African Mining September 2019 | Page 41

MINING IN FOCUS  Mechanisation not new Mechanisation is not a brand-new idea. South African underground mines have been grappling with its implementation since the early 80s, and they are still not close to an acceptable solution. Great strides have been made, nevertheless, and there are several examples that can serve as case studies for making mining in deep underground environments safer and improving efficiencies and productivity by introducing mechanised methods. Consulting engineer Roger Dixon has spent more than 47 years in the South African mining industry, many of those on projects aimed at introducing mechanised methods. Dixon was one of the guest speakers at the recent African Mining Network, of which African Mining is one of the sponsors. Dixon says a mine needs a clear vision and strategy to successfully introduce mechanised mining into platinum or gold mines in South Africa. “In 1994, when I worked at Anglovaal, we had a long-term vision and asked ourselves where we would get an individual rock drill operator from in 20 years,” says Dixon. At that stage, he adds, the average age of all rock drill operators in South African mines was older than 40. “No matter what we did, using non-mechanised methods was not going to be sustainable, so we introduced mechanised equipment, mostly on the Elsburg Reefs in the Witwatersrand Basin.” “More importantly, you have to pick the right team. The greatest soccer teams in the world appoint the best managers, who in turn buy the best players to suit their game plan. And in most cases, they never use old players. It should be the same in a mining operation.” Dixon emphasises the need to be adaptable to change. “If the geology becomes complex, for example, you have to be willing and able to change the original design. If there is too much dilution, the design needs to change, bearing in mind that these machines are large and they don’t like inclinations above nine degrees. “For the Target project we redesigned the infrastructure at Anglovaal’s Loraine mine in the Free State because the mine initially had a vertical shaft and a sub-vertical shaft, and all these new machines had to be cut up in 1.5m x 1.5m pieces to get them down the shaft. Eventually we replaced the sub-vertical shaft with a decline, and introduced a man-riding conveyor (the first in South Africa) and a monorail system,” says Dixon. "Using locally manufactured equipment will increase productivity and employment, and will drive down cost. He adds that the mine also redesigned the organisational structure. “Everything was centred around the drill rig operator, who worked alongside a Load Haul Dump (LHD) driver who did the cleaning, somebody responsible for the support and a charger-up. We did away with the seven supervisory levels in the traditional mine. This requires a total change in mindset, and it was maybe a step too far for the older, traditional miners.” Lonmin, under then CEO Brad Mills, had a great vision to mechanise their platinum operations in the late The problem at that stage, and it still is today, is that machines don’t work that effectively on inclines steeper than nine degrees. Mechanising thus often requires a mining company to redesign the entire infrastructure. It is difficult to adapt existing infrastructure to suit these big machines, and then it’s very challenging to prevent dilution. Part of the mechanisation process, says Dixon, is to involve all stakeholders, including communities and the labour unions. Gold Field’s South Deep mine is one of the few mechanised underground mines in South Africa. www. africanmining.co.za African Mining Publication African Mining African Mining  September 2019  39