Komatsu Australia has recently supplied two new 760 tonne PC8000-6 mining shovels, each powered by dual Tier 2-compliant Cummins QSK60 diesels, to Kalgoorlie's Super Pit in Western Australia.

28102011LatestMiningShovelsAtKalgoorliesSuperPit-(1).jpgThe new $17 million shovels join two older QSK60-powered PC8000-6 face shovels in the Super Pit. One has been in service since late 2003, the other since late 2005.

The Super Pit, Australia's highest-producing open pit gold mine, is the source of around 800,000 ounces of gold a year, requiring the moving of 89 million tonnes of gold-bearing ore and overburden a year in the Super Pit.

Kalgoorlie Consolidated Gold Mines (KCGM) manages the Super Pit operation for joint venture partners Newmont Australia and Barrick Gold of Australia.

High utilisation targets are set for the PC8000-6 face shovels, which are working in excess of 7000 hours a year and are subjected to a demanding maintenance regime.

"Any time a machine is down there is a flow-on effect to production targets," said Garry Giles, Komatsu project manager at KCGM.

"You can quickly have 10 to12 trucks banked up, and then these trucks have to be redeployed."

Garry manages Komatsu's shovel maintenance operation in the Super Pit, one that is based on Kaizen methodology, meaning 'change for the better' or 'continuous improvement'. It also has a strong safety culture with safety co-ordinator/leading hand servicemen Jeff Wynands recently being awarded a "safety champion" award by KGCM (see separate story).

To ensure the shovels meet the required level of availability, there is constant monitoring and critiquing of maintenance activities for improvement.

"There's a lot of pride in what we achieve here," said Garry. "We accept the fact there's no one else to blame but ourselves if we have a problem.

"Planned maintenance is the key in fact, over 75% of the maintenance we carry out on the shovels is planned maintenance, and that's world-class.

"We have people from all around the world coming here to see how we execute our maintenance practices and benchmark against them."

Fitted with 38 cu m buckets, the PC8000-6 'Super Shovels' deliver up to 60 tonnes of rock at a time to the haul trucks, 40 of which operate in the Super Pit.

The shovels are digging at a rate of 1300 to 1500 cubic metres an hour, and are taking less than 25 sec for a dig-to-dig cycle a remarkable time for such a big machine.

The Cummins QSK60 engines in the new PC8000-6 machines are Tier 2 emissions compliant. Tier 2 levels are the lowest regulated emissions in the world for off-highway engines over 560 kW (751 hp).

"Our operators are saying the Tier 2 machine is very responsive, more responsive than the older Tier 1 units," said Garry.

The distinguishing feature of Cummins Tier 2 engines is their modular common rail fuel system, including a high-pressure fuel pump generating around 1600 bar to enable cleaner, quieter and faster power delivery.

The system also prevents unbalanced fuelling between cylinders to significantly reduce engine vibration, noise and harshness, making the Tier 2 engine 80% quieter under load and at idle.

The QSK60 engines are proving themselves in KGCM's Super Pit operation, constantly handling load factors as high as 75-80% and providing a key link in the high utilisation requirements of the site.