Owing to current coal prices, depleting coal reserves and the increasing need for infrastructure investment, the local coal mining industry is focusing more on efficient mining and processing using existing infrastructure without added capital investment, says mining services group Ukwazi director and principal engineer Jaco Lotheringen.
“With the pressure on the coal price, the need for operations to deliver specification products at a low cost has materially increased over the past two years,” he tells Mining Weekly, noting that the uncertainty of coal prices over the medium term further increases the need for most coal companies or coal mines to decrease their unit cost of coal products to remain competitive.
“Low efficiency implies high cost and low production rates. In our experience, major aspects that materially influence efficiency in most African operations are dependable and accessible transport and port infrastructure, as well as the nature of the deposit and operational and mining efficiency,” says Lotheringen.
While establishing additional infrastructure will improve efficiency, Lotheringen points out that the fastest and easiest route to efficiency is appropriate strategic and short-term mine planning and design, as well as the implementation of production management processes.
Although high-efficiency mining methods and equipment cannot be applied to some existing mines, these mines should still be strategically designed and well planned to establish a lower cost base to be competitive, he says.
“If opencast strip ratios are higher and underground extraction ratios are lower than those of international competitors for the same coal quality, additional measures are required to remain competitive and deliver low-cost thermal coal to State-owned power utility Eskom and the international market.”
In light of this, short-term mine planning and transparency in the mining cycle are key areas where significant improvement can be made, he says.
“The implementation of an easy-to-use and tested short-term planning tool, in collaboration with a production management process, is essential to mining efficiently.”
Lotheringen adds that Ukwazi noted several successes – particularly at contractor-operated opencast coal mines – when it implemented short-term planning tools over the last year, such as Xact supplied by mining software developer RungePincockMinarco.
He explains that full collaboration between mining production and mine planning will allow for a weekly plan that is efficient, understandable, practically implementable and has a buy-in from the management team.
Further, members of the operational team understand exactly what is expected of them at the designated times, while production activities can be decoupled to meet the highest possible production rate.
Lotheringen says production can be increased through transparent collaboration and accountability, and not just through additional mining equipment or additional capital requirements. He has witnessed production improvements of up to 20% within less than a year, when mining has been managed as a process.
However, Ukwazi has noted that some coal operations have failed, through short-term-focused decisions to mine out of sequence or targeting the wrong areas that delayed rollover mining, or not adapting to economic difficulties.
Some coal operations have also tried to increase capacity by acquiring more equipment, rather than increasing efficiency using existing and appropriate equipment. Opencast production capacity is dependent on the available seam face length, efficient and safe access, box-cut sizing and rollover mining. These aspects have more to do with planning than simply adding equipment to a point where congestion increases cost, Lotheringen adds.
“A strategic revision of the mine plan, based on practical and efficient execution on a yearly basis, can add material value in that the appropriate areas are targeted at the right time to ensure a sustained and economic operation,” he believes.
Lotheringen notes that, while the Highveld and Witbank coalfields are being depleted, remaining coal projects are becoming more complex in terms of geological structures, depth, seam thickness and quality.
“Historically, projects were selected based on cost, production rate and available mining methods. In light of this, coal reserves with a high complexity and/or difficulty to mine were abandoned or divested, as it led to expensive coal.”
Nevertheless, he emphasises that the current availability of coal projects, coupled with the high capital expenditure (capex) to establish new mines, necessitates the re-evaluation of abandoned projects to enhance extraction of reserves using existing infrastructure.
“The opportunity for re-evaluation of these deposits does exist and can assist in replacing and finally increasing current capacity of coal production,” he stresses.
However, as mining of such complex reserves still requires capex, and because the cost of these projects is high, owing to capital recovery that has to be spread over smaller projects, mining also requires an ever-increasing level of geological confidence and specialist studies to improve the level of modelling, planning and scheduling, says Lotheringen.
In addition, the available reserves generally have lower qualities regarding calorific value, total sulphur and ash content, which necessitate an increase in blending and washing to achieve customer specifications.
“As the availability of suitable blending material is also rapidly decreasing, appropriate strategic planning is essential to enhance the available reserves of the Highveld and Witbank coalfields,” concludes Lotheringen.