Large Hollow Grinding Balls for Medium-Speed Coal Mills: Advanced Manufacturing and Reliable Wear Solutions

In coal mining, power generation and industrial pulverizing applications, medium-speed coal mills operate under demanding conditions. The grinding balls inside the mill continuously experience impact, rolling pressure and abrasive wear from coal particles. Therefore, the dimensional stability, material performance and service life of grinding balls directly affect mill availability and maintenance intervals.

As medium-speed coal mills become larger, traditional solid grinding balls face challenges including excessive weight, higher handling requirements and increased operating load. Hollow grinding balls provide an optimized solution by reducing unnecessary weight while maintaining a wear-resistant working surface.

Haitian Casting specializes in the development and manufacturing of large hollow grinding balls for medium-speed coal mills. The products are designed according to mill specifications, operating conditions and customer requirements. Haitian hollow grinding balls have been applied in Babcock E-Type medium-speed coal mills and are in service at steel, mining and coal-power enterprises including Baowu and CITIC-related projects.

Extra-Large Manufacturing Capability for Medium-Speed Coal Mills

Large coal mills require grinding balls with stable dimensions, reliable structure and consistent material performance.

Haitian Casting manufactures hollow grinding balls ranging from Ø600 mm to Ø1180 mm. The largest standard size reaches Ø1180 mm with a unit weight of approximately 4.60 tons.

The hollow structure reduces the mass accelerated and supported by the mill while maintaining the required wear performance of the working surface. Wall thickness, material grade and hardness are designed according to operating requirements.

Advanced Spliced Manufacturing Technology

Producing extra-large hollow grinding balls requires precise control of structure, strength and dimensional consistency.

Haitian Casting applies advanced spliced manufacturing technology, combining precisely designed sections into a complete hollow grinding ball through controlled manufacturing processes.

Compared with conventional large-scale machining methods, this approach provides greater flexibility for oversized products and improves manufacturing efficiency.

For Babcock E-Type medium-speed coal mills, Haitian grinding balls are engineered according to the mill design, with matching geometry, wall thickness and material grade developed during the engineering stage.

Customized Alloy Development for Different Operating Conditions

Grinding ball performance depends heavily on material selection. Coal characteristics, operating conditions and abrasive environments can significantly influence wear behavior.

Haitian hollow grinding balls use ZG35Cr2Ni2Mo low-alloy cast steel, optimized for a balance of wear resistance, strength and toughness. The standard surface hardness is HRC 35–40.

The material composition includes controlled levels of carbon, chromium, molybdenum and nickel to achieve stable performance under continuous grinding conditions.

Controlled Heat Treatment and Quality Stability

Heat treatment plays a critical role in determining the final mechanical properties of large wear-resistant castings.

Haitian applies controlled heat treatment processes, including annealing at 890°C, to optimize the internal structure and improve long-term stability.

Each batch is verified through hardness testing, metallographic analysis and dimensional inspection.

Full-Process Quality Control

Large hollow grinding balls require strict quality control to ensure reliable operation.

Haitian applies inspection procedures including:

Chemical composition analysis;

Spectrometer testing;

Hardness testing;

Dimensional inspection;

Ultrasonic testing;

Magnetic particle or dye penetrant inspection;

Metallographic examination.

The standard dimensional control includes diameter tolerance within ±5 mm and wall thickness tolerance within ±5 mm. Each shipment includes chemical composition certificates, heat-treatment records, hardness reports, dimensional inspection reports and NDT documentation.

Proven Applications and Reliable Performance

Haitian hollow grinding balls are supplied for steel, mining and coal-power industries. A reference installation at China Baowu Steel Group uses ZG35Cr2Ni2Mo hollow grinding balls in medium-speed coal mills with a 12-month warranty period.

The theoretical service life reaches 13,000 hours, with a warranty period of 18 months after delivery or 12 months of operation, whichever comes first.

Haitian Casting: Your Partner for Large Hollow Grinding Balls

With advanced structural design, spliced manufacturing technology, customized alloy development, controlled heat treatment and complete quality management, Haitian Casting provides reliable hollow grinding ball solutions for medium-speed coal mills.

With manufacturing capability up to Ø1180 mm, stable material systems and comprehensive inspection procedures, Haitian supports global coal, power generation and industrial customers with high-performance wear-resistant components.