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

Abstract

The research discussed in this article was performed to make the processing of sludge formed in the electrolytic refi ning of copper more effi cient. Results are presented from studies involving selection of the reagent regime and optimization of the conditions for leaching lead from tailings formed in the fl otation 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/(cm 2 ·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 fl otation 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.Improving the processing of sludge formed in the electrolytic refi ning of copper is important because the sludge contains large quantities of noble metals, selenium, tellurium and other valuable components. The complexity of the chemical and phase compositions of this raw material is the reason that many different approaches have been proposed for solving the given problem. The features and prospects of hydrometallurgical technology for processing sludge were discussed earlier in the scientifi c literature [1,2]. Figure 1 presents one of the main variants for the processing of sludge.The average indices that characterize the primary benefi ciation of sludge by this variant (Table 1) were determined based on the results of a large-scale laboratory study of its use in the oxidizing leaching of anode sludge from the Uralelektromed' company. The leaching operation was followed by fl otation.The results show that the proposed approach makes it possible to realize the main principle behind the technology: the recovery of more than 98% of the noble metals in the target product -fl otation concentrate. The fl otation tailings contain 734 no more than 0.03% gold and 0.5% copper. The other products obtained in the technology do not contain noble metals. One important benefi t of the technology is that it decreases the amount of sludge which needs to be refi ned by a factor of almost fi ve. The volumes of noble metals that are not fully processed are expected to decrease by a proportionate amount.An important step in the proposed scheme is the selection of effi cient methods for processing the tailings formed in concentrating the decopperized sludge by f...