Electricity + Control March 2021

DRIVES, MOTORS + SWITCHGEAR : PRODUCTS + SERVICES

Energy efficiency to drive mining in 2021

Towards the end of 2020, Danfoss Drives South Africa hosted a series of webinars focused on energy efficiency in the mining and minerals extraction sector. Emre Gören, Regional Sales Director Danfoss Drives, Turkey, Middle East & Africa, said: “Energy consumption patterns need to be addressed in earnest, in a bid to ensure that all industries de-carbonise towards a green- er and sustainable future. With an ever-growing demand to increase energy supply the mining industry needs to improve its use of energy-efficient technologies, such as electrical variable speed drives, which could reduce en- ergy consumption drastically. “The recently concluded Danfoss webinars – focusing on energy efficiency in mining – confirmed that the fundamentals of ac variable speed drive technology persist, but also highlighted that many elements are rapidly changing in order to move towards a more sustainable and environmentally friendly mining future. Increasingly, software is embedded in today’s processing components, offering new functionalities and enabling the ac drive to play a larger role in the processing plant,” Gören said. The webinars clearly demonstrated that convention- al motors run at a fixed speed, regardless of the actual output requirement, and in this way waste a tremendous amount of energy. They also showed that energy use can be reduced by 60%, by controlling motors with electrical variable speed drives. New motor types appear often, placing additional de- mands on motor-drive control. This in turn means the ac drive needs to be able to control an expanding variety of motor types, without burdening the end user with more complexity. In addition, new energy efficiency require- ments lead to more variable speed applications. Certain ac drives are designed exactly for the needs of mining and mineral processing plants, coping with extreme conditions, heavy loading and controlling equipment sometimes installed a long distance away. No matter how well the plant design is opti- mised, there is always a way to drive down costs further. Ac drives are used extensively for this pur- pose; robust to extend durability, and designed to contribute to optimising processes, reducing maintenance and saving energy costs. The min- ing and minerals processing industry presents some of the most challenging environments for production. Mine sites, mineral processing facil- ities, associated stockyards and ports facilities, are large-scale and often in remote locations. All Danfoss Drives ≥90 kW, incorporate a back-channel cooling design, with separate cooling paths for the power components, control electronics and an IP54 seal, between these two paths. This back-channel cooling removes about 85% to 90% of the power loss directly through the

heatsink, leaving only 10 to 15% of the total loss dissipated in the switch room. Consideration needs to be given to the outside air quality, but if it is suitable, using the heatsink cooling fans and appropriate mounting and ducting, filtered external air at temperatures of up to 50°C can serve to exhaust from 85 to 90% of the heat loss from the VSDs directly outside the switch room, without affecting the switch room pressurisation. The switch room air-conditioning system then needs to be sized only for the remaining 10 to 15% losses. This feature can reduce the air- conditioning requirements of switch rooms substantially and provide significant project cost savings, along with ongoing operational cost savings, compared to VSDs without such a design feature. It is recognised that the mining industry is a major consumer of energy, reportedly responsible for more than 40% of total industrial energy use. In sub-Saharan Africa, the energy intensive users group consumes a ma- jor proportion of electricity produced and it is reported that just under 50% of the energy intensive users in South Africa, are the mines.

Emre Gören, Regional Sales Director Danfoss Drives, Turkey, Middle East & Africa.

For more information contact Danfoss. Visit: www.danfoss.com

Smart, energy-efficient variable speed drives can contribute to substantial energy and cost savings in mining.

Electricity + Control MARCH 2021

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