Hollister Continues Production Increase
VANCOUVER - Great Basin Gold Ltd. reported that the Hollister Nevada operations produced 97,610 Au eqv oz for the year (2010: 95,186 Au eqv oz), compared to the forecast of 100,000 Au eqv oz for the year. Fiscal 2011 was the first year that all material extracted from trial mining activities was processed at our Esmeralda mill, which showed a marked improvement in Au recovery from 2010, increasing from 82% to 92%. The performance of the acid wash and carbon regeneration circuit, which was commissioned during November 2011, has not yet reached planned levels and the mill continues with the process of replacing carbon on a continuous basis which, in the short term, impacts on the amount of Au eqv oz sold as well as the cash costs reported. In an effort to mitigate the time delay in recognizing produced metal as revenue and the insufficient capacity of local refiners, a shipment of loaded carbon was sent to Rand Refinery in South Africa in late December 2011 at an additional cost of approximately US$35 per Au eqv oz. Regular shipments of carbon to Rand Refinery will continue until April 2012 when the improvements to the acid wash and carbon regeneration circuit is expected to be completed. The year-on-year cash costs decreased by 9% to US$674 per Au eqv oz which is only marginally above the 2011 forecast of US$650 per Au eqv oz.
Additional emphasis on ore development is improving mining flexibility with the availability of additional stopes allowing for improved grade blending of extracted ore and a more consistent performance on a monthly basis is expected during 2012. The completion of the Upper-Zone ramp now allows for easy access for delineation drilling, with information obtained improving mine planning and scheduling. The good operational performance from the Nevada Operations is expected to continue in 2012, with production of 90,000 to 100,000 Au eqv oz at a cash cost of US$700- 750 per Au eqv oz expected from trial mining.
The production ramp up at Burnstone continued during 2011, with ore development meters increasing by 149% from 1,167 meters in Q1 2011 to 2,900 meters in Q4 2011. Stoping square meters also increased by 77% from 3,760 in Q1 2011 to 6,653 in Q4 2011. Results from the long hole stoping mining method remain positive, with stoping widths of approximately 80 cm being achieved on a consistent basis. Improved dilution control on ore development is positively impacting on the head grade of material delivered to the mill. An 80 meter Graben fault was intersected in early 2011 and this, as well as infrastructural challenges experienced during the year, significantly impacted on the first year of production build-up at Burnstone. The temporary water handling system was unable to handle the volumes of water generated from the increasing mining activities, so underground flooding occurred in the latter part of 2011 and early 2012, which has impacted on the advancement of development. This short term issue has now been resolved following the upgrading of the temporary water handling system. Additional pumps and back-up pump columns are providing additional capacity to not only reticulate the water, but also to transport service water to all working ends, which will further improve rates of development and stoping. Permanent water reticulation infrastructure is under construction for completion in Q2 2012.