Mining Mirror May 2017 - Page 27

Manufacturers create engineered screen media from several different types of material, such as polyurethane, rubber, and perforated plates. mounted is now also compromised,” informs Mayhew-Ridgers. “You should also consider the alignment of weights on exciter gearboxes or multiple unbalanced motors if you install them next to each other,” he adds. The alignment of weights is crucial. When the unbalanced motors are connected by some kind of coupling, the unbalanced weights (of the unbalanced motors) need to hang perfectly next to each other in a vertical line. The same applies to exciter gearboxes where the weights on the opposing shafts should be symmetrical relative to a perpendicular plane through the middle of the length of the gearbox. If the weights are not properly aligned, it ultimately results in bolts breaking on the side plates while deck beams might crack. “The two factors that most often cause a vibrating screen to twist is an uneven floor level and non-aligned exciter drives; those are the first causes to look for when the vibrating screen shows symptoms of going off plane,” advises Mayhew- Ridgers. At the interface According to Derrick Alston, director of Kwatani, the screen panel (screening media) and vibrating screen interface are extremely important. A big problem though, according to Alston, is that the screen panels and the vibrating screens are manufactured by different companies. Kwatani is the original equipment manufacturer (OEM) that supplies the vibrating screen. Once the screen has been installed on site, the screen panel suppliers want to fit their products onto the decks, not always considering whether it is the best option for the screening machine. If the panels are replaced over time Mining in focus and do not fit properly, or the wear underneath the screen deck is not monitored, it could compromise and significantly reduce the lifespan of the screen. Alston believes both functions — the replacement of screening panels and the maintenance on the vibrating screen or overall wellbeing of the vibrating screen — should be managed by the same company, preferably the supplier of the vibrating screen. Alston says the Kwatani vibrating screening and feeding machines are robust. The life of such machines is normally five to 10 years (depending, of course, on the type of material processed), before it can be sent in for refurbishment at minimum cost. “However, if properly maintained, there is no reason why vibrating machines cannot last up to 15 or 20 years,” he adds. MAY 2017 MINING MIRROR [25]