Modern Mining November 2020

COMMODITY FOCUS – COAL

companies being held accountable for incidents. These legal consequences are driving new trends that may not always make operations easier. Where equipment on a coal plant is barricaded due to its moving parts, for instance, this may complicate the process of evaluation and maintenance. Mines will need to be innovative in keeping the momentum of their equipment performance initiatives, while ensur- ing the highest levels of safety. Wide range Multotec’s extensive range of products allows it to supply most of the equipment in a dense medium separation process in coal plants, and the company continuously improves the designs and capabilities of this equipment. “On the screening side, we have ongoing devel- opment of polyurethane screen panels to treat wet and sticky material without extra addition of water. Normally, more water is used to wash off clay mate- rial. The benefit here is of course reduced water usage,” explains Bekker. Multotec is also exploring the use of rubber for panels, due to its flexibility that helps avoid block- ages. It is also more wear-resistant. In terms of its wedgewire products, the company is incorporating a wider range of stainless-steel grades and profiles to improve efficiency and per- formance. Tests have been conducted with special wear coatings on wedgewire to improve opera- tional life, demonstrating that life expectancy can be increased quite dramatically.

“We prioritise safety in the handling and instal- lation of modular screen sections, so we regularly assess and improve our design for easier handling,” says Bekker. “As part of our leveraging of technology to monitor performance and predict maintenance requirements, we are evaluating the use of sensors in panels to indicate wear, pegging or damage. There is even scope to apply this technology to monitor the integ- rity of screen frames, to ensure optimal performance of the screen deck. These innovations help reduce unplanned downtime. Magnetic separation Multotec supplies a variety of magnetic sepa- rator drums, the most common being the low intensity magnetic separator used in coal. Magnetite consumption is as critical as always and most pro- nounced magnetite losses through conventional DMS recovery magnetic separators occur when the slurry level in the machine is not at optimum level. “Traditional manually adjustable overflow weirs require that operators see the problem and make the adjustment and this often happens only after significant losses and probing investigations to iden- tify this root cause. The market response has been to install self-levelling tanks, but these tank designs allows coarser, dense grit material to settle in the under pan and build up to the point where the grit wears through the drum shell resulting in major refur- bishment costs,” explains Bekker, adding that this problem is overcome with elaborate and expensive

Efficient plant operation requires that the right decisions be made quickly, to optimise equipment and mitigate risk.

26  MODERN MINING  November 2020