Improvement of the Metal Extraction and Removal of Harmful Impurities from Sulfide Ores by Polyoxometalate Oxidizers: Design of Experiments and Industrial Modeling

In the present study, a new method has been suggested to solve the problems of the very low solubilityof sulfide ores in acidic solution and also the production of toxic impurities for the first time. In this work, the polyoxometalate (POM) oxidizer was applied for the dissolution of sulfide ores, extraction of metals, and removal of toxic and harmful wastes. In this procedure, POMs were used as strong oxidizers of sulfur compounds to dissolve sulfide ores. Also, acid was applied as a solvent and catalyst to increase the reaction rate. The Taguchi experimental design along with the ProMax simulation software was applied for studying the leaching of sulfide ores by POM oxidizers as a novel plan in experimental to industrial scales. The optimum data achieved by the Taguchi method was used as the input data to the simulation and sensitivity analysis of the process was executed by the ProMax software. The effects of curicital operating parameters such as the concentration of acid (CA) in the 60-90 g/l range, the  reaction temperature (TR) with the values of 60-90 ºC, the rotation rate (R) with the amounts of 50- 300 rpm, the retention time (τ) in the 0.5-2.0 h range, the concentration of polyoxometalate oxidizer with the values of 0.1- 0.5 g/l, the acid types of H2SO4, HNO3, HCl, H3PO4, the grain sizes of sulfide ores (Sparticle) in the 0.5-3.0 mm range and polyoxometalate with the types of [Mo6O19]2-, [Mo8O26]4-, [V10O28]6- and [H2W12O40]10- on the extraction efficiency of metals and removal of toxic heavy metals from sulfide ores by polyoxometalates were investigated. The optimum conditions to extract maximize metals from the sulfide ores were obtained as the CA; 80 g/l, TR; 90 ºC, R; 300 rpm, τ; 1.0 h, m POMs; 0.5g/l, acid type of H2SO4, Sgrain;1.0 mm and POMs type of [H2W12O40]10-. Under optimized conditions, the extraction efficiency of zinc, copper, and lead and the removal of toxic heavy metals from sulfide ores were determined as above 85%, 81%, 83%, and 99.9% receptivity.