Extensive research and development, coupled with interfacing with customers from its group global footprint, has allowed Weir Minerals Africa to produce appropriate compounds for its locally manufactured rubber and composite mill liners. It is recognised that in minerals communition certain or bodies have a hardness close to or even more than the metal linings in mills, and it is essential to turn to materials such as rubber. This material as a lining provides an economic advantage and lower total cost of ownership as well as increased plant availability, the company says.It is necessary to have an intimate understanding of the application requirements for mills and scrubbers and be able to provide a fit-for-purpose solution which takes all factors into account. “These include efficiency, throughput rate, particle size as well as the ultimate grind,” Grant Stewart, Vulco® mill liner Product Manager at Weir Minerals Africa, says.
“Rubber is engineered to conform to the mill’s internal geometry to form an effective seal that prevents slurry from racing under the liner, thus virtually eliminating erosion of the mill shell. We are able to achieve this because we have the technical expertise and skills available through our global group infrastructure. We also have an extensive reference base in South Africa, USA, Australia and South America that we can draw on.”
Stewart says that interfacing with customers throughout the world results in a sharing of application information and means that rubber compounds are continuously being improved.
Weir Minerals Africa takes a holistic approach towards the design and optimisation of a milling duty, ensuring that the customer’s needs and requirements are fully catered for. “A complete analysis of each milling duty is conducted, with factors such as mill dimensions, mill speed, mill power, ore type, feed top size, feed size distribution, throughput, charge volume and makeup, density and product size being thoroughly reviewed,” Stewart says.
“Our linings are engineered to meet the product handling capabilities at the specific site and all Vulco® mill linings are designed to purpose fit the mill or scrubber. This allows easy and quick installation and ensures minimum downtime as well as optimising grinding circuit availability,” he says.
Specially formulated rubber compounds and designs improve wear and reduce downtime, and customised, engineered profiles based on current design data to fit specific requirements enhance operating economy in most grinding processes.
“We use state of the art computer modelling software to produce the optimum liner for a given application,” Stewart says. “Plate thickness, height and width of lifter bars, mill capacity and power draw are all taken into consideration during the design phases.
“Without a doubt technical capability is important in the selection of the most appropriate mill liner configuration and because no two applications are the same, we can offer a wide range of custom designed rubber and metal cap lining systems for ball, rod, SAG and FAG mills and scrubbers. We also supply other wear resistant products, such as ceramic/rubber wear plates, trunnion liners and custom-made plates for impact and abrasion protection,” Stewart says.
Rubber liners offer the significant advantage of lowering noise levels by as much as 10 dB, thus making working conditions healthier and safer. “In areas where noise pollution has a serious impact on the environment rubber or metal cap linings are the only choice,” Stewart adds.
Rubber linings are also up to 80% lighter than steel and are therefore far easier and quicker to install, resulting in reduced installation costs. “In addition, their special formulation means that they have maximised tear resistance and resilience which then results in increased longevity and reduced downtime,” Stewart says.
He adds that because of the reduced load on the bearings there is less stress on the mill heads. “By using our low-profile T track attachment system one reduces the need for frequent inspections, repair, and bolt tightening. These factors, coupled with the seal created when the rubber conforms to the mill’s internal surface to prevent leakage and slurry erosion of the mill shell, equates to faster changeouts and ultimately, greater mill availability.”