Ball mill

The largest central transmission ball mill currently has a cylinder diameter of up to 7.5 meters and a length of up to 13.2 meters. This type of large-scale equipment is primarily used in large mining operations and cement plants. The cylinder is made of high-strength alloy steel, with a wall thickness of up to 120 millimeters, significantly enhancing its wear resistance and service life.

The enormous size allows for a single-machine capacity of up to 1200 tons per hour (t/h), which is about 40% more efficient than traditional ball mills. However, it is important to note that such large equipment requires significant space and a robust foundation.

With a total weight reaching up to 900 tons, the equipment necessitates specialized vibration-damping structural designs.

The main bearing of a central transmission ball mill utilizes a double-row cylindrical roller bearing with a diameter of up to 2.5 meters. This large bearing can withstand enormous radial loads and supports transmission power of up to 12,000 kW. The lifespan of the bearing typically exceeds 100,000 hours.

The bearing employs a forced circulation lubrication system, with an oil tank capacity of up to 5,000 liters, ensuring stable operation over extended periods.

A temperature monitoring system provides real-time monitoring of the bearing temperature with an accuracy of ±0.1°C. This system can immediately trigger an alarm upon detecting any anomalies, effectively preventing damage due to overheating.

The gear ring of a central transmission ball mill features a segmented design, typically divided into 8 to 12 sections. Each segment can weigh up to 15 tons, facilitating easier installation and maintenance. The gear ring is made from high-strength alloy steel with a hardness of HRC58-62, significantly enhancing its wear resistance.

The tooth profile generally adopts a 20° full-depth involute shape, with a modulus of 32-40 mm. The contact ratio between the gear ring and the pinion is ≥1.5, ensuring smooth transmission.

The gear ring is bolted to the cylinder, with each bolt having a diameter of up to 80 mm and a tightening torque of up to 3000 N·m. This design ensures that the gear ring remains securely fastened during operation.

The drive shaft of a central transmission ball mill has a diameter of up to 800 millimeters and is forged from high-strength alloy steel 42CrMo. This design enables it to handle enormous transmission power of up to 12,000 kW, which is a 40% improvement over traditional designs.

The surface hardness of the drive shaft can reach HRC52-56, and it undergoes precision machining to maintain a cylindricity error within 0.02 mm. The shaft features multiple sealing structures with a minimum gap of 0.1 mm, effectively preventing lubricant leakage and the ingress of dust.

The drive shaft typically has a service life exceeding 20 years, significantly reducing maintenance costs for the equipment.

The central transmission ball mill is equipped with advanced noise reduction systems, keeping operational noise below 85 decibels. The external surface of the drum is wrapped with 50mm thick sound-absorbing cotton, which can reduce noise by 15-20 decibels. The gear transmission section is enclosed with a noise hood that is 30mm thick, providing an additional noise reduction of 10-15 decibels.

The bearing seats use elastic supports to diminish vibration transmission, further reducing noise by 5-8 decibels. The feed and discharge ends are lined with 20mm thick rubber liners to minimize noise from material impact. The entire equipment foundation employs a vibration damping design, achieving an isolation efficiency of up to 95%.

The control room is fitted with double-layer soundproof glass, each layer being 40mm thick, ensuring that indoor noise levels are maintained below 65 decibels.

The center drive ball mill is widely used in various industries due to its unique design and high efficiency. Here are its main application areas:
Mining and Mineral Processing Industry: The center drive ball mill is commonly used for grinding and crushing ores, particularly suitable for fine grinding of metallic ores such as gold, silver, copper, and iron. Its high energy efficiency and stability ensure high-quality and high-yield mineral processing.
Cement Manufacturing Industry: In the cement production process, the ball mill is used for grinding raw materials and clinker to produce cement. The center drive ball mill can provide uniform grinding results, improving the quality and strength of the cement.
Chemical Industry: The center drive ball mill is used in the chemical industry for grinding various chemical raw materials, such as pigments, ceramics, and coatings. Its precise control system can ensure the particle size distribution of the materials, meeting the needs of different chemical products.
Power Industry: In the power industry, the ball mill is used for grinding coal to produce coal powder suitable as fuel. The high-efficiency grinding capability of the center drive ball mill can improve the combustion efficiency of power plants and reduce energy consumption.
Building Materials Industry: The ball mill is also used for producing various building materials, such as limestone powder and gypsum powder. Its efficient grinding capability can meet the requirements for fineness and output in the building materials industry.