Modern Mining April 2017

MINING News

Randgold sustains quality of reserves and resources

Randgold Resources’ annual resource and reserve declaration, recently published as part of its annual report for 2016, shows attributable proved and probable reserves down by 1 % after another record produc- tion year. Total attributable resources of 25,5 million ounces (Moz) were down 8 %, reflecting mining depletion and changes to the method of reporting underground resources at the Kibali mine in the DRC. The group’s reserve grade, however, increased from 3,6 g/t to 3,7 g/t and Chief Executive Mark Bristow said this showed that Randgold has been able to replen- ish ounces at grades above or equal to its reserve base despite the high depletion rate from mining. “This means our current reserves have secured our business plan for at least 10 years of profitable production. In the meantime, our exploration teams continue to hunt for additional ounces to replenish these reserves as well as for our next big discovery,” Bristow said. Group General Manager Evaluation Rod Quick noted that Randgold continued to base its reserve calculations on a gold price of US$1 000/oz which, coupled with its emphasis on quality over quantity, gave it a robust reserve profile which would enable the company to continue manag- ing the cyclical nature of the gold market. In Mali, Loulo’s total ore reserves after depletion increased by 12 % to 5,3 Moz at 4,5 g/t as further drilling and design work

has been aligned with industry best prac- tice using stope optimiser software to report underground resources. In Côte d’Ivoire, Tongon’s resources and reserves decreased as a result of depletion and geological changes to the Northern Zone orebody following reinterpretation of the granodiorite contact boundary at depth after additional surface drilling. Drilling continues to probe for potential gains within and immediately below the current pit designs. The first of a number of satellite pits, Sekala, was brought into the resource statement which added 43 000 ounces of indicated resource. Further sat- ellites will continue to be tested in the coming year. In Senegal, the key development proj- ect, Massawa, saw an increase of total reserves at a 40 % higher grade. The increase in reserve ounces follows the incorporation into the project of 475 000 ounces from the Sofia Main deposit, while the increase in grade was driven princi- pally by the geological remodelling of the Central Zone ore lodes. Total reserves now stand at 2,6 Moz at 4,3 g/t, up significantly from the last year’s 2,0 Moz at 3,1 g/t. Drilling continues on the Massawa and Sofia deposits to increase ounces. Total mineral resource ounces are down 400 000 ounces year on year, principally due to the geological remod- elling and higher cost profile of Sofia and Massawa, leading to the reduction of low grade ounces. 

resulted in an increase of 520 000 ounces to the Gara ore reserves with the incor- poration of Gara Far South. Infill grade control gains at Yalea resulted in a partial replacement of depletion ounces. Total mineral resources increased by 1 %, net of depletion, driven by an increase of 461 000 ounces in Gara underground’s inferred resources. At neighbouring Gounkoto, total ore reserves net of depletion remained above 3 Moz year on year. This was largely due to the completion of the Gounkoto super pit feasibility study, leading to a significant gain in the open-pit ore reserves and the associated reduction of the underground reserve. At Kibali in the DRC, total reserves decreased to 9,2 million ounces at 4,0 g/t from 10,6 Moz at 4,1 g/t in 2015 follow- ing mining depletion and changes to the KCD underground geological model. The changes resulted from the reinterpreta- tion of the controls to mineralisation of the high grade lodes following a significant increase in mapping and grade control data. Although the remodel has resulted in geological model changes of a portion of the 5103 and 9105 lodes, it has also high- lighted the upside potential of the up and down plunge extension of the 3000 lodes as an underground target. Mineral resources are also down due to mining depletion, geological model changes and a change in the method of underground resource reporting which

The core yard at the Massawa project in Senegal. Massawa lies 700 km south-east of the capital city of Dakar and 90 km to the west of Randgold’s Loulo and Gounkoto mines across the border in Mali (photo: Randgold).

8  MODERN MINING  April 2017