JUSTIFICATION OF AN OPTIMUM OPERATING MODE OF A PNEUMATIC GRAVITY TABLE SEPARATOR WITH A PRODUCTIVITY OF 9 TONS PER HOUR

During operation of a gravity table separator it is necessary to consider a set of the interconnected technological parameters, each of which has an optimum value providing high overall performance of this machine. Optimum parameters of an operating mode of a gravity table separator with a productivity of 9 tons per hour were proved. The pitch and cross tilt angles of a screen deck, speed of an air stream, amplitude and frequency of fluctuations of a screen deck were defined. It was experimentally established that the pitch has optimum value of 7-10 degrees, tilt - 7-8 degrees. While meeting these parameters maximum efficiency of cleaning of the processed material was received. A size of a cross tilt angle of a screen deck influences thickness of a processed material layer on its working surface. So, at angles 7 and 4 degrees layer thickness respectively makes 40 and 60 mm in a middle part of a screen deck at the optimum kinematic mode. Excess of this indicator with respect to optimum size (30-40 mm) reduces overall performance of a gravity table separator. It was established that at the small aerodynamic resistance of underlying surface of screen deck (4 Pas) the changes of thickness of a layer on a screen deck surface significantly influence distribution of an air stream. For example, the coefficient an air stream speed variation on a screen deck with grain makes 42 percent, without grain - 17. At increase in aerodynamic resistance of screen deck underlying surface (700 Pas) the variation coefficient of an air stream on a screen deck with grain makes 6 percent, without grain - 19. Revealed that the increase in aerodynamic resistance of screen deck underlying surface reduces dependence of distribution of an air stream on thickness of a layer of the processed material. The sequence of setting of operating mode parameters of a gravity table separator providing high efficiency of seeds cleaning was stated