Recycling Technique Of Copper And Nickel From Electroplating Sludge

With the rapid development of electroplating industry, there will be more and more electroplating sludge. This is not only to bring great pressure on environmental protection, but also cause enormous waste of resources. Now, it is difficult to recover the copper and nickel from the electroplating sludge, because of the small production scale in industry, low treatment ability and complex metal components in electroplating sludge. Copper and nickel are common metals which are of high values in the electroplating sludge. However, there is less report for its industrialization treatment and the relative research is still in the laboratory stage.This paper presents the consolidated technology of sludge treatment with acid and ammonia to deal with electroplating sludge with or without chromium, respectively. The results show that the recovery rate of copper is more than 99% from the electroplating sludge which includes chromium leached by the sulfuric acid and is electrolyzed at 2.4V in 3h, and the Fe²⁺ can be oxidized to Fe³⁺ at the same time, Secondly, adjusting pH to 3.0 with sodium phosphate which was 1.4 times of theroretical value at 90℃, and the removal rate of iron, aluminium and chromium is more than 99%. Finally, the recovery rate of sodium phosphate is about 80% by NaOH.Using ammonia method to deal no-chromium electroplating sludge with N-902 as the leaching solution. On the conditions of the extraction concentration at 30%, O/A=1/5 and the extraction time at 10min, the extraction rate of Cu and Ni can reach 100%. The residual ammonia in the organic phase can be extracted with water and return to leach electroplating sludge. Finally, stripping with sulphuric acid at concentration of 4mol/L, A/O=3 and stripping time at 40min, Cu and Ni will be recycled about 97%.Nickel-containing solutions after the acid treatment mixed with that after ammonia treatment were strippen into the nickel extraction process, and obtained the nickel sulfate finally.The recycle of copper in intermediate experiment is very successful while the purity of copper is between 97% and 98%. It can be concluded that the method of recycling and the technics of recycling are very reasonable because the recovery rate of copper can reach 99%.