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Ethiopia is a landlocked country which is dependent on agriculture. Importing fertilizers such as phos- phate is prohibitively expensive and thus extensive exploration for sources of phosphate has been car- ried out. At least two major mafic complexes, Bikilal in west and Melka Arba in south Ethiopia, proved to contain large resources of low grade apatite. The apatite deposits are mostly fine grained which hampers the beneficiation. The Bikilal complex The Bikilal igneous phosphate deposit is contained in a large layered gabbro com- plex that hosts apatite, ilmenite and magnetite mineralisations. The deposit outcrops in deeply incised hilly terrain under a thin soil cover and would be amenable to openpit mining. Horn- blendites and hornblende gabbros con- tain variable amounts of apatite, ilme- nite and magnetite. Zones of enriched magnetite and ilmenite are often poor in apatite. They have been investigated as sources of iron and titanium. The Bikilal intrusive complex has been investigated in great detail during the last two decades. The exploration at Bikilal comprises more than 30 diamond drill holes with a combined length of more than 7 km. Extensive pitting and trenching have also been carried out. The exploration revealed that the Bikilal complex host two major apatite mineralisation sequences: an upper and a lower zone. The strike length of the upper zone is measured to be 1600 m and it con- tains two main layers of phosphate miner- alisation, with an average thickness of each layer of 30 m and 40 m. The strike length of the lower zone was measured to be 3000 m, between 60 m and 200 m thick. The estimated mineable reserve of the Bikilal phosphate deposit is 180 mil- lion tonnes, at a grade of 3.5% P 2 O 5 . A preliminary beneficiation trial reveals a commercial grade with an overall recov- ery of 3 to 5%. The latest evaluation of the apatite potential, carried out in 2004, concluded that the ‘ore’ was amenable to simple beneficiation, but an economical- ly viable process would need to be devel- oped. Exploration for Phosphate and Iron. MINERAL RESOURCES OF Phosphate in Ethiopia Lake Tana Addis Ababa Geology: Modified from Mengesha et al.(1996) Geological map of Ethiopia, second edition, 1:2,000,000 Precambrian Phanerozoic Intrusives High-grade Precambrian Undifferentiated gneisses and schists Low-grade Precambrian Metaultramafic-mafics Metavolcano-sediments Undifferentiated sediments Palaeozoic Rocks Gabbro Diorite Granite-tonalite Tillites Mesozoic Rocks Cenozoic Rocks Early-Mid Tertiary basalt Upper Tertiary-Quaternary - basalt Mid Tertiary-Quaternary - felsic rocks Early Tertiary sediment Upper Tertiary-Quaternary sediment Main Ethipoian Rift Addis Ababa Melka Arba Bikilal Simplified geological map of Ethiopia with locations of Bilkilal and Melka Arba phoshpate and iron deposits.
