Implementing and Improving the Mine Plan at the Mt Wright Project

摘要

The Mt Wright Project is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold - a wholly owned subsidiary of Resolute Mining Limited. Underground Development of the current Mt Wright orebody commenced in June 2006 and the first production ore was brought to surface in June 2007. The orebody is a rhyolite pipe containing fine-grained disseminated gold in a granite host rock. Ground conditions tend to be good to excellent throughout development, with some minor deformation experienced when stope-sized excavations are formed. The mine commenced as a sublevel open stoping (SLOS) operation with the intent to utilise development waste to back fill isolated upper level stopes while developing to the bottom of the known orebody. The mine plan intended to commence production with a bottom-up primary/ secondary stoping retreat through the main orebody utilising cemented fill. Some challenges were faced during the initial production phase that included: 1.Ongoing underground diamond drilling and updating of the block model resulted in some issues reconciling the grade control results to the resource model. This was primarily due to the high variability of grade which in turn caused difficulties in accurately identifying areas of low and high-grade. 2.The cost of establishing and operating a cemented fill plant to achieve the planned extraction sequence of the orebody had increased significantly beyond initial estimations. 3.Geotechnical conditions such as stress orientations, ground behavior and response to the forming of excavations learned through the mining of the upper level stopes were different to the assumptions made during the initial design. A number of in-house and external reviews of the mining method were completed which has resulted in a revised mining plan. This paper will summarise the challenges faced and the implementation of the mine plan to date.