MINING POWER SUPPLY
A power failure at an underground mine could lead to mineworkers becoming stranded
Photo by: Duane Daws
Fluctuating power supply or complete failure thereof at a mine, interrupting mining process, could result in serious consequences, emphasises power generation equipment designer and manufacturer Cummins Africa power solutions director Kenneth Gaynor.
Many African countries are susceptible to power fluctuations; therefore, mining com- panies have had to use genera- tors for stable electricity supplies, he says.
Multinational companies like Glencore, which has mines in South Africa and other countries like the Democratic Republic of the Congo (DRC), have to deal with energy supply demands not being met, which risks shutting down its mines, says mining project online portal African Mining Project Intelligence (Africa Mining IQ). The DRC has an energy distribution capacity of only 6% – many rural areas can, therefore, not support big mines.
However the research organi- sation explains that the search for constant power is not limited to Glencore in the DRC. Zimbabwe, Mozambique, Uganda and other African countries also host mines in similar predicaments owned by mining companies such as Australian global resources major BHP Billiton, British-Australian metals and mining corporation Rio Tinto and diversified miner Anglo American.
It is important that such mines have enough power to allow for operations to continue smoothly, as some of the largest mines in Africa operate 24 hours a day, says Africa Mining IQ.
“Early morning operations, night-time lighting systems, ventilation systems and lifts transporting mineworkers up and down shafts all need a secure electricity supply,” Gaynor explains.
When a power failure occurs, these pro- cesses could be interrupted, placing mineworkers in danger. They could also poten- tially be placed in harm’s way if they neglect to check whether a machine is switched off or attempt to fix equipment while unaware of a power failure. This could lead to mineworkers taking dangerous risks, as they might want to check if a machine has jammed without shutting it down properly.
While underground mineworkers could become trapped in the dark, mine- workers at openpit mines could try to fix nonexistent machinery problems, says Gaynor, adding that everyone who works at a mine has been trained to follow specific safety protocol to avoid injury.
Meanwhile, if a mine uses State-produced power from a country’s national grid, which supplies electricity generated by large power stations that are some distance from the mine, the loss of power could be attributed to several causes and could take several days to repair.
To counter the loss of electricity, mines use generators to ensure that operations continue.
Gaynor stresses that it is more economical for rural mines to use on-site generators for their electricity needs. However, he predicts that, in future, smaller power plants that are linked to the national grid, but located closer to mines, will be constructed in rural areas to meet the power requirements of mines and surrounding communities. “This will decrease the amount of power lost, owing to transmission, and reduce the associated costs.”
“[T]here are two types of generators suitable for use on mines – standby generators, which only work if the main power supply fails, and prime generators, which can meet the entire power supply demand of a mine. Prime generator systems are used in rural areas, which a country’s power grid has yet to reach,” he says.
The QSK95 generator series from Cummins can be used for standby and prime generator purposes. Generators can be modified to suit a mine’s needs, making each generator unique to the mine it powers, says Cummins.
Prime generators can constantly produce 20 MW of power, but standby generators can generate up to 1 000 MW of power over two or three days. However, Gaynor explains, standby generators are engineered to operate only for a short period to reduce the operational costs of mines when electricity supplies have failed.
“It is paramount that a mine uses one of the top generator brands, as they can easily be repaired, owing to spare parts avail- ability. Spare parts also need to be avail- able for the maintenance of older gene- rator models that still produce electricity efficiently,” he points out, noting that Cummins outlets across Africa stock parts for generators that are more than 15 years old.