Tantalum in Ethiopia

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MINERAL RESOURCES OF Tantalum in Ethiopia Tantalum is a strategic metal due to its use in one of the most widespread gadgets in modern society, the mobile phone. Tantalum is also used in other types of electronic equipment and is thus in high demand. At present Ethiopia supplies close to ten percent of the world consumption of tantalum and has a good potential for a considerable expansion of the production. The trade name for the most common tantalum-bearing mineral is ‘coltan’ whereas the mineralogical name is colum - botantalite or columbite. The Kenticha tantalum de - posit in Southern Ethiopia has Ta/Nb ratios up to 3:1, which makes the deposit economically very important. The Kenticha tantalum-be aring pegmatites were first discovered during a geological, 1:250 000 scale, mapping programme carried out by Ethiopian geologists in close co-operation with Soviet geologists in 1980. A major mapping and evaluation programme financed by the Soviet Union was carried out from 1981 to 1985. The purpose of the project was to determine the extent of the tantalum-bearing rocks and to evaluate their commercial potential. The Kenticha pegmatites are situated in the Adola area within the Pre cam - brian basement of southern Ethiopia, which is the southern part of the Arabian–Nubian Shield formed by accretion of ocean arc terranes. The Neo - proterozoic rocks can be divided into two distinct lithologic units: 2 tt bb aa rr a a Shendi Omdurmân Khartoum Kassala Abu Gamel ERITREA Keren Sebderat Adi Ugri San‘a Y E M E N Dhamar Yarim Lawdar Irqah Ash Shihr Al Mukalla Wad Medánî Om Hajer Gedaref Adwa Melau Adigrat Mek’ele Shaqra Ahwar Caluula Socotra Socot S t r ra Abd-Al-Kuri Abd-Al- A Ku K ri r The Brothers Gallabat ETHIOPIAN HIOP N Caseyr e Kosti Singa Dabat Sek’ot’a PLATEAU PL P A TE T A U Gonder Lalibela DJIBOUTI DJIB DJIBOUTI Bender Qaasim Qandala Renk Er Roseires NUBIAN N DESERT DESE E R T Dunkur Alefa Debre Tabor Dangila Mot’a Girshit’ Talo T Ta T Debre Mark’os A Debre Birhan Biye K’obe Dire Dawa Gulf of Saylac Tadjou TTadjoura adjou adjo ra r Karin Berbera Bullaxaar Shiikh Hargeysa Burao Ceerigaabo Qardho Ras Xaafuun Xaafuun Bender Beyla Nek’emte Ankober Addis Abeba Mi’eso Harer Laascaanood Eyl Dembi Dolo Koma A Nazret Degeh Bur Gore Hosa’ina Asela ETHIOPIA ETH T O O g a d e n Abera Waka Ginir Goba Batu B Megalo irga Alem e Maji Kara Gidole Burji Negele egele K’elafo El K’oran ora SOMALIA SOMALIAA Hobyo Hamer Koke Yabelo YYabelo Beled Weyne Xuddur Buulobarde Luuq Nimule Moyale Baydhabo Jawhar Lodwar Gulu U G A N D A Chalbi C h a lbi Desert Dese r t Marsabit Wajir Balcad Afgooye Uarsciek UUarsciek Baardheere Qoryooley Muqdisho (Mogadishu) Marka I N D I A N O C E A N Elgon on o K E N Y A Baraawe Afmadow Jilib lib Nanyuki Giamame GGiamame Ba B Shendi Omdurmân d Khartoum K Kassala s Abu Gamel Ga Keren Sebderat Adi Ugri San‘a Dhamar Yarim Ya im Lawdar Irqah Ash Shihr Al Mukalla Wad Medánî ed Om m Hajer Gedaref Adwa Melau M Adigrat Mek’ele Shaqra Ahwar Caluula Gallabat ab Kosti Singa Dabat Sek’ot’a PL P A TE T Gonder G e Lalibela Bender Qaasim Qandala Renk Er Roseiress Dunkur Alefa A Debre Tabor T Dangila gi Mot’a ot’a Girshit’ Debre ebre b Mark’os Mark ark’o a Debre Birhan Bi Bir Biirh Biye K’obe Dire Dawa Saylac S Karin Berbera Bullaxaar Shiikh Hargeysa Burao Ceerigaabo Qardho Xaafuun Bender Beyla Nek’emte k’ Ankober Addis Abeba Mi’eso Harer H Laascaanood Eyl Dembi Dolo Koma K A Nazre Nazret Degeh Bur Gore Hosa’ina os Asela Abera Aber Ginir nir Goba Megalo Maji Kara Burji Hamer Koke Beled Weyne Nimule Gulu Gilo Gilo y y aa bb AA Setit Setit CC HH OOO KKK E EE OO mm oo • Granite-gneiss complex • Ophiolitic fold and thrust belts The ophiolitic fold and thrust belts are composed of mafic and ultramafic volcanic rocks and metasediments. After several phases of deformation and metamorphism the units were intruded by a number of pegmatites among which the Kenticha pegmatite field stands out. The Kenticha pegmatite field Pegmatites are abundant throughout the southern part of Neoproterozoic rocks in the Adola area in southernmost Abay Abayy Mt. Mt M t. Kenya Ke K ny nya Embu m y Nairobi Kitui Kajiado Awash A w ash TT ana ana Dawa Daw a ww aa ss S S NN TTT MM R R AA MM HH AA NTS S N TT MM O O BB EE DD NN EE MM Garissa A U D O R A N G E A U D O R A N G E Ganale Ganale Wabi W abi Shebele Shebele JJ uu bb bb a a andeb andeb Kismaayo GG UU LL F F OO F F AA DD EE N N Webi Webi Shabeelle Shabeelle Ethiopia is located on the Horn of Africa bordering Sudan, Eritrea, Djibouti, Somalia and Kenya. Ethiopia, but are especially abundant in the Kenticha pegmatite field where they occur in an area of about 2,500 km2 . The pegmatites are emplaced at or near a major NNE-SSW-trending shear zone. They range from barren feldspar-muscovite pegmatites to different types of rare-element pegmatites. The Ta bearing pegmatite deposit in Kenticha Field is exposed over a 2.5 km long and 40-70 m wide area. It occurs in a package of steeply dipping serpentinites and talc-tremolite schists. The thickness of the pegmatite varies. In locations where both hanging and footwall contacts are exposed, thickness ranges from 40 m to 70 m. The upper part of the ore body is strongly weathered to a variety of clay minerals. The tantalite occurs in grain size from a few millimetres up to about 5 cm. Weathering has affected the feldspars
and most of the lithium-bearing mine - rals, whereas the tantalite is unaffected by the weathering. Mining is so far confined to the weathered part of the ore. The ore is simply dug out by a bulldozer, scooped up onto trucks and driven to a plant where the ore is mixed with water. Then the columbite concentrate is produced through a series of steps of screening, jigging and final treatment on shaking tables. The recovery is ap - proximately 70 percent. The remaining 30 percent is stored in a vast tailings pond for later use. The deeper part of the ore body is hard-rock, non-weathered pegmatite. This ore body has about the same tonnage as the weathered ore body, but has not yet been exploited. The Kenticha pegmatites display complex zoning. Apart from columbite, a number of lithium minerals such as lepidolite and spodumene are found. Fur - thermore small amounts of beryl and sulphides occur. Tantalum resource The Kenticha tantalum deposit is mined by the Ethiopian Mineral Development Share Company (EMDSC). • The production is around 100 tonnes of Ta 2 O 5 per year • The primary un-weathered ore re - source is measured to ca. 17,000 tonnes with a grade of 0.017% Ta O 2 5 • The proved ore reserve of the weathered zone plus a minor part of unweathered ore is ca. 4,700 tonnes with an average grade of 0.015% Ta O 2 5 The Ta/Nb ratio varies considerably from 1:1 and up to 3:1. Uranium contents Uranium is an abundant trace element in part of the ore deposit. The final tantalite concentrates typically contains just above Lake Tana Addis Ababa 0.5% uranium, well above the content which is acceptable to the European and North American markets. Additional commodities Main Ethipoian Rift High-grade Precambrian Undifferentiated gneisses and schists Low-grade Precambrian Metavolcano-sediments Metaultramafic-mafics Precambrian Phanerozoic Intrusives Gabbro Diorite Granite-tonalite Palaeozoic Rocks Mesozoic Rocks Undifferentiated sediments Cenozoic Rocks Early-Mid Tertiary basalt Upper Tertiary-Quaternary - basalt Mid Tertiary-Quaternary - felsic rocks Early Tertiary sediment Tillites Upper Tertiary-Quaternary sediment Simplified geological map of Ethiopia with mine symbol at Kenticha mine. The pegmatites in the Adola area display a variety of minerals of which the lithiumbearing phases such as spodumene and Li-micas over time may be valuable byproducts. In the Kenticha pegmatites, certain parts of the coltan mineralisation carry low levels of uranium. Uranium in coltan can be a problem or an asset depending on the level of uranium. In most parts of the Kenticha coltan, the uranium is above the critical level of 0.5%, as is the case of coltan mentioned above. This means that Europe will not allow import of this quality of coltan. Serpentinite Quartz core Weathered ore body Weathered tantalum ore body (white) underlying talc-tremolite schists and serpentinites. The quartz core is standing out. Plant is seen on the left side of photo. Geology: Modified from Mengesha et al.(1996) Geological map of Ethiopia, second edition, 1:2,000,000 3 MINERAL RESOURCES OF
Page 1: INFORMATION ON THE MINING POTENTIAL

Tantalum in Ethiopia

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