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The Difference between Ball Mill and Rod Mill

2022-06-13 17:32:51


Ball mills and rod mills are commonly used grinding equipment and are widely used in mineral processing plants. For users who don’t know these two devices, the ball mill and the rod mill are like a pair of “twins”, both of which are the same in length. How does the manufacturer distinguish these two devices? Under the circumstance that the overall operating cost of beneficiation production is high, the choice of grinding equipment has a great influence and is very important. Therefore, this article will analyze the characteristics of ball mills and rod mills from various aspects to help you better choose suitable grinding equipment.

1. Appearance characteristics
Although both the ball mill and the rod mill are cylindrical structures, the ratio of the length to the diameter of the cylinder of the ball mill is small, and in many cases the ratio is only slightly greater than 1, while the ratio of the length to the diameter of the rod mill is generally 1.5-2.0 , and the inner surface of the liner on the end cap is a vertical plane.
In terms of appearance, ball mills are more round and fat, while rod mills are more slender and long.


2. Characteristics of discharge
Ball mills can be divided into overflow type and lattice type ball mills, while rod mills are classified into overflow type rod mills and open type rod mills, and the diameter of the central axis of the discharge end of the rod mill is generally larger than that of ball mills of the same specification.


3. Characteristics of grinding media
The grinding media of ball mills are steel balls, while the grinding media of rod mills are steel rods. The difference in the grinding body is the main difference between the two.
Due to the different grinding bodies, their working methods also have their own characteristics. The steel ball of the ball mill is in point contact with the material; the steel rod of the rod mill is in line contact with the material, and the gaps between the rods are regular strips, which have a certain screening effect on the material.


4. The difference of medium filling rate
For different grinding methods, mill structures, operating conditions and media shapes, the media filling rate has a suitable range. Generally, the filling rate of ball mills is 40%~50%, and that of rod mills is 35%~45%. High or low filling rate of grinding media will affect the grinding effect.


5. Performance analysis
The performance characteristics of the ball mill are high production capacity, strong adaptability to materials, and relatively high degree of fineness of materials. Usually the discharge degree is between 0.074~0.4mm, the discharge particle size is fine, it is easy to be finely ground, and the energy saving is relatively significant. However, the phenomenon of over-grinding in the ball mill is serious.


The characteristics of the rod mill are that the product is relatively rough, but the particle size is uniform, containing less coarse sand and ore sludge, and the over-grinding is lighter, related to the condition of the ore.

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