DOI: 10.5593/SGEM2016/B12/S04.147


N. Bekturganov, G. Katkeyeva, Zh. Oskembekova, I. Oskembekov, M. Akubayeva
Wednesday 7 September 2016 by Libadmin2016

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-56-8 / ISSN 1314-2704, June 28 - July 6, 2016, Book1 Vol. 2, 1143-1150 pp

Calcium polysulfide is a promising reagent for concentration of oxidized ores of non-ferrous metals.
We have determined physical-chemical regularities of calcium polysulfide synthesis from elementary sulfur obtained from oil-processing wastes and calcium hydroxide solutions. Experiments confirm positive influence of polysulfides on synthesis process.
Interaction of sulfur with calcium hydroxide solutions was studied using probabilistic-deterministic experiment design.
Dependence of sulfur dissolution on temperature, interaction duration and polysulfide-ion concentration was determined. Based on partial dependence the mathematical model was designed in the form of generalized multi-factor equation:
a = 0,8exp(-2,21∙1011Т-5,905)(-0,0887С2 + 2,23С + 5,61)τ0,5.
Adequacy of the model is confirmed by results significantly correlating with experimental data (R = 0,96, tR= 52).
Using the mathematical model optimal parameters of calcium polysulfide synthesis were determined: ratio CaO:S:H2O=1:2:7; temperature 90°C; duration 60 min; initial concentration of calcium polysulfide 12,5 g/l by S2-. Sulfiding agent based on elementary sulfur with polysulfide degree 4,4 was obtained under above parameters.
Sulfur dissolution kinetics was studied using described mathematical model. Temperature dependencies of sulfur interaction with calcium hydroxide were obtained. It was found that activation energy of sulfur dissolution is 171,1 kJ/mole and the process occurs in kinetic mode.
Mechanism of calcium polysulfide formation is proposed together with structure model in the form of polysulfide systems.
Based on obtained data on thermodynamic properties of polysulfide systems we have determined the following parameters: ΔfH0298,15, S0298,15, ΔfG0298,15, Ср0298,15 of eight polysulfides: CaS2, CaS3, CaS4, CaS5, CaS6, CaS7, CaS8 и CaS9.

Keywords: oxidized copper ore, sulfidizing, sulfination agent, flotation, copper concentrate, сalcium polysulfide.

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