Pilot Crushtec International, Metso’s southern Africa distributor, has a light on the capabilities of the Lokotrack® ST2.8 scalpers, detailing just how they have improved performance at an alluvial ore operation in Zimbabwe.

Last year, the operator purchased three ST2.8 scalpers from its long-term supplier as it looked for a reliable and cost effective solution for mining under testing conditions.

Pilot Crushtec International CEO, Sandro Scherf, described the nature of the conditions in which the scalpers operate and how they are uniquely equipped to cope in tough working environments.

“Ore deposits are found in thick clay above the bedrock which varies in depths of between one-to-two-metres beneath the surface. Complete bush clearing is not an option, so surface and subsoil vegetation provide their own challenges, not to mention a rainy season and flash floods.”

This is where this scalper comes into its own, according to Scherf.

“An aggressive screen box with a 15mm throw (50% greater than any other comparative product) substantially reduces the chances of blinding and pegging,” he said. The scalper can be fine-tuned to suit a variety of soil and surface conditions, including sand applications.

There are also other significant benefits from the design.

“With such a powerful throw, the box can be run at a relatively low 750 revolutions per minute. This is not only beneficial to the scalping process, but has the capacity to increase the operational life of the machine as there is less wear on the screen box,” he said.

Current output is more than 100,300 tonnes per hour – well within expectations, according to Pilot Crushtec – and is assisted by the tines (fingers) mounted on the bottom deck. These serve to maintain production levels, even under the wettest conditions, the company said.

Even though the material is abrasive, there has been no need to change the tines (bottom deck) or bofar bars (top deck) after 12 months, Pilot Crushtec said.

Another important feature of the Lokotrack range is its two-way split option. Should only two conveyors out of three be required for a specific application, the third conveyor can be removed, instantly saving fuel, wear and tear and – from a safety perspective – removing the possibility of unnecessary entanglement with non-productive moving parts.

The scrapers have proven so effective the customer has since doubled the fleet from three to six Lokotrack ST2.8s.

The Lokotrack ST2.8 scalpers come with a 4,866mm x 1,524mm screen, a 4.5m³ feed hopper and CAT® 75kW engine. They weigh 26,000kg apiece, with the design incorporating easy access and working space to essential areas, including the engine compartment and screen box. The walkways, apron feeder cassette and conveyors are all manufactured from galvanised steel.

In addition to extracting ore, the customer operates a smelting operation on site where Pilot Crushtec International is supplying a Pilot Modular crushing and screening plant to process slag and waste material that contains pieces of metal, and increase material recovery.

“The crushing process enables the miner to recover the metal fragments which add significant value to the operation as a whole,” Pilot Crushtec said.

The products include a Pilot Modular GFH560 grizzly hopper, Pilot Modular BR0605 impact crusher, Pilot Modular DD2412 double-deck screen, four MC13600 conveyors and MC1000 belt magnet.