Girth gears for upgraded mine

Drive technology specialist SEW-EURODRIVE has announced that it is installing four of its large segmented girth gear systems at De Beer’s Venetia Diamond Mine in Limpopo province.

Venetia mine, in operation since 1992, is upgrading its two primary scrubbers and two secondary scrubbers, and the girth gear replacement is said to be an integral element of the project.

“We have planned the installations in close collaboration with Venetia mine, making sure our teams are ready when the mine’s shutdown periods allow,” says SEW-EURODRIVE project engineer Bruce Farthing.

The company explains that the expertise of the installation team was brought to the fore by the scrubber’s specific design. The bearing design in particular makes it impractical to bring the whole drum to ground before changing over the girth gear. Instead, the replacement has to be conducted with the drum in situ, at a height of about three storeys.

“In the first installation, we therefore assembled the girth gear on the ground, lifting it into position once the old components had been removed from the scrubber,” he says. “The challenge, of course, was to ensure no damage to any of the new components, which we managed with careful planning and experienced execution using large overhead cranes.”

These large girth gears measure 5.3 m in diameter and weigh about 6 t each. Given the scale of the equipment, the segmentation of the gear makes for easier transportation and handling. Farthing explains that each girth gear is made up of 10 identical segments which can be assembled on site.

The second and third installations – to be conducted on the two primary scrubbers – are scheduled for later this year. The contract includes the supply of SEW-EURODRIVE’s large two-stage industrial gearboxes and the external pinions to drive the girth gear. The motors are coupled to the gearboxes using a fluid coupling on a purpose-built, drop-in baseplate. Smaller gearboxes from its X series range are also coupled to the main gearbox as auxiliary drives for commissioning and maintenance.

Farthing notes that the company’s segmented girth gear systems have recently been a popular choice for South African customers, and that it has also recently supplied the solutions to applications in a paper mill and a cement mill.