Hollister and Burnstone Operations Update
VANCOUVER - Great Basin Gold Ltd. reported operational update for the three months ended September 30, 2011 . The Company will file its Management Discussion and Analysis and interim financial statements for the third quarter.
Hollister operations produced 26,045 Au eqv ounces1 from trial mining activities during the quarter (Q2 2011: 26,757 Au eqv ounces). During the quarter, ore tonnes mined from the Hollister project increased 5% to 26,474 (Q2 2011: 25,297 tonnes) and tonnes processed at the Esmeralda mill increased by 34% from 22,237 to 29,869. The contained grade of 0.9 Au eqv oz/t was lower than the 1.35 Au eqv oz/t reported for the previous quarter, but is in-line with the reserve grade of the Hollister ore body. Notwithstanding the significant increase in tonnes processed during the quarter, gold and silver recoveries at the Esmeralda mill remained within the targeted levels at 92% Au and 74% Ag, respectively. The installation of the acid wash and carbon regeneration system at the Esmeralda Mill was completed during the first week in October 2011 and dorÄ is planned to be poured on site starting at the end of October 2011 . Only 22,790 Au eqv ounces were sold during the quarter with 6,850 Au eqv ounces remaining at the refiner that will be sold.
Primary waste development was again focused on the Blanket Zone ("BZ") spiral ramp, the BZ Alimak raise, and the 5400 BZ I-Drift. During the quarter, the BZ Ramp achieved 1,136 feet (344 meters) of advance; 204 feet (62 meters) of development remained at quarter end to complete the ramp. The 5400 I-drift, which originates from the BZ Alimak raise, was advanced 169 feet (51 meters) to the east during the quarter, with 161 feet (49 meters) remaining to reach the +1 opt Au grade shells modelled from surface and underground drilling for the 3000N 1W area.
Operational improvements continued at Burnstone, with mechanized ore development increasing by 80% quarter on quarter to 2,786 meters. Ore to waste development ratio also improved, with ore representing 67% of total development during the quarter. Following increased infill and cover drilling to identify geological structures and faulting, improved geological data and refinement of interpretations, waste development was reduced from 1,872 to 1,403 meters during Q3 2011.
Further optimization of the Long Hole Stoping mining method continued during the period with a revised stope lay-out design implemented that increases the square meters available for stoping for each meter of ore development by 88% from 9 to over 17 square meters. The revised layout, which could allow larger stopes to be mined, is still in its trial phase but positive preliminary results are already evident. This stope design change would have a short term impact as fewer stopes would be available, initially, for mining because of the increase in development meters required to open up the larger stopes. However, over the longer term this change could positively impact the ore tonnes mined per meter developed as well as cash costs on a per ton and per ounce basis. Notwithstanding the impact of opening up the larger stopes, the stoping square meters increased by 45% to 7,408 square meters during the quarter (Q2 2011: 5,122 square meters), with stoping widths of between 60 - 80 cm being achieved on a consistent basis. The contained gold grade from stoped material also increased by 39% to 3.57 g/t. The contained gold grade from development ore also increased by 25% to 0.80 g/t. Stope block availability is expected to increase steadily during Q4 2011.
The Metallurgical Plant continued to perform in-line with expectations, with 209,224 tonnes processed during the quarter. Although the last of the lower grade surface stock pile material was milled during the quarter, plant recoveries improved to 89% mainly due to the higher grades of stope and development tonnes provided from underground.
Although recovered ounces of gold were below planned levels, the gold recovered increased by 33% quarter on quarter to 6,486 ounces with sales of 6,518 ounces recorded.