微波强化高铜烟灰选择性浸出过程机理研究

Separate treatment of copper smelting flue dust from electrostatic precipitators in an open circuit is very important for copper smelters to realize the comprehensive utilization of secondary resources and to reduce environmental impact. The comparison of conventional heating and microwave-assisted leaching of refractory rich-sulfide copper smelting flue dust were investigated by the analysis of phase composition, element distribution in different size of particles, occurrence state and mosaic size of valuable metals. The impact of thermal stress on mineral interface and microstructure was studied, then to reveal the dissociation mechanism of complex ores interface in microwave field induced by "Hot spots". The effects of microwave-assisted leaching factors e.g. microwave power, temperature, leaching time, liquid-solid ratio, etc, on leaching ratios of Cu, Zn, Fe and As were systematic investigated. Through research on ore particle dissolution and metal component dissolve behaviors to define the selective leaching characteristics in microwave field. The effects of process parameters on leaching rates were investigated also to establish the microwave leaching kinetics model. The enhanced leaching mechanism of liquid/solid transfer by microwave molecular polarization and thermal activation will be finally revealed. The successful realization of this project will provide a technological and theoretical prototype for microwave extraction of refractory copper secondary resources, and promote the development of environment-friendly metallurgical processes for an efficient resource cycle, energy-saving and cost-reduction, and a harmonic ecosystem.

含铜电收尘烟灰的开路处理对铜冶炼企业实现二次资源综合利用和污染减排具有重要意义。本项目拟以富含硫化矿相的难处理铜烟灰为研究对象，在分析原料相组成、不同粒度元素分布、有价金属赋存状态和嵌布粒度基础上，采用常压加热和微波加热浸出对比的方法，研究热应力作用对矿相界面和微观结构的影响，揭示了微波场中"超热点"作用下复杂矿相界面解离机制；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，查明微波辐射下矿物颗粒溶解特性和各组分溶出规律，阐明微波强化选择性浸出行为特征；考察浸出过程参数对反应速率的影响规律，建立微波浸出动力学模型，揭示出分子极化非热活化强化固液传递的微波浸出机理。项目的开展为二次铜资源的微波强化提取技术路线的应用提供可移植性理论依据，并积极推动以资源高效循环、节能降耗为主题与生态系统协调的绿色冶金新技术的开发。

铜烟灰主要来源于铜冶炼系统铜锍的熔炼与吹炼过程，其中除Cu外，还含有Pb、Zn、Fe、Bi等多种有价金属以及As等有害元素，直接返回铜冶炼系统，将增加入炉原料的杂质含量，恶化炉况、降低系统的处理能力,并影响电铜质量和制酸触媒寿命。铜烟灰的开路处理对铜冶炼企业实现二次资源综合利用和污染减排具有重要意义。在项目经费资助下，以奥斯迈特炉熔炼烟灰和转炉吹炼烟灰为对象开展研究。在分析烟灰的化学成分、物相组成等的基础上，采用谐振腔微扰法测试铜烟灰介电特性，介电常数和损耗正切范围为7.50~13.63和1.50×10-2~1.99×10-2。对于转炉吹炼烟灰，采用微波辅助加热硫酸直接浸出和常规加热直接浸出对比，发现微波浸出可以提高铜的浸出率2~5%；铜、锌的浸出反应活化能为17.63和25.92 kJ/mol，比常规加热浸出低，表明微波加热可以降低浸出反应能垒，提高浸出反应速率。对于熔炼烟灰，先对原料进行还原焙烧，再采用微波加热浸出和常规加热浸出对比，发现采用还原焙烧-微波浸出可以提高铜浸出率5~10%，提高锌浸出率2~6%，微波在促使烟灰复杂包裹体解离、促进少量硫化矿相浸出等具有明显的强化作用；动力学研究表明铜浸出反应的表观活化能为18.36kJ/mol，锌浸出反应的表观活化能为26.96kJ/mol；采用单因素实验、正交实验和响应曲面实验，研究了单因素影响规律和影响因素显著性；得到最佳工艺参数，该条件下铜、锌浸出率预测值为95.51%和90.6%，验证实验实际铜、锌的浸出率为95.65%和90.48%。项目的开展为二次铜资源的微波强化提取技术路线的应用提供可移植性理论依据，并积极推动以资源高效循环、节能降耗为主题与生态系统协调的绿色冶金新技术的开发。