Karpov Institute of Physical Chemistry (Russia):
Maslennikov A. N., Junior Researcher, anmaslennikoff@gmail.com
Zanaveskina S. M., Senior Researcher, svzanaveskina@mail.ru

A. V. Topchiev Institute of Petrochemical Synthesis of the Russian Academy of Sciences (RAS) (Russia):

Dmitriev G. S., Ph. D. in Chemistry, Senior Researcher, dmitriev.gs@mail.ru

Zanaveskin K. L., Ph. D. in Chemistry, Senior Researcher, zakon82@mail.ru

The experimental results related to the effect of processing parameters upon the Yaregskoye deposit leucoxene autoclave leaching with aqueous sodium hydroxide solutions are presented. The subject of investigation was leucoxene fraction, produced through quartz-leucoxene concentrate division in bromoform. The starting leucoxene and leaching products were studied by the AES, ICP-OES, XFA and SEM methods. The experiments were conducted in steel laboratory autoclave with a volume of 300 ml in the range of temperatures 150–200 °С, the range of NaOH concentration being 10–30 % and the range of liquid-solid ratio from 3 to 7 ml/g. As a result of the experimental studies, it was established that increasing liquid-solid ratio brings about increase in quartz dissolution rate. From the viewpoint of operating costs, the optimal liquid-solid ratio is equal to 4 ml/g. Change in starting concentration of alkali affects SiO₂ leaching degree. Increasing NaOH concentration to 25 % wt. leads to quartz dissolution rate increase. Further increase of alkali content in leaching solution produces only a minor effect. Leucoxene leaching in the range of temperatures of 150–170 °С even with retention time of two hours does not permit to obtain product containing 2.00 % SiO₂. To achieve quick dissolution of leucoxene grains, it is necessary to maintain reactor temperature of at least 180 °С. Temperature produces a higher effect upon process rate, than NaOH concentration. As a result of the experimental studies, the optimum conditions for leucoxene leaching process were determined: temperature not less than 180 °С, liquid-solid ratio — 4 ml/g, alkali concentration — 20–25 % wt., contact time of at least 80 min.
The studies were performed with the aid of the Russian Science Foundation Grant (Project No. 15-13-00171).

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