Nowadays, more and more manufacturers in China are using high‑chromium wear‑resistant liners. However, since all high‑chromium cast irons are brittle materials, even after heat treatment, conventional bolted fixing methods still make the liners prone to fracture. Therefore, high‑chromium liners are generally fixed without bolts, and in practice, the ring‑brick‑laid (circular interlocking) fixing method has proven to be the most reasonable. This method utilises the geometric shape of the mill itself, employs a mechanical structure for bimetallic combination, and takes advantage of the grinding media action during mill operation to achieve pre‑stressed self‑locking, thereby strengthening the liners as a whole and ensuring the stability and reliability of the high‑chromium cast iron liners with their high hardness and low toughness.

Theoretically, this installation method is suitable for mills of any size. However, in actual practice, even for small mills below φ2.6 m, brick‑laid liners can still collapse, causing inconvenience to production and maintenance. Chen Wei has analysed the causes of such collapse, and the findings are provided below for reference by manufacturers who produce or use high‑chromium brick‑laid liners.

(1) The formation of a “tight inside, loose outside” condition between liners is the main cause of collapse

Since self‑locking liners, like other liners, are cast in one piece and are difficult to grind, it is very hard to ensure that the joint faces between liners are perfectly matched from the inner circumference to the outer circumference, as shown in Figure 2.4.

If a “loose inside, tight outside” condition exists, the liners will not be lifted by excessive compressive force during operation, nor will gaps form at the joints due to surface wear, so operation remains relatively safe. Conversely, if a “tight inside, loose outside” condition occurs, the liners may lift due to excessive compressive force. This is because a lifting (tilting) moment is generated around the apex point. In addition, when the joint faces wear away, a clearance will develop between the liners, causing them to loosen and collapse. For older mills that have been in service for a long time, shell deformation makes the liners even more prone to collapse.

The best way to avoid the “tight inside, loose outside” condition at the liner joints is to reduce the height of the joint face, relocate the joint from the crest to the trough of the wave, and change the contact from a full surface to several raised pads, which are easier to grind if they do not meet requirements (Figure 2.5). Secondly, during installation, thin iron shims of 1–3 mm thickness should be placed at the joint contact faces. This not only compensates for the tilt caused by dimensional inconsistencies in the arc length direction of the liners (which is also a cause of collapse), but also uses the plastic deformation of the shims to ensure good contact and avoid gaps at the joint faces.

(2) Liner fracture during operation can also cause collapse

Theoretically, the greatest advantage of ring‑brick‑laid liners is that, due to the plastic deformation of the wedge blocks, the liners become increasingly tight during operation. Even if a liner fractures, it merely amounts to an increase in the number of liner pieces and should not cause any harm. However, in actual operation, gaps may form between the liners and the mill shell due to the following factors, as shown in Figure 2.6:

① The curvature of the liners does not match the curvature of the mill shell;
② Deformation of the mill shell;
③ Weld seams left on the inner surface of the mill shell.

Let us now analyse the consequences of fracture in brick‑laid liners under normal joint conditions. If a lifted liner fractures during operation, the impact of the grinding media and material will force the fractured liner to move toward the shell, creating a gap at the fracture surface, which loosens the liners and leads to collapse. This is particularly critical for older mills that have been in operation for a long time, where severe shell deformation causes more pronounced lifting of the liners, making fracture‑induced collapse more likely.

Due to the limitations of the liner material, fracture is unavoidable. Therefore, the most effective way to prevent collapse caused by liner fracture is to reduce the dimension in the arc‑length direction as much as possible during liner design, in order to minimise the lifting height of the liners caused by the three factors mentioned above. In this way, even if fracture occurs, no significant gap will form, and collapse can be avoided. During installation, strict quality control is essential: liners with incorrect curvature or those that cannot fit tightly against the shell must be re‑ground. The cement grout should be mixed with an appropriate proportion to ensure adequate filling quality, thereby minimising the gap between the liners and the shell. This not only helps prevent liner fracture but also ensures that, even if fracture does occur, essentially no gap will appear at the fracture surface, thus preventing liner collapse.