Study On Gold Leaching From The Waste Printed Circuit Boards By Pseudomonas Aeruginosa

With the rapid development of the electronics industry and the improvement of consumption capacity,the number of discarded electrical and electronic products has increased exponentially.In the context of sustainable development and a green economy,the use of environmentally-friendly and high efficient recycling technology to recover valuable components of e-waste can achieve economic,environmental and social benefits.In the existing academic literature,there are few studies on leaching gold from waste printed circuit board?WPCB?by using Pseudomonas aeruginosa.In this paper,pseudomonas aeruginosa was used to leaching precious metals from waste circuit boards,focusing on the cyanide production of Pseudomonas aeruginosa and the factors that can influence the gold leaching,so as to further explore the practical production and application of microbial gold leaching.The work mainly includes three parts:pretreatment of WPCB;research on culture and growth characteristics of Pseudomonas aeruginosa;and research on factors affecting bioleaching.According to the experimental results,the contents of gold,silver and copper in the WPCB powder after nitric acid leaching process were 0.144 mg/g,0.894 mg/g and0.180 mg/g,respectively.The removal rate of copper reached 99.65%,and the enrichment of precious metals was achieved,which reduced the influence of common metals in gold leaching experiments.The efficiency of bioleaching is affected by various factors such as pH,the addition amount of glycine,powder and nutrient salt,and other factors.The leaching efficiency of precious metals increases with the increasing of pH and decreases with the increase of WPCB powder addition.Excessive glycine would have an inhibitory effect on gold leaching.When the amount of glycine was 7.5 g/L,the maximum silver leaching efficiency of Pseudomonas aeruginosa reached 48.90%.When the amount of glycine added is 1.0 g/L,it is most advantageous for leaching gold.When the addition amount of WPCB powder was 0.1 g,the maximum gold leaching efficiency was40.02%.After adding nutrient salt NH₄Cl and?NH₄?₂SO₄,the effect of promoting the leaching of gold was more obvious than that of pH,glycine and powder,the silver leaching efficiency can reached 50.89%.However,the effect of?NH₄?₃PO₄·3H₂O is not obvious.According to the analysis of economic benefit,leaching precious metals from 1 ton WPCB with Pseudomonas aeruginosa can obtained a net profit of 309.07yuan.Microbial gold leaching technology can achieve economic and environmental benefits.