What is ball mill? How does it work?
Ball mill is grinder which is mainly used to reduce the size of ore material into powder size by using different sized balls.
The working principle of a ball mill is that as the cylindrical shell rotates, grinding elements in ball mills travel at different velocities.
That process makes collision force, direction, and kinetic energy between elements vary with the ball charge, and creates friction and rubbing forces, collision energy to grind material into particles.Inside of the ball mill, because of the friction forces made between the mill wall and balls, the latter rise in the direction of rotation until a helix angle does not exceed the angle of repose, and then the balls roll down with parabolic curves.
In the end, when the balls fall down from near the top of the ball mill shell, they impact and attrit material to reach the size reduction.
Ball mill design
Liners and plates
- Galvanized iron plate is most suitable for small ball mills without the demand of large grinding media.
- Manganese liners contain 12% to 14% manganese, and cost lower than that of galvanized iron plate.
- Ceramic or rubber linings are designed for continuous operation, and both can be used in wet or dry grinding.
- Ceramic liners are applied to a ball mill with flint pebbles or high-density ceramic balls as grinding media.
There are two chambers in a ball mill. The liners and plates are designed to lift balls when the ball mill rotates, so crushing is the main process in the first chamber.
In the second chamber, the diameters of the ball are smaller than that of the ball in the first chamber and are between 60-15mm.
Here the liners in the second chamber are used as “classifying lining” to sorts the media so that ball size reduces towards the discharge end of the mill. The grinding process takes place in the rolling point-contact zone between each charge ball.
Bearings of a ball mill
Cylindrical roller bearings suit for smaller ball mills.
Trunnion bearings and hydrostatic bearings are often installed on the large ball milling machine, but it means you need an oil pump to supply the oil for the bearings. The oil creates boundary between the bearing itself and the shaft.
The critical speed of ball mill
The optimum rotational speed is usually set to 65%-80% of the critical speed. Ball and pebble mills usually rotate at 70—85 % of critical speed. For dry grinding, the speed is usually much lower.
Ball mill grinding media
The common types of grinding media are steel balls, pebbles, and ceramic balls. Generally, a maximum allowed ball size is situated in the range from D/18 to D/24.
To effectively grind ore, the ball mills need to load 40% steel balls (with 30-80mm diameter)
The pebbles are lighter than steel balls, and the power input is directly proportional to the volume weight of the grinding medium. Therefore, when the grinding media are pebbles rather than steel balls, the power input and capacity of pebble mills are correspondingly lower.
A pebble mill is much larger than a ball mill in a given grinding circuit thus needs higher capital cost. However, compared to a ball mill with steel ball as media, a pebble mill is more economic due to great reduction in operating cost.
Which link is the ball mill mainly used for?
- 1Ball mills are employed in either primary or secondary grinding applications.
- 2In primary applications, they receive their feed from crushers. In secondary applications, they receive their feed from rod mills, AG mills, or SAG mills.
- 3The circuits of these mills are usually closed with a classifier under high cyclic loads.
What factors affect the output and efficiency of the ball mill
- drum diameter and the relation of drum diameter and length
- The physical-chemical properties of the feed material
- the filling of the mill by balls and their sizes
- the armor surface shape
- the speed of rotation
- the milling fineness
- the timely moving off of the ground product.
Which fields is ball mill widely used in?
Grinding ores in the beneficiation plant
The ball mill plays an irreplaceable role in the beneficiation plant. In the process of extracting metal ore, because of the ore minerals with fine dissemination, it is necessary to grind the ores to a finer size to dissociate the useful minerals and gangue.
Ball mill can ideally control the particle size and granularity, improving the recovery rate and output of useful minerals.
Preparation of non-metallic ores such as coal-water slurry
Ball mills are also widely used in the preparation process of coal water slurry.The coal water slurry needs to be comminuted by a ball mill in the wet grinding process.
The use of a single-machine system process can realize the large-scale coal water slurry plant.
A roller crusher, a large crushing equipment, can compensate for the insufficient capacity of the ball mill, and double the production capacity of the ball mill;
Powder concentrator can control the particle size and adjust the load distribution of the roller press and the ball mill, so as to realize the large-scale single-machine process system.The advantages of the two processes:
- 1The new technological processes can reduce the space occupation, and the number of equipment and auxiliary facilities. Finally, it can cut down investment by more than 10%.
- 2The new process adopts a large-scale, single-machine system to simplify the parallel control system and instrumentation, and reduces operating personnel.
- 3Reduce energy consumption per ton of pulp by 30-50%.
- 4Reduce wear medium consumption by 30-100%.
Ball mill is widely used in building materials and chemical industry
Cement consists of clinker, gypsum and other components mostly more easily ground than clinker.
The working principle is that cement is removed from the mill before over-grinding has taken place then it is separated into a fine fraction to meet finished product requirements.
The highest efficiency would be reach when recirculation factor or the ratio of mill throughput to fresh feed is up to three. The current cement production process includes both dry and wet grinding processes.
Ball mills used in cement production characteristics low energy consumption, large processing capacity, and large crushing ratio.
Ball mill manufactured by Fote Company-your best choice
Outstanding advantages of Fote ball mill
Save energy: Fully hydraulic operation helps to realize automatic operation, greatly improving reliability and longevity of the machine;
The flexible design of the discharge port: The discharge port is designed reasonably, and customers can choose the iron remover according to their needs;
Rotation parts: The cylinder, lining, medium, compartment board and discharge raft of the rotation part are all made up of high-quality original parts.
Large feeding unit: Reasonable feeding port design greatly increases feed volume;
High grinding efficiency and good quality of the liner: The lining and grinding body are made of alumina ceramic, quartz, SILEX or special materials, and it is designed with no iron pollution when crushing hard materials;
Closed system to reduce dust: Ultra-fine ball mill and classifier form a closed system with advantages of negative pressure delivery, low dust, reducing damage to the human body; Besides, the ball mill has higher product quality and cheaper operating prices.
Operation and repair: Reliability and safety, and easy maintenance Constant grinding granularity: With a certain ability to maintain the specified grinding fineness for a long period of time (balls are added regularly to compensate for its wear).
Sufficient parts supply and best service
- Sufficient supply of high-quality parts minimizes maintenance costs
- High-quality parts minimize maintenance cost
- The ball mill produced by Fote Machinery can minimize the wear during materials impacting due to extraordinary casting process, strong heat-treating ability.
- The grinding balls are made of high manganese steel characterizes good toughness and good manufacture ability with low price.
- Ball mill accessories include big gear, pinion, hollow shaft, ring gear, big ring gear, steel ball, compartment board, transmission, bearing, end lining and so on.
- Sufficient supply of each component aims at minimizing equipment repair and replacement time.
Fast delivery speed
Even during the Covid-19, as long as there is a trade permission in your country, we will deliver the products in the fastest way and promise that all production will be completed on schedule.
The following is the fastest shipping method and approximate delivery time according to the actual situation of different countries. (Only some customer countries/regions are listed)
|Location||country||city||Delivery method||Time required(day)|
|South Asia||India||Nhava Sheva||shipping||20|
|North America||The USA||LOG ANGELES||shipping||20|
|Papua New Guinea||PORT MORESBY||shipping||30|
Fote Machinery has set up a strong after-sales service to maintain on-site production and provide users with 24-hour online service.
|Model||Shell rotation speed
|Ф3200×4500||18||65||<25||0.074-0.4||As per process conditions||630||149|
|Ф3600×4500||17||90||<25||0.074-0.4||As per process conditions||850||169|
|Ф3600×6000||17||110||<25||0.074-0.4||As per process conditions||1250||198|
|Ф3200×4500||<25||As per process
|Ф3600×4500||<25||As per process
|Ф3600×6000||<25||As per process