Detailed explanation of the installation process of the liner of the grid ball mill

Grate ball mill liner installation is a critical step in ensuring efficient equipment operation and requires adherence to strict process procedures and technical specifications. Due to the unique structure of a grate ball mill, the liner installation process differs significantly from that of a conventional ball mill, primarily in the selection of liner type and installation sequence.

Pre-Installation Preparation and Liner Selection

Before installation, thoroughly clean the inner wall of the cylinder of any residual material and old liner fragments, and inspect the bolt holes for any casting burrs. Grate ball mills typically use annular groove liners or graded liners. These liners have arc-shaped grooves cast on the working surface, creating a circular graded structure upon installation, effectively enhancing the grading of the grinding media. For the first chamber at the feed end, a stepped liner is recommended, with the thin end aligned with the mill's rotational direction to enhance material lifting capacity. The back of the liner should be coated with a 1:2 cement mortar layer to enhance anchoring and cushion impact loads.

Staged Installation Process

The installation sequence follows the principle of "end cap first, then the shell": The end cap sector liner is installed starting from the bottom. After each liner is in place, bolt it immediately but do not tighten it yet. After half a circle of liner is installed and the shell is rotated 180°, the remaining half circle of liner is installed. Shell liner installation requires the use of special wedges. First, secure the lower wedge liner as a reference, then install it in four sections. After each quarter circle of liner is laid, rotate the shell 90° and temporarily secure it, ultimately forming a complete annular liner structure. The gap between adjacent liner plates is kept within 9mm, and gaps are filled with cement mortar to ensure overall rigidity.

Key Quality Inspection Points

After installation, the liner bolts must be inspected for tightness. All bolts must be equipped with dust-proof washers to prevent slurry leakage. Key parameters such as the stepped liner orientation and the taper of the bulkhead grate holes must be strictly verified against the design drawings. Cement mortar needs to be cured for 72 hours to reach full strength before it can be used for trial operation. During the trial operation, bolts should be regularly tightened using a torque wrench. Modern large-scale grate ball mill liner installation has introduced 3D laser positioning technology, which can control the installation accuracy error within ±2mm, significantly improving the equipment's operational stability.