Physico-chemical model of formation of Hypergene sulfates on example Sherlovogorsk Deposit (Eastern Transbaikalia)

The results of modeling using the program complex "Selector" processes of hypergene sulfate formation in career of the Sher-lovogorsk deposit in the temperature range of 0-45°C. Hypergene geochemical processes in the Sherlovogorsk field career developing at a fast pace and cover a significant part of the territory. The process of oxidation of ores and host rocks leads to the appearance of a large number of different minerals groups of sulfates, carbonates, oxides, hydroxides, etc. Sulfates are soluble and insoluble forms. Soluble ones are mainly represented by crystallohydrates with the formula Me²+SO₄nH₂O. Hypergene sulfates are ephemeral, the conditions of their occurrence and the limits of stability are rather limited, so the field studies are mostly not real. The method of computer modeling proposed by I.K. Karpov is based on the principle of work consisting in minimizing the Gibbs energy and building a thermo-dynamic model containing information about the qualitative and quantitative composition of the solution and the percentage of minerals dropped out of it, pH-Eh-parameters of the system. The simulated system imitates the process of water evaporation on the evaporative geochemical barrier. In this model, attention is paid to the magnesium, copper and zinc minerals. At 0°C, the first of zinc, copper, magnesium, cobalt, sodium, lead and calcium sul-fates, as well as quartz, hematite, alunite appear in the system. The variety of sulfates, the order of their appearance and the field of stability are established, the series of sulfates are composed depending on the temperature and the number of moles of water in the simulated system. Despite the large variety of sulfates formed on the geochemical barrier, the solution retains an increased concentration of zinc, copper, magnesium and other metals. This is due to the finding of natural-technogenic system in the culmination stage of the oxidation process, which is characterized by the presence of a large number of water-soluble metal sulfates, sulfides which are less stable in oxidative conditions, primarily sphalerite, chalcopyrite and galena. According to V.P. Zvereva oxidation of sphalerite leads to the formation of highly concentrated solutions, but of them there is no crystallization of technogene minerals, and zinc and sulfur completely passes into the solution. In the solution, with a small amount of water moles, the content of zinc, copper and magnesium and sulfur is high enough within n10 -n 10^-3, the pH ranges from 0.48-1.64, Eh = 1.13-1.22 Solutions are highly mineralized, even with a small amount of water moles in the model, a large amount of metals and sulfur is present in the solution, which determine low pH values and high reactivity.

Keywords

Authors

References