WANT A HOLE? YOU GOT IT!
A local mine drilling company this week launched a new type of tunnel boring method that it hopes will become a competitive means to make horizontal tunnels, bring down costs, speed up mining and improve safety.
Master Drilling, which is listed on the JSE, is testing the method – horizontal raise boring – at Petra Diamonds’ mine in Cullinan near Pretoria in a trial that entails drilling a 220m tunnel. The project employs 30 to 40 people.
Danie Pretorius, the CEO of Master Drilling, said the company was hoping the system could be applied in the mining, civil and energy sectors.
In the civil sector, horizontal raise boring could be used for excavating tunnels through mountains or hills, connecting parallel metro and railway tunnels, as well as for tunnels required to run underneath roads.
In the energy sector, horizontal raise boring could be used for nuclear storage tunnels or short tail races in hydroelectric plants.
The advantages connected with horizontal raise boring include less need for support compared with conventional drilling and blasting methods, which use explosives.
“The continuous excavating cycle, and the circular structure of the excavation, leave a stronger profile tunnel,” Master Drilling said in a brochure issued at the Mining Indaba in Cape Town this week.
“In certain locations, it is impossible to assemble a tunnel boring machine due to its length and size. Under the circumstances, establishing a plant for horizontal raise boring operations is quicker and easier to implement,” the company added.
“Horizontal raise boring technology is more costeffective and is, in some cases, a more reliable system compared with a tunnel boring machine system,” Master Drilling said.
Koos Jordaan, the executive director of Master Drilling, said horizontal raise boring could develop into a new tunnelling method.
Horizontal raise boring also consumes far less power than a tunnel boring machine does.
Jordaan said aspects of the horizontal raise boring system had been patented and added that horizontal raise boring could diversify the services provided by Master Drilling.
Horizontal raise boring could double or triple the productivity compared with drilling and blasting, which advances at 2m a day.
Horizontal raise boring also requires fewer people than drilling and blasting does.
Another advantage of horizontal raise boring is that it
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Pretorius declined to disclose the investment that the company had made in the new technology.
Teon Swanepoel, Petra Diamonds’ mining executive, said there were vast benefits that could flow from horizontal raise boring “if it worked”.
Swanepoel said that horizontal raise boring created a “consistent tunnel shape” compared with drilling and blasting, which create an irregular shape and is a “violent exercise”.
“Horizontal raise boring is an all-round safer activity when compared with drilling and blasting.”
Master Drilling has operations in South Africa, in other African countries, including the Democratic Republic of Congo, Mali, Zambia, Sierra Leone and Tanzania, and in Latin America, the US and China.
DEEP DIVING Cullinan An example of the effectiveness of the machine at Petra Diamonds’ mine in