Optimum ratio of operating speed to critical speed of a trommel is_____________________?
A. 0.33-0.45
B. 1.33-1.45
C. 0.5-2
D. 1.5-2.5
A. 0.33-0.45
B. 1.33-1.45
C. 0.5-2
D. 1.5-2.5