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Specialised equipment supplier Multotec says it is evolving its offering to the coal sector in line with the latest trends emerging from end user operations.

Multotec’s Garth Jones, responsible for site services, says companies operating within the local and international coal sector form a major customer base for the company and that in this segment Multotec differentiates itself through its process and applications knowledge, as well as by the broad range of products focused on coal.

“Central trends in this sector include outsourcing of maintenance requirements through maintenance contracts, which are rapidly coming to be regarded by customers as a value-added service to boost plant availability,” he says. “The most recent development in this arena is a move to structuring maintenance contracts on a rand- or cent-per-ton basis, making it possible for coal operators to predict their costs more accurately.

“Another trend in coal is that the complexity of the equipment is shifting quite rapidly into the suppliers’ arena. This is actually an efficient approach, since suppliers like us are specialists in our field and our technical support for the lifetime of the equipment frees up plant personnel to focus on their core operations.”

He adds that pressure from tightening environmental regulations has given rise to a trend to reduce emissions and water usage, while striving for a more efficient overall recovery of energy. In response, Multotec continues to make major investments in R&D to boost the efficiency of its equipment.

“An excellent example of the innovations that are emerging is the greater open area panels for vibrating screens, which are boosting screen efficiencies and reducing magnetite losses — the highest cost confronting a coal processing plant,” adds Rhodes Nelson, from Multotec’s screening team. “The latest development follows a significant investment in tooling that has allowed us to produce an injection moulded polyurethane screen panel that dramatically increases the open area and drainage. This innovative new screen panel provides a significant open area that, in some cases, has been shown to be double what was previously achieved with conventional Multotec Hi-Flow panels for the same aperture, and with double the drainage capability.”

GM of Multotec’s solid liquid and magnetic separation division, Ernst Maritz, says that the company’s low intensity magnetic drum separators, used in conjunction with the correct wash water system and screen cloth design, are also achieving significant savings on operating costs by reducing magnetite consumption.

To address the need for improved longevity, the introduction of new and better materials of construction to reduce costs is a continuous process and Multotec’s range of wear resistant material has resulted in significant maintenance cost savings and improved plant availability. The company recently introduced a revolutionary new material for manufacturing wedgewire screen products for the coal industry. The new speciality material has exceeded all original expectations in terms of wear life and performance in local and Australian coal operations.

“Both our development team and the clients at whose sites we’ve tested the new material have been astounded at its performance,” he comments. “In centrifuge baskets, this material improves the overall efficiency of the process for longer periods than ever before, as a result of slower wear of the aperture. In other words, the material maintains the integrity of the aperture far longer than any material previously used.

“We’re also trialling some new ceramic materials for dense media and classification cyclones to achieve greater cost savings. Reducing energy consumption is a key driver and one of our major successes has been the development of a flame-proof air-cooled overbelt magnet for underground tramp iron removal that uses less energy.”

In terms of water savings, closed water circuits, more efficient filters and enhanced dewatering using centrifuges are coming to the fore. To this end, the company has developed an environmentally friendly water filter press believed to be a world first. Traditionally, hydraulically operated filter presses are used in process and water reclamation plants, but these conventional products are associated with a high risk of contamination from oil and other lubricants during operation. Maritz says it has become essential to overcome this challenge to protect the environment and assist mining companies to comply with environmental legislation.

On the process side, coal operations are seeking more effective ways to beneficiate fine coal particles and here Multotec has a focus on improving the efficiency of fine coal dense medium separation (DMS) and is looking at high density DMS as a pre-concentration stage, using a special magnetic separator to carry out the densification. The company is also looking at combinations of water-based gravity concentrators such as spirals, teeter bed separators and water-only cyclones.

And, to address the need for accurate measurements in the coal sector in line with an international trend towards online analysers, Multotec has invested in new online analysis technology in collaboration with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), in Australia, to provide accurate analyses of coal elements.

“This technology can measure the level of carbon, hydrogen and oxygen directly in the raw particles of coal which is not possible with the traditional prompt-gamma neutron activation analysis,” he says.

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