Innovative new liner bolts can be seated more securely, prolonging equipment life
Within every ore grinding mill is a slurry that is essential to its processes. However, unconstrained, this mix of water and grit becomes the enemy of the very mill designed to hold it.
When bolts are not properly tensioned, mill liners become loose, and the slurry works its way into the bolt pocket. Eventually, the abrasive slurry leaching into the bolt pocket can result in bolt erosion, causing premature failure of both the bolts and the mill shell.
The problem with typical liner bolts is their geometry.
In conventional liners, the oval radius of the bolt is 1/8-inch per side smaller than the oval radius of the liner. The resulting angularity deviation between the liner bolt pocket and bolt creates two high-stress points of contact. This poor interface becomes an issue the moment the mill goes into service, eventually causing premature failure that can require a total shutdown in order to tighten loose bolts or replace broken liners.
Valley Forge & Bolt has developed a liner bolt innovation to improve the reliability of mill liners and liner bolts in ore grinding mill applications. The Sealing Mill Liner Bolt is designed with a polymer sealing ring that conforms to the liner bolt pocket, eliminating gaps and stress points.
“The head shape with the seal conforms to the liner pocket for better fit, so the bolts only need to be re-torqued once,” said Brooks. “The seals also help absorb heavy impacts and reduce the bolts’ chances to loosen.”
The Sealing Mill Liner Bolts produce effective sealing of the bolt to liner pocket throughout the full range of bolt capacity, including during very low loading conditions. Sealing Mill Liner Bolts, as well as the company’s companion product, Sealing Mill Ridgeback® Liner Bolts, hold liners more securely than conventional liner bolts.
“Both the Sealing Mill Liner Bolts’ and Sealing Mill Ridgeback® Bolts’ heads increase contact surface by conforming to the shape of the tapered surface of the pocket. This eliminates points of stress and, with that, problems common to ore grinding mills,” said Brooks. “It gives mines an economical way to maximize the life of their bolts and help prevent expensive unplanned shutdowns.”
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