What is the critical speed of ball mill?

The formula for critical speed is CS = 1/2π √(g/(R-r) where g is the gravitational constant, R is the inside diameter of the mill and r is the diameter of one piece of media. This reduced to CS = 265.45/√(R-r).

What are the parameters should optimize in the ball milling machine?

The three main parameters applied in this study are Ball to Powder weight Ratio (BPR), time milling process, and rotational speed (rpm).

How much balls should be loaded in a ball mill for working?

Generally, filling the mill by balls must not exceed 30–35% of its volume. Productivity of ball mills depends on drum diameter and the relation of drum diameter and length.

Why is the speed of ball mill critical for effective size reduction?

The difference in speeds between the balls and grinding jars produces an interaction between frictional and impact forces, which releases high dynamic energies. The interplay between these forces produces the high and very effective degree of size reduction of the planetary ball mill.

What is optimum speed of ball mill and why?

Ball mills have been successfully run at speeds between 60 and 90 percent of critical speed, but most mills operate at speeds between 65 and 79 percent of critical speed. Rod mills speed should be limited to a maximum of 70% of critical speed and preferably should be in the 60 to 68 percent critical speed range.

Why is rotational speed important for ball mills?

In particular, they mentioned that as rotation speed increases, distinct avalanche, continuous avalanche, cascading motion, cataracting motion and centrifugal motion appear sequentially. In this final stage, the outermost layer balls are placed stationarily with respect to the inner wall of the jar.

What is ball to powder ratio?

The ball to powder ratio (BPR) is a processing parameter that is frequently used in both mechanical (ball) milling and mechanical alloying.

How do you calculate ball to powder ratio for ball milling?

The true density of balls are around 7.5. Then, the optimal mass ratio of ball to powder in ball mill is 7.5*24/(2.5*17.6)= 4.09 to 7.5*21/(2.5*11.2) = 5.63.

What is ball milling ratio?

Generally, filling the mill by balls must not exceed 30%–35% of its volume. The productivity of ball mills depends on the drum diameter and the relation of ∫ drum diameter and length. The optimum ratio between length L and diameter D, L:D, is usually accepted in the range 1.56–1.64.

How do you calculate ball mill capacity?

Mill internal load volume (m3) = (19.55*297.96)/100 = 58.52 m3 (2) Ball volume in total mill load could compute by Equation 3. Mill Ball (%) = 100{[(ball volume in the 0.4 m3 sample)* 58.52] / 0.4}/297.96 (3) According to the results (Table 1), the ball filling percentage was obtained 1.3%.

At what speed maximum size reduction will take place in ball mill?

0.5 cycles per second
At this speed, the balls are carried almost to the top of the mill and then fall in a cascade across the diameter of the mill. In this way, the maximum size reduction is obtained by the impact of the particles between the balls and by attrition between the balls. It is usually 0.5 cycles per second (cps).