含锗锌浸渣微波强化浸出锗的机理研究

Hydrometallurgical zinc residue contains a large amount of germanium that is of extremely high comprehensive recovery value.The environmentally friendly new technology of acid leaching of germanium from germanium-bearing zinc residue enhancing by microwave irradiation is proposed in this project. The process and mechanism of microwave enhanced sulfuric acid leaching of germanium-bearing zinc residue is critical for the new technology. The analysis of chemical composition, the size of particles and the occurrence of valuable metal elements would be studied. By the comparison of conventional heating and microwave-assisted leaching of zinc residue, the temperature increasing behaviors of zinc residue, sulfuric acid solution and leaching system under microwave heating are researched. The effects of microwave-assisted leaching factors e.g. microwave power, temperature, leaching time, liquid-solid ratio, etc, on leaching ratios of Ge, Zn, and Fe would be systematically investigated. By researching the influences of microwave-assisted leaching on the leaching behavior of germanium and the dynamic control steps, the leaching reaction kinetics mechanism is proved. The changes of physicochemical properties of leaching product are studied, and then microwave leaching strengthening mechanism is revealed. The expected results will provide the theoretical and scientific basis for the comprehensive utilization of resources and pollution reduction in the zinc smelting enterprises.

湿法炼锌浸出渣中含有大量的锗，具有极高的综合回收价值。本项目拟采用微波强化含锗锌浸渣的浸出过程，发展环境友好的含锗锌浸渣提锗新工艺，而微波强化含锗锌浸渣的浸出过程及机理是该新工艺的关键所在。在分析原料化学组成、粒度和有价金属元素赋存状态的基础上，采用常规浸出和微波加热浸出对比的方法，研究含锗锌浸渣、浸出剂以及浸出体系在微波场中的升温行为；探索微波功率、浸出温度、浸出时间、液固比等微波辅助浸出过程参数对组元浸出率的影响规律，研究微波强化对锗的浸出行为及动力学控制步骤的影响，探明浸出反应动力学机理；研究浸出产物的物化性质变化，并探讨微波浸出强化机理，为锌冶炼企业提高资源综合利用率和污染减排，实现该技术工业应用提供理论基础和科学依据。

锗因具有十分独特的物理化学性质而被广泛应用于国民经济的各个领域。世界锗的资源相当贫乏。湿法炼锌浸出渣中含有大量的锗，具有极高的综合回收价值。本项目采用微波强化含锗锌浸渣的浸出过程，发展环境友好的含锗锌浸渣提锗新工艺。主要成果如下：（1）锌浸渣的主要成分为铁酸锌(ZnFe2O4)、石膏(CaSO4•2H2O)、半水石膏(CaSO4•0.5H2O)、铅矾(PbSO4)、闪锌矿((Zn,Fe)S)和少量石英（SiO2）。未发现独立的的锗化合物。物相分析表明：锌浸渣中锗58%以上赋存在铁酸盐中，另有20%左右的硅酸盐，锗的氧化物含量在8%左右，还有11%可溶于水的锗酸盐。（2）采用两种浸出方法，使锗进入溶液：一是常规加热浸出，二是微波加热浸出。常规热酸浸出反应受温度和硫酸浓度影响显著。提高温度可增加铁酸锌的溶解速度，温度越高，单位时间内锗溶解速率越高。增加硫酸浓度，锗的浸出率在低酸度时是升高的，酸度达到一定值后锗的浸出率有下降趋势。微波加热浸出主要与硫酸浓度、时间、温度有关。随着硫酸浓度的提高，各金属的浸出率快速提高。延长浸出时间，浸出效率提高。浸出温度的升高有利于锗的浸出。常规加热浸出浸出率可达63.2%，微波加热浸出其浸出率可达69.7%，浸出率提高约6.5%，说明微波可以有效提高锗的浸出率。（3）锌浸出渣微波加热浸出过程的动力学研究显示，反应主要是铁酸锌的溶解。微波能诱发矿物显微结构变化，促使矿物颗粒产生裂纹和孔隙，加速反应界面更新，改善物料的浸出特性，微波辅助浸出是一种有效提升锗浸出率的方法。