tonkolili iron ore mine, sierra leone, west africa - mining technology | mining news and views updated daily
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 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.
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.
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.
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 andtransportedto 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.
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.
SRK Consulting was engaged in December 2008 to conduct a mineral resource estimate for theiron ore mine. BCM Group was awarded the mining contract and Hawk was engaged as the civil works contractor for the first phase.
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.
extraction of iron from its ores, iron dressing, reduction & production | science online
Iron is the most important metal in heavy industries, Iron is the fourth most abundant element in earths crust after oxygen, silicon and aluminum as it forms (5.1 %) of the mass of the earths crust and this mass increases gradually as we come close to the center of earth, Iron occurs only in the form of pure metal (90%) in meteorites.
Iron ( 26Fe: (18Ar), 4S2, 3d6 ) is found in the earths crust in the form of natural ores which contains different iron oxides mixed with impurities such as Silica (SiO2), (Al2O3), CaO, and MgO, and some harmful impurities such as s, p and As, The suitability of the ore in the extraction of iron economically depends on three factors which are:
The ore is Hematite, chemical name is iron III oxide, the chemical formula is Fe3O4, It has a blood red colour, it is more easily reduced, Iron is from 50-60 %, place of deposits is Oasis area (western desert) and western part of Aswan.
The ore is Limonite, chemical name is Hydrated iron III oxide, the chemical formula is 2Fe2O3.3H2O, It has a yellow hydrated oxide & it is easily reduced, Iron is from 20-60 %, place of deposits is Oasis area.
Magnetite is a compound behaves as a mixture of two oxides: FeO (iron II oxide, the oxidation number of iron = +2), Fe2O3 (iron III oxide, the oxidation number of iron = +3), so, the oxidation number of Fe in Fe3O4 is (+2, +3), Magnetic iron oxide is a mixed oxide because when it reacts with conc. acids, two types of salts are produced.
Extraction of iron or its metallurgy is the process of obtaining this metal in a form where it can be put to practical use, and this process of extraction consists of three stages: Ore dressing, Reduction of ores and Iron production.
The aim of ore dressing is increasing the concentration of iron in the ore by removing the unwanted impurities and improve the properties of the ore which helps in the successive stages of extraction, The ore dressing process is carried out to improve the physical and mechanical properties of iron ore and includes Crushing process, Sintering process, Purification and concentration of the ore.
Crushing process is used to obtain iron ore in small size that can be reduced easily, Sintering process is used to obtain the fine particles of iron ores in large size, As a result of the crushing process & cleaning furnace a huge amount of fine particles of ore are obtained which can not be used directly in high furnace directly, these particles must be treated to collect them in a larger size to be similar & homogeneous and this process is called sintering.
The sintering process is the process of treatment of the fine particles of iron ore obtained from crushing process or in cleaning furnace to collect them in a larger size to be similar and homogeneous particles fit for reduction process.
Purification & concentration process is the process of using surface tension properly, magnetic or electrical separation to remove the unwanted impurities which are chemically combined or mixed with ore to increase the percentage of iron in the ore.
Ore-dressing process is also carried out to improve the chemical properties of ores by roasting, It means heating the substance strongly in the air for drying the ore, expelling humidity, converting the iron ore into oxide, increasing the ratio of iron in the ore, oxidation of some harmful impurities as (S and P).
Roasting is the process of heating iron ore strongly in dry air for drying the ore and expelling humidity, It is used to increase the percentage of iron in the ore and for the oxidation of some impurities such as sulphur and phosphorus.
Roasting of iron is very important in the ore dressing process but this process pollutes the environment, Ore dressing is important for iron ores before their reduction to remove most impurities and improve the physical & chemical properties of the ore.
It is very important to dress iron ores before reduction as the iron ore dressing improves physical, mechanical and chemical properties of the ores and makes it suitable to be reduced easily and effectively, The disappearance of the luster of a piece of iron when it is heated because the iron has the tendency to form a layer of iron oxide on its surface after heating.
The reduction process is the process of reducing iron oxides to iron by carbon monoxide resulting from coke in the blast furnace or by a mixture of carbon monoxide and hydrogen gases (water gas) resulting from natural gas in the Midrex furnace.
Reduction of Fe2O3 by using a mixture of carbon monoxide and hydrogen (water gas) that is produced from natural gas (93% methane) in the Midrex furnace to produce Spongy iron, Spongy iron is the iron mixed with impurities where it is produced from the midrex furnace and it has holes similar to that in the sponge.
After the reduction of iron ores in the blast furnace or Midrex furnace, the third step in which the production of different types of iron such as cast iron and steel, The steel industry depends on two essential processes:
Tags: Blast furnaceCast ironCokeConcentration of the oreCrushing processElectric FurnaceelementsExtraction of IronExtraction of Iron from its oresHeavy industriesHematiteImpuritiesIronIron configurationIron dressingIron importanceIron ore dressingIron oresIron oxidesIron percentageIron productionIron reductionLimoniteMagnetic iron oxideMagnetiteMeteoritesMethaneMidrex furnaceOpen-hearth furnaceOre dressingOxygen convertersPurificationReducing agentReduction of iron oresReduction of oresRoastingSideriteSintering processSpongy IronsteelSteel industry