Red Back Mining Inc
A Growing Gold Producer - Africa
Message: Initial Underground Resource at Paboase and Suraw Chirano Reserve/Resource Updat
| March 30, 2009 | |||
| Red Back Mining Inc.: Initial Underground Resource at Paboase and Suraw Chirano Reserve/Resource Update | |||
|
VANCOUVER, BRITISH COLUMBIA--(Marketwire - March 30, 2009) - Red Back Mining Inc. (the "Company" or "Red Back") (TSX:RBI) announces an initial inferred resource for the Paboase South and Suraw underground deposits at its Chirano Gold Mine ("Chirano") in Ghana. The Company is also pleased to provide updated Mineral Reserves and Mineral Resources estimates at Chirano. Paboase and Suraw Based upon a 2008 first phase exploration program below the Paboase and Suraw open pits, the Company's consultants, Hellman and Schofield, have calculated an inferred underground resource as a first step in evaluating the economic potential of developing a second underground operation at Chirano. ----------------------------------------------
Paboase + Suraw
Inferred Underground Resource Estimate
2g/t gold cut off
----------------------------------------------
Deposit Tonnes Au (g/t) Ounces
(Mt) (Moz)
----------------------------------------------
Paboase South 2.27 3.5 0.25
----------------------------------------------
Suraw 1.87 4.1 0.24
----------------------------------------------
Total - - 0.49
----------------------------------------------
- Paboase South and Suraw Underground Resources are reported above a 2.0g/t
cut off and below the 2248m and 2224m elevations which are the base of
current open pit designs. Gold grades for the reported underground
resource model have been determined using Ordinary Kriging (OK) with
grades interpolated into parent blocks with dimensions of 2m (east) by 25m
(north) by 25m (elevation). Gold estimation and model blocks were
constrained within geologically derived wireframes.
Commenting on the new underground resource, Richard Clark, President and CEO of the Company, stated: "We are very encouraged by the initial inferred resources under the central part of the Chirano pit complex. Infill drilling of the surface deposits at Chirano over the last 3 years has identified the potential for other high grade underground operations, in addition to the Akwaaba Deeps discovery which is now in development. The new Paboase and Suraw underground resources clearly confirm this potential. Work will now continue at Paboase and Suraw towards establishing our second underground operation at Chirano." Chirano Resources The revised open pit and underground resources at Chirano as at December 31, 2008 are as follows: ----------------------------------------------
Open Pit Resource Estimate
1g/t gold cut off
----------------------------------------------
Resource Tonnes Au (g/t) Ounces
Category (Mt) (Moz)
----------------------------------------------
Measured 18.46 1.92 1.14
----------------------------------------------
Indicated 11.82 1.68 0.64
----------------------------------------------
Stockpiles 2.17 1.05 0.07
----------------------------------------------
Total Measured
and Indicated 32.46 1.78 1.85
----------------------------------------------
Inferred 5.26 1.7 0.28
----------------------------------------------
----------------------------------------------
Underground Resource Estimate
2g/t gold cut off
----------------------------------------------
Resource Tonnes Au (g/t) Ounces
Category (Mt) (Moz)
----------------------------------------------
Indicated
----------------------------------------------
Akwaaba Deeps 6.10 6.00 1.17
----------------------------------------------
Inferred
Akwaaba Deeps 0.40 3.4 0.04
Paboase South 2.27 3.5 0.25
Suraw 1.87 4.1 0.24
----------------------------------------------
Total Inferred 4.54 3.7 0.53
----------------------------------------------
- Open pit Mineral Resources are reported above a 1g/t cut off inclusive
of ROM/low grade stockpiles. Gold grades for the reported open pit
resource have been determined using Multiple Indicator Kriging (MIK) based
on block dimensions of 12.5m (east) x 25m (north) x 6m (elevation) and
using a selective mining unit of 2m (east) by 5m (north) by 2.5m
(elevation). Gold estimation and model blocks were constrained within
geologically derived wireframes. Due to the homogenous nature of the data
no top cut has been applied to the resource data prior to estimation.
It is observed that higher values in the dataset have little influence on
the grade of the deposit.
- Akwaaba Underground Resources are reported above a 2.0g/t cut off and
below the 2212mRL which is the base of the Akwaaba open pit. Gold grades
for the reported underground resource model have been determined using
Ordinary Kriging (OK) with grades interpolated into parent blocks with
dimensions of 5m (east) by 25m (north) by 10m (elevation). Gold
estimation and model blocks were constrained within geologically derived
wireframes.
- Paboase South and Suraw Underground Resources are reported above a 2.0g/t
cut off and below the 2248m and 2224m elevations which are the base of
current open pit designs. Gold grades for the reported underground
resource model have been determined using Ordinary Kriging (OK) with
grades interpolated into parent blocks with dimensions of 2m (east) by
25m (north) by 25m (elevation). Gold estimation and model blocks were
constrained within geologically derived wireframes.
- Open Pit and Akwaaba Deeps Mineral Resources are inclusive of Ore Reserves
The Company's consultants, AMC Consultants, have re-estimated Mineral Reserves for the Chirano mine, which are reported below as at 31 December 2008: ---------------------------------------------------------------------------
Area Proven Probable Total
---------------------------------------------------------------------------
Tonnes Au Ounces Tonnes Au Ounces Tonnes Au Ounces
(MT) (g/t) (Moz) (MT) (g/t) (Moz) (MT) (g/t) (Moz)
---------------------------------------------------------------------------
Open Pits 17.4 1.68 0.9 4.5 1.39 0.2 21.9 1.62 1.1
---------------------------------------------------------------------------
Stockpile 2.2 1.05 0.1 - - - 2.2 1.05 0.1
---------------------------------------------------------------------------
Total 19.6 1.61 1.0 4.5 1.39 0.2 24.1 1.57 1.2
---------------------------------------------------------------------------
---------------------------------------------------------------------------
Akwaaba
Deeps - - - 8.2 4.21 1.1 8.2 4.21 1.1
---------------------------------------------------------------------------
Notes:
Open Pits
- Numbers may not add correctly due to rounding
- The Mineral Reserve estimate was made using a gold price of US$700, no
change from previous Mineral Reserve estimate
- Various cut-off grades were used to estimate the Open pit inventories
and form the Mineral Reserve depending on material type and location
with an average breakeven cut-off drade in the range of 0.60g/t and
0.65 g/t.
Akwaaba Deeps
- The Underground Mineral Reserve is based on SLC design and comprises
development and production (stope) ore. Development ore includes only
the Indicated Resources that are intersected by the development
headings.
- For the SLC Stopes only Indicated Resource was included in the stoping
shapes for production levels 2175mRL to 1775mRL
- All unclassified material (zero grade) lying within the above SLC
Stopes was included as planned dilution essential for the mineable
SLC shape. Similarly a small portion of Inferred resource (and its
grade) required to define the SLC Stoping shapes was included as
planned dilution with modeled grade. The total quantity included
amounts to 1.08% of the SLC Stoping tonnes.
- A minimal quantity of inferred resource lying within the ore
development was also included as planned dilution with modeled grade.
The total quantity included amounts to less than 0.24% of the ore
development ounces. All Inferred resource & unclassified material
lying at the extremes of the ore body was excluded from the mine
design and SLC Stoping shapes.
- The reserve estimate is based upon a cutoff grade of 2.2g/t and a gold
price of US$700/oz.
Akwaaba Deeps Mineral Reserves have increased modestly since the previously reported reserve (News Release: July 29, 2008). The increase is due to enhancement of the reserve model following continuing geotechnical analysis. Development at Akwaaba Deeps continues on track with the decline now advanced 730 metres and to a depth of 85 metres from surface. The first production from sub-level caving is expected to commence in the second quarter of 2009. Production will then ramp up to approximately 50,000 tonnes per month in the third quarter, with a steady state mining rate of 100,000 tonnes per month expected to be reached on schedule in early 2010. About Red Back Red Back is an unhedged African focused gold producer. It owns and operates the Chirano Gold Mine in Ghana (90% interest) and the Tasiast Gold Mine in Mauritania (100% owned). Major plant expansions at both Chirano and Tasiast are well advanced with commissioning underway. Aggressive exploration programs aimed at increasing the Company's resource and reserve base at both Chirano and Tasiast are continuing. The independent Resource estimate reported herein was undertaken by Nic Johnson (Member of the Australian Institute of Geoscientists) of Hellman and Schofield Pty Ltd with more than five years experience in the use of geostatistics for estimation of recoverable resources in gold deposits. For the purpose of reporting under National Instrument 43-101 Mr. Johnson is regarded as a Qualified Person. The independent Surface Mineral Reserve estimate reported herein was undertaken under the supervision of Bruce Gregory (Member of the Australasian Institute of Mining and Metallurgy), Principal Mining Engineer of AMC Consultants Pty Ltd with more than five years experience in Ore Reserve estimation. For the purpose of reporting under National Instrument 43-101 Bruce Gregory is regarded as a Qualified Person. The independent Akwaaba Deeps Undergound Mineral Reserve estimate reported herein was undertaken by Tony Silveira (Member of the Australasian Institute of Mining and Metallurgy), Senior Mining Engineer of AMC Consultants Pty Ltd with more than five years experience in Ore Reserve estimation. For the purpose of reporting under National Instrument 43-101 Tony Silveira is regarded as a Qualified Person. The technical contents of this release have been reviewed by Hugh Stuart, BSc., MSc, a Qualified Person pursuant to NI 43-101. Mr. Stuart is the VP - Exploration of the Company and a Member of the Australasian Institute of Mining and Metallurgy. Samples are prepared and analyzed by fire assay using a 50 gram charge at the Analabs facility in Bibiani, Ghana in compliance with industry standards. Field duplicate samples are taken and blanks and standards are added to every batch submitted. Selected samples from this lab are check assayed each month at other Analabs laboratories worldwide. |
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