废弃印刷线路板中铜的两步浸出工艺优化

Optimization of two-step leaching of copper from waste printed circuit board

以化学-生物两步浸出工艺回收废弃印刷线路板(WPCBs)中的金属,利用钢铁酸洗废水作为化学浸出的浸出剂,后续生物浸出则采用嗜酸性氧化亚铁硫杆菌作为浸出微生物,探究了WPCBs中铜浸出率和酸洗废水中铁去除率的影响因素。利用响应面分析法对铜浸出的条件进行优化,得出转速553.43 r·min^(-1)、温度42.57℃、投加量20.23 g·L^(-1)、颗粒尺寸1.80 mm为最佳浸出条件,此条件下铜浸出率预测值为100.08%。铜化学浸出动力学模型符合湿法冶金中液固相反应的"收缩核动力学模型",相关系数可以达到0.98以上,过程主要受残留固体膜层的控制。生物浸出实验表明,WPCBs投加量对嗜酸性氧化亚铁硫杆菌毒性影响较大,抑制作用较强,对铜浸出和铁去除均有不利影响,实验表明最适的投加量为60 g·L^(-1)。

Metals were recovered from waste printed circuit boards （WPCBs） by chemical-biological two-step leaching process. Steel pickling wastewater was used as a leaching agent for chemical leaching and subsequent bioleaching was performed using the Acidithiobacillus ferrooxidans as leaching microorganisms. The influencing factors of copper leaching rate in WPCBs and iron removal rate in steel pickling wastewater were investigated. The response surface methodology was employed to optimize the leaching parameters. The optimum leaching con- ditions were determined as rotating speed of 553.43 r· min-1, temperature of 42.57℃ , dosage of 20.23 g · L-1 , particle size of 1.80 ram, and the leaching rate of copper was found to be 100.08%. The kinetic model of copper leaching conformed to the ＂ shrinkage kinetics model of liquid-solid reaction in hydrometallurgy, and the correlation coefficient can reach above 0.98. Bioleaching experiments showed that the dosage of WPCBs had a great effect on the toxicity of Acidithiobacillus ferrooxidans and had a strong inhibitory effect on copper leaching and iron removal. The experiment showed that the optimum dosage was 60 g·L-1.