Studies on Separating Performance of Brown Rices aud Sands by a Sand Separator with a Combination of Drawing and Blowing

Abstract

This study was concerned chiefly with separating capacities of brown rices and sands, using a sand separator with a combination of a drawing and blowing fan and with a blowing fan. The sand separator consisted essentially of a screen and fan. The differences of the static pressures, wind velocities, frequencies, feeding rates of the brown rice and sand sizes might be considered as the main separating factors. River sands which were screened with a standard sieve and ranged from 1.41mm up to 5.66mm, and painted by water colors to clearly distinguish sands from brown rices were used as the experimental materials. The number of sands used was 50 grains a test.
The main results were as follows;
1) Use of the sands painted by water colors made easy to distinguish sands from brown rices.
2) In the case of a combination of drawing and blowing, the cumulative recovery of sands was deeply concerned in the wind velocities of drawing, feeding rates of the brown rice, differences of static pressures and frequencies.
3) The screening time that the cumulative recovery of sand became 100% decreased gradually with the increase of the difference of static pressures, and it arrived at the minimum value, and then it gradually increased. Generally speaking, in the condition of higher value more than about 10mm Aq in the difference of static pressures, the cumulative recoveries might be high values by and large.
4) It was clear that a high recovery of sands was deeply concerned in the condition of fluidizing of the brown rice bed.
5) The discharging rates of brown rices in the discharge end of sands decreased gradually with the increase of the difference of static pressures.
6) The flowing velocities of brown rices might be largely influenced by the differences of static pressures rather than frequencies of the screen.
7) The flowing distance in the brown rice bed of sands subjected to the influence of the flowing velocities of the brown rice and the depths of its bed.
8) It was clear that a combination of drawing and blowing was able to make dusts discharge easily, and its separating capacity was not less than that of blowing.