The Tongon mine (Tongon) is owned by an Ivorian company, Société des Mines de Tongon SA, in which Randgold has an 89% interest, the State of Côte d'lvoire 10% and 1% is held by a local company.
Tongon is an open-cut mining operation and employs the four standard mining practices of drill, blast, load and haul. Mining started in April 2010 and Tongon has a ten year Life of Mine (LOM). Two main pits are scheduled in the LOM as follows:
- South Zone (SZ) pit will be mined from 2010 to 2016 to the final pit bottom
- North Zone (NZ) pit, which is smaller than the SZ, will be mined from 2015-2019
- Both the SZ and NZ pits have potential for more resources.
ACHIEVED IN 2010
- Phase 1 of the process plant ore treatment circuit commissioned
- First gold poured and shipped on schedule in Q4
- Gold recovery higher than planned at 92.2%
- 95% of operational labour successfully employed locally
TARGETED FOR 2011
- Produce 260 000 to 270 000 ounces of gold
- Complete and commission second stream of process plant treatment circuit
- Complete and commission sulphide treatment process circuit
- Complete and commission secondary and tertiary hard rock crushing circuits
- Reduce Lost Time Injury Frequency Rate by 20%
- Connect mine power supply to Ivorian grid
- Achieve ISO 14001 environmental certification
Resources and reserves
The 2008 geological model for both the SZ and the NZ pits was updated with the advanced grade control drilling holes. New geological models were therefore produced for the SZ in July 2010 and for the NZ in August 2010. The models indicated a drop in ounces for the SZ and an increase in the NZ. The depletion for 2010 was 903 779 tonnes at 2.7g/t for 79 907 ounces.
Tongon started production during the fourth quarter of 2010 and 355 000 tonnes of ore was milled at a grade of 2.67g/t. The mine produced 28 126 ounces at a total cash cost of US$459/oz sold. Profit from mining was US$4.4 million. This was impacted by 23 428 ounces that were unsold at year end resulting from disruptions in Côte d'Ivoire following the disputed elections in November 2010.
Mining operations are carried out by Mine de Tongonaise SA (ToMi), a contract mining company and subsidiary of DTP Terrassement. The mine operates 24 hours a day based on a working roster of three eight-hour shifts. The major load and haul mobile fleet consists of one liebherr 984 and three Liebherr 9350 diggers and 15 Cat 777F haul trucks. The mining fleet has an annual capacity of approximately 26Mtpa at a strip ratio of 4:1.
The Tongon plant design is based on well-established gravity/flotation and Carbon in Leach technology. The plant is designed to treat 3.6 million tonnes per annum of oxide, transition and sulphide ores which can be campaigned through the plant separately or fed in a combination if required. There is a common primary crushing plant for oxides and sulphides. Oxides, which may at times contain high clay quantities and moisture content, have been identified to potentially cause material handling problems when processed through the full crushing circuit. As a result, the design allows the plant to bypass the secondary and tertiary crushing circuit, thus feeding primary jaw crusher product of size 100% passing 300 millimetres directly onto the ball mill feed conveyor, bypassing the stockpiling facility.
Transition and sulphide ores are treated through a primary, secondary and tertiary crushing circuit to produce a ball mill feed of size 100% passing 20 millimetres. The primary crushing plant consists of a complete standby circuit, which allows higher, but also more consistent throughput and better maintenance planning. Milling consists of two ball mills when treating oxide, transition or sulphides. The discharge from each is pumped in separate cyclone feed pump and classifier systems.
First ore was fed through mill no1 in October 2010. The feed rate was steadily increased via one mill, as the process circuits and systems were debugged, up to the designed throughput rate of 456tph.
Gold recovery of 92.2% was better than forecast and overall 28 126 ounces of gold was produced.
Overall mill availability was 72.6% for 2010. A gradual increase in mill availability was obtained from 69.7% in October to 77.6% in December. Commissioning issues mainly associated with feeding the softer clay containing ore through the system were systematically addressed by the engineering team as part of the commissioning process which included ongoing modifications and operational enhancements with respect to the relevant process sections to facilitate ease of tonnage throughput and improvement in efficiency of key process circuits.
The power plant availability and utilisation were 90% and 51% respectively for 2010. All 20 of the power plant generators, including the PLC automatic synchronisation, were commissioned ahead of the plant start-up.
The Korogho substation is 90% complete. The main outstanding items are the installation of the related equipment and the 33kv link to the national grid. The forecast grid power line completion date is the second quarter of 2011.
TONGON AND POUNGBE VILLAGE ELECTRIFICATION
An agreement between Tongon and enterprise d'electricite, CIE and Power Management and Electrical Services was reached with respect to the electrification of Tongon and Poungbe villages. The project started in January 2011 and is scheduled for completion in the second quarter of 2011.
The software system 'On Key' from Pragma which was chosen as the CMMS system to be used at Randgold's operating mines has been 80% installed at Tongon. Loading of the lubrication and preventative maintenance tasks for the process plant is complete. Extensive configuration work remains to streamline the generation of job cards for these tasks and ensure these fit in with the existing business processes and staffing configurations.
Health and safety
The Lost Time Injury Frequency Rate (LTIFR) was 2.7 for the year. This higher rate is due to the increase in activities in the construction phase and start of plant operation. Mine management intensified safety education for employees, most of whom have not had previous exposure to mining, in order to instil behaviour-based safety management systems. Safety policies were drafted during the year and several workshops were conducted for the implementation of the OHSAS 18001 system.
Malaria control has been implemented from the onset of the construction phase and into operations phase. An entomologist from South Africa was invited to site to recommend further actions to prevent the high number of malaria cases that occur during the rainy season. These actions, including education on behavioural changes of employees, are being implemented.
Environmental policies were drafted during the year and workshops were held for the implementation of the ISO 14001 system, certification of which is targeted for 2011.
The labour complement, excluding contract labour, is planned at 304 of which 82% are Ivorians. The recruitment has been based on Randgold's strategy of sourcing skills and experience primarily from the local villages, then from the northern Côte d'lvoire region, followed by Côte d'lvoire as a whole and then lastly going out into the international labour market. Within the local villages the policy of spreading the recruitment between them, according to agreed percentages has been applied. To date, 70% of the operational labour has been recruited from local villages. This same recruitment ratio has been applied to all operational contractors.
In terms of exploration, 2010 was a critical year which saw great improvements in our understanding of the Senoufo Greenstone Belt. This followed the completion of an airborne EM survey flown in January, which enabled not only a reinterpretation of the geological and structural framework but also a target generating and prioritisation exercise. Since then, follow-up work was focused on the most prospective targets within a 15 kilometre radius from the plant. These have been advanced through mapping, RAB, RC drilling and trenching. For more detail, see the exploration section of this report.