The grinding equipment commonly used in grinding operation of concentrator includes rod mill and ball mill, both of which are used to grind materials. So why design into two different devices? Here are 7 differences between the ball grinding mill and rod grinding mill summarized by Nile Machinery:
1. Different shapes. Rod mill and ball mill machine have different cylinder shape ratios. The ratio of cylinder length to the diameter of rod mill is generally 1.5-2.0, and the inner surface of the liner on the end cover is a vertical plane. The ratio of the cylinder length to the diameter of the ball mill is small, which is usually only slightly greater than 1. In addition, the rotating speed of the cylinder of the rod mill mining equipment is lower than that of the ball mill of the same specification, so that the medium in it works in a cascading state.
2. Different discharge methods. The commonly used ball mills are grid type ball mill and overflow type ball mill, while rod mill does not use grid plate for discharging, only overflow type and open type. The diameter of the hollow shaft at the discharge end of the rod mill grinding machine is generally larger than that of the ball mill of the same specification.
3. Different working method of grinding media. Rod mills usually use steel rods with a diameter of 50-100mm as grinding media, while mineral ball mills use steel balls as grinding media. Due to the different shapes of grinding media, their working modes have their own characteristics. When the steel rod is moving, the gap between the rods is a regular strip, which increases the screening effect on the material, brings the large particle material to a high place during the working process and makes the large particle material get good crushing effect. Therefore, the contact between steel rod and material is line contact, while that between steel ball and material is point contact, which is the difference in the working mode of the grinding media.
4. Different filling rate of grinding media. The media filling rate refers to the percentage of grinding medium in mill volume. For different grinding methods, mill structures, operating conditions and media shapes, the media filling rate has a suitable range, too high or too low will affect the grinding effect. Usually, the filling rate of the ball mill is 40%-50%, and that of the rod mill is 35%-45%.
5. Different applicable materials. The rod mill is suitable for brittle materials, such as coal. In addition, due to the less over-crushing phenomenon, rod mill is suitable for tungsten tin ore or other rare metal ore and usually used in gravity or magnetic separation production line or used in the first stage of two-stage grinding. The application range of ball mill is wider, which can grind metal, nonmetal or stone.
6. The discharge fineness is different. The grinding fineness of ball mill is finer with 0.074-0.4mm, while the output fineness of the rod mill is between 0.833-0.147mm.
7. Different performance. The process characteristics of rod mills are that the product is rough, but the particle size is uniform. There are less coarse particles and slime, and the over-grinding capacity, strong adaptability to materials, high fineness of materials, fine discharge size, easy fine grinding, and significant energy saving, but its over-crushing phenomenon is serious.
The above are the differences between rod mills and ball mills, so how to choose in production? Nile engineers suggest that if customers want to grind brittle materials, rare metal ores, select rod mills; then select ball mills for other materials. If the customer does not require the discharge fineness but requires high output, select the rod mill, otherwise select the ball mill. In addition, rod mill can be selected for gravity separation, magnetic separation production line or the first stage of secondary grinding, and ball mill is selected for other separation methods. Nile machinery's ball mill and rod mill have high-cost performance. If you are interested, please call the contact number 008615137168510 or contact online customer service for quotation and product introduction.
