critical speed - Nickzom Blog

The image above represents the mill speed.

To compute for mill speed, two essential parameters are needed and these parameters are Speed Percentage (N%) and Critical Speed (N_c).

The formula for calculating mill speed:

MS = N% x N_c

Where:

MS = Mill Speed
N% = Speed Percentage
N_c = Critical Speed

Let’s solve an example;
Find the mill speed when the speed percentage is 12 and the critical speed is 10.

This implies that;

N% = Speed Percentage = 12
N_c = Critical Speed = 10

MS = N% x N_c
MS = (¹²/₁₀₀) x (10)
MS = (0.12) x (10)
MS = 1.2

Therefore, the mill speed is 1.2 m/s.

Calculating the Speed Percentage when the Mill Speed and the Critical Speed is Given.

N% = ^MS / _N_c

Where;

N% = Speed Percentage
MS = Mill Speed
N_c = Critical Speed

Let’s solve an example;
Find the speed percentage when the mill speed is 24 and the critical speed is 6.

This implies that;

MS = Mill Speed = 24
N_c = Critical Speed = 6

N% = ^MS / _N_c
N% = ²⁴ / ₆
N% = 3

Therefore. the speed percentage is 3 m/s.

Continue reading How to Calculate and Solve for Mill Speed | Ball Mill Sizing

The image above represents shaft power | ball mill length.

To compute for shaft power | ball mill length, six essential parameters are needed and these parameters are Value of C, Volume Load Percentage (J), % Critical Speed (V_cr), Bulk Density (s.g), Mill Length (L) and Mill Internal Diameter (D).

The formula for calculating shaft power | ball mill length:

P = 7.33 x C X J X V_cr x (1 – 0.937) x [1 – ^0.1/_{2^{9 – 10Vcr}}] x s.g. x L x D^2.3

Where:

P = Shaft Power | Ball Mill Length
J = Volume Load Percentage
V_cr = % Critical Speed
sg = Bulk Density
L = Mill Length
D = Mill Internal Diameter

Let’s solve an example;
Find the shaft power | ball mill length when the volume load percentage is 8, the %critical speed is 10, the bulk density is 3. the mill length is 14 and the mill internal diameter is 16.

This implies that;

J = Volume Load Percentage = 8
V_cr = % Critical Speed = 10
sg = Bulk Density = 3
L = Mill Length = 14
D = Mill Internal Diameter = 16

P = 7.33 x C X J X V_cr x (1 – 0.937) x [1 – ^0.1/_{2^{9 – 10Vcr}}] x s.g. x L x D^2.3
P = 7.33 x 1 x 8 x 10 x (1 – 0.937) x [1 – ^0.1/_{2^{9 – 10(10)}}] x 3 x 14 x 16^2.3
P = 36.94 x [1 – ^0.1/_2^-91] x 3 x 14 x 588.133
P = 36.94 x [1 – ^0.1/_4.038e-28] x 24701.609
P = 36.94 x [1 – 2.47e+26] x 24701.609
P = 36.94 x -2.475e+26 x 24701.609
P = -2.259

Therefore, the shaft power | ball mill length is – 2.259 W.

Continue reading How to Calculate and Solve for Shaft Power | Ball Mill Length