Modern Mining September 2015

MINING News

The processing plant at the Namoya gold mine in the DRC (photo: Banro).

Banro reports on performance at DRC gold mines

rate towards commercial levels as well as optimising the stacking process with the agglomerated heap leach in order to improve percolation and gold extraction. For the third quarter of 2015, Namoya is preparing for the delivery of the Cat 777 mining fleet additions. The Namoya Summit deposit has been cleared for delineation and is planned to be ready for production activities during the fourth quarter of 2015. 

In its financial and operating results for the second quarter of 2015, Canada’s Banro Corp, which operates the Twangiza and Namoya gold mines in the DRC, says that Twangiza continued to outperform expec- tations, resulting in a 60 % increase in gold production to 34 325 ounces fromQ2 2014 production of 21 431 ounces. During the second quarter of 2015, the plant at Twangiza processed 428 661 tonnes of ore (compared to 340 654 tonnes during the second quarter of 2014 and 428 844 tonnes in the first quarter of 2015), maintaining the first quarter of 2015 achievement of 101 % of design capacity. Ongoing debottlenecking and incre- mental process improvements allowed for throughput levels to be maintained while increasing the proportion of non-oxide material to an average of 43 % for the quar- ter. Ore was processed during the second quarter of 2015 at an indicated head grade of 3,01 g/t Au (compared to 2,44 g/t Au during the second quarter of 2014 and 3,21 g/t Au during the first quarter of 2015) with a recovery rate of 82,2 % (compared to 84,3 % during the second quarter of 2014 and 80,7 % in first quarter 2015). During the second quarter of 2015, the Namoya mine produced 10 525 ounces of gold from a total of 330 267 tonnes of ore, stacked and sprayed on the heap leach pads, at an indicated head grade of 1,53 g/t Au. Stacking levels at the begin- ning of the second quarter decreased substantially from those achieved in March 2015, as a result of the impact of modify- ing the mine plan to allow for earlier access

to the Kakula reserve pit, as well as the adverse impact of unseasonably high rains on the delivery of materials and supplies. During the second half of June and early July, Namoya achieved stacking rates in excess of 5 000 tonnes per day (tpd) leading to material stacked in July of 151 026 tonnes. Further improvements are expected in August and September. Namoya’s focus is on ore delivery in order to support the increases in the stacking

BK11 kimberlite resource estimate updated Tango Mining, listed on the TSX-V, has com- pleted an updated NI 43-101 resource for the past-producing BK11 kimberlite dia- mond mine in Botswana. The mine is part of the Orapa/Letlhakane kimberlite district and the resource is contained in a dia- mond-bearing, champagne-glass shaped kimberlite pipe with a surface area of 8,7 hectares (revision based on new geophysi- cal modelling).

Based on the 2015 market, diamond valuation experts advise a minimum aver- age price of US$236/ct, a modelled price of US$260/ct and an upside price of US$285/ct. The resource is based on the evaluation of 6 392 m of core drilling and 1 473 m of large diameter drilling. Sampling and min- ing produced approximately 19 000 ct that was valued up until February 2012 and ana- lysed in terms of size frequency distribution. Tango has run feasibility studies in parallel with the resource work and is pre- paring a NI 43-101 Preliminary Economic Assessment report. As part of this work, recently completed rock hardness measure- ments have enabled autogenous mill sizing to be conducted. The deposit is considered as soft in the greater diamond industry and an autogenous mill retrofit to the existing plant is being assessed. Botswana Power Corporation grid power has been installed to the site boundary and will be more cost effective than the histori- cal andmore expensive diesel generators. 

The updated estimate comprises 17,4 Mt of inferred resource containing a total of 780 820 carats of which approxi- mately 9,0 Mt averages 6,8 cpht for a total of 608 000 ct with higher-grade areas being identified at 9,8 cpht. BK11 contains good quality white dia- monds in the top 10 % of global gem diamond production in terms of value per carat. The recovery of a 1,5 ct high quality Type IIa D colour diamond is significant as it indicates the presence of top quality stones within the BK11 kimberlite, with the poten- tial for large +100 ct stones.

September 2015  MODERN MINING  5