Improving production throughput with innovative screen media

FLSmidth is in the final stages of a trial study to test a new hybrid poly wire modular panel in a screening process. The new type of modular panel is being used to solve maintenance and production issues that arose from previous types of screen media being used in the silica operation. The trial has been carried out in conjunction with Rietvlei Silica Mine, a Glencore Merafe Venture Operation, situated near the town of Rustenburg in the Northwest Province of South Africa.

The vibrating screens in the trial were originally designed to use woven wire screens. The screens are 5x10’ double deck units used as secondary screens in the production of silica sand. The original design used two of the woven wire screens per deck. The woven wire had to be replaced due to localized wear patterns that had created holes in multiple areas of the screen surface. The handling and installation of new woven wire screen media posed safety issues. The plant decided at that point to replace the woven wire with modular polyurethane panels.

The change to the modular polyurethane panels resolved the safety and replacement issues, but decreased production to a maximum of 1,500 tonnes per module, per shift due to the reduction in effective "open area percentage" (Oa%) with the system being used.

The mine approached FLSmidth's screen media experts looking for a way to change to a safe modular system that would increase the system's throughput.

After analyzing the process and vibrating equipment, FLSmidth made recommendations concerning the setup of the feed to the equipment as well as the use of a new hybrid poly wire modular panel on the bottom deck. Rietvlei Silica Mine agreed to both recommendations and the work began.

The poly wire modular panel is a standard 1x1’ panel that consists of a "flat top" woven wire screen (20.0 Ap x 7,1 Vibro Optimax wire) that is encased in polyurethane around the edges to enable it to be fixed to the frame using the standard "pin and sleeve" or "bolted pin system" fixing devices. The effective Oa% of the poly wire modular panel is 48%, which is comparable to the effective Oa% of a standard woven wire screen when installed.

The trial was tracked and recorded by FLSmidth's Screen Media Technical Manager, Jannie Engelbrecht, with the assistance of the mine's Jacques Labuschagne.

Mr. Labuschagne commented on the improvements, saying, “We struggled to put through 1,500 tonnes per shift while not sacrificing on the quality of our product with polyurethane panels. With the poly wire panels we were able to increase our production to above 2,000 tonnes per shift while accommodating more fines and were still able to produce a quality product.”

This equated to more than a 33% increase in production, which means an additional 10,000 tonnes per month.

A final goal of life expectancy has still to be finalized; currently, the poly wire panels wear rate indicates that the life will be comparable with the previous modular polyurethane panels supplied by a competitor.

The trial with the poly wire panel in a silica operation has been successful in reaching the initial goals of the study by increasing production throughputs whilst offering safe maintenance solutions. This innovative solution has resulted in a happy and satisfied customer and may open other partnership opportunities between FLSmidth and the Glencore Group in the future.

CONTACT: Ian Hewat

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