What is ball mill?

Ball mill is a kind of dressing equipment that crushes materials into extremely fine powder. Ball mill mainly uses grinding bodies (usually steel balls or ceramic balls, etc.) installed in a rotating cylinder to impact and grind materials to achieve the required fineness.

Ball mills are widely used in mining, building materials, chemicals, cement, metallurgy, materials, electricity and other industries.

Ball mills can grind various grindable materials dry or wet.

Therefore, ball milling is used to grind various ores, mineral powders, raw materials and other materials.

What are ball mills used for?

Ball mill is a machine that continues to crush ore or other materials after crusher. It is a mechanical equipment that obtains finer particle products required by the process through the impact, extrusion and friction of steel balls or grinding media. It is used in many industries.

Ball mill used for mining and metallurgy

Ball mill used for building materials

Ball mill used for chemical industry and materials science

.Ball mills used for ceramics and refractory materials

Ball mills used for food and pharmaceuticals

Ball milling environmental protection and energy

How does a ball mill work ?

Do you know the working principle of ball mill? The working principle of ball mill is based on the dynamic interaction between the internal grinding media (steel balls, ceramic balls, etc.) and the materials to be ground driven by the rotating motion of the cylinder, and the crushing and refinement of the materials are achieved through the combined action of impact, extrusion and shear force.

The core process of ball mill balls begins with the uniform rotation of the cylinder driven by the motor. The inner wall of the cylinder and the grinding media and materials move together due to friction. When the cylinder speed reaches the critical value, the medium is lifted to a certain height due to centrifugal force and then detached from the cylinder wall. Under the action of gravity, it falls freely in a parabolic trajectory, which has a strong impact and crushing effect on the material;

At the same time, the medium forms a dynamic accumulation layer in the cylinder due to rolling, sliding and filling of materials, which produces continuous extrusion and grinding effects, causing the material particles to crack, peel and refine under repeated stress.

The material crushing process is accompanied by the rotation of the cylinder and presents a spiral propulsion. The newly added material is crushed by the medium at the feed end and gradually migrates to the discharge end. The fine particles flow to the discharge port through the gap between the media, while the coarse particles are retained in the high energy area due to their large mass and continue to be ground until the particle size requirements are met.

The energy transfer efficiency is affected by the cylinder speed, medium filling rate, medium size and material characteristics. Too high a speed will cause the centrifugal force of the medium to exceed the friction force and rotate against the wall (“centrifugal operation state”), losing the grinding function;

On the contrary, at a low speed, the medium only moves in a cascading manner (interlayer sliding), and the impact energy is insufficient. In actual operation, ball mills need to optimize energy efficiency by adjusting the speed, medium ratio and ventilation volume (controlling temperature and dust).

For example, dry ball mills are often supplemented with airflow to assist discharge and cooling, while wet ball mills improve grinding efficiency and reduce agglomeration by adding grinding aids and water media.

Structural composition of ball mill

Ball mill is a commonly used grinding equipment. Its structural design is designed to achieve the goal of efficient grinding and refining of materials. Ball mill is mainly composed of feeding device, drum, discharging device, transmission device, electrical control system and supporting device, etc.

These components cooperate to complete the grinding in mining, metallurgy, chemical industry and other industries. The structure and function of ball mill will be introduced in detail below.

Seven parts of grinding ball mill

1. Feeding device

The feeding device of ball mill is located at one end of the machine body, usually composed of feeding hopper and screw conveyor. The feeding hopper is used to introduce materials into the drum, while the screw conveyor can smoothly feed the materials into the drum. Whether the design of feeding device is reasonable or not directly affects the operation effect and grinding quality of ball mill.

2. Drum (cylinder)

The drum of ball mill is the core component of the whole equipment. It is subje

ct to the weight of itself and liner, partition plate, grinding body and materials in the mill (bearing static load). It is composed of cylinder and inner liner.

The drum is a hollow cylinder, and the inner lining is used to protect the inner wall of the drum from wear. A certain number of grinding bodies (usually steel balls) are installed in the drum, and the material is ground together with the grinding bodies in the drum. The material of the drum is mostly Q235 steel plate or 16Mn steel plate, which has good impact resistance and weldability.

3. Liner

The function of the Mill ball liner is to protect the drum and adjust the movement state of the grinding body.

4. Transmission device

The transmission device of the ball mill is mainly composed of a motor, a reducer and a transmission shaft. The motor drives the reducer, and then transmits power to the drum through the transmission shaft to realize the rotation of the drum. Whether the design of the transmission device is reasonable or not directly affects the operating stability and energy consumption of the ball mill.

5. Discharge device

The discharge device of the ball mill is located at the other end of the body, and it is usually composed of a discharge barrel and a screw conveyor. The discharge barrel is used to discharge the ground material from the drum, and the screw conveyor smoothly transports the material to the next process. Whether the design of the discharge device is reasonable or not directly affects the production capacity and grinding effect of the ball mill.

6. Electrical control system

The electrical control system of the ball mill includes functions such as main motor control, feed control, discharge control and equipment protection. Through the electrical control system, the start and stop, speed adjustment, feed amount control and other operations of the ball mill can be realized to ensure the normal operation and production efficiency of the equipment.

7. Support device

The support device of the ball mill is mainly composed of bearings and bearing seats. The bearings are used to support the drum and transmission device so that they can run smoothly. The bearing seat is used to fix the bearing to ensure its stability during the working process.

Each component of the ball mill plays an important role. Reasonable structural design can improve the grinding efficiency of the ball mill, reduce energy consumption, and ensure the stable operation of the equipment. SMAT can optimize the structural parameters and design the ball mill according to the specific production requirements according to different production requirements to achieve the best grinding effect.

13 types of ball mills

Ball mills are one of the most widely used high-fine grinding machines in industrial production. There are many types of ball mills, such as tubular ball mills, rod ball mills, cement ball mills, overflow ball mills, ceramic ball mills, grid ball mills, etc. Each type of ball mill has its own characteristics and application scenarios.

Below SMAT will introduce the 13 types of ball mills and the characteristics of each ball mill in detail.

• Dry ball mill
• Wet ball mill
• Ceramic ball mill
• Grate ball mill
• Overflow ball mill
• Tubular ball mill
• Rod ball mill
• Cement ball mill
• Ultrafine laminated mill
• Hand ball mill
• Horizontal ball mill
• Energy-saving ball mill

1. Dry ball mill

Dry ball mill is a kind of equipment that grinds materials in a dry state. The grinding process does not require liquid medium and relies on air or inert gas to assist in discharging. Features: Dry ball mill has strong material adaptability and is suitable for ores and other materials of various hardness. The material can be finely discharged and can be ground to a finer particle size. Large production capacity: intermittent, cyclic and continuous production can be achieved. A discharge grate is set at the end of the cylinder to discharge the material through airflow; Application: It is widely used in cement plants, ore dressing plants, chemical plants and other industries for grinding cement clinker, slag, limestone, non-metallic minerals (graphite, kaolin) and other materials.

2.Wet ball mill

Wet ball mill is a ball mill that needs to add liquid medium (usually water) during the grinding process. Through “wet” grinding, the impact force is transmitted by liquid medium. Features: High grinding fineness: can grind materials to extremely fine particle size. Good mineral processing effect: helps to improve the dissociation degree of ore. Reduce grinding temperature: effectively reduce the temperature during grinding. Reduce material agglomeration: the slurry has strong fluidity and high discharge efficiency; Application: commonly used in industries that require extremely fine particles or materials that are very easy to agglomerate, such as ore processing, cement clinker grinding, ceramic raw material preparation, etc.

3. Ceramic ball mill

Ceramic ball mill is a ball mill whose liner is made of ceramic materials such as alumina and zirconium silicate. Features: Energy saving and power saving: more energy-saving than other ball mills. Stable and reliable performance: easy to operate and safe to use. Uniform fineness: the fineness of the grinding operation can be controlled by the grinding time. Application: mainly used for material mixing, titanium dioxide grinding, and Chinese medicine crushing. It is suitable for mixing and grinding of ordinary and special materials.

4.Grate ball mill

Grate ball mill is a ball mill with a grate discharge method. A “grate plate” (a discharge partition plate with holes) is provided at the end of the cylinder. Features: Forced discharge: It has a forced discharge function and increases the processing capacity.Reduce over-crushing of ore: effectively reduce the over-crushing of ore. Complex structure and high maintenance cost; Application: Commonly used for coarse grinding operations, suitable for processing coarse materials, iron ore pre-grinding, cement raw material preparation, and nickel ore pellet production.

5. Overflow ball mill

Overflow ball mill is a ball mill that discharges naturally through the “overflow port” at the end of the cylinder and controls the discharge speed based on the slurry liquid level. Features: Uniform discharge particle size: The particle size of the discharged material is relatively uniform. Good crushing effect: The material can be ground more fully. Simple structure, no grate plate wear problem;

6. Tubular ball mill

A tubular ball mill is a ball mill with a larger ratio of barrel length to diameter (length-to-diameter ratio>3), similar to a “pipeline” structure. . Features: High grinding efficiency: Reasonable feed port design and conical structure at the discharge end improve grinding efficiency. Energy saving and environmental protection: It forms a closed system negative pressure conveying with the classifier to reduce dust pollution. It occupies a large area and has high energy consumption; Application: It is widely used in cement plant products, can be used for open flow grinding and circulating flow grinding, talcum powder fine processing, diatomaceous earth purification, and nuclear fuel uranium ore grinding.

7. Rod ball mill

A rod ball mill is a ball mill that uses “steel rods” instead of steel balls as grinding media, and has a larger barrel length to diameter ratio (length-to-diameter ratio>5). Features: Larger grinding particles: Suitable for materials with larger grinding particles. Selective crushing: It has a certain selectivity for material crushing.Application: Commonly used for processing ores with higher hardness, limestone pre-crushing in cement plants, coarse grinding of gold mines, and stone processing.

8. Cement ball mill

Cement ball mill is a ball mill specially used for cement production, usually a horizontal model with a cylinder diameter of 1.5~4 meters. . Features: It has strong adaptability to materials and can adapt to different types of materials. Double-bin design (one bin for coarse grinding, two bins for fine grinding); Easy to adjust the fineness of the grinding product: the fineness of the grinding product can be adjusted as needed.

9. Ultrafine laminated mill

Ultrafine laminated mill is a high-efficiency and energy-saving ball mill that achieves ultrafine grinding through the principle of “laminated crushing” (materials form a material layer under high pressure). Features: Ultrafine crushing can crush materials to ultrafine particles, and the product particle size can reach less than 1μm. Very low wear (layered contact between the medium and the material);Application: Suitable for materials that require ultra-fine grinding, such as some fine chemical raw materials, nano calcium carbonate, graphene raw materials, and pharmaceutical API micronization.

10. Hand ball mill

The hand ball mill is a small, manually operated ball mill, named because it requires manual feeding and start and stop. Features: Easy to operate, manual operation, and easy to use. Suitable for small batch production and small batch material grinding. Small capacity (usually <10L), strong portability; Application: Commonly used in laboratories or small-scale production, mineral analysis, pigment sample preparation, and alloy composition research.

11. Horizontal ball mill

The horizontal ball mill is a ball mill with a horizontally installed cylinder (horizontally arranged) opposite to the vertical ball mill. Features: Stable structure, horizontal installation makes the equipment structure more stable. It occupies a large area and requires supporting structures; Application: Suitable for grinding a variety of materials, such as ore, cement, ceramics, calcite ultrafine grinding, etc.

12. Energy-saving ball mill

Energy-saving ball mill is a ball mill that uses energy-saving technology and reduces energy consumption through structural optimization (such as variable frequency motor, double-layer cylinder). Features: Energy-saving and power-saving, more energy-saving than traditional ball mills. Stable performance, stable and reliable equipment performance. Use static and dynamic pressure bearings to reduce friction loss;Application: Suitable for various material grinding scenarios that require energy saving, energy-saving transformation of cement plants, large-scale production of non-metallic minerals, etc.