MechChem Africa May-June 2021

New composite liners for large sag mills As the mining industry moves to larger semi-autogenous (SAG) mills for higher productivity, Multotec is developing and applying innovative liner designs to optimise performance and wear life. Sam Hearn, Multotec’s global sales and business development manager, talks about the development. M ultotec is developing and ap- plying innovative liner designs to optimise liner performance, mill efficiency and liner wear life for higher productivity semi-autogenous grinding (SAG) mills. Hearn, global sales andbusiness development manager, Multotec. Hearn highlights howMultotec usesDEM software to simulate the interactionbetween themill charge and the liners, and to evaluate liner profile over the life of the liner.

us to accurately model the performance and wear of our mill liners. This includes predict- ing the liners’ wear life, to avoid unscheduled downtime and to extend the time between replacements.” Emphasising that no twomill liner applica- tions are identical, Hearn says that this simu- lation can guide very specific refinements in the liner design for each customer. Adetailed understanding of the operating conditions is vital to ensure that the final solution delivers optimal results. He notes that the traditional use of steel liners in large SAGmills presents a number of challenges. For instance, there may be bend- ing stress inside the steel liner due to inexact fitting on the mill’s curved surface, and the higher rigidity of steel compared to rubber makes it less than optimal for absorbing the energy of the rock material inside the mill. “This is where our composite liners come into their own,” he says. “These innovative lin- ers combine the impact resistance of Hardox 500 steel inserts and the absorption capacity of our specially formulated wear-resistant rubber compound. Through the simulation, the structural integrity of the liners can be verified, while the geometric layout of the liners can be optimised.” The composite liners are locally manu- factured at Multotec’s extensive facility in Spartan, Gauteng, in an advanced process that includes its unique submerged cutting technique to preserve the surface hardness of the liners. “We combine our innovative design capacity with the latest tooling capability and production technology for large-scale manufacture,” says Hearn. Following the design and manufacturing process, Multotec conducts field trials to compare to the relative performance of composite and steel liners. “We are confident that, given our product improvement processes and simulation abil- ity, the wear life of our liners will achieve and often exceed expectations,” he says. www.multotec.com

“Our strong analysis capabilities in the design process – including discrete element analysis (DEM) and finite element analysis (FEA) – allow us to continuously evolve the application of our composite liners,” says Sam

“DEM analysis considers a range of vari- ables such as the ore’s bond work index, its specific gravity, the size of the grindingmedia, themill speed and the slurry density,” he says. “Sophisticated simulation capability allows

Multotec uses DEM software to simulate the interaction between the mill charge and liners; and to evaluate liner profile over the life of the liner.

Multotec is developing and applying innovative liner designs to optimise performance and wear life in large high-productivity SAG mills.

24 ¦ MechChem Africa • May-June 2021