Leaching kinetics of sulfides from refractory gold concentrates by nitric acid

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. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The research was funded by the Russian Science Foundation, grant number 18-19-00186. The SEM/EDS and microprobe analysis were funded by State Assignment, grant number 11.4797.2017/8.9

ANTIMONY-CONTAINING RAW MATERIALS PROCESSING METHOD

FIELD: technological processes. SUBSTANCE: invention relates to the antimony containing raw materials processing. Method comprises bringing the original antimony-containing raw materials and aluminum chips into contact with the alkali aqueous solution in percolation mode, ensuring the antimony cementation from the antimony-containing compounds by the aluminum. Aluminum consumption is 110–130 % of the stoichiometrically required, and the alkali content in the initial aqueous solution is 20–30 g/l. EFFECT: enabling reduction in the reagents consumption and an increase in the antimony from the feedstock extraction limiting degree.Изобретение относится к переработке сурьмусодержащего сырья. Способ включает приведение в контакт исходного сурьмусодержащего сырья и алюминиевой стружки с водным раствором щелочи в режиме перколяции с обеспечением цементации сурьмы из сурьмусодержащих соединений алюминием. Расход алюминия составляет 110-130% от стехиометрически необходимого, а содержание щелочи в исходном водном растворе составляет 20-30 г/л. Обеспечивается снижение расхода реагентов и повышение предельной степени извлечения сурьмы из исходного сырья