DRILL & BLAST
CUTTER FOR GOLD VEIN MINING Gold veins, be it vertical or near-vertical, often constitute a challenge to miners. Te small size of the ore body over great length and only little exposure to surface makes it difficult to mine economically. Open-pit mining of such ore bodies often comes to an end soon, due to the high stripping ratio and the enormous environmental impact. Underground mining is expensive for the development and for mining due to the tight working conditions in the fissures. A combination of both – cutter mining to about 250m depth and underground mining below cutter mining – reduces development time and cost considerably and generates revenues at a very early stage of a new mining project. Koidu, a BGS company, holds diamond mining leases in Sierra Leone for kimberlites, mostly kimberlite dykes. Jointly, the idea was conceived to use trench cutter equipment as a mining tool to excavate these dykes to greater depth. Despite the remote location of the leases in eastern Sierra Leone a test was carried out with a BC 33 cutter in 2010. Te cutter width chosen was 800mm, based on Koidu’s assumption of a dyke width between 800 and 1,000mm.
A SUSTAINABLE AND SELECTIVE MINING SYSTEM Te selective cutter mining system for gold veins will concentrate on the excavation of the vertical or near-vertical ore body only. Tere are several key advantages of such a system, including the fact that mining of so far uneconomic small ore bodies and veins becomes viable. Tis approach allows operators to avoid open pit mining with a large environmental footprint and mine dumps and it doesn’t require any underground development – meaning
Near vertical gold veins, Kubi Mine. Graphic courtesy of Asante Gold
Alternative view of the near-vertical gold veins at the Kubi Mine
there is a much lower installation cost. Minimum dilution of ore (almost zero strip ratio) is another advantage. Additional benefits include increasing the mine lifespan after open pit mining ends without increasing the environmental footprint as well as increasing the mine life without any additional infrastructure. Finally, time to mine is extremely short and equipment can be used on several ore bodies or even mine sites. Mining has always been at the centre
Bauer cutter with hose winding system on a mine shaft project in UK
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of various interests. Economic viability, environmental impact and social acceptance are key factors that must be balanced to achieve a sustainable mining solution.
Cutter vein mining with its no, or
very low, additional environmental impact and optimised economics by mining the ore body only, can achieve a much better acceptance from the authorities, and the public, than conventional mining. Cutter mining systems help to satisfy the demand for the much-needed commodities in our modern society that are increasingly focused on sustainability.
Stefan Schwank and Ulrich Schoepf are with Bauer Maschinen.
www.bauer.de
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