Fariraishe Nyoni - South Africa

Fariraishe is an undergraduate mining engineering student at the University of Zimbabwe. He started his undergraduate studies in 2013 and is set to graduate in September 2018 with a Bachelor of Science Honours in Mining Engineering. In his third year, Fariraishe worked at Anglo American Underground Platinum, where he started his current project which aims to increase the blast advance in underground platinum mines. The project received interest from the mine which went on to allow Fariraishe to carry out numerous trials throughout the mine.

Fariraishe has also participated in Engineering Paperette Poster Presentations where he presented the same project. He enjoys solving engineering problems and has a passion for blasting and explosives science.

Burn cut optimisation to increase blast advance at Unki mine

In underground blasting, the pull of the initial cut is the limiting factor for the success of the rest of the round. Unki mine had been failing to obtain target underground blast advance of 3m using a 9hole cylindrical burn cut for its blast, creating a lot of problems in costs and safety. This project was aimed at optimising the 9hole cylindrical burn cut's effective pull by increasing the depths of the relief holes in the cut. By improving the pull of the first cut, a critical step is made towards improving the entire round and solving the problem of advance. In testing, relief holes were drilled to depths longer than that of the cut's charged holes by an increasing depth of 100mm through each trial. The overall objective was to achieve a blast advance of 3 metres or better, using an economic method and the existing drilling equipment at Unki.

Increased pull would result in savings of both time and cost at Unki mine and would also allow the mine to achieve target blasted production ore values. The testing was done in the Chazezesa 9South underground section at Unki mine. Full blast rounds utilising the 9hole cylindrical burn were drilled and blasted. After completing al testing and analysing results, this data suggested that an average advance of 3.08 metres was being obtained through the application of relied holes increased in depth by 300mm. The trials consistently showed an average advance increase of 0.28m. This provided a solution to the problem of failure to meet target advance at Unki mine. The charge was also analysed to only increase the drilling costs by 5% which is within an acceptable range, considering the ore gained from the improvement in blast advance and the costs of re-drilling, charging and blasting the bootleg left by failure to meet target advance.

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