[miningmx.com] — THERE is great excitement about a promising new technology which could make deep underground mining possible and ensure the future of South Africa’s gold industry.
Deep underground mines are engineering miracles, but the limitations of the available technology have long been evident to South Africa’s gold industry.
The world’s deepest mine is AngloGold Ashanti’s Mponeng, which extends about 4km underground. To be able to mine much deeper than this, where millions of currently inaccessible – or uneconomic – fine ounces of gold lie, would require a breakthrough.
Significantly, AngloGold was recently the first group to herald such a breakthrough with an apparently large degree of certainty. Within three to five years the group wants to develop machines to replace mineworkers at the stope face.
This target not only involves machines that can do the work of humans at the “coalface”, but also means the end of mining methods in standard use for more than a century.
AngloGold, and probably all its peers, wants to mine gold without using blasting to break up rocks.
Technology that can replace explosives in underground mines has for decades been the industry’s holy grail. There have been some premature announcements of a breakthrough. However, since the 1960s much such technology has been developed and successfully deployed in certain types of mines.
This includes a number of breakthroughs – from machines that extract coal from the underground seam to hydraulic fracking for freeing natural gas from underground shale.
For subsurface gold ore in hard rock there is unfortunately still nothing that works as well as drilling holes in the stope face and filling it with explosives.
The end of blasting operations is the primary target of the AngloGold Ashanti Technology and Innovation Consortium (AGATIC), a partnership created last year that includes a number of international capital goods manufacturers and research groups as members.
Through brainstorming sessions led by Robbie Lazare, the group’s vice-president of South African operations, AngloGold wants to find ways to mine deeper.
Within 10 years it hopes to remove people even further from the front and eventually, years later, even mine from the surface and possibly employ a leaching process. That is AGATIC’s “technology roadmap ”.
According to Reuters, Gold Fields chief executive Nick Holland is planning to introduce mine robotic technology in the future.
Peopleless mines
Peopleless mining will remain in the realm of science fiction for at least the next 40 to 50 years, says Jeremy Green, a researcher at the Council for Scientific and Industrial Research (CSIR).
But mining without blasting could become a reality considerably sooner.
“Things that were unthinkable five years ago have become possible. Just think what the car you drove a decade ago looked like.”
Green has been working together with a multidisciplinary team on the CSIR’s mine robot programme since 2009. If everything goes according to plan, they should produce a prototype robot to replace blasting by 2018.
The team’s first objective is to deliver, by March 2013, a prototype robot that really improves on the drilling-and-blasting method. The project has a budget of almost R40m.
Drilling and blasting as a rule involve a strict schedule of one daily simultaneous round of blasting in all of a mine’s stope faces. This usually takes place late in the afternoon with the changeover from day to night shift.
The mining teams must all complete their cleaning up and drilling on schedule and vacate the mine before blasting takes place, because of the obvious dangers.
If a mining team does not have its blasting materials ready on time, it loses that day’s chance of making progress on the stope face.
This, says Green, often happens and such lost rounds regularly number up to one-third of all blasting opportunities. Technology to lessen this problem could in some cases therefore improve both gold production and turnover by as much as a third.
The CSIR is developing a robot that can smooth the running of this cycle.
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