AngloGold Ashanti CEO Srinivasan Venkatakrishnan (Venkat)
Photo by: Duane Daws
JOHANNESBURG (miningweekly.com) – South Africa’s largest gold miner AngloGold Ashanti has now produced 1 600 oz of gold using its exciting new technology, which mines “all of the gold, only the gold, all the time, safely”.
AngloGold’s Tau Tona gold mine, near Carletonville, has become the first pukka production site of the “game-changing” technology, which leaps over mechanisation into automation. (Also watch attached video).
The technology is referred to as the South African Technology Project because of the company’s big-hearted decision to allow it to be migrated to all of South Africa’s hard-rock narrow-reef non-group mines, including the hard-pressed platinum mines.
Despite widespread cost cutting in the latest quarter to March 31, which saw AngloGold reduce its all-in sustaining costs (AISC) by 22% to $993/oz, the project budget was one of the few that remained untouched because of the “bang” the company expects to get from every “buck” it spends on it.
Blast is totally eliminated using the technology, which introduces a safer working environment and eliminates dilution.
“It’s making significant inroads,” AngloGold Ashanti CEO Srinivasan Venkatakrishnan (Venkat) told Mining Weekly Online at a media roundtable on Monday, when the company reported it was once again generating free cash flow, albeit a moderate $9-million, which has not happened since March 2012.
AngloGold Ashanti South Africa chief operations officer Mike O’Hare flashed pictures of the new technology’s new equipment on to a large screen at Monday’s presentation of AngloGold Ashanti’s first-quarter results, which saw overhead and exploration costs fall 34% year-on-year as AISC was reduced in far greater proportion than the currency benefit. (See pictures on attached video).
The project is already into its twenty-fifth drill hole and now has machines that are drilling even the narrowest of reefs in local orebodies.
“We’re putting more effort into the technology, which is the key lever we have to improve the productivity levels in South Africa and also turn the declining trend,” Venkat told Mining Weekly Online.
Reduction of drilling time is under way, as is the building of backfill at scale underground, the tackling of both thin- and wide-reef orebodies and the drilling of holes adjacent to one another, or “skin to skin”.
Four new holes drilled skin-to-skin using AngloGold Ashanti’s new gold-mining technology have reconfirmed that the raise-boring method can extract all the reef.
Ten per cent to 20% of its South African gold is destined to be produced using this technology in areas left unmined as support, which includes gold-rich shaft-pillar structures, and not where mining is currently taking place.
Targeted are the areas that are no-go for conventional drill-and-blast mining, which causes risky seismicity.
The technology thus facilitates a step up of South Africa’s gold production and the arrest of the decline of the last eight years.
Taking advantage of this accessible but sterilised gold is being prioritised ahead of the eventual aim of deploying the technology below current infrastructure in the ultra deeps of 5 km and beyond.
Once the technology is developed to scale and boosted by bulk, it can be used at depths of 5 km and beyond.
Meanwhile, measurement devices placed in each of the backfilled holes have given the thumbs up to the backfill engineering employed.
As the backfill takes 20 days to cure, a drilling sequence is being designed to ensure its most efficient deployment.
The first thin-reef machine has been delivered to AngloGold’s Great Noligwa mine, where it is turning an uneconomic reef into an economic one.
“We’re watching that very carefully and will report on that in the quarters as we progress,” O’Hare told Mining Weekly Online.
Some 150 m length of hole at 8 m an hour have now been drilled using reverse circulation (RC) drilling and the target is to extend the hold to 300 m at the same rate.
The influence of lower-cost RC drilling in different reefs is being carefully studied.
It is clear that the technology has the potential to change the face of South Africa’s struggling precious metals mining business, as no precious metal is left behind owing to backfilling doing the job of pillars.
Pictures were shown on large screens of 30-m-long holes, at a 27° dip, in perfect take-out of the precious reef, which means the waving goodbye of mine call factors.
Pictures have also shown the large quantities of waste that no longer need to be brought to surface.
Operation of the system 24 hours a day, 365 days a year would change the face of narrow-reef hard-rock mining, which has always been dogged by the need to evacuate the mine ahead of blasting and to stay out until all the dust has settled.
A number of non-group gold and platinum miners have already approached AngloGold about also making use of the technology, which has to be adapted to fit specific orebody depth and width.
“We’ve not sought to keep this to ourselves. We’re looking at the greater good of South Africa,” Venkat commented to Mining Weekly Online earlier this year.