Features of the Leaching of Lead from Slurry-Production Middlings by Industrial Complexons

The research discussed in this article was performed to make the processing of sludge formed in the electrolytic refining of copper more efficient. Results are presented from studies involving selection of the reagent regime and optimization of the conditions for leaching lead from tailings formed in the flotation concentration of decopperized sludge. The main components of the raw materials that were studied: lead oxysulfate (up to 60%) and oxidized complex compounds of antimony (up to 30%). Industrial complexons were proposed for use as the solvents. The tests showed that preference should be given to the use of alkaline solutions of oxyethylenediphosphoric (OEDP) acid. The kinetic features of the process were studied by using a method which employs a rotating disk of synthetic tribasic lead sulfate. The experimental rate constant for the leaching of lead in an OEDP solution reaches 6·10⁻⁶ g-ion/(cm²·sec). It was established that the process is diffusional in nature and that the effect of temperature is negligible. A large-scale balance experiment involving the removal of lead from flotation tailings was performed in a laboratory. The experiment established that the level of recovery of lead in an alkaline solution of OEDP reaches 85% and that the other important components of the sludge (antimony and noble metals) remain almost entirely in the undissolved residue.