Modern Mining May 2017

CRUSHING, SCREENING AND MILLING

commissioned at coal mine

to convey raw material to the crushing plant. The main features of the apron feeders are the heavy-duty chains and rollers which are attached to the main frame and which are manufactured by Caterpillar. The design of the feeders is such that impact energy is reduced to a minimum. Four feeders are available, des- ignated the D4, D7, D9 and D11 and offering effective widths from 1 500 mm to 4 000 mm. Nel says that MMD Mineral Sizing (Africa) is increasingly positioning itself as a turnkey solutions provider rather than just a supplier. “We have strengthened and expanded our local in-house design and engineering capa- bilities considerably in order to provide faster turnaround times and at the same time pro- vide engineering solutions which comply with customers’ specific specifications and unique requirements,” he says. “We’re also becoming involved during earlier stages of our customers’ projects and every so often we’re contributing to the pre-feasibility and feasibility stages. In addition, we’re teaming up where appropriate with other suppliers during such phases.” In another development, MMD has installed a custom designed and manufactured dust hood on one of its semi-mobile plants at the request of the client in order to control the dust generated from the dump trucks that tip raw material into the semi-mobile sizing station. “The dust hood is very effective and the client is considering whether to fit hoods to its other stations,” says Nel. Despite the recession in mining, MMD

solutions for the underground UK coal indus- try, initially designing and manufacturing in-line breakers. In 1980 he invented the twin- shaft mineral sizer which provided a technical breakthrough in mineral reduction. The original mineral sizer developed by MMD was specifically designed to work in the confined space of underground coal mines and was able to handle tonnages of up to approxi- mately 1 500 t/h. Building on the success of this original 500 Series machine, MMD now has a wide range of sizers with the biggest machine being the 1500 Series which was first supplied to operate within the oil sands industry in Canada. Depending on the sizer shaft centres, machines can be configured for primary, sec- ondary or tertiary crushing and all can be customised to the client’s requirements. The full range of MMD sizers can also be supplied in fixed, mobile or semi-mobile configurations, with units being wheeled, tracked or mounted on skids. Detailing the advantages of MMD’s mineral sizers, Nel says that they are very compact and lightweight compared to more traditional crushers of the same capacity. He also points out that they have the ability to process not just hard, dry rock but also soft, abrasive and sticky materials which can often cause problems for conventional crushers. Moreover, the output from the machines is an accurately sized prod- uct with minimal fines. Complementing its mineral sizers, MMD has a range of heavy-duty apron plate feeders

Above: A 625 Series primary sizer (cap machine) in MMD’s workshops in Longmeadow ready for dispatch to a gold mine in Burkina Faso.

Above left: The fourth semi-mobile station at Exxaro’s Grootegeluk open-pit coal mine.

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May 2017  MODERN MINING  35