Challenges and Lessons Learnt Operating the Tiwest ‘North Mine’ (Cooljarloo Mine, Western Australia)

摘要

The Cooljarloo North Mine has been shaped not only by operational and processing challenges, but by climatic and economic factors. This paper outlines some of these challenges and discusses how the operating strategy has been altered over time to mitigate the impacts. Since commissioning the wet concentrator in 1999, there have been many typical operational challenges to maximising valuable heavy mineral (VHM) recovery. These include: varying in pit feed grades, different slimes types and volumes, sizing extremes between VHM and trash minerals and decreased equipment reliability handling rocky ore. These issues were successfully mitigated by: 1.in pit extraction strategies, 2.upgrade of the de-sliming circuit, 3.thickener modifi cations and fl occulent changes, 4.installing upgraded and additional spiral capacity, and 5.various Feed Preparation Plant screening initiatives. Combined with the ingenuity, persistence and patience of the operating team, VHM recovery >95 per cent has been achieved. However, typical processing challenges have not been the only hurdles. Reduced rainfall and water availability has necessitated the strategic co-disposal of tailings and slime to increase the speed of water recovery: groundwater abstraction and water storage strategies have also been altered. With an observed reduction in the speed and magnitude of groundwater recharge, overburden backfi ll scheduling has become a priority mine planning function. Combined with the above challenges, the prevailing foreign exchange rate and mineral product prices have impacted profi tability. At the height of the Global Financial Crisis in 2009, major changes to the operating strategy were made to maintain a viable dry mining operation in 2010. Working with the mining contractor the existing scraper and semi-fi xed Feed Preparation Plant set up was replaced with a movable in pit dozer trap facility. The end result of changes to the mining method and primary screening was a ten per cent reduction in unit costs. This article will elaborate on some of the above mentioned challenges and successes achieved over the past ten years of operating the Cooljarloo North Mine.