Extraction and Separation of Copper and Zinc from Metallurgical Dusts and Slags of Brass Production by Electrochemical and Extraction Methods
摘要
The composition of brass metallurgical waste is determined using X-ray fluorescence analysis. The copper content in the slag is shown to reach 15 wt %; the zinc content, 83 wt %. Sulfuric-acid leaching was performed to separate zinc from the metallurgical dust. Optimal process parameters are selected as: leaching duration 60 min, sulfuric acid concentration 0.1 M. After the sulfuric-acid leaching, the acid solution is subjected to electrochemical treatment, in order to recover copper and zinc; the copper cake (copper in unoxidized form), to copper–ammonia leaching for 40 min. The concentration of copper in the copper–ammonia solution reached 35 g/L. At the final stage, solvent extraction of copper from the copper–ammonia leach solution is carried out, for which the most effective extracting agent has been selected. Extracting agents of different nature and classes are studied: D2EHPA (a strong acidic organophosphorus extractant), DХ510А and LIX54 (classified as β-diketones). The concentration of extracting agentnts ranged from 50 to 100%, the diluent is kerosene. Copper stripping from the copper–ammonia extract was performed using 2 M sulfuric acid. The best extractant is found to be LIX54 (50% concentration in kerosene). The final stage is copper electrowinning from the stripping solutions at a current density of 3 A/dm2, with a current efficiency of 65%. Based on the conducted research, a process flow-sheet is developed for the recovery of copper and zinc from the brass metallurgical dust.