Scrap Metal Iron, Copper, Gold Recovery Circuit Board Test

Recent decades, the electrical and electronic equipments were used in all aspects of life. At the same time a large number of e-waste are discarded. The circuit board is the basis of electronic components. It not only has large quantities, also contains a large number of valuable resources. Besides the circuit boards also contain lead, chromium, halogen and other toxic and harmful substances, if not properly dispose it will cause serious pollution.This paper summarizes the existing and recycling condition of waste PCBs. Analyzed the scrap of circuit board elements by X-ray and ICP. The result showed that:waste PCBs containing a variety of metallic elements. Not only have basic metals such as iron, copper, aluminum, etc. also contain large quantities of precious metals as gold, silver, palladium and so on. The iron, copper and aluminum contents were 264.619mg/g,290.667 mg/g,39.481mg/g, and precious metals gold, silver, palladium contents were 0.088mg/g,0.351 mg/g, and 1.480 mg/g.The oxidation-acid (hydrogen peroxide-sulfuric acid system) leaching iron, copper and other base metal elements of circuit board scrap. And the gold left in the dregs is extracted out by solvent extraction method.The pretreatment experiments take the circuit board scrap as the processing object, the test result indicate:the iron, copper can be effectively leached out by the hydrogen peroxide-sulfuric acid. When taking 10.0g waste circuit board, the best reaction condition is:Hydrogen peroxide solution is 15ml, sulfuric acid 9mol/L, reaction time is 150min, temperature is 50℃, the leaching rate of iron may achieve 90.3% and the copper leaching rate can get to 94.6%.In the solvent extraction experiment take the diethyl malonate as the extractant. Respectively, research compared rate (the volume of organic phase and aqueous phase ratio), pH value, extraction time, and the liquid phase of gold concentration influence to the gold extraction rate. Experimental results show that at room temperature, when the compared rate is 0.5, extraction time is 20min, pH is 0.5, the gold extraction rate can reach more than 94%, while diethyl malonate in solution of gold have a higher extraction rate, even if the low concentration of gold in solution, its extraction rate reached above 90%.In the microwave extraction process, with the microwave power increases, gold extraction rate increased rapidly. When the microwave powers to 708W, the gold extraction rate could reach 94.9%; when the extraction time to reach the 480s, the gold extraction rate could achieve 92.8%.By microwave heating of the extraction system, diethyl malonate extract the gold has a higher extraction rate than at room temperature.As to acidic waste liquid, not only can recycle base metal also be possible to transform heavy metal to the stable solid and reduces environment pollution by alkalizing method,.