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

Bizyaev O. Yu., Chief Designer;
Ustinov I. D., Supervisor of the Research Training Center, Doctor of Chemical Sciences, gornyi@mtspb.com

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

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

The results of polygradient vibration separation tests for coal were analyzed and demonstrated that the use of a trapezoidal screening surface renders higher screening efficiency and specific screening capacity values as compared to a flat screen. This effect is due to the greater mobility of the granular material, with its finer particles exiting through the side walls of the trapezoidal screen and coarser particles released through the bottom screen surface. An analysis of previous research in the theory of vibration screening suggests that this effect of preferential separation of the finer fraction through the inclined screening surfaces of a trapezoidal sieve can be achieved even with the same mesh sizes of the side and bottom surfaces. This is due to the fact that particles close to the near-mesh grain size are less likely to pass through inclined sieve sections. The tests were carried out using a specially designed test bench based on a pilot-scale screen with orbital motion of the screen box. A flat and a trapezoidal sieve were installed on the screen. After a series of tests, the efficiency of coal screening on a flat sieve was 80.2 % for the grade of –4 mm and 81.3% for the grade of –1.6 mm, with the specific feed rate of 13.0 t/(h·m2). The efficiency of coal screening on a trapezoidal sieve was 84.4 % for the grade of –4 mm and 84.8% for the grade of –1.6 mm. The design specific performance for the horizontal projection of the screen was 15.9 t/(h·m²).
The work was carried out under the grant issued by the Russian Science Foundation (project No. 17-79-30056).

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