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Feasibility to Mine Completion – The Real Impacts on Project Economics


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Author A Harris, K Laughton and J Ranford


The Angas Zinc Mine (Angas) is a poly-metallic, underground mine in the Adelaide Hills that has been developed through arguably one of the most volatile financial time periods in living memory. From boom times during the commencement of the project, the global financial crisis (GFC) through the stabilisation of the operating period and then a subdued capital market for the period where mine life extension was targeted, the financial environment has always presented a different set of challenges. Indeed even the Underground Operators’ Conferences that have been held across the span of the project allude to these changes: ‘Boom and Beyond’, Launceston (2008); ‘Safe, Innovative and Sustainable’, Canberra (2011) and ‘Managing the Margin’ in Adelaide (2014).

Angas gives a
rare opportunity to see the entire life-of-mine of a project and its economic
performance within a relatively short time frame. Angas, owned and operated by
Terramin Australia Ltd (Terramin), will have undergone resource estimation drill
out, feasibility study, permitting, commissioning, operating and completion and
rehabilitation all within a period of approximately ten years. A number of
sensitivities of the project were tested, particularly in the bankable
feasibility study (BFS) stage and the aim of this paper is to identify the
factors that impacted the operations profitability the most, whether they were
identified preproduction or not. The key sensitivities assessed in the BFS were
typical of similar studies, including operating costs, metal recoveries, capital
costs, zinc prices, lead prices and exchange rates. The manner in which these
sensitivities presented themselves in real life were not as anticipated and
modelled in the feasibility study and were also heavily impacted by technical


Harris, A, Laughton, K and Ranford,
J, 2014. Feasibility to mine completion – the real impacts on project economics,
in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 99–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).