This study was cncerned with the relationship between separating capacities of brown rices and sands and separating factors of frequencies, wind velocities, feedings and sand sizes, using a sand separator with the blast or suction fan. The wind velocity was represented by the maximum of it in an opening of the screen. Sands used were river sands which were screened with a standard sieve, and their sizes ranged from 0.5 mm to 6.0 mm. And they were painted by water colors.
The main results were as follows ;
1 . The relation between separating factors of brown rices and sands might be represented by using the rate of recovery of sands.
2. The sand sizes mixing in rices ranged from 0.5 mm to 6.0 mm, and the sand sizes of 0.2 mm to 0.3 mm consisted of mainly of them.
3 . In the case of blast, the accumulating recovery of sands was arrived at the value of 100 % under the condition of wind velocity 8 m/s, feedings 200 kg/h, frequency 475 cpm. And in the case of suction, it was arrived at the value of about 95 % under the condition of wind velocity 5 m/s, feedings 200 kg/h, sand size 2.83 mm and frequency 500 cpm.
4 . Though the rate of recovery of sands increased with the increase of both wind velocities and frequencies, it decreased when the wind velocity was over 9 m/s in the case of blast and 7 m/s in the case of sution.
5 . It is clear that the main factors of sand separating are frequencies and wind velocities.