Technical Study On Selective Extracting Cobalt And Copper From Wastewater Treatment Iron Sludge

ABSTRACT:Cobalt and Copper are non-ferrous metals which closely related to human beings, Cobalt is used as an important raw material in the production of a variety of carbide alloys,high temperature alloys,corrosion-resistant alloys, catalysts and magnetic materials, et al. Copper is widely applied in electrical and electric, transportation industry, light industry, defense industry and machinery manufacturing, et al. Because of the lack of cobalt resources and the consumption levels of cobalt increases sharply in recent years with the development of economy, and copper consumption is also growing year by year in China, strengthening comprehensive recycling use of cobalt and copper secondary resources has a great important significance.In this paper, the wastewater treatment sludge with high iron was used as the raw material. Up to now, there are many problems exist in the treatment of acid leaching process, such as the large consumption of acid, long technical process, low metal recovery, high requirement of the equipment and leaching of metals with impurities, et al. Using of "selective leaching process by ammonia-extraction of copper and cobalt by solvent extraction-concentration crystallization" process research, The process was in short flowsheet with simple equipment and high metal recovery.Through the study of each single factor experimental conditions in the ammonia leaching process, the results show that when the concentration of ammonia and ammonium sulfate were3.0mol/L and1.5mol/L, liquid-to-solid ratio was8:1, leaching time was5h, reaction temperature was50℃, the leaching rate of cobalt and copper respectively reached83.22%and75.33%.The ammonia leaching process made cobalt, copper and other valuable metals into the leaching solution effectively, while almost no dissolved iron, thus, the subsequent iron removal process could be omitted. leaching liquor was used in the extraction process to extract copper and cobalt directly.Using ammonia leaching liquor as the research object, through experimental study of extraction process by Lix973-stripping copper by sulfate, the results showed that:1) The best conditions for copper extraction:at O/A ratio of1:1, contact time of2min, with the5%Lix973and at room temperature. Under such conditions, over99.29%copper are extracted.2) The best conditions for copper stripping:at O/A ratio of2:3, contact time of lmin, with the160g·L-1H2SO4and at room temperature. Under such conditions,96.13%copper are stripped.Using copper raffinate solution as the research object, through experimental study of extraction process by P507-stripping cobalt by sulfate, the results showed that:1) The best conditions for cobalt extraction:at O/A ratio of3:2, contact time of lOmin, with the5%Lix973and at room temperature. Under such conditions, over98.92%cobalt are extracted.2) The best conditions for cobalt stripping:at O/A ratio of1:2, contact time of5min, with the90g·L-1H2SO4and at room temperature. Under such conditions,98.73%cobalt are stripped.After concentrating crystallized of the aqueous phase which from the extraction process, obtained the products of cobalt sulfate and copper sulfate, The yield of the cobalt and copper respectively reach79.43%and73.57%in the entire process.