In a first for South African mining, Gold One’s Modder East mine has rolled out an innovative infrastructure to use emulsion explosives for all 70 of its underground narrow-reef stope panels, as part of its strategy to reduce its cost per ton mined.

Developed and installed in partnership with leading blasting company BME over the past three years, the unique rapid reloading system includes the world’s deepest vertical emulsion pipeline of 318 metres to deliver emulsion from surface to storage tanks underground. Used with BME’s narrow-reef pump technology, this system has allowed Modder East to move away from the use of cartridge explosives and fully convert to BME’s emulsion explosives.

“The new arrangement will allow us to achieve our campaign goal for the coming year of a 0,8 metre advance per panel per day – a substantial improvement on the 0,65 metres we used to average,” said James McArdle, explosives and technical manager at Modder East. “The cost savings and productivity improvements convince us that this technology will be the only way for mines to go in the future.”

Specialised transporters in the haulages are filled with BME’s Megapump emulsion from the underground tanks and delivered to re-filling stations near the stope face, from where the BME Minicharger portable charging units (PCUs) are filled.

“With collaboration from BME experts, we have already shown that our targeted advance rates can be achieved,” said McArdle. “Our crews are receiving intensive training to further improve their drilling discipline, and the improved results are coming through.”

He said the increase in the daily advance rate could generate additional gold mined per 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 said.

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 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 also eradicates theft.

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 re-pumped frequently and stored for extended periods before use.