Among other countries, minerals processing equipment manufacturer Multotec has supplied scientifically engineered rubber mill and scrubber liners to mining operations in Botswana.

These liners have been deployed for various customers – including in the US, Zambia, Côte d’Ivoire, Botswana, Namibia and South Africa – and have been deployed in the diamond, platinum-group metals, iron-ore, zinc, lead, copper, gold and coal processing industries.

The liners are developed using advanced computer simulations to ensure optimal configuration for efficient performance and have been implemented in mills, chutes and plants.

Further, Multotec has demonstrated the power of 3D scanning technology during a mill liner installation at a gold processing facility in Alaska, in the US, marking the first time the company has used this technology to support an installation. This approach enabled precise fitting and optimised liner performance.

“In this case, the client supplied us with 3D scans of the mills, allowing us to design the liners remotely, creating shorter turnaround times and greater accuracy. The liners were then designed, manufactured and fitted perfectly in the mill,” says Multotec senior mechanical engineer Ralph Hollenstein.

Multotec places a strong emphasis on ensuring that its liner design is optimal for the life of the products and their performance.

The company also conducts condition monitoring on installed liners to ensure enhanced uptime by facilitating proactive maintenance.

Scientific Design Approach

Multotec adopts a scientific approach in its mill liner design, focusing on process flow and charge trajectories to enhance both the performance and durability of the liners.

By using advanced modelling techniques, Multotec provides mill operators with precise guidelines to keep a mill operating in its optimal regime.

As part of the design process, Multotec uses the discrete element method (DEM) to predict the behaviour of the mill charge, comprising ore and grinding media, and the performance of the mill throughout the lifespan of the lifter.

DEM is also employed to predict liner wear and the evolution of the liner profile over time.

“This technology enables us to simulate wear on the liners and track how the material interacts with the changing liner profile as it wears down. From these wear simulations, we can identify areas of high wear within the mill and use this information to optimise the liner design, adding material in high-wear zones while reducing material in areas that don’t require as much reinforcement,” explains Hollenstein.

Multotec’s liner optimisation system integrates advanced tools, including the simulation tool MillTraj, DEM for advanced multiparticle simulation, and 3D scanning technology for mill liners. These tools enable precise condition monitoring, comprehensive management and effective liner design for enhanced performance.

MillTraj focuses on the trajectory modelling of grinding mill liners and lifters, with key applications including simulating lifter designs and configurations to understand their impact on the motion of the grinding charge (balls and material) inside mills and optimising mill liner profiles to improve grinding efficiency and reduce wear.

MillTraj also provides insights into the trajectory of grinding media to ensure optimal energy transfer and to avoid damaging the mill shell.

Further, Rocky DEM offers extensive capabilities for simulating particle dynamics across various industrial processes. Its functionalities include simulating particle dynamics such as collisions, breakage and flow for a range of material types.

Rocky DEM also enables modelling and optimising equipment such as mills, crushers, conveyors and screens to improve performance; while also conducting wear analysis to predict and mitigate component degradation, ensuring longer equipment life and the ability to handle complex particle shapes, providing more accurate simulations for irregular materials.

Advanced 3D Laser Scanning

Multotec employs advanced 3D laser scanning technology to accurately assess mill liner wear – a data-driven approach that enables the company to create precise liner replacement schedules and estimate the remaining lifespan of the mill liners, ensuring efficient relining operations.

“The 3D scanning is a service we provide to our customers for condition monitoring in various countries and across multiple commodities. In some cases, customers use similar scanners to perform the scans themselves. They then send us the scan data, and we then interpret the results and generate detailed reports,” says Hollenstein.

Multotec focuses on the entire comminution circuit as a whole rather than just the mill liner design, which ties in with conducting plant audits to assist customers to optimise their efficiency.

“When we work with customers . . . we take a more holistic approach by helping them to assess and identify any problem areas and work with the entire plant/milling circuit to resolve those issues,” he says.