Innovative infrastructure to use emulsion explosives for all 70 of gold miner Gold One’s underground narrow-reef stope panels at its Modder East mine, on Gauteng’s East Rand, has been initiated as part of the miner’s strategy to reduce its cost per ton mined.
Developed and installed in partnership with blasting company BME over the past three years, the rapid reloading system includes the world’s deepest vertical emulsion pipeline of 318 m to deliver emulsion from surface to storage tanks underground. Used with BME’s narrow- reef pump technology, this system enables the Modder East mine to move away from the use of cartridge explosives and fully convert to BME’s emulsion explosives.
Modder East explosives and technical manager James McArdle explains that the new arrangement enables that the mine to achieve its campaign goal for 2017 of a 0.8 m advance per panel per day – a substantial improvement on the 0.65 m per panel per day achieved prior to using emulsion explosives. “The cost savings and productivity improvements convince us that this technology will be the only way for mines to go in the future.”
Specialised underground transport vehicles are filled with BME’s Megapump emulsion from the underground tanks and delivered to refilling stations near the stope face, from where the BME Minicharger portable charging units are filled.
McArdle adds that, with collaboration from BME experts, Modder East has already shown its targeted advance rates can be achieved. “Our crews are receiving intensive training to further improve their drilling discipline, and the improved results are coming through.”
The increase in the daily advance rate could generate additional gold mined each month.
“The beauty of using this emulsion system includes the time saved to get the product underground, as well as the efficiencies gained by not having to manually manage explosive cartridges – which are also closely regulated for safety and security reasons,” he highlights.
The emulsion-filled bags, or bladders, that fit onto the hand-held Minichargers weigh just 18 kg each – making them lighter and easier to carry than the cartridge boxes traditionally moved from surface to the stope face for blasting.
The handling and storage of emulsion is much less onerous than the procedures for cartridges, as it is classified as a 5.1 oxidiser – rather than an explosive – and is only sensitised when actually inside the drill hole. This explosive property assists in minimising the likelihood that explosives will be stolen.
The highly stable characteristics of BME’s double-salt emulsions have allowed them not only to be pumped to this record-breaking depth, but also to be repumped frequently and stored for extended periods before use.