Study On Recovery Process Of Valuable Metal Copper And Zinc In Electroplating Sludge

The electroplating industry produces a lot of waste water during production,and the waste water usually contains Cu,Ni,Zn,Cr,Fe and other multi-metals.Electroplating plants usually use chemical precipitation methods to treat producte wastewater,so that the wastewater meets national discharge standards.but such treatment will produce a large amount of sediments.Therefore,these sediments contain a large number of complex heavy metals and must be treated safely,If it is disposed of at will,it will cause great harm to human body and ecological environment.Electroplating sludge contains a variety of heavy metal components,and its grade is often higher than that of metal-rich ore.It is a cheap secondary renewable resource.In order to recover the metal resources in the electroplating sludge and realize the harmlessness of the sludge,this article uses copper and zinc electroplating sludge as raw materials and sulfuric acid as the leaching agent,and uses acid leaching,extraction,back extraction,evaporation and concentration,chemical precipitation and other processes for recovery.First,this article studies the basic properties of electroplating sludge,studying its moisture content,leaching toxicity,corrosiveness,p H and heavy metal content determination.Studies have shown:(1)The water content of electroplating sludge is42.8%,the p H value of electroplating sludge is 8.69,the leaching toxicity of copper and zinc is 0.424 mg/L,0.604 mg/L;(2)The dry sludge contains copper 56.475 %,zinc 15.66 %,iron 4.74 %.By studying the basic properties of electroplating sludge,it lays a foundation for the leaching of electroplating sludge and the recovery of heavy metals.Research on the acid leaching,extraction-reverse extraction-evaporation concentration and zinc recovery process of electroplating sludge.(1)Research and analyze the solid-liquid ratio,leaching temperature,leaching time,p H,raw material particle size and acid in the acid leaching process The influence of factors such as the number of leaching on the leaching rate.Studies have shown that the solid-liquid ratio is 1:10,the leaching temperature is 25 ℃,the leaching time is 30 min,the p H is 0.5,the raw material particle size is 150 mesh,and the leaching rate of heavy metals Cu and Zn in electroplating sludge are both above 99 %.(2)In the process of extracting copper with extractant,study the influence of controlling the initial concentration of copper,p H of the aqueous phase,comparison and extraction equilibrium time on the extraction of copper.Studies have shown that: the initial concentration of copper is 2g/L,the p H of the solution is 2,the concentration of the extractant is 30 %,the comparison is controlled at 1:4,and the extraction equilibrium time is 10 min,the extraction rate of copper reaches 98.8 %.(3)Using sulfuric acid for back extraction,the results show that: when the concentration of sulfuric acid is 4 mol/L and the ratio of O/A is 1:1,the back extraction rate of copper is 94.6 %.The copper sulfate pentahydrate product is recovered by evaporation and concentration,and its content reaches 98.4 %.(4)Obtain zinc hydroxide product through iron and zinc separation experiment.(5)The waste slag generated from the treatment and disposal of electroplating sludge is converted into regenerated gypsum through process technology,and bricks are made with the mixture of regenerated gypsum,clay,mountain soil and coal gangue,and the leaching toxicity of the bricks is determined.The leaching concentration of Zinc is 0.06 mg/L,and the leaching concentration of zinc is 0.4 mg/L,which realizes the harmlessness and resource utilization of waste residue.The production optimization plan obtained from the experiment was applied to the actual production workshop for trial production,and three indicators were established for the qualification rate of recycled gypsum,the monthly treatment volume of electroplating sludge,and the content of copper products to evaluate the effect of the trial production.The results show that after using the experimental optimization scheme,the qualified rate of regenerated gypsum has increased from79 % to 91 %,the monthly electroplating sludge processing capacity has increased from 595 tons to 810 tons,and the content of copper products has increased from50 % to 70 %,indicating good results.This paper also analyzes the economic,environmental and social benefits of heavy metal recovery from electroplating sludge.The harmless and resourceful treatment of electroplating sludge has certain economic benefits on the basis of deducting the treatment cost.The purchase of treatment facilities and equipment requires a series of investments,but this is an environmental protection investment project.These facilities and equipment are mainly used for the comprehensive utilization and harmlessness of solid waste,so it has good environmental and social benefits.