Falémé iron ore deposits
The iron ore deposits of Falémé are located in the Kédougou region in the southeast of the Republic of Senegal , near the border triangle Senegal- Mali - Guinea and are named after the border river Falémé , in whose catchment area they have been identified.
Geology and mineralogy
The iron ore deposits of Falémé consist of lenticular ore bodies lined up like a string of pearls in crystalline slates of sedimentary and / or volcanogenic origin. The constant stratigraphic position of the ore bodies and the adjacent rock, a marble train lying in the hanging wall, which serves as a guide horizoncould be detected in almost all deposits suggest a primarily sedimentary formation of the iron ore. However, the shape and extent of the ore bodies as well as the mineralogical-petrographic composition of the ore and its adjacent rock suggest contact metasomatic formation (Marcona type), possibly in the wake of granitic intrusives. The primary ores have a relatively coarse-grained magnetite intergrowth of 0.01 to over 2 mm, with an average of 0.25 mm, which means that digestion and enrichment are favorable. On the other hand, they show relatively high sulfur contents in the form of pyrite or pyrrhotite, which were formed after the iron ore was formed. The distribution of pyrite-pyrrhotite is partly dependent on the depth , with mainly pyrite predominating towards the outcrop and increasingly pyrrhotite after the depth . In addition, regularities of the distribution of the sulfur content within the ore bodies and the predominance of pyrite or pyrrhotite depending on the petrographic composition of the adjacent rock could be determined. The formation of sulfur-free secondary oxidation ores essentially depends on the location of the ore bodies and their morphological position. For example, the ore bodies of Koudekourou, which are folded but lying flat to the surface, are almost completely oxidized (martitized) to their base. The steep and morphologically high ore bodies of Kouroudiako and Karakaene have comparatively lower amounts of oxidation ores, while in the steep, deep ore bodies of Farangalia and Goto, a lower degree of martitization and, accordingly, a lower enrichment of the Fe content can be observed.
history
The occurrences were first mentioned by Skawych in 1933. 20 years later, Soule de Lafont employed in the investigations of granites of Saraya in 3 Prospektionskampagnen with the iron ores of Falémé River (1955 to 1958). 600 m of tunnels and 700 m of boreholes led to an estimate of 60 million t of pending oxide ore with around 60% Fe and 40 million t of roller ore and canga with 53 to 55% Fe. At that time, the small quantities of reserves made a deposit exploration seem unreasonable.
Between 1962 and 1972, a number of new investigations in the Falémé area were carried out mainly by the Bureau de recherches géologiques et minières (BRGM) . They were primarily focused on sulphide ores and comprised mainly aerial and soil geophysics, core drilling and geological interpretations of the Kouroudiako, Karakaene and Koudekourou areas. In 1974, the BRGM-Krupp consortium dealt with initial considerations, processing attempts and planning drafts for a 10 million t pellet project. The Société des Mines de Fer du Senegal Oriental (MIFERSO) was formed in February 1975 with the Republic of Senegal, the companies Kanematsu Gosho, SEREM and Krupp as partners for a phase-wise exploration of the iron ore deposits . Exploration began in 1975 and completed in 1980.
There is no mining in the Senegalese part of Falémé; a development project agreed in 2007 failed.
exploration
.jpg)
.jpg)
The investigations were carried out in five dry seasons between 1975 and 1980. Field work, such as geological and geophysical investigations, boreholes, mining shafts and large sample wells as well as the overall organization of the field work were carried out by the BRGM. Krupp participated in the ore sampling in Falémé and worked on the laboratory, semi-technical and large-scale processing, pelletizing and metallurgical tests, with the involvement of the Study Society for Iron Ore Processing (SGA).
In phase IA, a general prospecting was carried out to select the ore deposits to be explored. Kouroudiako, Karakaene, Safa / Kabelea, Farangalia, Goto, Koudekourou, Kouroukobi, Khosse and Guebouria were examined. In Phase IB, activities were focused on the Safa, Kouroukobi, Farangalia and Goto deposits. For Farangalia and Goto there were about 135 million t each of probable and possible primary magnetite ore reserves with an average of about 45% Fe, which could be enriched to over 68% Fe in processing experiments using weak-field magnetic separation. Oxide rich ore deposits in Koudekourou and Kouroudiako were also confirmed in this phase, but according to the first estimate they fell by 56 and 26 million t respectively. less important than the primary ores. The primary magnetite occurrences at Farangalia and Goto were explored in Phase IIA. About 110 million t of usable magnetite ores with Fe contents of 42 to 48% could be detected in each of the two deposits, whereby in numerous processing tests, including 2 pilot tests, the possibility of enriching the ores with high-quality pellet feed concentrates with over 67% Fe confirmed. Also in phase IIA, near-surface oxide ores with 52 to 53% Fe were extracted from 41 pits in Koudekourou and Kouroudiako. An enrichment to 56 to 60% Fe could be achieved by means of refining, with gravimetric processing to about 63% Fe.
Phase IIB provided more core drilling in Farangalia with reliable evidence of 114 million t and in Goto of 144 million t of utilizable primary magnetite ores with 42 to 45% Fe. With a quantity output of 52% or 58% with or without downstream flotation, perfect pellets could be burned from the concentrates.
Full wells drilled in Phase IIB in Koudekourou led to the detection of richer oxide ores with up to 64% Fe at the depth. The total reserves increased to 130 million t with an average of about 59% Fe. Numerous samples from mine shafts were enriched to over 63% in pilot tests using a jig and Humphrey spirals . Additional full wells in Koudekourou, Kouroudiako and Karakaene led to the determination of further reserves and the confirmation of the above-mentioned raw ore qualities in phase IIC. The ore reserves increased to 226 million t in Koudekourou and 73 million t in Karakaene. The ore reserves in Kouroudiako were estimated at 48 million tons. Six large samples were taken from two 50 m deep shafts in Koudekourou. Large-scale refining tests resulted in the rich oxide ores with a quantity output of 82 to 85% lump ore and sinter feed with over 63% Fe.
The exploration was completed with Phase IID. The oxide ore reserves determined or estimated so far could be quantified as safe reserves through subsequent drilling work. Two large samples were taken from a 50 m deep shaft in Kouroudiako, which - again with a total output of around 83% - yielded lump ore with over 64% and sinter feed with over 62% Fe.
Products
From the primary magnetite ores from Farangalia and Goto, both acidic and basic blast furnace pellets as well as direct reduction pellets of high quality can be produced. The oxide ores from Koudekourou, Kouroudiako and Karakaene can be used to extract ores for direct use in blast furnaces and for sintering.
| Lump ore | Sintered ore | |
|---|---|---|
| Grain size (mm) | 30/25 - 10 / 6.3 | 10 / 6.3-0.03 |
| With | max 5% excess | max 5% over-, |
| With | 5% undersize | 10% undersize |
| Chemical analysis (%) Fe | 64 | 62-63 |
| FeO | 1-2 | 1-1.5 |
| Si02 | 2.5-3.5 | 3.5-5 |
| Al203 | 1.5-2 | 2.5-3.5 |
| CaO | 0.03 | 0.08 |
| MgO | 0.03 | 0.05 |
| P | 0.03 | 0.03 |
| S. | 0.04 | 0.04 |
| Na20 | <0.01 | 0.01 |
| Physical properties (ISO drum strength) | ||
| > 6.3 mm (% by weight) | 80-84 | 71-73 |
| <0.5 mm (% by weight) | 10-12 | 5.5-6.0 |
On the basis of the different ore types detected in separate deposits, i.e. H. the oxide ores in Koudekourou, Kouroudiako and Karakaene and the magnetitic primary ores in Farangalia and Goto, alternative and differently combined projects can be designed. The essential basic tonnage for the capacity utilization of the railways and ports is an annual production volume of 12 million t.
literature
- Gerhard Haubold: Large iron ore project in Senegal , GDMB , Erzmetall 34 (1981) No. 10
- Souléye Wade: Contribution à l'étude des gisements de fer de la Falémé (Sénégal Oriental) , Nancy, INPL , 1985, 303 p.
Individual evidence
- ↑ Kourou Diakouma at Geonames
- ↑ Karakaéné at Geonames
- ↑ Kodi Kourou in Geonames
- ↑ Senegal wins the lawsuit against the French steel company ArcelorMittal
