The Tonkolili iron ore mine was initially developed by UK-based African Minerals (AML) through its subsidiary Tonkolili Iron Ore in Sierra Leone, West Africa.
The mining lease for the project was approved in August 2010. In September 2011, the Chinese steel company Shandong Iron & Steel Group acquired a 25% interest in the Tonkolili iron ore project from AML.
The project development involved a fully integrated mine, rail and port infrastructure, which was planned to be developed in three phases. The first phase of development commenced direct shipping iron ore production in November 2011.
AML initiated the shutdown of its Tonkolili iron ore operation due to insufficient working capital in December 2014. Shandong Iron and Steel Group acquired the remaining 75% interest in the Tonkolili iron ore mine for more than $170m in April 2015. Shandong Iron & Steel stopped operations after its licence was cancelled by the Sierra Leone Government in 2019.
The Sierra Leone Government handed over the operations of the Tonkolili Iron Ore mining to the Chinese Kingho Mining Company through the Ministry of Mines and Mineral Resources in September 2020.
The Tonkolili mine is Africa’s second-largest iron ore mine and one of the largest magnetite deposits globally with an estimated operational period of more than 60 years.
Tonkolili iron ore mine geology and reserves
The Tonkolili iron ore deposit is located within the Sula Mountain range and forms part of a banded iron formation (BIF) featuring a north east-south west trending magnetic anomaly. The mine contains four contagious ore bodies, Simbili, Marampon, Numbara, and Kasafoni.
These are underlain by amphibolites, amphibolite-hornblende schists, phyllites and amphibolites associated with basaltic lava flows of the Sonfon Formation.
Each of the ore bodies is open at depth and characterises primary magnetite mineralisation underlying the secondary hematite/goethite style mineralisation.
The Tonkolili iron ore mine covers a 408m² area with an estimated resource capacity of up to 13.7 billion tons of iron ore.
Tonkolili mine development
The first phase of development included the establishment of a mine, reconstruction of the Pepel Port, 74km of existing railway, and the construction of a new 126km narrow gauge railroad as logistics transportation system. First phase direct shipping hematite iron ore production increased up to 20 metric tonnes per annum (Mtpa) in 2013.
Shandong Iron and Steel Group achieved a capacity of 20MMtpa in phase one development and had plans to increase production up to 25mtpa in phase two.
However, Kingho Investment Company (Kingho) restarted operations at the mine under the New Tonkolili Iron Ore Project. It completed the first phase of the project, including raw ore mining and processing, as well as shipping and sales.
Kingho began the first shipment of iron ore from the mine in January 2021 to China and commenced its full-scale operation in March 2021.
The second and third phase developments will involve the construction of a primary magnetite ore concentrator and an iron and steel industrial park for mining, dressing and smelting.
Mining and processing of ore at Tonkolili mine
The first phase open-pit mining operation was carried out using two RH120E excavators, two PC1250 excavators, and 28 777D/F haul road trucks. Extracted ore was processed at a wet processing plant, which is supplemented by a mobile crushing, washing and screening plant and a semi-mobile crushing plant.
Direct shipping iron ore was loaded into the rail cars using front end loaders and transported to the Pepel port where bottom dump trains are used to discharge iron ore onto the 3,000 tonnes per hour (tph) in-loading and stacking system. The iron ore was exported from the port by a fleet of four trans-shipping vessels.
Other infrastructure facilities at the Pepel Port include two stockpile material handling facilities, a 160-person camp, and a dredging facility.
Financing for Tonkolili mine
The first phase of the iron ore mining project under African Minerals received $100m of subordinated standby facility from Standard Bank. An £80m placement with institutional investors was also completed for the first phase of construction in February 2010.
China Railway Materials Commercial Corporation (CRMCC) invested £167.8m in the project.
Contractors involved with the Tonkolili mine development
SRK Consulting was engaged in December 2008 to conduct a mineral resource estimate for the iron ore mine. BCM Group was awarded the mining contract and Hawk was engaged as the civil works contractor for the first phase.
China Civil Engineering Construction Corporation (CCECC) was involved in the construction of the 126km railway track from Lunsar to Tonkolili.
Hatch Goba was contracted to improve rail and port infrastructure between the Tonkolili mine and the Pepel port.
Ausenco was appointed as the front-end engineering design (FEED) engineer for phase two of the Tonkolili iron ore project in February 2014.
Worley Parsons, which carried out the definitive feasibility study (DFS) and the FEED study for the first phase, was engaged to conduct an infrastructure engineering study for the second phase of the project.