For a select few, a “screen test” could lead to fame and fortune on the big screen. Although most of us haven’t made it to that prestigious status, there are more applicable screen tests on which we get to play a part within the mining industry. Recently, a series of screen panel trials of the FLSmidth screen media range was undertaken, and we’re proud to say that they delivered many outstanding performances.
The trials were carried out at a number of mine sites in Australia to assess screen performance across a range of ores and screening systems. Tested ore types included bauxite, diamonds, gold, iron ore, lithium and nickel. Additionally, a number of the trials were used by the site managers as real-time comparison tests between the sites’ existing screen media and the FLSmidth product.
The trials generally had two primary goals:
- Improve wear life of the media
- Reduce the incidence of pegging
In all trials, the FLSmidth product exceeded expectations—and also delivered a number of additional benefits. Detailed by ore type, the following trial reports show the advantages of using FLSmidth screen media in these applications.
The primary targets of the bauxite trial were to improve the wear life of the installed deck and reduce the incidence and frequency of pegging. As a result of feed zone panels cracking due to load, the average wear life of the deck was 7–8 months. Improved wear life would also translate to improved deck efficiency and lower operating costs.
With the initial focus of working on improving the operation performance of the feed zone—the first 1200 mm of the deck—FLSmidth installed a series of standard PIPO® Two 500 micron aperture panels. The trial quickly progressed to a full-deck trial following the results achieved with the PIPO Two panels in the feed zone.
The result of the bauxite trial was an increase in deck wear life of around 225%, taking the longevity of the deck panels from an average of 7–8 months wear time to an incredible 18 months before deck replacement was necessary.
Blinding – Occurs when dirt, minerals and other fine or sticky materials adhere together and bridge across the apertures of the screen media blocking other materials from passing through.
Pegging – Happens when irregular materials can't pass through the screen apertures because they are of similar size to the screen media holes and may become lodged.
With a deserved reputation for hardness and aggressive wearing, diamonds present a challenge for virtually any processing equipment. The trial, on a wet classification deck, was initiated with three targets: improve wear life, improve screen efficiency, and reduce the operating cost of the deck.
The trial screen utilized 305x305 mm media with pin and leg—or pin and sleeve—fixings. Existing deck structures could be used without any modifications, which meant easy panel change-outs (between the existing screen and the FLSmidth product) and real-time performance comparisons.
At the start of the trial, the mean time between failures (MTBF) of the existing panels on the banana screen's top deck was around 6–7 weeks. The bottom deck and media recovery screens suffered from heavy pegging.
The FLSmidth panels on the top deck delivered a 50% increase in wear life MTBF. The unique FLSmidth XIF™ panels installed on the bottom deck experienced minimal pegging for their total service life.
The equipment at site was a standard 5x16 low-head gravity feed screen. Identifying the problems—increasing pegging and substantially reduced efficiency—was the easy part of the equation. Finding the best, most efficient and cost-effective solution for this gold application was more of a challenge. The goal was a non-pegging (or at least pegging-resistant) panel design that was compatible with the screen’s existing fastening system.
A site trial of the FLSmidth-designed patented XIF modular polyurethane screen panel was initiated. The existing system was duplicated for the trial to provide a real-time comparison in terms of pegging performance and wear resistance.
Installed at both the feed and discharge ends of the screen, the unique design of the XIF screen panel significantly reduced pegging and improved operational efficiency.
The first screen media trial in iron ore was a full-spectrum direct comparison trial of systems and fastening types with FLSmidth product compared against product from three direct competitors. The trial’s objective was to document which product would provide extended wear life and improved screen efficiency.
A combination of the PIPO Two and PIPO Three panel design and fastening systems was fitted in the screening equipment since these designs utilize the chevron pattern for its high-percentage open area, and have beneficial anti-pegging and de-blinding characteristics.
Upon completion of the first trial, the customer acknowledged that the FLSmidth product range was the only screen media to have met all the test criteria.
A second iron ore trial was initiated to target improved wear life of a banana screen deck, with rubber screens on the top deck and polyurethane on the bottom deck. The design of the screen support structures and fixing systems allowed for straight, like-for-like substitution on the top and bottom decks.
The FLSmidth rubber screen installed on the top deck lasted around 25% longer than the previously used media. The FLSmidth polyurethane panels fitted to the bottom deck lasted around 50% longer. As the open areas of the top and bottom decks were maintained, overall deck efficiency remained high.
The lithium site where we tested our screen media was using a mixture of 305x305 mm by 500 micron, 630 micron and 650 micron screens. The screens were of various thicknesses with either pin-and-sleeve or pin-and-leg fittings used for fine classification and media recovery. The target criteria for the lithium trial included de-pegging and extended wear life.
In what turned out to be a comprehensive assessment process, various screen designs were trialed, including conventional slots and XIF-style apertures. A range of performance characteristics for the media recovery floats and sinks, wet classification and the dewatering operations at the site were evaluated.
All FLSmidth panels that were trialed measured 305x305 mm of various thicknesses. A combination of standard slots and several iterations of 305x305 mm XIF panel designs—including different frames and different polymer types—were trialed depending on the application and function.
The de-pegging performance of the FLSmidth screens over the now-extended life of the deck significantly improved media recovery and moisture content at the discharge end.
At the nickel site, a wet classification double-deck screen (5 mm top deck and 2.5 mm bottom deck) was processing limonite (900 dtph + 1,000 tph water). A second double-deck screen was processing saprolite (6,000 dtph + 650 tph water). The criteria set for the nickel trial were to reduce cost, improve screen efficiency and to extend the MTBF.
A budget was set for screen panels for the two screening machines at the nickel site. Plant availability was running at around 70% with the screen circuits seen as an area for improvement.
The screen’s support structure limited our choice of media. FLSmidth’s professional service crew elected to trial the FLSmidth PIPO Two system panels, utilizing a combination of strengthened, staggered slots to improve top-deck wear along with high, open-area flexible XIF panels to reduce pegging and improve efficiency on the critical bottom deck.
The results included a 30% reduction in the screen panel budget, an increase in mechanical availability to 95%, and a correspondingly significant improvement in MTBF.
Each of these industry screen media trials were conducted in real time at working mine sites. In all cases, the various sites’ representatives acknowledged the improvements the FLSmidth screen media achieved in operational efficiency. In addition, they were each able to note the significant impact it made on improving their bottom line. These impressive results place FLSmidth screen media in the spotlight, and we expect to see this screen star coming soon to sites near you.
CONTACT: Shane McLoughli