Quarry Southern Africa May 2017 - Page 20

Wirtgen SA demonstrated the capabilities of the 2200SM, its smallest machine, in supporting and enhancing profitable mining operations in South Africa. of trials with the 2200SM at three different coal mines in the Delmas and Ogies area. The demonstrations began at two open cast coal mines in Mpumalanga. At both sites, blocks of about 50m x 100m directly on the coal seam were cleaned out to give the miners enough space to work. The 2200SM cut and crushed the coal, loading it directly onto the mines’ 40-ton ADTs. Ninety-six percent of the material mined at these two mines was <53 mm, with fines content (<1 mm) comprising less than 14% without the need for drilling, blasting and primary crushing – well within expected result parameters. Instantaneous production rates reached over 800tph in most cases, and the average production rate was more than 400tph. “The machine was also put to the test in sandstone interburden and with great results,” says Newby. “This means that thin seams of coal, waste and interburden can be effectively mined selectively, easily separating the product from the waste,” he says. The third demonstration took place at an open cast coal mine in Delmas, with the primary objective of improving the yield at the production plant. “The 2200SM surface miner mined highly selectively, separating coal from waste and ensuring that good, clean coal was sent to the plant with minimal contamination and no crushing required,” says Newby. “Overall, on coal we were able to get instant cutting and loading times of up to Wirtgen surface mining leaves precise and stable slopes behind as well as flat, easily manoeuvrable areas. 18 _ QUARRY SA | MAY 2017 about 650 tonnes per hour (tph) and our effective production – including stoppages, truck exchanges, turnaround times, reversing times and so on – was about 420tph,” he continues. “So if you think about it, a small machine doing 420tph straight to the plant, there’s no need for drilling and blasting, you don’t need to even wash the material. And they eliminate a lot of stoppages – the machines can work while it’s raining, and when there’s lightning you don’t have to evacuate the pits. At the end of the day, it’s a lot safer and more cost-effective than conventional mining methods.” Mining other materials The ability of the surface miners to selectively mine is particularly beneficial for mines with thin seams, for example. After the successful use of two Wirtgen 2200SMs at the Kavkazcement limestone mine, three Wirtgen 2500SMs were purchased to extend capacity. The machine can be set to cut to a specific depth, and material can be cut and hauled with precision, significantly reducing contamination. This has additional benefits on the wash plant side, because it significantly improves yields. “A perfect example is our operation in Australia, at Fortescue Minerals Group (FMG), an iron ore mine,” says Newby. “The iron ore there is not the same as what we find in South Africa. Our iron ore is massive, like Sishen, it’s extremely hard, the surface mining machines won’t work here in those conditions. At FMG it works because the iron ore there is more of a weathered and friable material, and there are thin seams in riverbeds. You’ve got kilometres of iron ore interlaced with interburden and