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The Faleme iron ore deposits are located in the Birrimian volcano-sedimentary complex, forming part of the Diale-Dalema series of the Birrimian Supergroup that was subjected to contact metamorphism. Primary magnetite within the metamorphic aureole has undergone supergene oxidation (martitisation) to produce the haematite-rich iron deposits that can be seen as prominent hills across the plains of SE Senegal. The Bureau de Recherches Geologiques et Minieres of France and Societe des Mines de Fer du Senegal Oriental have conducted several phases of prospecting since 1957, to delineate the primary magnetite and oxidised haematite deposits and to assess the grade, beneficiation characteristics and marketability of the iron ore. Ten ore types were defined in the three Koudekourou Hills, which contain 276 000 000 t of resources at 58.4% Fe: surface; massive kaolinitic; massive brecciated boxwork; magnetite-rich; friable grey; powdery; argillaceous; sulphide-rich magnetite; mixed limonitic; and mixed haematite. Types 1-4 and 8 are common to Koudekourou East and Centre, 5-7 are specific to Eastern Hill and 9-10 to Central Hill. A haematite feasibility study in 1992 indicated that, at the time, the resource could not compete internationally in terms of size and accessibility, but there is now a growing iron ore market and additional resources are available in the area. The project faces some mining challenges, such as the amount of magnetite in the haematite product that will be acceptable, though sullphide-rich magnetite ore with positive metallurgical test results was included as part of the resource at Koudekourou West. Previous evaluations only considered the secondary haematite deposits as economically viable, so it is important to delineate accurately the magnetite/haematite contact zone to optimise resource tonnage. Logistical constraints also exist but the resource is well situated for the European iron ore market., The Faleme iron ore deposits are located in the Birrimian volcano-sedimentary complex, forming part of the Diale-Dalema series of the Birrimian Supergroup that was subjected to contact metamorphism. Primary magnetite within the metamorphic aureole has undergone supergene oxidation (martitisation) to produce the haematite-rich iron deposits that can be seen as prominent hills across the plains of SE Senegal. The Bureau de Recherches Geologiques et Minieres of France and Societe des Mines de Fer du Senegal Oriental have conducted several phases of prospecting since 1957, to delineate the primary magnetite and oxidised haematite deposits and to assess the grade, beneficiation characteristics and marketability of the iron ore. Ten ore types were defined in the three Koudekourou Hills, which contain 276 000 000 t of resources at 58.4% Fe: surface; massive kaolinitic; massive brecciated boxwork; magnetite-rich; friable grey; powdery; argillaceous; sulphide-rich magnetite; mixed limonitic; and mixed haematite. Types 1-4 and 8 are common to Koudekourou East and Centre, 5-7 are specific to Eastern Hill and 9-10 to Central Hill. A haematite feasibility study in 1992 indicated that, at the time, the resource could not compete internationally in terms of size and accessibility, but there is now a growing iron ore market and additional resources are available in the area. The project faces some mining challenges, such as the amount of magnetite in the haematite product that will be acceptable, though sullphide-rich magnetite ore with positive metallurgical test results was included as part of the resource at Koudekourou West. Previous evaluations only considered the secondary haematite deposits as economically viable, so it is important to delineate accurately the magnetite/haematite contact zone to optimise resource tonnage. Logistical constraints also exist but the resource is well situated for the European iron ore market.

Both deposits have undergone folding, faulting and thrusting. Four similar iron ore occurrences have been recognised at each: laminated and massive ores, probably developed in basins and pseudo-graben; collapse breccias preserved in palaeosinkholes that developed in dolomites; and lower-grade conglomeratic and gritty ores of the overlying succession. The Sishen orebody is thicker, more continuous and significantly larger, with 895 000 000 t of open-cast mineable reserves as against a potential 228 000 000 t at Sishen South, which comprises a number of small, narrow, isolated orebodies. On average, ores at Sishen South contain 0.25% more Fe, 0.09% less K2O and 0.019% less P as well as having less interbedded shale in the laminated and massive ores. The footwall of the high-grade ores, a low-density intrusive sill, is expected to result in less impact of ore dilution on product grades than the banded iron formation at Sishen as it will be readily removed by heavy-medium separation., Both deposits have undergone folding, faulting and thrusting. Four similar iron ore occurrences have been recognised at each: laminated and massive ores, probably developed in basins and pseudo-graben; collapse breccias preserved in palaeosinkholes that developed in dolomites; and lower-grade conglomeratic and gritty ores of the overlying succession. The Sishen orebody is thicker, more continuous and significantly larger, with 895 000 000 t of open-cast mineable reserves as against a potential 228 000 000 t at Sishen South, which comprises a number of small, narrow, isolated orebodies. On average, ores at Sishen South contain 0.25% more Fe, 0.09% less K2O and 0.019% less P as well as having less interbedded shale in the laminated and massive ores. The footwall of the high-grade ores, a low-density intrusive sill, is expected to result in less impact of ore dilution on product grades than the banded iron formation at Sishen as it will be readily removed by heavy-medium separation.

The Complex, in the Transvaal, consists of metamorphosed granitic and gabbroic rocks, the latter containing a number of titanium-vanadium-magnetite-rich zones. Ilmenite occurs in the soil overlying the Complex as a residual product of in-situ weathering. Detailed experimental work has been carried out on two segments of the magnetite-rich rocks and on the ilmenite-rich soil. A variety of microstructures were found, with metamorphism having caused spheroidation of exsolved ilmenite lamellae and the subsequent formation of secondary ilmenite along the boundaries of the magnetite grains. This has been altered by weathering. Martitisation of the magnetite was common. There were differences between the chemical compositions of the ilmenite in the rocks and in the sand ore, the latter having higher TiO2 contents. Variation in chemical composition and in grain size both play an important role in the magnetic susceptibility of the ilmenite grains during magnetic beneficiation. Depending on the influence of the residual magnetite, the (secondary) haematite was found to concentrate in either the magnetic or the non-magnetic fraction., The Complex, in the Transvaal, consists of metamorphosed granitic and gabbroic rocks, the latter containing a number of titanium-vanadium-magnetite-rich zones. Ilmenite occurs in the soil overlying the Complex as a residual product of in-situ weathering. Detailed experimental work has been carried out on two segments of the magnetite-rich rocks and on the ilmenite-rich soil. A variety of microstructures were found, with metamorphism having caused spheroidation of exsolved ilmenite lamellae and the subsequent formation of secondary ilmenite along the boundaries of the magnetite grains. This has been altered by weathering. Martitisation of the magnetite was common. There were differences between the chemical compositions of the ilmenite in the rocks and in the sand ore, the latter having higher TiO2 contents. Variation in chemical composition and in grain size both play an important role in the magnetic susceptibility of the ilmenite grains during magnetic beneficiation. Depending on the influence of the residual magnetite, the (secondary) haematite was found to concentrate in either the magnetic or the non-magnetic fraction.