Processing of Cake of Molybdenum Mining and Metallurgical Production by Electrooxidation in Chloride-Containing Solutions

Abstract

One of the types of technogenic metal-containing raw materials of Almalyk MMC JSC (Uzbekistan) is waste processing of molybdenite concentrate of previous years, based on nitric acid opening of sulfide concentrate: cakes stored in the tailings of the plant, allowing to some extent to increase the output of the plant's main products. In their composition, wt%: 4.1 Mo; 2.0 Fe, 3.87 S, 78.98 SiO2, 5.26 CaO,. Purpose: development of technology for the extraction of Mo. Au, other components from molybdenum cakes by electrooxidation in hydrochloric acid medium. Interest in the method is caused by the modernization of hydrometallurgical technologies, due to the increase in environmental requirements for them, and also due to the emergence of new hydrometallurgical equipment. We used a two-chamber electrolysis plant for Mo-cake leaching, with a membrane, a direct current source, 20 A, generating active chlorine: hypochlorite ions at the anode. Mo(VI), Аu(III), Cu(II) ions were analyzed by photocolorimetric and spectrometric methods (ICP -Agilent 7500 IСP MS). The concentration of NaClO was determined according to the State Standard 18190-72, free chlorine was determined by titration with methyl orange. The behavior of gold in Mo-cake in contact with hypochlorite ions is considered. The oxidation of Mo cakes in a hydrochloric acid medium by hypochlorite ions generated anode at the anode has been studied, the parameters of their electrooxidation have been calculated, and the leaching products have been studied. The method of electrooxidation, in the presence of HCl, on the basis of 3-factor planning of the experiment, regression equations were obtained. Checking their adequacy, according to the Fisher criterion, by comparing the calculated and experimental data on the degree of extraction of these metals, showed the adequacy of the proposed process models. A technology for the electrooxidation of molybdenum cake has been developed, which is an alternative to the existing scheme of oxidative roasting of molybdenite concentrate, followed by soda leaching of molybdenum from the cinder, with cyanide processing of cake for gold. It has been established that the electrooxidation of Mo-cakes makes it possible to process them efficiently, with through extraction of gold up to 90%, molybdenum -up to 72.6%.