Name: Bonikro mine.
Location: The Bonikro gold mine is located in the Oumé project area, in central to southern Côte d’Ivoire, about 230 km north-west of Abidjan.
Controlling Company: Bonikro is owned and operated by LGL Mines CI SA. Newcrest owns 89.89% of the company, with the balance held by the Côte d’Ivoire government (10%) and a minority shareholder (0.11%).
Brief History: While artisanal mining is part of the local tradition in the region, industrial-level gold mineralisation was discovered at Bonikro only in the 1990s.
After receiving the environmental permit, construction of the mine started in 2007, with commercial production starting in August 2008.
Newcrest acquired its interest in Bonikro as a result of the merger with Lihir Gold in August 2010.
Brief Description: Bonikro is a conventional openpit mining operation. The predominant method of gold recovery is carbon-in-leach, with about 40% of the gold recovered through a gravity circuit.
Products: Gold.
Geology/Mineralisation: The geology of the Bonikro deposit is dominated by a granodiorite intrusion (felsic) into mafic volcanics and sedimentary rocks, with a strike length of 1 000 m and a width of up to 300 m. The granodioritic intrusion has been intersected in drilling up to 500 m below surface.
Mineralisation occurs primarily in predominantly stockwork veining and as structurally controlled shear zones. The shear zones are developed in the felsic and the mafic rocks, while the stockwork mineralisation is exclusively confined to the felsic rocks. The deposit geology allows for two distinct domains to be defined – the mafic shear (geologically distinct shear in the mafic rocks), and the felsic domain (the geologically interpreted granodiorite intrusive).
Reserves: Proven and probable mineral reserves as at December 31, 2015, were estimated at 13-million dry tonnes, grading 1.3 g/t of gold.
Resources: Mineral resources as at December 31, 2015, were estimated at 32-million dry tonnes, grading 1.4 g/t of gold.
Mining Method: Bonikro is a conventional truck and excavator openpit mine.
Major Infrastructure and Equipment: Standard drilling and blasting techniques are used in hard rock, along with free digging in soft areas. Selected blast holes are sampled and assayed for production-grade control purposes in hard rock and trench sampling is conducted in soft areas.
Broken and freely dug rock is loaded by an excavator into haul trucks. Depending on the block model determination or grade control results, the mined material is delivered to the run-of-mine pad, primary and secondary crusher, low-grade stockpile or waste rock dumps. The predominant method of gold recovery is through carbon-in-leach technology.
Prospects: The Stage 4 cutback of the Bonikro pit was completed in October 2015, with the pit placed on care and maintenance in the same month. Processing of stockpiles continues.
Contact Person: Newcrest public affairs senior specialist Jason Mills.
Contact Details:
Newcrest Mining,
tel +61 3 9522 5690,
fax +61 3 9525 2996,
email jason.mills@newcrest.com.au, and
website http://www.newcrest.com.au.