The coal sector is dirty and contributes to a more heavily polluted planet – this was a key theme at Mining Indaba conference in February.

If equal energy is injected into taking action and incorporating cleaner technologies to improve the sector’s carbon footprint as it is into discussing its environmental impact then coal-dependent economies (like South Africa) would not be at risk, RIKUS IMMINK, Multotec’s CEO of South African operations tells LAURA CORNISH.

The coal industry may be suffering at the hands of widespread global concern that it is polluting the environment but the solution lies in implementing clean technologies – not eliminating production and coal-fired power generation.

This article first appeared in Mining Review Africa Issue 3, 2020
Read the full digimag here or subscribe to receive a print copy here

“Third world countries like South Africa depend on coal to generate more than 90% of the country’s energy requirements. Drastically reducing or eliminating this would result in dire consequences for thousands upon thousands of jobs,” Immink starts.

Further contextualising the situation, Immink highlights that South Africa’s emissions by 2025 and 2030 will be in a range between 398 and 614 Mt CO2–eq as per National Policy and according to the South African government. “This does not warrant trying to eliminate coal from driving our economy, Immink states.

Investing time and focus on clean technologies

Technology is rapidly advancing in the mining industry and coal companies need to tap into technologies that can help produce cleaner coal.

“Multotec’s product portfolio within the coal sector is significant and we want to contribute towards and be part of a clean coal revolution,” Immink highlights.

The company is heavily committed to investing in the research, development and implementation of efficient and environment-friendly products that can, have and will continue to improve the coal sector’s environmental impact.

And while the biggest contribution to polluting the environment lies with coal-burning power stations, this impact can be significantly reduced if the mines ensure the delivery of a lower ash, and lower sulphur product to burn, highlights Bheka Majola, MD of Multotec Process Equipment.

Multotec has committed itself to assisting the sector wash its coal as efficiently as possible to produce a low ash, high CV product. “We have made significant headway in achieving this with various products and are looking to further introduce new technologies to improve on these objectives,” Majola continues.

For example

Multotec is currently active on two different sites where it is successfully treating coal fines using a DMS cyclone (as opposed to spirals). “This enables us to cut at significantly lower cut point in order to produce a cleaner coal product,” Majola reveals. While the fines DMS process is not new, Multotec is successfully achieving uncompromised throughputs by using large diameter cyclones that operate at lower pressure.

“Throughput is integral here as our coal mines are generating much larger volumes of fine material as their ore bodies mature.”

To further contribute to cyclone performance body of knowledge, Multotec has done some work to determine the effect of placing magnets on the outside of DMS cyclones.  

This was work that has previously been done and Multotec wanted to develop this work further in order to contribute to efficient DMS operations across the Industry. 

“Traditionally, there has always been a limitation on coarse medium in DMS plants because the medium is not stable for efficient separation.  We have seen that the addition of a magnetic solenoid around the around the cyclone achieves stable medium differentials using coarse medium.

“Coarse medium has the advantage that it is cheaper and easier to recover and customers can achieve costs saving while not compromising on separation efficiency. Our drive is always centred around helping the industry improve its process knowledge and this is just one area we are contributing towards and hope the industry will benefit from,” Immink notes.

Another area of improvement Multotec hopes to launch soon is the introduction of intelligent cyclones. The incorporation of artificial intelligence software, linked to sensors on the cyclone, will provide predictive operational functionality, enabling clients to avoid unplanned breakdowns and disruptions.

Through a partnership with an AI specialist in the United States, Multotec will soon be ready to test its sensor, which is being designed to have the ability to interpret multiple features off one set data – vibration, roping, flaring, pressure differentials, blockages, etc.

The company’s focus on improving the efficiency and performance of its spirals continues to receive equal attention.

In 2019 the company announced successfully taking ‘low cut’ spiral technology to the next level with its new SX10 low density spiral whose reduced cut point of 1.55 g/cm³ delivers considerable advantages over the cut points of between 1.6 and 1.8 g/ cm³ typically achieved in the industry today.  Of importance the SX10 achieves the low cut densities without compromising on throughput.

The result is a cleaner coal with less waste being achieved in a single stage – which saves on capital costs as no further spiral stages are required for cleaning down the line.

Read more about coal

“Our SX10 spiral is successfully operating on a coal mine in North America and we have also supplied for testing into the Australian coal market. Because the spiral is three turns taller than our traditional spirals they are well suited to Greenfields projects but we are working on a solution that will allow them to be retrofitted into existing plants as well,” Majola notes.

A spiral aimed at reducing sulphur content in coal should follow shortly behind the SX10.

“Test work to date has successfully reduced sulphur content but further work is required before testing on site. We are however confident that we will be able to launch a commercially viable low sulphur (less than 1%) spiral to market that delivers a cleaner coal product  for strict European users and also reduces the potential for spontaneous combustion,” Majola concludes.