Great Basin Gold Provides Operational and Exploration Update
VANCOUVER, March 7, 2012 /PRNewswire/ - Great Basin Gold Ltd. ("Great Basin Gold" or the "Company"), (TSX: GBG; NYSE Amex: GBG; JSE: GBG) provides updates on progress at operations and exploration and drilling results for its Hollister Project and Burnstone Mine.
- Hollister operations and exploration results continue to deliver
- Hollister 2012 Production Targets - 90,000 to 100,000 Au eqv oz at a cash cost of US$700 - 750 per Au eqv oz1
- Significant progress on Burnstone ramp up since the end of December 2011
- Water issues resolved
- Reef development ends up 19% to 38
- Reef development rates achieving planned levels of 40 meters per reef development end per month
- Square meters available for stoping up 71% to 12,356 sq meters with an additional 6,000 sq meters partially developed
- Productivity underground improving through de-bottlenecking and infrastructure development, and
- Mine expected to be cash flow positive (after capital investment) by early Q3 2012
- Burnstone 2012 Production Targets - 90,000 to 100,000 Au oz at a cash cost of US$900 - US$1,000 per oz
Ferdi Dippenaar, Great Basin Gold President and CEO, commented: "With improvements, both made and planned, to underground infrastructure at Burnstone, the build-up is proceeding well to reach our milestone of 1,500 ore development meters per month in Q2 2012 and our interim production milestone of 10,000 oz per month in early Q3 2012. This will lay the foundation for the project to achieve its potential optimal production rates of 220,000 - 250,000 Au oz per annum, and including Hollister, for the Company to achieve 320,000 - 350,000 Au eqv oz in total production per annum.
The exploration results for Burnstone, and even more so Hollister, underscore the highly prospective nature of the two ore bodies. Although exploration expenditure was cut back in 2011 to ensure that cash flow was directed at our Burnstone Mine development, more exploration is planned at Hollister, and later also at Esmeralda, as cash resources become available.
We understand the faulting and flooding at Burnstone and have plans in place to deal with them, including temporary water handling, which should see a significant improvement to performance in 2012."
PROGRESS AT OPERATIONS
The Nevada operations continue to deliver results from trial mining activities in line with the previously announced production targets. Additional emphasis on ore development is improving mining flexibility with the availability of additional stopes allowing for improved grade blending of extracted ore and more consistent performance on a monthly basis. The completion of the Upper-Zone ramp now allows for easy access for delineation drilling, with information obtained improving mine planning and scheduling. Pouring of doré at the Esmeralda mill is still impacted by the underperformance of the acid wash and carbon regeneration circuit. The improvements to the circuit, which will allow for all recovered metal to be poured on site again, are expected to be completed by April 2012. In the interim, an estimated 20,000 Au eqv oz contained in carbon available at the end of February 2012 will be processed at Rand Refinery during March 2012. 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 from trial mining.
South African operations
The Burnstone Mine continues to make progress in early 2012 towards resolving certain issues that have restrained the planned production build-up.
Underground flooding experienced in the latter part of 2011 and early 2012 had an impact on the advancement of development. This issue has 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 improve rates of development and stoping. Reef development ends have increased from 32 in December 2011 to 38 by the end of February 2012. As the remaining 12 temporarily flooded ore development ends become available during the quarter, the mine plans to meet its first development milestone of 1,500 ore development meters per month in Q2 2012, allowing the mine to reach its first production milestone of 22,000 sq meters of stoping and a production rate in excess of 10,000 oz per month in early Q3 2012. To achieve these rates, the mine will need a minimum of 38 ore development ends and each development end must advance on average by approximately 40 meters a month. By the end of February 2012, ore development rates in excess of 38 meters per end per month were being achieved.
In order to alleviate congestion and to prepare for the planned increase in blasted ore tonnes as development rates increase, removing blasted material from underground received preferential attention during February 2012. Drilling of stopes, however, also continued during this period which should allow for an increased rate of production build up from March 2012. Over 12,356 sq meters (up from 7,205 in December 2011) were available for stoping at the end of February 2012, with just over 6,000 additional sq meters under development. 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 feed grade of material delivered to the mill.
The continuing development of stoping blocks will open up additional development ends at increasing rates. This will allow ore development to increase to an average of 2,500 meters per month from approximately 63 development ends by Q4 2012. This additional development is expected to provide additional mining flexibility with an estimated eight months of mineable reserves being available by the end of 2012, and further enhance the production build up during 2013 and 2014 to steady state production. The Company is also focusing on infrastructure improvements to enhance capacity and productivity of ore handling underground, which includes a previously completed automated ore loading system, an ore conveyer belt system from C Block, a decline ramp down to the shaft bottom to allow for effective spillage clean-up and the completion of the first of three permanent clear water and settler dams by July 2012.
Following a review of the current production levels and progress of underground development and infrastructure, the Company expects Burnstone to produce between 90,000 to 100,000 Au oz at a cash cost of US$900 - US$1,000 per oz for the 2012 fiscal year. These cash cost targets represent a marked improvement on the US$1,737 per oz achieved in 2011. As planned, the high ratio of development to stoping ore will continue to impact on the head grade delivered to the mill and cash costs for the balance of 2012.
All equipment required for the production build up is in place. All of our mining teams are currently in place and are undergoing intensive refresher team training to enable them to plan, assess and adjust to the constantly increasing rate of production.
The expected production range also contemplates the previously mentioned upgrade and completion of underground and shaft infrastructure. The Company expects that achieving the planned production build-up will allow Burnstone to turn cash flow positive after capital investment (using a gold price of US$1,650/oz and a US$/ZAR exchange rate of 7.5) during Q3 2012.
At Hollister, highlights include drilling results from the SE Gwenivere target, Upper Level drilling, and Upper Level mine infrastructure plans, as well as advances in the geothermal system mapping and planned drilling for 2012.
At Burnstone drilling strategies are improving the modeling of structures that, in certain areas, displace the Kimberley Reef horizon. Channel sampling continues to underpin positive grade and channel width trends in the mine development.
Underground Drilling and Exploration
Underground exploration and stope delineation drilling has continued during the latter half of 2011 and in January 2012. In total, 89 boreholes for 26,304 feet (7,971 meters) have been completed. These comprised 29 exploration and cover boreholes testing Clementine and SE Gwenivere targets (totaling 13,114 feet or 3,974 meters), 28 Upper Level (formally Blanket Zone) exploration/evaluation holes (totaling 6,908 feet or 2,093 meters), and 32 stope delineation holes (totaling 6,282 feet or 1,904 meters). After reduction to one rig following Q2 2011, the operation has gradually built up to four underground rigs operating: one for epithermal vein/stope delineation, two small man portables for Upper Level evaluation fan drilling, and a larger LM-90 rig commissioned specifically for the current drilling program under the Hollister open-pit excavations. Summary statistics are shown in Table 1.
Table 1: Hollister summary drilling statistics over the period July 2011 - January 2012
|UG Exploration & Cover||29||92||1.7||0.953||32.62||1.5||51.8||22.170||9.1|
|UG Upper Level evaluation||28||101||3.2||0.414||14.175||1.3||45.3||7.119||17.5|
|UG Stope delineation||32||134||1.2||0.639||21.892||3.7||128.0||7.068||5.0|
Note: (Table 1) Average grades to date of all intersections are around 0.4 opt Au (14.17 g/t Au) over 3.2 feet (1 meter) width.
Upper Level exploration
A ramp and an alimak raise accessing the Upper Level zones (previously Blanket Zone) of mineralization around the Tertiary - Ordovician unconformity has been completed to 5278 Level, from which I drifting has progressed towards high grade (+1 opt Au) shells formed above the Clementine (16-20) and Gwenivere (8-10) vein systems. This infrastructure has been vital in enabling the initiation of short fan drilling by recently commissioned Bazooka and SJ 252 drilling rigs. Highlights from the Upper Level exploration and evaluation drilling are shown in Table 2 (below). This phase of drilling is providing the basis for targeting trial stoping areas, and it is expected that there will be a commensurate increase in Indicated resources resulting from this work.
Table 2: Upper Level drill highlights
|Upper Level evaluation||Drill Hole ID||
|Vein System||Vein ID||From||To||Au (opt)||Au (g/t)||Ag (opt)||Ag (g/t)|
Other UG Exploration drilling
During the period under review, 29 boreholes (13,114 feet or 3,974 meters) were completed, providing more infill coverage on the Clementine system, as well as exploring and providing more definition on the SE Gwenivere target. Highlight intersections
(>0.3 opt/10 g/t Au) are given below. The SE Gwenivere veins continue to give exciting high grade intersections over narrow widths, which do add complexity to the vein modeling.
Table 3: Highlight intersections (> 0.3 opt / 10 g/t Au) for underground exploration and cover drilling
|Veins||Drill Hole ID||
|Vein System||Vein ID||From||To||Au (opt)||Au (g/t)||Ag (opt)||Ag (g/t)|
Stope delineation on the Gwenivere and Clementine vein systems continued, and a total of 32 boreholes have realized a further 134 vein intersections. Highlight intersections (>0.7 opt/25 g/t Au) are given below:
Table 4: Highlight intersections (> 0.7 opt / 25 g/t Au) for stope delineation drilling
|Veins||Drill Hole ID||
|Vein System||Vein ID||From||To||Au (opt)||Au (g/t)||Ag (opt)||Ag (g/t)|
A phase of detailed surface mapping was completed during the summer field season, and has now been integrated with the sub-regional and minesite scale collation and interpretation of airborne magnetic, ground CSAMT (high resolution resistivity) and gravity data. The detailed surface work is providing significant support to the CSAMT interpretations (correlation of high resistivity spikes with volcanic vents/geyserites and hydrothermal breccias zones), as well as providing clear evidence for the western extension of Gwenivere/Clementine system, supported by volcanic features at surface. Currently 15 significant vent areas, have been identified which indicates an ideal environment for mineral formation/deposition.
Drill programs planned for the 2012 field season have been refined to test numerous features detailed by the geological synopsis. The Hatter Graben area will be drilled to a resource classification should adequate funds be available, and the Butte East and South Velvet targets which are supported by the mapping and CSAMT interpretations. CSAMT high resolution resistivity data has been integrated with the surface mapping, plus empirical borehole data, and a number of new vein system targets are emerging from this work.
The 2011 Mineral resource update for Hollister has been delayed due to QAQC issues with Ag analyses over the period from July 2010 to June 2011. Pulps have been check assayed and certain changes have been made with respect to the preparation and acid digestion procedures for the assays. It is anticipated that the resource estimate will be completed before the end of Q1 2012 and made available during Q2 2012. In the meantime, a very rigorous Indicator Kriging model has been applied for testing and forecasting trial mining tonnages and grades.
Underground and Surface Evaluation
Infill drilling from surface is being undertaken to tighten up on the evaluation and structural geometry of certain mining blocks. Each drill station is providing four "umbrella" intersections around a vertical "mother hole", and Kimberley Reef intersections approximately 100 meters apart. Since the discovery of Graben faulting in the B2 area underground in January 2011, 45 surface boreholes have been completed. Table 5 shows summary surface drilling statistics and Table 6 Kimberley Reef intersections from the infill surface drilling program.
Table 5: Summary surface infill drilling statistics - Kimberley Reef
Underground evaluation is principally conducted and effected by channel sampling of exposed sidewalls of development drives and stope panels. Horizontal or shallow dipping cover drilling is undertaken for development control. The summary gold grade (g/t), channel width (cw) and gold content (cmg/t) statistics for the various mining blocks up to the end of January 2012 are shown below in Table 6. To date, nearly 18,000 channel samples have been taken.
Table 6: Summary Channel Sample results to end January 2012
|N = 17,829|
These results are in-line with or better than mine development expectations. The Life-of-Mine plan indicates an average channel width of 68 cm compared to the 45 cm reported in the Feasibility Study.
The opening up of Kimberley Reef exposures with the underground mine development has provided a major increase in evaluation data, namely through channel sampling and mapping. The previous phases of surface drilling leading up to the feasibility study and subsequent mine development, because of their vertical orientation, missed intersecting numerous post - mineral (i.e. after formation of the Kimberley Reef) faults. Certain undetected structures, including Graben structure in the B2 mine block area with an 80 meter movement, have seriously disrupted the mine development momentum. Preliminary investigations into conducting a 3D seismic survey have been undertaken, which will only be completed within a 15 to 18 month period.
In order to better develop the structural model of the mine, orientation studies have been initiated testing Downhole Radar and a Magneto-Telluric ground IP system. These geophysical methods may provide more timely and ongoing cost effective "mapping tools" so as to further mitigate structural discontinuities of the Kimberley Reef.
The Company has received notification from Gold Fields Limited ("Gold Fields") that it intends to seek rescission of an agreement under which Gold Fields cancelled a 2% net smelter royalty over a majority of Area 1 of the Burnstone mine. Under that transaction Gold Fields cancelled the royalty for consideration of ZAR 80 million ($11 million) and on the condition that Gold Fields should receive certain Mining Charter score card credits from the South African government. As Gold Fields has not received these credits, the Company and Gold Fields are seeking a mutually acceptable outcome and management does not expect this issue to have an impact on the Company's near term cashflow, development or production targets set in this release.
Technical information herein has been reviewed and approved by Phil Bentley, Pr.Sci.Nat., Great Basin Gold's Vice President: Geology & Exploration. Mr Bentley is a Qualified Person as defined by Canadian Securities Regulations in National Instrument 43-101.
President and CEO
Samples collected from the Hollister Project are delivered to Pinnacle
Assay Labs (Lovelock, Nevada) and / or Inspectorate America Corporation
(Inspectorate) in Sparks, Nevada. Vein samples are analyzed by
standard fire assay procedures. For standard fire assay, vein sample
preparation consists of drying and jaw-crushing the entire sample to
90% passing 10-mesh, taking a 300 g sub-sample using a Jones splitter,
and then pulverizing the 300 g sub-sample to 90% passing 150-mesh using
a large capacity ring and puck pulverizer. A 30 g charge is fire
assayed. All metal determinations are by gravimetric finish.
Laboratory Quality Assurance/Quality Control (QA/QC) is monitored using
coarse reject blanks and assay standards, duplicate fire assays, and
Inspectorate's internal standards and blanks. Coarse blanks (barren
rhyolite or landscape marble) and assay standards are inserted into the
sample sequence as blind samples prior to submitting the samples to the
laboratory. Inspectorate also inserts assay standards and blanks into
the sample stream. QA/QC results are within acceptable limits.
Samples collected from the Burnstone Mine are delivered to ALS Chemex in Johannesburg, South Africa. Borehole core and channel samples of Kimberley Reef are analyzed by standard fire assay procedures. For standard fire assay, vein sample preparation consists of drying and jaw-crushing the entire sample to 70% passing 10-mesh (2mm), taking a 400 g sub-sample using a Jones splitter, and then pulverizing the 400 g sub-sample to 90% passing 150-mesh using a large capacity ring and puck pulverizer. Three 50 g charges are fire assayed. All metal determinations are by gravimetric finish. Laboratory Quality Assurance/Quality Control (QA/QC) is monitored using coarse reject blanks and assay standards, duplicate fire assays, and ALS Chemex internal standards and blanks. Coarse blanks (barren basalt or quartzite) and assay standards are inserted into the sample sequence as blind samples prior to submitting the samples to the laboratory. ALS Chemex also inserts assay standards and blanks into the sample stream. QA/QC results are within acceptable limits.
This document contains "forward-looking statements" that were based on Great Basin Gold's expectations, estimates and projections as of the dates as of which those statements were made. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as "outlook", "anticipate", "project", "target", "believe", "estimate", "expect", "intend", "should" and similar expressions. Forward-looking statements are subject to known and unknown risks, uncertainties and other factors that may cause the Company's actual results, level of activity, performance or achievements to be materially different from those expressed or implied by such forward-looking statements. These include but are not limited to:
- uncertainties and costs related to the Company's exploration and development activities, such as those associated with determining the extent of mineral resources or reserves which exist on a property;
- uncertainties related to feasibility studies that provide estimates of expected or anticipated costs, expenditures and economic returns from a mining project; uncertainties related to expected production rates, timing of production and the cash and total costs of production and milling;
- uncertainties related to the ability to obtain necessary licenses, permits, electricity, surface rights and title for development projects;
- operating and technical difficulties in connection with mining development activities;
- uncertainties related to the accuracy of our mineral reserve and mineral resource estimates and our estimates of future production and future cash and total costs of production, and the geotechnical or hydrogeological nature of ore deposits, and diminishing quantities or grades of mineral reserves;
- uncertainties related to unexpected political, judicial or regulatory proceedings;
- changes in, and the effects of, the laws, regulations and government policies affecting our mining operations, particularly laws, regulations and policies relating to
- mine expansions, environmental protection and associated compliance costs arising from exploration, mine development, mine operations and mine closures;
- expected effective future tax rates in jurisdictions in which our operations are located;
- the protection of the health and safety of mine workers; and
- mineral rights ownership in countries where our mineral deposits are located, including the effect of the Mineral and Petroleum Resources Development Act (South Africa);
- changes in general economic conditions, the financial markets and in the demand and market price for gold, silver and other minerals and commodities, such as diesel fuel, coal, petroleum coke, steel, concrete, electricity and other forms of energy, mining equipment, and fluctuations in exchange rates, particularly with respect to the value of the U.S. dollar, Canadian dollar and South African rand;
- unusual or unexpected formation, cave-ins, flooding, pressures, and precious metals losses (and the risk of inadequate insurance or inability to obtain insurance to cover these risks);
- changes in accounting policies and methods we use to report our financial condition, including uncertainties associated with critical accounting assumptions and estimates;
- environmental issues and liabilities associated with mining including processing and stock piling ore;
- geopolitical uncertainty and political and economic instability in countries which we operate; and
- labour strikes, work stoppages, or other interruptions to, or difficulties in, the employment of labour in markets in which we operate mines, or environmental hazards, industrial accidents or other events or occurrences, including third party interference that interrupt the production of minerals in our mines.
For further information on Great Basin Gold, investors should review the Company's annual Form 40-F filing with the United States Securities and Exchange Commission www.sec.com and home jurisdiction filings that are available at www.sedar.com.
1Gold equivalent ("Au eqv") calculations use US$1,650/oz for Au and US$30/oz for Ag.
SOURCE Great Basin Gold Ltd.