90% IAMGOLD, 10% Government of Burkina Faso
The Essakane project is located in north-eastern Burkina Faso, West Africa. It straddles the boundary of the Oudalan and Seno provinces in the Sahel region of Burkina Faso and is approximately 330 km northeast of the capital, Ouagadougou. It is situated 42 km east of the nearest large town and the provincial capital of Oudalan, Gorom-Gorom.
Burkina Faso is a landlocked nation. It is surrounded by six countries: Mali to the north, Niger to the east, Benin to the south east, Togo and Ghana to the south, and Côte d'Ivoire to the south west. It covers an area of 274,000 km² and has an estimated population of more than 18 million people. The Essakane deposit is located within a 100.2 km² mining permit that is surrounded by six exploration permits covering a total area of 1,266km².
IAMGOLD commenced management of the Essakane project following the acquisition of Orezone Resources in February 2009. Essakane began commercial production in July 2010. The plant expansion to accommodate a substantial increase of hard rock, was completed on time at the end of 2013.
The Essakane Project occurs in the Paleoproterozoic Gorouol greenstone belt in northern Burkina Faso. The local stratigraphy can be subdivided into a succession of lower-greenschist facies metasediments (argillites, arenites and volcaniclastics), conglomerates and subordinate felsic volcanics, and an overlying Tarkwaian-like succession comprising siliciclastic metasediments and conglomerate. Each succession contains intercalated mafic intrusive units that collectively comprise up to forty percent of the total stratigraphic section.
The region preserves evidence for at least two regional deformational events. D1 structural elements such as the Essakane host anticline are refolded by a series of NNE-trending F2 folds. Later localized deformation occurs near the margin of a calc-alkaline batholith in the south of the project area. The Markoye Fault trends NNE through the western portion of the project area and separates the Paleoproterozoic rocks from an older granite-gneiss terrane to the west.
Essakane is an orogenic gold deposit characterized by quartz-carbonate stockwork vein arrays and is hosted within the lower meta-sedimentary sequence. The deposit occurs in an upright asymmetric anticline that plunges shallowly to the northwest. The highest concentration of quartz veins and gold mineralization occurs in the 50-70m thick ‘main arenite unit’, and spatially in the hinge zone and eastern fold limb of the host anticline.
There are two distinct structural controls on gold mineralization: (i) gold associated with bedding parallel deformation; and (ii) gold associated with structures formed by the anticlinal folding event. The vein arrays are complex and consist of: (i) early bedding parallel laminated quartz veins; (ii) late steeply dipping extensional quartz veins; (iii) axial planar veins and pressure solution seams in the fold axial zone.
Alteration in the host arenite unit typically consists of a sericite > carbonate > silica ± albite ± arsenopyrite ± pyrite assemblage. Arsenopyrite and pyrite occurs within and adjacent to quartz veins are disseminated throughout areas of wallrock alteration. Traces of chalcopyrite, pyrrhotite, galena and hematite can occur with the arsenopyrite. Gold occurs as free particles within the veins and also as intergrowths in arsenopyrite on vein margins or in the host rocks. The regolith profile within the deposit area consists of one to three metres of laterite, a 30 to 50 metre thick upper saprolite zone and a 10 to 30 metre thick lower saprolite zone that is underlain by competent rock. The Essakane deposit has a strike length of 2,500 metres and is open to the north, although economic mineralization follows the fold plunge to become progressively deeper. Mineralization has been confirmed to 270 m vertically below surface but the full depth extent in the fold hinge and east limb has not been tested.
Despite the proportion of soft rock declining from 42% in 2013 to 18% by
the end of 2014, the combination of increased throughput capacity and
improved grades from the heart of the deposit pushed 2014
production levels higher by 33%.
Feed to the plant is a blend of two designated ore types, with fresh rock representing about 80% of mill feed and the remaining 20% predominantly saprolite material.
Mining is carried out using a conventional drill, blast, load and haul surface mining method with an owner fleet.
Feed to the plant is a blend of two designated ore types from the EMZ pit, hard rock and transition ores. Future feed from Falagountou pit will provide new Saprolite feed material to the mill at first as well as further transition and hard rock ores.
Essakane ore is processed using two stage of crushing, SABC grinding and carbon-in-leach ("CIL") gold plant. Nameplate mill capacity was increased to 10.8 mtpa following the successful mill expansion completed in 2014.
The Company saw production at Essakane increase by approximately 15% in 2015 and the mine achieved its second year of record production. In 2016, the focus continues to be on mine optimization, lowering unit costs and increasing mine and mill efficiencies at higher proportions of hard rock. Attributable production in 2016 is expected to be in the range of 365,000 and 375,000 ounces.
The revised life-of-mine plan for Essakane, completed in December 2015, demonstrates a mine life of 8.2 years and average attributable gold production of 368,000 ounces per year. Given the positive results returned to date, we continue exploration of Essakane’s extensive 1,300 kilometer land package and see the potential to extend its mine life in the future.