South African gold mining firm Gold Fields is planning to trial two new mining techniques at its South Deep mine, with the aim of unlocking 40 million ounces of reserves worth around $50bn.
The decision came after the company’s current destress mining methodology was considered too costly and risky for mine workers, particularly following the two fatal accidents on 17 and 27 May.
Gold Fields performed a ground support remediation programme, under which it appointed International Geotechnical Advisory Board (IGAB) to help roll-out safer and more cost-effective mining methods.
IGAB proposed to introduce two alternative techniques; 4X4 Meter Destress and Inclined Mining Slot, to replace the existing destress mining method.
According to the company, the current destress mining technique cuts rocks horizontally by applying a lot of stress to them, but requires a great deal of time and money.
Gold Fields CEO Nick Holland was quoted by Bloomberg as saying: “I wouldn’t say we’ve been mining in the wrong way, the current method is very sound.
“If we can make things easier, all the better.”
The 4X4 Meter Destress method reduces destress mining from a three-pass system to a one-pass system, by increasing the dimensions of the excavation area, making the way for machines to take over mining operations from workers.
Under the Inclined Mining Slot method, the pit can be opened, extracted and back-filled without the need for support structures and workers.
The whole process can be performed by machines, which would speed-up the practice of mining gold.
“It is much quicker, easier and probably will be cheaper,” Holland added.
The company will pilot both the methods at different areas of the mine during the period between 2014 and 2015, and will select to continue with in the next 12 months.
Gold Field aims to produce 650,000oz to 700,000oz of gold from the mine by 2017, which will be worth $900m a year.
Gold Fields estimates that the mine would run for around 70 years at such production rates.
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