Ural Federal University named after the first President of Russia B. N. Yeltsin, Ekaterinburg, Russia:

M. Yu. Shirev, Post-Graduate Student, e-mail: m.sсhirev@yandex.ru
V. A. Lebedev, Head of a Chair of a Light Metals Metallurgy

“Russian Magnesium” JSC, Asbest, Russia:

R. H. Abzalov, Technologist

There were made the trial tests of synthetic carnallite production from the spent electrolyte of magnesium electrolytic cells and the chlorine-magnesium solution after serpentine leaching. The main variable parameters were the initial concentration of magnesium chloride in a solution, temperature and bischofite-electrolyte mixture batch. The tests were carried out in a Z-shaped mixer which had a steam jacket and exhaust system. The formation of carnallite in the low-water system is fixed at 23.2–34.8% (mas.) of magnesium chloride in initial solution. At the high concentrations of MgCl₂, the carnallite synthesis is complicated and quantity of formed carnallite phase is low. The dissolution of spent magnesium electrolyte and bischofite-electrolyte mixture salts goes on with a heat consumption. Carnallite synthesis is the exothermic process. Constant temperature of reaction mixture indicates the induction period or several processes, which heat effects equalize each other. It is positioned, that the total duration of process is defined by the free water content in a reaction mixture at an evaporation stage. The total water content in the dry friable product is up to 35–40 % (mas.). The bischofite-electrolyte mixture addition intensifies the process, but the drops product quality. For realization of carnallite synthesis process in industrial scale, the screw or agitator mixer with heated body and removal of evaporated water steams from apparatus is applicable. The dissolution of spent electrolyte components in a chlorine-magnesium solution, carnallite synthesis, water excess evaporation and formed product drying are realized consistently in the apparatus.

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