提高废弃线路板两步生物浸出金回收率的优化

Optimization to Improve Gold Recovery during Two-Step Bioleaching of Waste Circuit Boards

采用两步生物浸出法浸提废弃线路板中的金属。第一步利用氧化亚铁硫杆菌浸提废弃线路板中的铜并探讨了其影响因素,第二步选用紫色色杆菌浸提第一步处理后残留物中的金,在单因素试验基础上,以金的浸出率为响应值,采用Box-Behnken(BB)设计,利用Design-Expert软件对响应值进行4因素3水平的多元二次回归拟合分析,从而提高浸金率。结果显示,氧化亚铁硫杆菌在pH=2.0、Fe2+浓度44.3g/L,粒径75～147μm,粉末添加量0.5g的条件下,4d能提取99%的铜;在第二步中,使用响应面确定最佳浸出条件为:pH=10.5、甘氨酸4.02g/L、硫酸镁5.67 mg/L、温度31.0℃,金浸出率可达72.58%。

Two-step bioleaching process was applied to extract metal from waste printed circuit board（PCB）.In the first step,copper in waste PCB was extracted by Acidithiobacillus ferrooxidans and its influencing factors were discussed.In the second step,gold was extracted from residue of first step with Chromobacterium violaceum by single factor experiment.Taking gold leaching rate as response value,Box-Behnken（BB）design was adopted to improve gold leaching rate,and response value was analyzed by multiple quadratic regression analysis of 4 factors and 3 levels with Design-Expert software.The results show that 99% of copper can be extracted by Acidithiobacillus ferrooxidans at pH value of 2.0,Fe^2＋concentration of 44.3 g/L,particle size of 75～147μm,and pulp density of 0.5 g for 4 days.Gold leaching rate is 72.58% under the optimum conditions including pH value of 10.5,glycine concentration of 4.02 g/L,MgSO4 concentration of 5.67 mg/L,and temperature of 31.0℃.