Modern Mining June 2015

MINING News

Encouraging results from Buckreef heap leaching Tanzanian Royalty

“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.  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. 

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

Loading cyanide into the 6-t capacity carbon-in-column (CIC) gold adsorption plant at the Buckreef project (photo: Tanzanian Royalty).

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 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

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.

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-

14  MODERN MINING  June 2015