Name: Twangiza mine.

Location: The Twangiza mine is located in the South Kivu province of the Democratic Republic of Congo (DRC).

Controlling Company: Banro Corporation, through its DRC subsidiary, Twangiza Mining.

Brief History: The Twangiza gold deposit was discovered by Miniere des Grande Lac (MGL) in the 1950s. The company followed the occurrence of alluvial gold deposits upstream from the Mwana river to the current Twangiza deposit. MGL tested the deposit through 8 200 m of trenching and 12 100 m of adits on seven levels, collecting 17 400 samples. In the mid-1970s, Charter Consolidated undertook detailed exploration, including the excavation of numerous close-spaced adits into the mineralised zone.

In 1996, Banro acquired control of the Twangiza property. During the following year, it undertook a $9-million exploration programme, which included 10 490 line-kilometres of airborne geophysics, 1 613 samples from 16 adits and 8 577 drill core samples from 9 122 m of core drilling along 800 m of strike. This represented less than 20% of the identified mineralised trend.

Twangiza became Banro’s first producing openpit gold mine when it entered production in October 2011, starting commercial production in September 2012.

The mine started with a refurbished plant, designed primarily to process oxide material at 1.3-million tonnes a year. Since commissioning, the plant has been improved and expanded to 1.7-million tonnes a year and has been shown to process a blend of oxide material with harder nonoxide material comprising partially weathered transitional rock-containing residual sulphides and fresh rock containing sulphides.

Brief Description: The Twangiza property consists of six exploitation permits totalling 1 164 km2. The deposit comprises an oxide portion and a transition rock/fresh-rock portion, with a focus on the oxide component.

With mill throughput at full capacity of 1.7-million tonnes a year, Twangiza is expected to produce more than 10 000 oz of gold each month, with an expected mine life of 14 years from currently defined reserves.

Products: Gold.

Geology/Mineralisation: The Twangiza area is underlain by sediments of Proterozoic age that have been intruded by porphyry sills, folded into a series of broad anticlines and synclines and subjected to very low-grade metamorphism. The gold mineralisation at the main Twangiza deposit is hosted within mudstones, siltstones, greywackes and porphyries along the crest of a major anticlinal structure. Gold mineralisation is of hydrothermal origin and is associated with sulphides that occur in quartz-carbonate veins, and disseminations throughout the host rocks. Unlike the Twangiza main deposit, the mineralisation at Twangiza north is associated predominantly with feldspar porphyry sills that have intruded westerly dipping shales and siltstones, with the mineralisation in this lithology being nonrefractory. This mineralisation is open at depth and to the north where recent regolith mapping has indicated that the gold-in-soil anomalism has been masked by recent colluvial and alluvium material. Other significant gold occurrences on Banro’s Twangiza concessions include Tshondo and Mufwa.

Reserves: Total proven and probable reserves as at December 31, 2014, were estimated at of 22.38-million tonnes grading 2.28 g/t of gold.

Resources: Total measured and indicated resources as at December 31, 2014, were estimated at 109.28-million tonnes grading 1.5 g/t of gold. Inferred resources were estimated at 12.99-million tonnes grading 1.15 g/t of gold.

Mining Method: Conventional openpit truck and shovel method.
Major Infrastructure and Equipment:Twangiza’s processing plant comprises crushing and scrubbing, milling and classification, gravity and intensive cyanidation, trash removal, carbon-in-leach, carbon safety and detoxification, tailings dam storage and return, acid wash, elution, electrowinning, regeneration, a gold room, reagents and consumables, as well as air and water services.

Prospects: Banro is actively pursuing several alternatives to enhance the economics and financial returns relating to the Twangiza mine. These include optimal ore blend for enhanced recoveries, low-cost power alternatives, process optimisations to improve throughput constraints and metallurgical recoveries, process enhancements to increase processing capabilities to meet the requirements of additional hard-rock resources and delineating additional high-grade resources from the known deposits and from a number of prospects. Possible future expansions of operations will be evaluated to maximise net present values at market discount rates.

Contact: Investor relations.

Contact Details:
Banro Corporation,
tel +1 416 366 2221,
email ir@banro.com, and
website http://www.banro.com.