St. Petersburg Mining University (St. Petersburg, Russia):

Baldaeva T. M., Postgraduate Student, baldaeva.t.m@gmail.com

REC «Mekhanobr-Tekhnika» (St. Petersburg, Russia):

Gladkova V. V., Senior Engineer, gladkova_vv@npk-mt.spb.ru
Ustinov I. D., Marketing Director, Doctor of Chemistry, ustinov_id@npk-mt.spb.ru

Perm State University (Perm, Russia):

Otroshchenko A. A., Head of Laboratory, alfa.distress@gmail.com

Development of low-water-consumption technologies for mineral materials processing is a priority technological direction in mining and processing industry, providing for conservation of energy and mineral resources. Air-tight thermal modification of mineral coal increases porosity and simultaneously alters amorphous and crystalline phases ratio, thus providing favorable conditions for subsequent dry beneficiation of coal. Physical and mechanical properties of the Kuzbass mineral coal were the subject to a comparative study before and after thermal modification, and the effect of these properties upon vibratory screening of the coal products in question was studied. Petrographically, the initial sample of coal was mostly represented by vitrain and by a subordinate quantity of fusain. Cindery part amounted to 15 %, and was represented by aluminosilicates and insignificant amount of pyrite. Bulk material angle of internal friction was calculated through angle of natural repose. Conditional coefficient of sliding friction was determined for isometric coal particles moving upon steel square-mesh sieve. Flow properties were studied with the help of free outflow viscosimeter. Uneven structure (roughness) of coal surface and its alterations during thermal modification were also studied. Vibratory classification tests were conducted using circularmotion and straight-line screens. It is shown, that thermochemical modification of mineral coal permits to significantly change its physical and mechanical properties, notably, decreasing specific power consumption in its crushing by 20–30 %, and also increasing its calorific efficiency. Technologically, the temperature range of 500–550 °С is preferable for thermochemical modification, providing for formation of so-termed semi-coke. It was established, that vibratory screening efficiency of thermally treated coal is notably higher, than that of mineral coal, not subjected to thermal modification.
The studies were performed with the aid of the Russian Science Foundation Grant (Project No. 15-17-30015).

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