| 摘要 |
A method of grinding coal in a ball grinder containing one ring of balls and lower and upper pans which are in contact with the balls, wherein raw coal is fed under gravity in the axis of the grinder to the rotating bottom of the grinder in the centre of the ring of balls, from where it is moved by centrifugal force to a position between the lower surfaces of the balls and the lower pan for the first grinding, from where following grinding it moves to the outside of the ring of balls, where it is subjected to initial separation by the action of a stream of air flowing upwards out of the bottom of the grinder, after which part of it undergoes a second grinding and then final separation, characterized in that the stream of air flowing out of the bottom of the grinder, after mixing with the ground material, is directed to the upper surface of the ball, whereby it is divided into two streams, of which one is reflected from the upper surface of the ball and, collecting small particles, is directed upwards for the final separation, while the second stream with larger particles is directed between the upper ball surface and the upper pan towards the inside of the ring of balls, where it undergoes a second grinding, and after passing to the inside of the ring of balls the stream of air is deviated upwards, carrying small particles for final separation, while the larger particles fall to the bottom of the grinder for repeated grinding.<IMAGE>
|
