Grinding Mill Liners

In many industrial applications, the importance of proper liner design in grinding mills cannot be overstated. There are primarily two categories of Grinding Mill Liners: HIGH PROFILE and LOW PROFILE. The high profile liner is specifically engineered to provide a higher lift to the grinding media, making it essential in mills designed for primary grinding. Conversely, lower profile liners are utilized in ball mills that function as the secondary sort in a grinding circuit, as a reduced lift allows for increased friction. This type of functionality is crucial for achieving optimal contact with the media's larger surface area. In addition to lift, liner designs must cater to the TYPE and SIZE of the grinding media used. Various liner profiles have been developed for these needs, which include RIPPLE LINERS, WAVE LINERS, SINGLE STEP LINERS, DOUBLE STEP LINERS, SHIPLAP LINERS, and LIFTER BARS, also known as KICKER BAR LINERS. Key measurements influencing performance consist of the WIDTH of the valleys, the HEIGHT of the lifting segments, and the overall THICKNESS of the liner.

YiTong products are distributed globally, ensuring a commitment to quality above all else. We believe in providing our customers with superior high value-added goods. Let's build a prosperous future together.

A liner occupies space within the mill, which will subsequently decrease the available tonnage. Therefore, the choice of liner design is critical during mill construction; an inappropriate design can lead to increased power and steel consumption, further diminishing both grinding efficiency and mill throughput.

Liners vary not only in design but also in the materials from which they are constructed. For instance, MANGANESE STEEL liners are used in rod mills and ball mills that accommodate larger media exceeding two inches. Alternatively, CHILLED CAST IRON LINERS are formulated with unique content and casting methods. A great example of this would be NIHARD LINERS. Recently, RUBBER LINERS have gained popularity in secondary grinding processes due to their effectiveness.

For operators, the most significant impact from liners comes down to wear. As a liner wears down, its lifting capacity diminishes, leading to lower profiles that affect the media's cascade. The result is an increase in unground material, and eventually, the bigger ore can no longer be processed efficiently. It's essential to replace the liners when this occurs.

Whenever you need to restart a mill after a full liner replacement, it’s advisable to start with reduced tonnage and gradually increase to maximum capacity. New liners tend to have too much lift, which can result in media being thrown too high and disrupting the cascade action. As the leading edge of the liners wears down, the tonnage can then increase, enabling a continual improvement in grinding quality thanks to extended processing time for the ore. However, this process has its limits; if the liners wear too thin, efficiency will decline until complete replacement is necessary.

Grinding Mill Rubber Liners

Rubber linings have evolved considerably, combining rubber plates with cast manganese lifter bars, ensuring that the major part of the mill's surface is protected by an abrasion-resistant surface. This design holds significant advantages, ensuring each component sustains the lifting load while resisting abrasion.

Over the years, rubber liner manufacturers have collaborated closely with mill operators to improve both the material compounds and designs necessary for optimal performance in specific applications.

While rubber liners may not be the ultimate solution for every grinding situation, they present several attributes that enhance their appeal:

Abrasion Resistance: Modern rubber compounds are engineered to withstand wear and tear from abrasion. Their longevity in regrind mill applications is well-documented, often exceeding that of cast metal liners in terms of cost-effectiveness.

Impact Resistance: This quality is particularly relevant in larger grinding mills. Rubber liners are adept at absorbing the impacts of larger media, thus protecting the overall mill structure and extending its service life.

Weight: With rubber weighing around 15% less than an equivalent volume of steel, rubber liner systems alleviate stress on the mill structure and reduce the power draw. Additionally, lighter liner components are easier to handle, making them safer to install—an essential factor in the modern milling environment where labor resources may be limited.

For more Liner Plate information, please contact us for professional assistance.

Noise: As noise control becomes increasingly crucial in the workplace, rubber mill liners facilitate a quieter operation, benefitting primary mills with larger grinding media significantly.

Tight Seal: Rubber liners can be manufactured to close tolerances, and their deformability allows them to serve as tight liners. This prevents abrasive wear on the mill structure. A vital advantage for gold operations is the minimization of free gold accumulation beneath or between the liners.

Flexibility: Rubber's natural flexibility is particularly noteworthy in grate discharge applications, as it helps prevent clogged grates—an aspect we will delve into further in this document.

The design specifics of rubber mill liners are tailored to meet the unique requirements of various grinding applications. This section will concentrate on three key design concepts: combination liners, rubber grates, and rubber-covered pulp lifters.

Rubber & Steel Combination Liners

Historically, it has been acknowledged that rubber alone might not suffice for certain grinding applications. Consequently, patents were issued for combination liners that extend rubber's capabilities into these areas. Despite advancements in rubber technology, there remain applications where rubber alone is inadequate, thus, combination liners are still prevalent. These settings include semi-autogenous mills as well as primary single-stage ball mills.

The updated design for combination liners features rubber plates accompanied by separate metal lifter bars. This retains most of the liner's volume as rubber, ensuring the benefits remain accessible. The liner may take the form of a plain contoured slab or include molded intermediate rubber lifters, depending on the specific grinding media and feeding demands.

Metal lifters secure the rubber plates in place, with a low-cost mild steel spacer between the rubber slabs and lifters to prevent movement. This spacer is a one-time use component, as it typically experiences no wear and does not require replacement, leading to significant cost savings.

The lifter bar’s design is contingent on the grinding application and mill size, but must maintain two key dimensional criteria. Firstly, the lifter’s edges should extend a minimum of 25 mm over the rubber plates for adequate clamping. Secondly, a base depth of at least 25 mm should be maintained to avoid lateral movement. A smooth, flat surface on the lifter base is essential for proper seating on the metal spacer. Lifter bars are affixed to the shell with oval head taper grade 5 forged bolts.

This design yields several advantages: Limiting scrap loss in metal lifter bars during changeouts through mild steel spacers; providing a stable base for the lifters; ensuring that no metal is present in the rubber plates, thereby simplifying manufacturing and lightening installation burdens.

Careful consideration must also be given to the metallurgy of lifter bars to align with the grinding application. For high-impact environments, such as large SAG mills, high-impact resistant Cr-Mo steel is typically necessary, while lower-impact scenarios might utilize abrasion-resistant castings, such as Nihard, to maximize durability.

Want more information on Culvet Pipe? Feel free to contact us.