The image above represents critical mill of speed. Two essential parameters are needed to calculate the critical mill of speed: mill diameter (D) and diameter of balls (d).
The formula for calculating critical mill of speed:
Nc = 42.3/√(D – d)
Where:
Nc = Critical Speed of Mill
D = Mill Diameter
d = Diameter of Balls
Let’s solve an example;
Find the critical speed of mill when the mill diameter is 12 and the diameter of balls is 6.
This implies that;
D = Mill Diameter = 12
d = Diameter of Balls = 6
Nc = 42.3/√(D – d)
Nc = 42.3/√(12 – 6)
That is, Nc = 42.3/√(6)
Nc = 42.3/2.44
Nc = 17.26
Therefore, the critical speed of mill is 17.26 m/s.
Calculating for Mill Diameter when the Critical Speed of Mill and the Diameter of Balls are Given
D = (42.3 / Nc)2 + d
Where;
D = Mill Diameter
Nc = Critical Speed of Mill
d = Diameter of Balls
Let’s solve an example;
Find the mill diameter when the critical speed of mill is 20 and the diameter of bills is 10.
This implies that;
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Nc = Critical Speed of Mill = 20
d = Diameter of Balls = 10
D = (42.3 / Nc)2 + d
So, D = (42.3 / 20)2 + 10
D = 4.47 + 10
D = 14.47
Therefore, the mill diameter is 14.47.
Read more:Â How to Calculate and Solve for Shaft Length | Ball Mill Sizing
Calculating for the Diameter of Balls when the Critical Speed of Mill and the Mill Diameter are Given
d = D – (42.3 / Nc)2
Where;
d = Diameter of Balls
Nc = Critical Speed of Mill
D = Mill Diameter
Let’s solve an example;
Find the diameter of balls when the critical speed of mill is 15 and the mill diameter is 10.
This implies that;
Nc = Critical Speed of Mill = 15
D = Mill Diameter = 10
d = D – (42.3 / Nc)2
So, d = 10 – (42.3 / 15)2
d = 10 – 7.95
d = 2.05
Therefore, the diameter of balls is 2.05.
Read more:Â How to Calculate and Solve for Shaft Power | Ball Mill Length
How to Calculate Critical Mill of Speed With Nickzom Calculator
Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the critical speed of mill.
To get the answer and workings of the critical speed of mill using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.
You can get this app via any of these means:
Web – https://www.nickzom.org/calculator-plus
To get access to the professional version via web, you need to register and subscribe for NGN 2,000 per annum to have utter access to all functionalities.
You can also try the demo version via https://www.nickzom.org/calculator
Android (Paid) – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator
Android (Free) – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator
Apple (Paid) – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8
Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Materials and Metallurgical under Engineering.
Now, Click on Ball Mill Sizing under Materials and Metallurgical
Now, Click on Critical Speed of Mill under Ball Mill Sizing
The screenshot below displays the page or activity to enter your values, to get the answer for the critical speed of mill according to the respective parameters which is the Mill Diameter (D) and Diameter of Balls (d).
Now, enter the value appropriately and accordingly for the parameter as required by the Mill Diameter (D) is 12 and Diameter of Balls (d) is 6.
Finally, Click on Calculate
As you can see from the screenshot above, Nickzom Calculator– The Calculator Encyclopedia solves for the critical power of mill and presents the formula, workings and steps too.
