Screening media solutions are small and low-cost wear parts when compared with major equipment in the mining and mineral processing industry. Due to their size and individual cost, these panels are often taken for granted even though poorly performing screen media can result in the loss of production, increased maintenance, downtime and poor product quality.
Screening media panels are therefore a critical part of mineral and aggregate processing as they help separate the desired particles from the unwanted ones. The screening process ensures that only the valuable particles are further processed, which increases efficiency and reduces operational costs.
Choosing the appropriate screening media therefore impacts the quality of the final product and has a significant bearing on the operation’s bottom line. Given the wide pool of screen media solutions to choose from – ranging from rubber and woven wire to wedge wire and polyurethane – there are various important factors that influence the choice of screen media to ensure the right solution for the right application.
“Screen media panels are critical in the overall processing equation. Wrong panel selection can be detrimental, leading to common enemies of efficient screening such as pegging and blinding, which in turn lead to reduced throughput and poor screening efficiency,” says Currie.
Factors to consider
Commenting on some key factors that affect screen media selection, Currie highlights that one of the principal considerations in any buying decision must be the support from the screening media supplier. It is important to consider the supplier’s technical support, manufacturing support and service support capabilities.
As a leading supplier of mineral processing equipment, FLS has many years of experience with the advantages and limitations of each type of screening medium, allowing it to provide ideal recommendations that are as customised to each operation’s processes. Every mine needs screen media solutions that are configured exactly for the specific challenges faced at that particular operation.
In addition, FLS provides screen media optimisation services and field trials as part of a service to provide tailored recommendations for panel type, size, aperture size and shape, position, motion and other important parameters.
On the technical front, one of the important factors is material characteristics. This includes the type of material being processed, size distribution, shape of material, moisture content, weight and density, abrasiveness, corrosiveness, stickiness and temperature, amongst others.
“Given the wide array of screen media panels and material options available, a determination of the ideal screen arrangement must consider numerous operation and material characteristics. If this is not done, one may be left with a poorly performing screen,” says Currie. “For example, if the material is abrasive, a more wear-resistant screening medium would be ideal.”
In addition, operation characteristics such as application and process, capacity required, feed rate and percentage of feed being recirculated have a big influence on the choice of screening media. The chosen screen panels should have the capacity to handle the required feed rate and throughput without causing excessive wear or damage to the screen itself.
“Equally important is the choice of a screen medium based on its ability to efficiently separate the desired material from the unwanted material,” says Currie. “Informed by the application and process type, operations should choose the screening media type that gives them the longest wear life possible. This not only increases screening efficiency and productivity, but also reduces waste and operational costs.”
New era
Speaking of long wear life, FLS is launching its NexGen polyurethane, a heavy duty and hard-wearing screen panel for large particle applications. Combining physical properties of rubber and polyurethane elastomers, the NexGen has better wear-resistance in highly abrasive applications where rubber and traditional polyurethane panels generally struggle.
“The new NexGen polyurethane material screen panel is ideally suited for early stage screens and trommels where there is generally high abrasion. Due to its extremely durable properties, it lasts longer than rubber or standard polyurethane in those high-impact applications. In some instances, it has been proven to offer double the screen panel wear life of rubber in these high-abrasion applications,” says Currie.
One of the major benefits of the long wear life is the reduction of costs. Frequent screen panel replacement leads to high maintenance and opportunity cost, whilst also lowering equipment productivity. In addition, regular replacement means that screen maintenance personnel have to spend an incredible amount of time on the screen changing panels, increasing safety risk in the process.
“With increased wear life also comes a significant reduction in waste, not just in the material itself, but also in the supply chain. Less frequent panel changes mean that there is less energy used, less transport required and less stock needed, which in turn is a huge sustainability tick for our customers,” says Currie.
With screening panels, he adds, screening efficiency is a very big factor. “Whenever we design our screens, we target at least 95% screening efficiency. With the premium material that we have used in designing the NexGen polyurethane panels, we are able to run a smaller ligament, which can give us more open area. A higher percentage of open area in screening panels improves screening efficiency and material throughput. This is because it gives particles more opportunities to pass through the screen,” says Currie.
Case studies
The NexGen polyurethane material screen panel, which made its official debut at Electra Mining Africa 2024, comes to market on the back of a nearly three-year testing regime across commodities. A case in point was at a major iron ore mine in the Northern Cape, South Africa, where the NexGen polyurethane material significantly increased wear life.
The mine, explains Currie, conducted a multi-supplier wear optimisation study on its vibrating screen panels. Along with several other manufacturers, FLS supplied a full deck of its most suitable wear material. The company’s premium NexGen polyurethane panels were installed side-by-side with multiple different options, including standard thermoplastic polyurethane (TPU) injection moulded panels, injection moulded rubber and other open cast polyurethane options. The application experienced high-wear rates and the aim was to improve panel wear life to increase cost efficiency and availability, while decreasing panel maintenance costs.
The panels were installed on a double-deck scalping screen situated in the mine’s beneficiation plant. A competitor’s injection moulded panels were removed from operation and scrapped due to high wear just two weeks into the trial, as were other injection moulded panels from other suppliers after one month of installation. The pattern was repeated several times and all competitor panels were replaced in the early stages of the trial.
In comparison, the NexGen polyurethane screen panel proved to be highly durable and cost-effective, lasting six months, with a wear rate significantly outperforming other competitor materials. No panel failures were experienced and only normal wear and tear was seen on the polyurethane borders. The tonnage passed over the screen was 1,1-million tonnes of -80 mm iron ore material, with a total of 2 622 run hours.
Elsewhere, FLS recommended the NexGen to a coal mine in Australia, which was looking to increase the productivity of its vibrating screens and decrease its maintenance costs. Historically, FLS had performed a lengthy optimisation process and recommended standard modular polyurethane and wedge wire screen media for the plant. The polyurethane panels had a wear life ranging from three to six weeks of continuous operation and management was looking to reduce the total cost of operation.
FLS screen media experts analysed the situation and recommended the NexGen polyurethane screen panels, which were installed across the feed and intermediate section of a drain and rinse screen to assess the media performance. The vibrating screen was run for a cumulative utilisation period of three weeks before the first inspection shutdown.
The test went on for another five weeks to monitor the wear rates and ligament loss on the trial panels. The total duration of the trial was about 18 weeks and the test panels were replaced with new panels at least once during this period to gauge repeatability. In fact, the new panels survived for ten weeks, compared to the five weeks of most of the standard polyurethane panels used. Doubling the screen media wear life lowered maintenance time and media costs, while increasing safety and productivity.
Local manufacture
Currie tells Quarrying Africa that following the conclusion of the test period, the manufacture of the NexGen polyurethane screen panels commenced at FLS’s Delmas, Mpumalanga, South Africa facility. At the time of writing, the company was busy revamping the facility to bolster local screen media manufacturing capacity.
“We have also invested in a new machine specifically for the manufacture of NexGen polyurethane screen panels as well as additional moulding stations. We are focused on boosting our local manufacture within the region to allow us to respond quickly to our customers’ needs,” concludes Currie.
