The composition of coals mined in different areas can vary widely. Since the very early days of mining, coal quality has been improved by removing unwanted mineral matter. Over time, coal processing plants have evolved considerably. In a one-on-one with Modern Mining, Ernst Bekker, product specialist cyclones at Multotec, unpacks some of the new trends in coal processing.
Commenting on some of the major trends in coal processing, Ernst Bekker, product specialist cyclones at Multotec, says coal miners are today sweating their assets, and want longer lifecycles from their process equipment. This means that better maintenance is required. Customers are also wanting shorter lead times for stock; they want to hold less stock on site and rather rely on the supplier for quick delivery.
“Over the past couple of years, we have seen coal processing equipment on mines being pushed to the limits of its design capability, with higher tonnages placing more demands on equipment. Mines are therefore relying more on suppliers to maintain equipment and ensure that it performs optimally. This requires closer working relationships between the supplier and customer; in the past suppliers would be called upon only when necessary,” says Bekker.
The average age of coal processing plants is increasing steadily, he says, as not many new plants are being constructed. To keep these plants operational, suppliers are required to ensure that their equipment lasts longer but remains reliable and efficient.
Water scarcity and acid mine drainage is a growing focus at coal plants, where there is a strong drive towards zero liquid discharge and maximum water recycling. “Mines want to reduce their water usage in the process plant, and so suppliers must also look at how they can contribute. This requires that our equipment designs carefully balance water use and efficiency; the customer still needs a high level of performance from our equipment, in spite of using less water. The concern with water conservation is also driving a strong focus on dry beneficiation,” says Bekker.
The focus on beneficiation of fine coal is becoming more intense, he adds. While fines were generally discarded in the past, mines now want to recover this resource for commercial and environmental reasons. The required dewatering process, however, can be costly.
“We find that new coal plants are smaller and simpler in design, moving away from complexity and towards fewer items of equipment in the flowsheet. This often leads to fewer large units being installed instead of multiple smaller units. In certain situations, this can result in a change in separation or performance efficiency and it is the supplier’s responsibility to ensure the impact on the process is minimised,” he says.
As mines look to streamline their operations, they would prefer to deal with fewer suppliers – to reduce the points of contact they need for procurement. Monitoring and automation of coal plants, reasons Bekker, is thus being increasingly adopted as a strategy to inform and expedite decision-making. As mines embrace the Fourth Industrial Revolution, plant operators are capturing real time data and looking to analyse and interpret it in greater detail.
“The state of the global and local economy means that coal mines continue to be price sensitive in their procurement. This focus on the bottom line can mean short-term gains from cheaper products, but can also undermine longer-term efficiencies if the equipment’s performance is not optimal. It is important that qualified process staff remain integrally involved in making procurement decisions,” he says.
Remote monitoring of coal plants is an innovation that is also being pursued by a number of mines, especially as the COVID-19 pandemic continues to affect how people must work. This holds potential for the sector, although most plants will continue to rely on a physical presence of managers and operators for some time to come.
“To provide context, valuable progress has been made on a Mpumalanga coal mine, where a ‘digital twin’ model has been applied. This gives managers the ability to test operational changes on a virtual platform, before applying them to the real-life operation,” says Bekker.
A key driver of developments in coal processing is efficiency, says Bekker. Mines and plants are pushing the boundaries of equipment performance, to maximise coal recoveries while holding down costs. In addition, coal is now competing with other forms of energy sources like solar and wind power which are becoming more cost-competitive.
“In terms of using technology to monitor operations remotely, the COVID-19 pandemic has also been a factor. It has accelerated the pace of these trends, as a way of allowing more social distancing in the workplace and work-from-home arrangements,” he says.
Bekker adds that there is a growing realisation that coal is a limited resource in South Africa, as older mines close down and our traditional coalfields become depleted. This is driving initiatives to make better use of the deposits currently being mined.
The impact of climate change is now undeniable, he says, with weather patterns being altered. In areas where coal plants must operate in drier conditions, innovations are required that allow plants to mitigate these effects through water-saving beneficiation.
“Efficient plant operation requires that the right decisions be made as quickly as possible, both to optimise equipment and to mitigate risk. This time factor is driving developments in data technology, so that data can be analysed with speed and accuracy,” he says.
The safety focus on mines is continually more intense, adds Bekker, with senior people in mining 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 ensuring the highest levels of safety.
Exclusive article originally published by Modern Mining.