Modern Mining: Featured News

The board of TSX-listed Endeavour Mining Corporation has approved the construction decision for the company’s Ity CIL project at its mine in Côte d’Ivoire following the robust results obtained from its Optimisation Study. The project has a US$412 million initial capex.

Endeavour operates several mines across West Africa in Côte d’Ivoire (Agbaou and Ity), Burkina Faso (Karma) and Mali (Tabakoto). A fifth mine, Nzema in Ghana, is regarded as non-core and – at the time of writing – was in the process of being sold to BCM International. Endeavour is also developing the Houndé project in Burkina Faso, now at a very advanced stage (see page 6 of this issue).

Site layout of the Ity CIL project in Côte d’Ivoire.

The Ity CIL Project Feasibility and Optimisation studies were conducted to analyse the economic viability of constructing a straightforward gravity circuit/CIL plant as an alternate processing route to the current heap leach process. Following the publication of the November 2016 Feasibility Study (FS), the Optimisation Study (OS) was prepared to better capture the value created from the recent exploration success recorded at Ity.

Sébastien de Montessus, Endeavour’s President and CEO, said the study clearly positioned Ity as the company’s next flagship asset with robust project economics, a strong long-life production profile, and significant exploration upside.

“Its average annual production in the first five years of 235 koz with AISC below US$500/oz and an after-tax IRR of +20 % even at a low gold price of US$1 000 per ounce are proof of the compelling economics of the project.

“With the upcoming first gold pour at Houndé and Ity CIL construction expected to be completed within 20-months, we remain on track to achieve our strategic milestones of becoming a +800 000 ounce per year gold producer with group AISC below US$800 per ounce and mine lives above 10 years by 2019.”

Jeremy Langford, COO, added: “We have optimised the Ity CIL project by maximising the construction and operational synergies between Agbaou, Houndé and Ity, and by leveraging the same designs, components, equipment and spare parts where possible from one project to the other, along with incorporating our extensive construction expertise. The construction team is excited to transition from Houndé to Ity and to continue to build on its construction track-record.”

The Ity CIL Project Optimisation Study was managed by Endeavour’s in-house development team and independently prepared by Lycopodium Minerals with the support of six globally recognised engineering firms.

The process plant design has been simplified and optimised to maximise the replication of the Houndé design, where applicable, to capture working capital inventory synergies.

An optimised site layout allows the current heap leach operation to run independently of the CIL project. As such, the construction of the CIL project is not expected to impact the heap leach operation.

The updated mineral reserve estimates were undertaken by Snowden Mining Industry Consultants. Compared to the 2016 Feasibility Study reserves, a total of 1,0 Moz has been added.

A number of schedules were completed to test the impact of limiting stockpile size and it was found that there was limited benefit to allowing for large stockpiles. As such, the mining sequence and stockpile management have improved in the Optimised Study compared to the Feasibility Study. Whereas previously the mining period was nine years followed by the processing of stockpiled low-grade ore for another five years, the current mine plan is based on 12 years of mining followed by the processing of stockpiled low-grade ore for another two years.

A combination of strategic pit staging and stockpiling allows gold production to be brought forward, with about 1,2 Moz mined in the first five years from commissioning and 1,5 Moz in the last 10 years. The overall grade profile declines gradually over the life of mine as higher-grade deposits such as Bakatouo, Daapleu and Mont Ity/Flat are mined upfront.

The mine planning, resource and cost estimation for the Feasibility Study was based on an owner-operated mining operation using 90-tonne haul trucks and a maximum mining movement of 16 Mt per year with a vertical advance of approximately 40 m per year. The company sees these figures as conservative in nature due to the annual rainfall at the Ity project. Mining is scheduled to commence three months before the start of the processing plant to pre-strip the pits and stockpile ore.

The mining fleet contract has been awarded to Komatsu to benefit from synergies relating to minimising spare parts inventory and maintenance costs, as both Houndé and Karma have similar fleets.

Following updated resource and reserve estimates, the key change to the design basis is an increase in throughput from 3 Mt/a feed to 4 Mt/a feed based on a blend of primary and oxide ore. The process route comprises conventional primary crushing followed by a SAG and ball milling circuit (SABC) with recycle pebble crusher, a gravity circuit and a conventional CIL plant. Soluble copper from the Bakatouo asset is blended with the low copper Daapleu ore into the plant process schedule until depletion of Bakatouo.

The CIL circuit comprises eight CIL tanks (up from six in the FS) containing carbon for gold and silver adsorption with oxygen sparged from two 25-tonne PSA oxygen plants and an 18-tonne split Anglo (AARL) elution circuit. Electrowinning and induction furnace smelting complete the gold doré production process.

A cyanide detoxification and arsenic removal circuit is included in the process facility design for treatment of process residue before discharge to the fully lined 57 Mt Tailings Storage Facility (TSF), located adjacent to the processing facility.

The overall life of mine recovery rate has increased from 83 % in the Feasibility Study to 86 % in the Optimised Study due to the addition of high-recovery Bakatouo oxide and fresh ore, Mont Ity ore and better recovery on Daapleu sulphides following additional testwork.

Capital costs include the construction of a 58 km, 91 kV overhead power line, which connects to the national grid at Danane and terminates with a substation at Ity which will be owned by Côte d’Ivoire Energie (CIE). A full 26 MW full high-speed diesel back-up power station provides 100 % redundancy.

The schedule anticipates the project being completed within 20 months from EPCM award. 

Contact Modern Mining

Title: Editor
Name: Arthur Tassell
Email: mining@crown.co.za
Phone: +27 11 622-4770
Fax: +27 11 615-6108

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Name: Bennie Venter
Email: benniev@crown.co.za
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