Study On Copper And Nickle Recovery From Electroplating Sludge By Emulsion Liquid Membrane Technique

During the process of dealing with electroplating liquid, many plants use chemistry precipitation method. However, this method has the disadvantage of producing lots of electroplating sludge which contains varies of non-degradable heavy metals, such as Cu, Ni, Zn, Cr etc. Random dump of these sludge can lead to environmental pollution, also, high concentration of heavy metals will be wasted. It's necessary to recovery electroplating sludge because of it's higher concentration of heavy metals even than high-grade ore.After analyzing the physical and chemical properties of electroplating sludge from Zhongshan city, choosing H2SO4 as leaching reagent, this paper studies the best condition when Cu2+ and Ni2+ reach the maxing leaching rate, which is add 4ml 10% H2SO4 to one gram sludge, oscillate 0.5 hour at ordinary temperature. In this study, the emulsion liquid membrane system for copper was established by using N902 as carrier, for nickle using P507, both Span-80 as surfactant and H2SO4 as intemal aqueous phase. And the extraction behavior of N902 for copper and P507 for nickle was studied with different operating conditions such as emulsifying stirring speed, emulsifying stirring time and separating stirring time. The effects of volume ratio of oil phase to internal phase, milk phase to leaching liquid phase, concentration of H2SO4 in internal aqueous phase, volume fraction of Span-80 and carrier in the oil phase and pH of water phase on the extraction yield of copper and nickle were investigated.The study results showed that the extraction yield of Cu2+ reached above 96% and the enrichment concentration of Cu2+ reached 13751 mg/L when the leaching liquid was treated in the conditions that the emulsifying stirring speed was 3500r/min, emulsifying time and separating stirring time were both 10min, the concentration of H2SO4 in internal aqueous phase was 2.5mol/L, the carrier concentration (volume fraction, the same as the following) was 3%, the surfactant concentration was 5%, the ratio of oil and water was 1:1, the ratio of emulsion and water was 1:5 and the pH of the leaching liquid was 5.0; the extraction yield of Ni2+ reached above 96% and the enrichment concentration of Ni2+ reached 12910mg/L when the leaching liquid was treated in the same operating conditions as Cu2+'s and the concentration of H2SO4 in internal aqueous phase was 1.5mol/L, the carrier concentration was 6%, the surfactant concentration was 8%, the ratio of oil and water was 1:1, the ratio of emulsion and water was 1:5 and the pH of the leaching liquid was 4.0. Applying the best experimental condition to the real sludge leaching liquid, it showed that the extraction yield of Cu2+ reached 95.53% and Ni2+ reached 95.19% which were nearly above results.