Study On Leaching Of Gold From Waste Circuit Boards By Using Cyanogenic Bacteria

With the growth of the global economy and the improvement of industrial level,waste electronic and electric equipment has been increasing.Due to the continuous improvement of people's living standards,the service life of electronic and electrical equipment is gradually reduced,and more and more electronic waste is generated.Under the current background of sustainable development,using microbial metallurgical processes to recover precious metals in electronic waste can effectively achieve economic benefits.At present,there are not many related literatures on the use of Pseudomonas fluorescens and Pseudomonas aeruginosa to perform gold immersion experiments from waste printed circuit boards.This article mainly studies the mixed leaching of gold and silver from waste printed circuit boards by Pseudomonas fluorescens and Pseudomonas aeruginosa,and focuses on the growth curve,cyanogen production and leaching rate of cyanogenic bacteria.The main contents of the experiment are:pretreatment of waste printed circuit boards;research on growth characteristics of cyanogenic bacteria;determination of cyanogenic ability of mixed bacteria by different influencing factors;determination of gold leaching rate of mixed bacteria by different influencing factors.This research shows that the content of gold,silver,and copper in waste printed circuit boards after nitric acid pretreatment is 0.389mg/g,0.134mg/g,and 0.925mg/g.The copper removal rate can reach 99.69%.Precious metals were enriched to reduce the impact of other impurity metals on the leaching efficiency.The study found that under the optimal conditions of Pseudomonas fluorescens:Pseudomonas aeruginosa=2:1,the amount of bacterial solution added was 5ml,the amount of sample added was 0.1g,and pH=9,the maximum gold leaching rate was 39.2%and the maximum The silver rate is50.5%.The influence of CaCl₂,MgCl₂,NaCl and other nutrients on the leaching rate is also studied.It is found that NaCl has the greatest influence on the leaching rate,which can make the gold leaching rate and the silver leaching rate reach 67.33%and 69.33%,respectively.Finally,through economic benefit analysis,a net profit of 4627.5 yuan can be obtained by processing 1 ton of WPCB.The microbial method has the advantages of low energy consumption,small pollution,simple process,easy operation,low cost and environmental friendliness.The research results have certain theoretical and application value.