THE requisite levels of support are critical to ensure optimal performance of a mill circuit, as is the correct selection of the mill circuit pump. Attention to both these aspects will facilitate cost efficient and optimum operation of the circuit. “However,” cautions general manager pump products at Weir Minerals Africa, Marnus Koorts, “each is as important as the other.”
Weir Minerals Africa has a focus on delivering reliable solutions to customers that will provide the required performance while facilitating the lowest total cost of ownership. Koorts says, “This has seen the Warman mill circuit pump become the preferred choice across numerous plants in Africa.”
Commenting further, Koorts says that the requisite support level often requires significant investment by the pump’s original equipment manufacturer and means having the correct parts readily available on or close to a customer site.
“This should be backed by the technical competency required to keep the pump running,” he says.
“What is essential to understand is that a mill circuit pump is not an off-the-shelf solution. Mill circuit pumps are engineered to provide optimum performance under the arduous operating conditions on individual customer sites and need to be configured to achieve the requisite hours between scheduled maintenance shutdowns,” he says.
“Close collaboration with customers and a comprehensive understanding of the plant’s operating parameters are crucial to ensure the solution provided will meet the operational requirements,” he says.
One of the primary considerations when it comes to mill circuit pumps is the ability to handle large particles and high flow rates. Wear and tear in these pumps are directly proportional to the size of particles passing through, necessitating specific construction materials and design features.
Koorts says a major differentiator is that the Warman mill circuit pumps are physically larger for the same flow rate, reducing wear by operating at lower speeds.
This strategy has paid major dividends for customers and is one of the reasons for the popularity of the Warman brand in Africa.
“Another crucial aspect is the engineering of the hydraulic chamber, which enhances wear resistance and increases efficiency. This is achieved through the unique design of the vanelet which significantly minimises unwanted turbulence and reduces both wear and energy consumption,” he explains.
The reduced energy consumption not only contributes to the bottom line but also ensures a relatively short payback period for the capital investment.
Rubber liners and alternatives
“Material selection for mill pumps often sparks debate, but experience in the field has shown the undeniable benefits of rubber liners,” Koorts says. “Rubber liners extend wear life, handle impact associated with large particles, and are more cost effective and easier to handle.” Recognising the advantages, Weir Minerals has made substantial investments in rubber production facilities to manufacture these liners for customers.
However, when applications demand it, a wide range of metal options are also available. Koorts says good examples would be Hyperchrome A61 alloy which is particularly good for fine particle wear that’s often seen between the impeller and the throat bush, and Ultrachrome A05 alloy which would be used for the shell as it works well with general coarse particle abrasion.
“If the wear characteristics are higher than anticipated in an application, this is where the interchangeability of components plays an important role. Most of our designs allow for interchangeability between metal and rubber components based on specific wear characteristics.”
Koorts also points out that over time, changes in the slurry composition or ore grade processed by a plant can affect pump efficiency and increase wear.
He says that Warman mill circuit pumps offer standard and low flow liner capabilities, enabling operators to adjust the flow rate as needed without compromising the original installation.
Retrofitment
Retrofit optimisations are increasingly common as mineral processing plants evolve and seek to reduce their total cost of ownership. Weir Minerals Africa has made substantial investments in an engineering team capable of seamlessly integrating the Warman mill circuit pumps into existing installations, and they work closely with engineering, procurement, construction management (EPCM) contractor, and project houses ensuring all stakeholders can make an informed decision regarding pump selection and configuration.
