Thermodynamics of arsenates, selenites and sulfates in the oxidation zone of sulfide ores. XI. Solubility of the synthetic analogue of chalcomenite and zinc selenites at 25 °С

I. V. Charykova, V. G. Krivovichev, N. M. Ivanova, V. V. Semenova.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2015. V. 144. N 1. P. 70-80

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Language: Russian

Abstract

The understanding of mechanisms of the selenium’s behavior in the near-surface conditions is one of actual problems of modern mineralogy and geochemistry and it is very important for the solving of some environmental problems. The present work was aimed to synthesize CuSeO₃·2H₂O (analogue of chalcomenite), ZnSeO₃·2H₂O, ZnSeO₃·H₂O, with studying their solubility in water. The synthesis was carried out by boiling-dry of aqueous solutions of Cu and Zn nitrates with sodium selenite. Obtained samples were identified by X-ray diffraction, IR spectroscopy and Raman spectroscopy. Solubility was determined by the isothermal saturation in ampoules at temperature 25°C. The solubility value was calculated with aid of the software package Geochemist’s Workbench (GMB 9.0). Products of solubility have been calculated for chalcomenite CuSeO₃·2H₂O (10^-10.63), ZnSeO₃·2H₂O (10^-8.35) и ZnSeO₃·H₂O (10^-7.96). Eh-pH diagrams were calculated and compiled by means of the software package GMB 9.0. The used databank includes thermodynamic characteristics for 46 elements, 47 base particles, 48 oxidation-reduction pairs, 551 particles in a solution, 624 solid phases. Eh-pH diagrams for Zn—Se—H₂O and Cu—Se—H₂O systems have been compiled for average contents of these elements in underground waters of oxidation zone in sulfide deposits.

Key words: analogue of chalcomenite, zinc selenite, X-ray diffraction, Raman spectroscopy, isothermal saturation, saturation time, products of solubility, coefficient of activity, ionic power.