Hoisting and diesel use drive up costs at underground and open cast mines.
Beneficiating ore underground could help mining companies become up to 30% more energy efficient.
Speaking at the 2016 Solar Show Africa, Thor Govender, a risk engineering manager at energy services consulting company Arint, said optimising hoisting at mines could save energy and drive down costs.
Citing data from a range of sources, he said diamond mines are the most efficient in terms of hoisting as the ratio of ground hoisted to minerals recovered stands at 99.9%.
Gold and iron ore producers recover 80% of ore from the ground that is brought to surface, whereas coal mines recover only 50%.
Another cost driver at underground mines are leakages in compressed air.
For illustrative purposes, Govender used an electricity price of R1 per kWh to show how one just 10mm hole in a standard compressed air system can cost companies almost R300 000 a year.
In addition to fixing leaks in compressed air systems, “up to 40% of energy can be saved by changing from pneumatic to electric systems,” he said.
Compressed air comprises 17% of all electricity consumed by underground mines and about 80% of costs associated with typical compressed air systems are energy costs.
According to Govender, one of the main cost drivers of open cast mines is diesel, particularly through the use of dump trucks.
Given that 40% of diesel used by these trucks is burned while idling, investing in electric trucks, stop-start technology and in-pit beneficiation methods can go some way to optimising energy usage and cutting costs.
He also said optimisation in terms of truck specifications, the gradient of mines and conserving energy on “downruns” can help to reduce operating costs.
While energy efficient solutions can easily be designed into new mines, he said that reviewing hoisting and air compression methods can provide existing mines with a good starting point.
He also said that existing mines stand to benefit from motor replacement strategies, where older motors are replaced with new energy efficient machines as and when they fail.
Source: Mineweb