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14
MODERN MINING
June 2015
MINING News
Reserve growth at Twangiza extends mine life
Banro Corporation has provided an update
of its mineral resource and mineral reserve
estimates at its wholly-owned projects on
theTwangiza-Namoya gold belt in the DRC.
The annual review of resources and
reserves at the company’s four core proj-
ects, Twangiza, Namoya, Lugushwa and
Kamituga, has resulted in a substantial
increase in mineral reserves with the
conversion of transition and fresh min-
eral resources into mineral reserves at
Twangiza, one of the company’s two oper-
ating mines.
The Twangiza proven and probable
reserves have increased 59 % to 1,64 mil-
lion ounces of gold (22,38 Mt at 2,28 g/t
Au) with the inclusion of non-oxide mate-
rials in the reserve pit shell which have
been proven to be economically treat-
able with the existing plant. This expands
the Twangiza mine life utilising the exist-
ing plant to 14 years. At Namoya, Banro’s
second mine, the proven and probable
mineral reserves have decreased 5 % to
1,27 Moz (20,53 Mt at 1,92 g/t Au), primar-
ily due to mining depletion.
Banro’s overall mineral reserves have
grown by 23 % to 2,91 Moz (42,91 Mt at
2,11 g/t Au) at a US$1 200/oz gold price.
Banro’s total measured and indicated
resources for all its properties amount to
7,73 Moz (154,91 Mt at 1,55 g/t Au) while
inferred resources total 5,26 Moz (97,78 Mt
at 1,67 g/t Au).
“The reserve growth at Twangiza has
been achieved through the proven ability
of the current plant to economically pro-
cess non-oxide materials existing within
the reserve pit shell. This achievement will
extend the mine life of the current installed
operations to 14 years, and provide a foun-
dation for future optimisation and the
possible future expansion of the existing
Twangiza operations,” commented Banro’s
CEO and President, John Clarke.
During 2014, the company scaled down
its exploration activities at its Twangiza,
Namoya, Lugushwa and Kamituga proj-
ects and focused its geological expertise
on supporting the production growth at
Twangiza, development at the Namoya
mine and identification of near mine high
grade targets.
Canada’s Tanzanian Royalty Exploration
Corporation reports that assay results from
leachant (pregnant solution) collected
from its heap leach pads and the pregnant
leachate solution (PLS) holding pond at
its Buckreef South Pit gold mine process-
ing plant in Tanzania have returned highly
encouraging results.
The company found that the permeabil-
ity and leaching degree of the padmaterial
was improved by mixing river sand with
the mineralised material on the pad. The
assay results for samples collected from
Pad 1 returned moderate values ranging
from 0,3 mg/
ℓ
to 0,8 mg/
ℓ
over a 20-day
period. This is attributed to the intensely
clayey nature of the leach materials, hence
the decision to improve permeability and
percolation on Pad 2.
Encouraging results from Buckreef heap leaching
Tanzanian Royalty
has also commenced
pumping and eluting
the leachant generated
from Pad 1 through
the carbon elution
c o l umn s , ma r k i ng
the second progres-
s i ve s t ep t owa r d s
gold recovery at the
Buckreef project.
The company says
that it is notable that
the head grade (mg/
ℓ
)
from the pregnant
leach solution in the
PLS pond increases as
the leaching progresses. Moreover the
discharge grade (mg/
ℓ
) from the carbon
columns into the barren leach solution
(BLS) indicates >98 % capture from the PLS.
Truck-stacking of material on Pad 3 (of
4) commenced on 6 May 2015 and is in
progress. The strategy of the company is
to fill all four pads now at Buckreef, tak-
ing advantage of the fact that the greater
degree of gold in the leachate occurs early
in the process rather than later, provided
that permeability is maintained at a favour-
able level.
Joseph Kahama, Chairman of Tanzanian
Royalty and COO (Tanzania), commented:
“The analytical assay results from the
leachant that continues to be generated
from Heap Leach Pads 1 and 2 illustrate
the amenability of the Buckreef South Pit
deposit to heap leaching, which is typi-
cally lower in capital and operating costs
than other gold recovery methods. The
leaching kinetics will be strengthened via
the addition of an agglomeration unit to
significantly increase percolation and per-
meability, thus enhancing the excellent
initial oxide recoveries so far reported.”
Jim Sinclair, the company’s President
and CEO, added: “This is another critical
step on our company’s path to production.
Not only have we demonstrated that heap
leaching represents a viable gold recovery
option at Buckreef but the cyanide soluble
leach assay data will allow us to better map
and quantify recoverable gold for the sub-
stantial resource blocks – not only for the
Buckreef South Pit but also for the nearby
Buckreef Main deposit and the Tembo and
Bingwa satellite deposits.”
The Buckreef Gold Mine Re-Develop
ment project was acquired from the
Tanzanian State Mining Company
(Stamico) in December 2010. Under a
Heads of Agreement concluded with
the state-owned company, Tanzanian
Royalty has the right to earn a 55 % inter-
est in Buckreef with Stamico holding the
remainder.
The project is located in north-central
Tanzania immediately to the south of
Lake Victoria and 110 km south-west of
Mwanza. The project area comprises the
dormant Buckreef gold mine and four
prospects with known mineralisation:
Buckreef, Buziba, Tembo and Bingwa.
Loading cyanide into the 6-t capacity carbon-in-column (CIC) gold adsorption
plant at the Buckreef project (photo: Tanzanian Royalty).