以碲粉形式回收。

Recovering Tellurium and Valuable Metals from Complex Cu-Te-Bi Slag by a Synergistic Approach of Oxidation Leaching

With Cu-Te-Bi slag obtained after the pyrometallurgical treatment of copper and lead anode slime as the raw material, the processing technique consisting of neutral leaching, a synergistic process of oxidation leaching, copper precipitation with oxalic acid, bismuth precipitation by hydrolysis, and tellurium reduction with sodium sulfite was adopted to separate and recover tellurium and valuable metals in the Cu-Te-Bi slag. The effects of sulfuric acid concentration, hydrogen peroxide dosage, NaCl concentration, leaching time, leaching temperature, liquid-solid ratio on the leaching rates of copper, tellurium and bismuth by the synergistic leaching method, the effect of excessive oxalic acid coefficient on copper precipitation, the effect of ending pH value on bismuth precipitation rate, as well as the effect of Cl- concentration on tellurium reduction rate were all explored. Results showed that the leaching rates of copper, tellurium and bismuth reached 98.2%, 90.1% and 99.3%, respectively, with the sulfuric acid concentration of 4 mol/L, the hydrogen peroxide dosage of 0.6 mL/g, the NaCl concentration of 2.5 mol/L, the leaching time of 1 h, the leaching temperature of 80 ℃, as well as the liquid-solid ratio of 3 mL/g. By adding oxalic acid at an amount of one time the theoretical value, the copper recipitation rate reached 99.2%; the bismuth precipitation rate reached 97.72% with the ending pH=2; the reduction rate of tellurium reached 95.6% when Cl- concentration was 0.8 mol/L. It is shown that copper can be recovered in the form of copper oxalate, bismuth recovered in the form of bismuth oxychloride and tellurium recovered in the form of tellurium powder.