Ball mill liners come in various forms and can be classified from multiple perspectives, including working surface shape, material, installation position, connection method, and function. The following is a comprehensive classification based on common references:

🔹 Classification by Working Surface Shape

This is the most common classification method. The shape of the liner directly affects the movement of the grinding media and the grinding efficiency.

• Flat liners: The surface is flat or may have cast-in patterns. They have low friction, provide strong grinding action, and are suitable for fine grinding compartments.
• Ribbed liners (or lifter bars): Composed of a flat liner with raised ribs. They can lift the grinding media to a greater height, providing high impact energy, and are suitable for the first compartment (coarse grinding), especially when the feed material is coarse.
• Ridge liners: Similar to ribbed liners but with semicircular or trapezoidal ridges cast on the flat surface. They are rigid and not easily deformed.
• Stepped liners: The working surface has an inclined stepped profile. They ensure uniform lifting of the grinding media at the same layer, and the liner surface wears evenly. They are widely used in crushing compartments.
• Corrugated liners: There are two types: those with larger wave peaks and pitches, which are suitable for rod mills; and those with smaller wave peaks and pitches (small-corrugated liners), which are suitable for fine grinding compartments and are often bolted.
• Hemispherical liners: These help avoid circular wear grooves, reduce metal consumption, and are suitable for crushing compartments.
• Classifying liners: These enable automatic classification of steel balls along the axial direction of the mill – larger balls remain at the feed end for crushing coarse material, while smaller balls move toward the discharge end for fine grinding.
• Other shapes: These include tapered liners, hyperboloidal liners, spiral-angle liners (energy-saving liners), grooved liners, etc. Some references summarise common shapes into nine types, such as wedge-shaped, flat-convex, strip-shaped, rudder-shaped, K-type rubber liners, and B-type rubber liners.

🔹 Classification by Material

• Metal liners: Traditional materials include high‑manganese steel (good toughness and work‑hardening properties). Modern materials widely used include medium/high‑carbon alloy steel, high/medium/low‑chromium cast iron, and bimetallic composite wear‑resistant materials.
• Rubber liners: They offer advantages such as wear resistance, energy savings, and noise reduction, and perform well in wet grinding applications in mines.
• Other materials: These include stone liners, ceramic liners, magnetic liners (which form a protective layer by attracting magnetic materials – long service life but brittle), and polyurethane liners.

🔹 Classification by Installation Position

• Shell liners: Installed on the inner wall of the mill shell.
• End liners (or head liners): Installed at both end covers of the mill.
• Manhole liners: Installed at the mill access door.

🔹 Classification by Connection Method

• Bolted liners: Fixed to the shell with bolts.
• Bolted liners: Fixed by embedding, self‑locking (e.g., dovetail interlocking), or other means.

🔹 Classification by Function

• Ordinary liners: Mainly used to protect the shell and lift the grinding media.
• Classifying liners: In addition to the above functions, they also enable automatic classification of steel balls.

💎 Summary

In general, the selection of the appropriate liner type should be based on a combination of factors, including mill type, material properties, grinding stage (coarse or fine grinding), and specific process requirements.