Optimization of process parameters for the selective leaching of copper, nickel and isolation of gold from obsolete mobile phone PCBs
Optimization of process parameters for the selective leaching of copper, nickel and isolation of gold from obsolete mobile phone PCBs
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DOI：
10.1016/j.clet.2021.100180
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
Mudila Dhanunjaya Rao;K. Singh;C. Morrison;J. Love
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文献类型：
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作者：
Mudila Dhanunjaya Rao;K. Singh;C. Morrison;J. Love
从报废的移动的手机印刷电路板（PCB）中顺序分离贱金属和贵金属是开发具有材料循环性的回收工艺的重大挑战。在这方面的贡献，一个简单的，生态友好的，和有效的浸出过程中开发的溶解铜和镍从废弃的移动的手机多氯联苯，以促进分离的富金残留物。对缩小尺寸的多氯联苯进行化学预处理后，产生了金属部分，为此对铜和镍的浸出参数进行了优化，包括浸出剂的类型、温度、时间、纸浆密度和搅拌速度。发现在30 °C下使用3.0 M硝酸以50 g/L的浆料密度、2 h的停留时间和500 rpm的搅拌速度发生贱金属的定量溶解;在这些条件下，没有金溶解。实验设计分析采用响应面法也进行了验证的过程。最后，浸出过程的动力学进行了研究，并表明符合化学控制的表面反应模型，活化能为39.7和18.4千焦/摩尔的铜和镍。重要的是，在这项工作中优化的浸出工艺避免了对高温的需要，减少了能源消耗和废水的产生，从而使废弃的移动的手机多氯联苯得到更清洁的处理，以便从主要的贱金属中分离出金。
The sequential separation of base and precious metals from the end-of-life mobile phone printed circuit boards (PCBs) is a significant challenge for the development of recycling process that exhibit material circularity. In this contribution, a simple, eco-friendly, and efficient leaching process is developed for the dissolution of copper and nickel from obsolete mobile phone PCBs to facilitate the isolation of a gold-rich residue. Chemical pre-treatment of downsized PCBs produced a metallic portion for which the leaching parameters for copper and nickel were optimised, including the type of leaching reagent, temperature, time, pulp density and agitation speed. It was found that quantitative dissolution of base metals occurred using 3.0 M nitric acid at 30 °C with a 50 g/L pulp density, 2 h residence time, and 500 rpm stirring speed; under these conditions, no gold was dissolved. Design of Experiment analysis using Response Surface Methodology was also undertaken to validate the process. Finally, the kinetics of the leaching process were studied and shown to conform to the chemically controlled surface reaction model, with activation energies of 39.7 and 18.4 kJ/mol for copper and nickel. Importantly, the leaching process optimised in this work avoids the need for high temperatures and reduces energy consumption and effluent generation, leading to the cleaner processing of obsolete mobile phone PCBs for the separation of gold from the dominant base metals.