19 July 2012 – Electricity accounts for 95% of gold mining company Gold Fields’s energy consumption in South Africa. Plans by public power utility Eskom to significantly raise electricity prices over the coming years, as well as concerns by Gold Fields around security of supply makes reducing electricity consumption a priority for the company, according to its integrated annual review.
“Indeed, the nature of our mature, deep underground mines means this is an essential component in the South Africa region’s long-term operational sustainability,” the report states. “It is in this context that our business process re-engineering programme in South Africa is targeting reduced energy consumption of around 5% in 2012.”
This will build on a 17% reduction in electricity consumption already achieved by the company between 2007 and 2011. “Although this will not fully negate the impact of Eskom’s price increases, it will reduce the risk of production losses as a consequence of higher pay-limits,” the report says.
The gold mining company has undertaken a number of initiatives to increase its energy efficiency. It has introduced enhanced systems for compressor management to improve efficiency and reduce operational time in line with requirements for compressed air. It has optimised its pumping by using automated monitoring systems to control efficiency, maintenance and replacement. It has optimised its surface refrigeration plant through the use of an energy management control system.
In addition, the company is investigating opportunities for the development of compressed air-less mines, using hydraulics and electricity to power drilling and other activities (thus avoiding the significant latent power wastage of pneumatic systems). Plans are also being finalised for the implementation of an ice-based underground cooling system at the Gold Fields Kloof Driefontein complex to reduce pumping demands. The higher cooling potential of the ice means much less water needs to be pumped back to surface. In addition, solid ice is less prone to warming than water as it gains kinetic energy during its descent (i.e. the Joule Thompson effect). Application of this technology is expected to achieve average savings of up to 10 MW a year. Plans are also in place for its application at South Deep by 2015.
Gold Fields says it continues to work with Eskom in the pursuit of further energy efficiency and energy security measures. These are being financed with the help of about R200 million (US$28 million) from Eskom’s Demand Side Management (DSM) programme. This includes high-efficiency auxiliary fans at the Kloof Driefontein complex to replace existing 45 kW auxiliary fans. Following a pilot, Gold Fields has placed an order for 1,000 units, which have been shown to use 30% less electricity than the existing fans. These will be fitted at the Kloof Driefontein complex, South Deep and Beatrix. Collectively they are expected to save 13 MW a year.
Gold Fields is also investigating the potential for large scale third-party solar power generation on its land at the Beatrix gold mine in the Free State.