The offering of specialised equipment supplier Multotec to the coal sector is evolving in line with the latest trends emerging from end-user operations.

Multotec site services GM Garth Jones says companies operating in the local and international coal sector form a major customer base for the company. In this sector, Multotec differentiates itself through its process and application knowledge, as well as its broad range of products focused on coal.

“Central trends in this sector include the outsourcing of maintenance requirements through maintenance contracts, which are rapidly being regarded by customers as a value-added service to boost plant availability. The most recent development is the attempt to structure maintenance contracts on a rand-per-ton or cent-per-ton basis, enabling coal operators to predict their costs more accurately,” he notes.

Jones points out another trend in the coal mining industry: “The complexity of the equipment is shifting quite rapidly into the suppliers’ arena. This is an efficient approach, since suppliers, such as Multotec, are specialists in the field and our technical support for the lifetime of the equipment frees up plant personnel to focus on core operations.”

He says that pressure from tightening environmental regulations has resulted in a trend to reduce emissions and water use while striving for a more efficient overall recovery of energy. Therefore, Multotec continues to invest in research and development 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,” says Multotec manufacturing deputy MD Rhodes Nelson.

He says that this “latest devel- opment follows a significant investment in tooling, which has enabled us to produce an injection-moulded polyurethane screen panel that dramatically increases the open area and drainage”.

Multotec solid liquid and magnetic separation division GM Ernst Maritz says 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 operating cost savings by reducing magnetite consumption.

The need for improved longevity has resulted in the introduction of new and better construction materials. Cost reduction is a continuous process and Multotec’s range of wear- resistant material has resulted in significant cost savings in maintenance and improved plant availability.

The company recently introduced a new material for manu- facturing wedgewire screen products for the coal industry. Maritz states that 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 the screen product’s performance. In centrifuge baskets, this material improves the overall efficiency of the process for longer periods than before, as a result of slower wear of the aperture. The material, therefore, maintains the integrity of the aperture far longer than any material previously used,” he notes.

Maritz adds that the company is “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 flameproof air-cooled overbelt magnet for under- ground tramp-iron removal that uses less energy.”

Centrifuges are also coming to the fore in terms of water savings, closed water circuits, more efficient filters and enhanced dewatering. As a result, the company has developed an environment-friendly water- filter press, which it believes to be a world first.

Traditionally, hydraulically operated filter presses are used at 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 in complying with environmental legislation.

Meanwhile, coal operations are seeking more effective ways to beneficiate fine-coal particles. Multotec focuses on improving the efficiency of fine-coal dense medium separation (DMS) and is considering high-density DMS as a preconcentration stage using a special magnetic separator to carry out the densification.

The company is also considering combinations of water-based gravity concentrators such as spirals, teeter bed separators and water-only cyclones.

Further, to deal with 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 Organ- isation, in Australia, to provide accurate analyses of coal elements.