The processing of refractory gold-containing concentrates by hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in the ores. This paper describes the investigation of the kinetics of HNO3 leaching of sulfide gold-containing concentrates of the Yenisei ridge (Yakutia, Russia). The effect of temperature (70–85 °C), the initial concentration of HNO3 (10–40%) and the content of sulfur in the concentrate (8.22–22.44%) on the iron recovery into the solution was studied. It has been shown that increasing the content of S in the concentrate from 8.22 to 22.44% leads to an average of 45% increase in the iron recovery across the entire range temperatures and concentrations of HNO3 per one hour of leaching. The leaching kinetics of the studied types of concentrates correlates well with the new shrinking core model, which indicates that the reaction is regulated by interfacial diffusion and diffusion through the product layer. Elemental S is found on the surface of the solid leach residue, as confirmed by XRD and SEM/EDS analysis. The apparent activation energy is 60.276 kJ/mol. The semi-empirical expression describing the reaction rate under the studied conditions can be written as follows: 1/3ln(1 − X) + [(1 − X)−1/3 − 1] = 87.811(HNO3)0.837(S)2.948e−60276/RT·t.

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This paper details the hydrometallurgical method of processing of refractory gold antimony flotation concentrate. Investigation of feed material has been occurred. Mineralogical analyses (XRD, SEM-EDS) and chemical analyses of the concentrate have been studied. Mainly, the material consists of compounds of antimony, silicon, calcium, sulfur and iron. The main phases are quartz, stibnite, calcium carbonate and ankerite, pyrite and arsenopyrite have been found as well. The feature of antimonite’s dissolving in alkaline solutions has been reviewed. The dependences of effects of the temperature, time, L/S ratio and NaOH concentration on the antimony and sulfur extraction from the feed flotation concentrate have been determined. During alkaline sulphide leaching of the starting material several physicochemical characteristics of gold dissolution have been identified. Agitated cyanide gold leaching test of the pre-treated cake was conducted. Gold recovery was 32.2%. The obtained low indexes of gold recovery are based on cyanidation. A nitric acid leaching of disantimonied cake was proposed.

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This article covers a hydrometallurgical method for processing of a gold-antimony flotation concentrate in alkaline sulfide solutions. Thermodynamic analysis of the reaction stibnite with sulfide sodium and sodium hydroxide was performed. The chemical and phase compositions of the investigated material, mainly represented by compounds of antimony, silicon, calcium, sulfur and iron are studied. Phase composition: quartz, stibnite, quicklime, pyrite, dolomite and arsenopyrite. The dependences of the influence of sulfide sodium and sodium hydroxide concentration, and the liquid to solid ratio on antimony extraction into solution were determined by methods of mathematical experiment planning. The calculated values ​​of the determination coefficients testify to the adequacy of the chosen two-level model. The optimum parameters of the process were obtained: L/S ratio = 4,5; the nitric acid sulfide sodium concentration was 61.09 g/L; sodium hydroxide concentration was 16.47 g/