低品位氧化锌矿氨-碳酸氢铵浸出制备氧化锌工艺的研究

Study on Leaching Low-grade Zinc Oxide Ore in the System of NH_3-NH_4HCO_3-H_2O for Preparing Zinc Oxide

采用氨-碳酸氢铵溶液从低品位氧化锌矿中浸出制备氧化锌。研究结果表明,在氨水浓度7mol/L、碳酸氢铵浓度0.62mol/L、浸出温度50℃、氧化锌矿粉粒度为177μm、液固比5:1、浸出时间3h的条件下,锌一段浸出率为87.2%,经过二段浸出,锌总收率可提高至95.9%;浸出液采用足量锌粉还原除杂后,净化液中铜为0.51mg/L,铬为0.18mg/L,铅可降至0.10mg/L以下;净化液经过蒸氨和焙烧制得的氧化锌含量为99.53%(以氧化锌计)。该方法具有工艺简单、能耗低、浸出率较高、浸出过程对环境较友好等优点。

A process using NH3-NH4HCO3-H2O system as the leaching agent has been applied for treatment of low-grade zinc oxide ore.The impurities in the leachate were removed by zinc powder through replacement reaction.Results showed that the ores of 177 μm size were leached for 3 h at 50 ℃ in the presence of 7 mol /L ammonia and 0.62 mol /L NH4HCO3 and liquid to solid ratio of 5：1,the leaching rate of Zn reached 87.2%.The yield of Zn was up to 95.9% after two stage leaching.After purification,the contents of Cu and Cd in leach liquor were 0.51 mg /L and 0.18 mg /L,respectively,while that of Pb was less than 0.10 mg /L.The purity of zinc oxide reached 99.53% after distillation of ammonia and calcination.The method has the advantages of simple process,low power consumption,high extraction rate of zinc and environmentally benign.