Traditionally, lining systems in grinding mills have been composed of metal castings, but inherent problems exist in some all-metal systems; therefore, rubber composite lining systems have been introduced by pumps and rubber lining specialist Weir Minerals Africa as an alternative to grinding mill applications.
“Our Vulco composite lining systems range combines rubber and metal. The resilience and shock-absorbing properties of rubber improve the wear properties of metals,” says Weir Minerals mill lining systems product manager Grant Stewart.
He explains that the inherent characteristics of Vulco rubber compounds are elasticity, high tensile strength and corrosion resistance, which make rubber the preferred mill-lining material, as opposed to steel. Rubber’s elasticity enables it to be restored to its original profile after impact and high tensile strength prevents tearing.
“All-metal liners are prone to cracking as they become thinner, owing to wear, which causes unscheduled shutdowns and replacements and, thus, unnecessary additional costs for the customer. During maintenance, cracked liners may dislodge and fall inside the mill, which could endanger workers,” Stewart points out.
He says the composite lining systems use the resilience of rubber to cushion the impact of the materials in the mill on the metal elements, while the base-plate construction and vulcanised rubber sections reduce and control cracking, even when the liner has worn quite thin.
Compared with conventional metal liners, Vulco composite lining systems can be replaced in a shorter time, saving up to 50% on downtime, which increases production. The cost savings resulting from reduced downtime and improved productivity make the composite lining system particularly attractive in grinding mill applications.
As a result of demand and foundry capacity, the lead time for cast liners can be as long as 50 weeks, while the lead time for composite systems can be less than half of that.
“About 95% of the mills to which we have supplied the composite liner attest to its success in a host of applications. In some instances, the life span of the grinding mill increased from eight months to twelve months, which equates to a 25% increase in operating life,” he says.
Technological innovation is one of Weir Group’s key focus areas, resulting in extensive investment in ongoing product development. As part of this global family, Weir Minerals Africa regularly draws on ideas and new skills within the group to ensure that local cus- tomers have access to good- quality products and extensive knowledge and experience.
“We seek not only to improve our technology, but also to focus on the development of our personnel and key skills.
“We have a good young team and will continue to invest in their development to supplement their theoretical competence with practical exposure to difficult applications across various commodities. Although new graduates are academically qualified, in my experience, this business is 85% science and 15% experience, which we aim to build as quickly as possible through our focused approach to learning,”says Stewart.