Thakur Pooja, Kumar Sudhir
Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 India.
3 Biotech. 2021 Nov;11(11):454. doi: 10.1007/s13205-021-02977-4. Epub 2021 Oct 2.
Shredded dust originated during mechanical dismantling of waste electrical and electronic equipments (WEEEs) is enriched source of some valuable metals which might be lost as unworthy waste. Composition analysis of shredded dust printed circuit boards (PCBs) revealed the presence of 12.75 mg g copper (Cu) and 10.34 mg g silver (Ag) along with some other metals (Fe, Ni, and Au). Low concentration of precious metal, such as gold (Au i.e., 0.04 mg g) classified this shredded dust as low-grade scrap. Despite low concentration of Au this e-waste can be considered as potential "secondary ore" to recover other valuable metals like Ag. To improve the efficiency of Ag bioleaching using SAE1, pretreatment of e-waste was done using cost-effective ferric chloride (FeCl) chemical lixiviant. The concentration of FeCl lixiviant was optimized to recover Cu metal prior to bioleaching process. Bioleaching of Ag was done under optimized conditions by SAE1 using 100 mL Luria Broth (LB) medium, 5 g L glycine, pH 9, temperature 30 °C and 150 rpm. 95% Cu was recovered with 1% FeCl prior to bioleaching. Ag solubilization was increased for treated e-waste (36%) as compared to untreated e-waste PCBs (25%). Prerecovery of Cu enhanced Ag bioleaching, as available cyanide was utilized by Ag metal. Therefore, this study provides an economical hybrid method to enhance retrieval of precious metal (Ag) by SAE1 with economic and ecofriendly redox lixiviant even from low-grade e-scrap.
The online version contains supplementary material available at 10.1007/s13205-021-02977-4.
在废旧电子电气设备（WEEE）机械拆解过程中产生的碎尘是一些有价值金属的富集来源，这些金属可能会作为无价值的废物而流失。对碎尘印刷电路板（PCB）的成分分析表明，其中含有12.75毫克/克的铜（Cu）和10.34毫克/克的银（Ag）以及其他一些金属（铁、镍和金）。贵金属如金（Au，即0.04毫克/克）的浓度较低，因此这种碎尘被归类为低品位废料。尽管金的浓度较低，但这种电子废物仍可被视为回收银等其他有价值金属的潜在“次生矿石”。为了提高使用SAE1进行银生物浸出的效率，采用具有成本效益的氯化铁（FeCl）化学浸出剂对电子废物进行预处理。在生物浸出过程之前，对FeCl浸出剂的浓度进行了优化，以回收铜金属。在优化条件下，使用SAE1在100毫升的鲁氏肉汤（LB）培养基、5克/升甘氨酸、pH值为9、温度30℃和150转/分钟的条件下进行银的生物浸出。在生物浸出之前，用1%的FeCl回收了95%的铜。与未处理的电子废物PCB（25%）相比，处理后的电子废物的银溶解率提高了（36%）。铜的预回收增强了银的生物浸出，因为银金属利用了可用的氰化物。因此，本研究提供了一种经济的混合方法，即使从低品位电子废料中，也能通过SAE1和经济环保的氧化还原浸出剂提高贵金属（银）的回收效率。
在线版本包含可在10.1007/s13205-021-02977-4获取的补充材料。
