Full definition
Mill liner rubber refers to a specialized compound typically made from natural rubber (NR) or a blend of NR and styrene-butadiene rubber (SBR) that is molded into wear-resistant panels for use in the interior of grinding mills, such as ball mills, semi-autogenous (SAG) mills, and rod mills. These liners play a critical role in protecting the steel shell of the mill from abrasion and impact, consequently enhancing the grinding process’s efficiency. One of the primary advantages of rubber liners is that they can significantly reduce noise levels, achieving reductions of 10-20 dB compared to traditional steel liners. This noise reduction contributes to improved working conditions in the milling environment, which is an essential consideration for occupational health and safety.
Rubber liners are designed with a hardness range of 35-55 Shore A, which is soft enough to absorb impact forces generated by the grinding media. Key properties of mill liner rubber include exceptional abrasion resistance with a measurement of less than 100 mm³ DIN, high resilience with an 80%+ rebound rate, and excellent tear resistance. The design of lifter bars, which may consist of rubber lifters or rubber/metal composites, is crucial to optimizing the mill's performance. Rubber lifters are typically used in primary and pebble mills, while composite designs incorporate a rubber body with steel or chrome inserts on the leading face to maximize wear resistance.
The advantages of using rubber liners over steel include a weight reduction of 30-50%, which diminishes the structural load on the mill and reduces wear on the bearings. Additionally, rubber liners exhibit better corrosion resistance in wet grinding environments, can have a lifespan of 2-3 times longer than steel in fine grinding applications, and have similar longevity in coarse applications. However, it is essential to note that rubber liners cannot withstand impacts from very large grinding media, specifically those exceeding 100 mm in diameter; in such cases, steel or composite liners are recommended. Mill liner rubber is commonly used in facilities with ball mills (typically under 6 meters in diameter), SAG mills utilizing composite liners, and regrind mills, all adhering to OEM specifications for each mill type.