New platinum-mining projects should focus on cooling strategies that lower electricity reliance and diversify air and cooling demands, asserts diversified miner Anglo American sub- sidiary Anglo Operations principal engineer for ventilation and occupational environment Marco Biffi.

He points out that historically low energy costs and consistent availability enabled conventional low-efficiency systems for cooling to operate continuously.

However, with unreliable power supply and increasing energy prices, Biffi maintains that modern platinum mine cooling strategies should be provided on demand to reduce unnecessary supply.

“Projects that have not requested an electricity supply allocation from power utility Eskom will struggle with energy supply in the next two years, which brings into play the possibility of using alternative power generation systems to ensure that production and income generation are not delayed,” he explains.

In addition, the efficiency of existing platinum operations could benefit from the introduction of similar corrective measures.

Biffi asserts that, owing to South Africa’s high levels of insolation and the favour- able subtropical location of most platinum operations, the use of solar power is presenting itself as one of the most feasible energy alternatives to power cooling and ventilation systems.

“While the capital costs of establishing solar power plants are high, increasing electricity charges are making this option increasingly financially attractive,” he says.

Platinum major Anglo American Platinum (Amplats) has conducted prelimi- nary investigations into the feasibility and design of one such solar plant that would produce 10 MW of power for its operations.

Biffi adds that fuel cells are also an alternative for the provision of small to medium-sized power requirements.

Fuel cells can be used to power surface and underground vehicles, as well as to electrify isolated sites, while reducing the carbon footprint of any operation.

“They are ideal for the provision of standby power, and can easily be used underground as backup power for communication systems, without the problems associated with conventional emergency power sources,” he says.

Earlier this year, Mining Weekly reported that Amplats would be testing a fuel-cell-powered mine locomotive at its Dishaba operation during the first half of this year.

Strategies in Practice

Biffi, a former principal refrigeration engineer at Amplats, uses strategies implemented at the company’s operations to demonstrate the alternatives available to platinum producers.

He points out that the company’s focus is on the improvement of ventilation and cooling plant efficiency, as well as on increasing the use of waste heat energy to recover additional power.

“The strategies implemented by Amplats in the past few years have been aimed at reducing power consumption through the inclusion of heat pumps and solar power units, the use of energy saving lighting and limited cycling of the major equipment,” he notes.

The company plans to diversify its approach, using energy recovery strategies, thermal storage, solar energy, fuel-cell technology and cogeneration from waste heat energy.

Meanwhile, Amplats plans to incorporate a number of these new energy efficient developments during the design of its future platinum operations.

The company reports that it is currently operating a 1 MW Pelton wheel water turbine at its Union mine Spud shaft, which is linked to a series of underground air coolers that require a constant flow of chilled water.

Biffi claims the turbine recovers about 45% of the energy required to pump the same water back to the surface, while reduc- ing the increase in water temperature.

In addition, the company reports that it has reduced the quantity of used air that is handled underground at its operations by 8.7%, with a reduction of 5% in air power through the use of improved seals and airlock technology.

Biffi emphasises that the challenge remains to improve the efficiencies of current platinum operations without affecting safety and productivity, which will require a balanced and well-structured approach.

To subscribe to Mining Weekly's print magazine email subscriptions@creamermedia.co.za or buy now.