Overview
The Tasiast gold mine is an open pit operation located in north-western Mauritania and is approximately 300 kilometres north of the capital Nouakchott.
Tasiast began commercial operations in 2008. Red Back completed the purchase of Tasiast on August 2, 2007. Kinross acquired its 100% interest in the Tasiast gold mine on September 17, 2010 upon completing its acquisition of Red Back Mining Inc. Infrastructure on site supports an open pit mining operation and associated processing facilities consisting of a 3 Mt/a CIL mill and a run of mine (ROM) dump leach.
The deposit is open along strike and at depth and Kinross is currently analyzing process options for the Tasiast expansion. The company is targeting to commence construction of the new production facilities in mid-2013, and to ramp up production in 2015.
Currently high-grade ore is treated through a CIL circuit, while lower grade oxide ore is heap leached. In 2011, the mine produced 200,619 ounces of gold.
Location
Mauritania, with an area of approximately 1,030,400 sq km, is located in north-western Africa and covers the western portion of the Sahara Desert. Mauritania is bordered by the Atlantic Ocean to the west, Western Sahara and Algeria to the north, Mali to the east and Senegal to the south. It is one of the most underdeveloped countries in Africa. The vast majority of the population is Muslim and only 41 percent of the population is literate.
The 312 square kilometers project is located 250 km southeast of the city of Nouadhibou and is accessible by the SNIM rail line which passes approximately 96 km to the north of the camp. It can also be reached by 4X4 vehicles on unpaved roads and sandy tracks from Nouakchott and from the Atlantic port of Nouadhibou. An airstrip has been constructed at the mine site and is used for light aircraft travelling to and from Nouakchott.
Geology
The Tasiast Permit Area encloses the 4 main Precambrian greenstone belts of the western compartment of the Reguibat shield, known as the Tasiast-Libzenia Domain. The Reguibat Shield consists of a core of west to east accreted, north-south trending Archean and Lower Proterozoic terranes dating from 2.6 Ga in the domal basement gneisses to 1.78Ga as the peak metamorphism in the metavolcanics. The package was cratonized at the end of the Eburnean Event and has been stable since 1700Ma. The Reguibat shield is bound on all sides by Pan African orogenic belts and covered in the south by the extensive intra-cratonic sediments of the Taoudeni Basin.
The Tasiast Mine Area is underlain by the Aouéouat greenstone belt, a 70 km long by 15 km wide N-S trending belt.
Gold mineralization in this area is similar to that found in Canadian Archaean terranes such as the Abitibi Greenstone Belt. Deposit types that occur within the Tasiast area consist primarily of gold-bearing shear hosted deposits.
Exploration work has identified north-south trending, intensely sheared, gold-mineralized zones extending over a strike length of 10km.
Mineralization dips to the east between 30 and 60 degrees and is hosted by a folded sequence comprising Banded Iron Formation (BIF), Felsic Volcanics and intermediate to mafic volcaniclastics.
The structure is interpreted as a broad, regional antiform that is cored by a felsic volcanic unit approximately 200 m wide at the present surface elevation with structurally controlled mineralisation sitting close to either margin and within the core of the fold.
Gold mineralization is associated with structurally controlled late, discrete faults and shears, quartz-veining and silica-flooding, within all rock types.. There is ubiquitous bleaching due to prograde epidotization and retrograde chloritization and later overprinting hydrothermal sericitization. Generally late, brittle, quartz-carbonate veining is overprinted by the remobilization and replacement of magnetite by secondary pyrrhotite. Coarse visible gold is common within the micro-fracturing and veinlets associated with the main shears.
Mining & Operations
The Tasiast gold mine was officially opened by the President of Mauritania, His Excellency Sidi Mohamed Ould Cheikh Abdallahi, on July 18, 2007. Red Back completed the purchase of Tasiast on August 2, 2007. Commissioning of the Tasiast plant continued through 2007 with commercial production declared in January 2008.
Based on positive results from the ongoing resource conversion drill program, an expansion of the Tasiast plant from 1 million tonnes per annum (mtpa) to approximately 2.5 mtpa was implemented with operation commencing in the fourth quarter of 2009. All ore and waste is mined via conventional, open pit mining methods. The operation utilises selective mining techniques to separate ore and waste. The mining fleet is a combination of 120 tonne hydraulic excavators loading 90 tonne trucks. Provision has been made for drilling and blasting all primary materials.
The treatment plant flowsheet is based on three stage crushing, ball milling, pre-leach thickening, and a six stage CIL circuit. Gold is recovered by an elution circuit with electro-winning of the gold onto wire wool cathodes. The loaded wire wool is smelted to produce a final bullion product. A gravity circuit will be installed in the grinding circuit to prevent build up of coarse gold during processing of the higher grade primary ores. Following a positive testwork program in 2008, low grade oxide material is now being processed by dump leaching.
At the end of 2009 TMLSA employed 454 people, of which 64 are expatriates. The mine power is provided by three 2.7MW HFO generator sets with eight 1.0MW diesel generators in reserve have been commissioned.
Based on positive results from the ongoing resource conversion drill program, an expansion of the Tasiast plant from 1 million tonnes per annum (mtpa) to approximately 2.5 mtpa was implemented with operation commencing inthe fourth quarter of 2009. All ore and waste is mined via conventional, open pit mining methods. The operation utilises selective mining techniques to separate ore and waste. The mining fleet is a combination of 120 tonne hydraulic excavators loading 90 tonne trucks. Provision has been made for drilling and blasting all primary materials.
The treatment plant flowsheet is based on three stage crushing, ball milling, pre-leach thickening, and a six stage CIL circuit. Gold is recovered by an elution circuit with electro-winning of the gold onto wire woolcathodes. The loaded wire wool is smelted to produce a final bullion product. A gravity circuit will be installed in the grinding circuit to prevent build up of coarse gold during processing of the higher grade primary ores. Following a positive testwork program in 2008, low grade oxide material is now being processed by dump leaching.
At the end of 2009 TMLSA employed 454 people, of which 64 are expatriates. The mine power is provided by three 2.7MW HFO generator sets with eight 1.0MW diesel generators in reserve have been commissioned.
Processing
High grade ore processing is based on three stage crushing, ball milling, and a carbon-in-leach circuit. Lower grade oxide ore is processed in a run-of-mine heap leach facility (5 pads). Tailings slurry from the CIL process is pumped to the tailings storage facility (TSF). The TSF is a specifically engineered facility, currently comprising two imperviously lined paddock dams located one kilometer south west of the processing plant. After settling of the solids, process solution is recovered and pumped to the plant for re-use.
The mill has an 8,000 tonnes per day capacity.
The Tasiast expansion project is Kinross' top development priority and is the cornerstone asset in the company's long-term growth strategy.
Kinross is currently analyzing process options for the Tasiast expansion, including milling, heap leaching and different combinations of both, and is expected to make a preliminary selection of a processing option at the end of the second quarter of 2012. The Company is targeting to commence construction of the new production facilities in mid-2013, and to ramp up production in 2015. The construction period and start dates are expected to be confirmed following completion of the project feasibility study, expected in the first half of 2013.
In 2011, Kinross completed the construction of the West Branch dump leach and ADR (Adsorption, Desorption and Refining) facilities, the initial phase of the project expansion at Tasiast.
In 2011, the mine produced 200,619 ounces of gold.
