AngloGold Ashanti prepares a new technology for everyday drilling in undergrowned mines
Speaking at presentation of half-year results, Sheppard said in response to Mining Weekly Online that the machine was continuing to show pleasing progress ahead of its ultimate design still having to be determined.
“Overall, it’s looking pleasing,” he said.
The latest-generation Mark IV reef-boring machine is being put through its paces at the TauTona gold mine’s lower carbon leader shaft pillar and other machines have also been deployed at the Savuka gold mine carbon leader shaft pillar project.
Setting out technology in its half-year presentation document as a top-five priority, AngloGold revealed that talks are under way with the Department of Mineral Resources for permission to conduct continuous, round-the-clock operations, which will significantly strengthen the business case for the fuller introduction of its new raise-boring technology, which dispenses with conventional drilling and blasting.
Mining 365 days a year instead of the current 260, which the blast-free technology allows, provides the necessary time to complete the number of holes each machine drills a month.
“We’re busy with a whole suite of research and development, and following quite a rigorous programme of stage-gating, to make sure we’re spending our money in the right areas and getting out proverbial bang for our buck,” Sheppard told Mining Weekly Online.
Ultrahigh-strength backfill product has also been developed to be able to pump over the required 1 000 m distance, a prerequisite for a full production mining cycle.
The new raise-boring technology produced 100 kg of gold for AngloGold Ashanti in 2014 and was targeted to be competitive with conventional mining in 2015.
The company has used the raise-bore technology to drill in shaft pillars that are unsafe to mine conventionally.
So far, the technology has put the company in a position to mine “all the gold and only the gold all the time” and to overcome the current drill-and-blast constraint of only being able to work 66% of each day.
The need for the new technology is compelling, as only 60% of the gold ore in South Africa’s rich Witwatersrand basin is accessible using current drill-and-blast technology and 40% of the gold is left behind in pillars to keep seismicity at bay.