Manganese Mine significantly improves screening efficiency with Metso's modular rubber screen media

A large manganese ore processing plant with an annual capacity of 1.5 million tons employs a three-stage crushing circuit with closed-loop screening, using Metso crushers throughout the process. During production, screen blinding was particularly severe, reaching approximately 50%. The problem worsened during the rainy season when material adhesion became more pronounced, resulting in screening efficiency of only 60%-70% and high circulating loads. Additionally, the polyurethane screen media previously used had a short lifespan, requiring replacement every 2-3 months on average. This led to high screen consumption and labor costs, while also increasing safety risks associated with frequent maintenance.

Starting with the lower deck: Proof through performance

In 2016, the mine first encountered Metso's vibrating screen wear protection solutions and learned about the advantages of Metso's modular rubber screen media. As a trial, mine management followed Metso's recommendation to test the performance of the modular rubber panels on the check screening vibrating screen after secondary crushing—the machine with the highest throughput—and signed the first supply contract for the lower deck panels. In this three-stage closed-circuit process, the check screening equipment after secondary crushing consists of one 2160 double-deck vibrating screen fitted with domestic polyurethane screen media.

The upper deck panels had 25x25mm apertures with a blinding rate of 50%-60%, while the lower deck panels had 10x20mm apertures with a blinding rate of 40%-50%. Due to low screening efficiency, the return material contained a high proportion of -10mm particles, which not only affected the performance and crushing effect of the tertiary crusher but also reduced the service life of the crusher's key components and liners. Under these conditions, the modified lower deck panels needed to first address the blinding and material adhesion issues to improve screening efficiency. Second, they needed to reduce the product size of the undersize material and lower the feed size to the mill. At the same time, the service life of the panels had to be extended to achieve the fundamental goal of reducing production costs.

To address this, Metso provided a solution using Trellex® 300LS modular rubber screen media. The 300LS panels combine injection-molded modules, molded apertures, and highly elastic natural rubber material to deliver high effective open area percentage and consistent material performance across the entire screening surface, ensuring efficient screening while preventing blinding and material adhesion. The T40 high-elasticity rubber material also allows effective forward and reverse rotation switching, not only enhancing wear resistance but also improving the passage of fine particles.

In October 2016, the first batch of Metso Trellex® 300LS modular rubber screen media was installed and put into operation. "Replacing a Metso modular screen panel takes only 3 minutes. In contrast, replacing a polyurethane panel previously required two workers and 4 hours. In the future, we'll only need to replace locally worn modules rather than the entire screen deck. This dramatically reduces our downtime and lowers maintenance costs," the mine manager noted.

After nearly 11 months of operation, the Trellex® 300LS panels have performed reliably, with no replacements needed so far. Now, the lower deck panels experience almost no blinding or material adhesion, and screening efficiency has improved by approximately 15%. More importantly, both screening throughput and accuracy have increased. The -10mm content in the return material (oversize) has been significantly reduced, and the final product size of the undersize material has decreased from 10mm to 8.5mm, improving grinding efficiency in the ball mill.

Upper deck follows, further enhancing performance

Impressed by the outstanding performance of Metso’s modular rubber screen media, the mine was eager to proceed with the upper deck modification, signing a second supply contract with Metso. In May 2017, the second batch of Trellex® 300LS modular panels was installed on the upper deck. Unlike the lower deck, the upper deck used T60 high-strength, high-wear-resistant rubber panels, which more effectively withstand the impact of harder and coarser feed material, significantly extending panel service life. At the same time, the natural rubber’s unique elasticity prevents blinding and material adhesion, increasing the upper deck’s effective open area to 35%, further reducing circulating loads and improving screening efficiency to over 90%.

The comparison below shows the upper deck before and after modification: the left image shows severe blinding on the polyurethane panels, while the right image shows almost no blinding on Metso’s T60 rubber panels.

Continuous collaboration, ongoing development

"Although the initial investment cost was higher, the actual benefits delivered by Metso’s panels have been far more significant. This investment has absolutely been worth it," said the mine manager. In September 2017, under a third supply contract, the mine also replaced the pre-screening vibrating screen media with Metso 300LS modular rubber panels. This maximized screening efficiency across the entire operation, driving the highest possible production benefits for the entire crushing and screening line.

Note: Metso Outotec was officially established on July 1, 2020. This article was prepared prior to that date under the former company name.