Download Potash in Ethiopia

EthiopienFS_Potash_Ethiopia 1/4/11 3:09 PM Page 1
Potash in Ethiopia
The potash potential of Ethiopia
was dormant until World War II
where Italian and other foreign
companies initiated exploration
activities in different parts of the
extremely hot Danakil Depression of northern Ethiopia, where
temperatures regularly exceed
+50°C. The companies exploited
a number of mineral resources,
such as potash and sulphur. The
Danakil depression is found down
to 110 m below sea level. The
evaporites of the central parts of
the Danakil Depression cover an
area of 1165 km2, the major part
of which is known as the Salt
Plain.
The Afar region of north-east Ethiopia
is covered by Quaternary lacustrine
sediments and volcanic rocks of the
East African Rift Valley. The central part
of the Danakil Depression is covered by
a thick evaporite succession (Salt
Formation), which is partially covered
by Quaternary volcanic rocks.
The Salt Formation is composed of a
thick evaporite succession of gypsum,
anhydrite, mixed with layers of halite
and potash salts, as well as shales.
Mount Dallol is a type area for the Salt
Formation. It is a regular salt mountain,
situated in the middle of the Salt Plain.
This formation was uplifted by volcanic
action, and has numerous craters and
hot springs.
Lake
Tana
ft
Addis Ababa t
E
Ri
n
ai
M
High-grade Precambrian
Undifferentiated gneisses
and schists
Low-grade Precambrian
Metavolcano-sediments
Metaultramafic-mafics
Precambrian
Phanerozoic Intrusives
Gabbro
Diorite
Granite-tonalite
Palaeozoic Rocks
Tillites
Mesozoic Rocks
Undifferentiated sediments
Cenozoic Rocks
Early-Mid Tertiary basalt
Upper Tertiary-Quaternary - basalt
Mid Tertiary-Quaternary - felsic rocks
Early Tertiary sediment
Upper Tertiary-Quaternary sediment
Simplified geological map of Ethiopia showing Danakil Derpessoion hosting potash deposits.
km2, but only a small part of this area
has been explored. Gypsum is the most
widespread lithology on the surface,
but halite and potash salts are also
found both as isolated outcrops on the
surface and at depth. The gypsum beds
form the outermost units of the evap-
Geology of potash deposits
The potash deposits occur within the
evaporite sequence, which is essentially confined to the areas, below the
present sea level, of the Danakil
Depression. The salt formations on the
surface cover an area of about 1165
an
oi
p
hi
Geology: Modified from Mengesha et al.(1996)
Geological map of Ethiopia, second edition, 1:2,000,000
MINERAL RESOURCES OF
Danakil Depression
Evaporites at the Danakil Depression.
orite sequence and thickness of the
sequence is unknown; however, the
deepest hole drilled remained in salt to
a depth of about 1000 m. Several
potash horizons are recognised,
although only the uppermost have
been explored.
MINERAL RESOURCES OF
EthiopienFS_Potash_Ethiopia 1/4/11 3:09 PM Page 2
On Mount Dallol a sequence of evenly bedded layers of salt 20–30 cm thick, interbedded with thin clay and gypsum layers is
exposed. The salt is stained in red, brown and
yellow colours due to the oxidation of iron
and sulfur emanating from fumarolic vents.
A cap rock of gypsum and clay overlies the
salt sequence and is believed to represent the
last stage of evaporite deposition in the
basin. Sylvite, carnallite and sulphur outcrops occur around the central crater of the
mountain.
Potash Resources
Exploration work carried out by various companies until now has revealed the presence of
two ore bodies at the Danakil Depression.
These are the Crescent and Musley ore bodies.
Crescent Ore Body
The ore body is irregular in shape, relatively
flat lying and about 1000 m long and 100 m
wide. The deposit surrounds a bubbling
spring of magnesium chloride-rich water;
located on the surface and occurring down to
c. 90 m, mainly in the form of carnallite and
some sylvite. The maximum thickness is up
to c. 60 m. The ore reserves in the Crescent
ore body have been estimated to be 10–12
million tonnes with a cut-off value of 25%
sylvite. From this reserve it is expected to be
possible to recover around 3 million tonnes
from a 1.5 m thick layer.
Musley Ore Body
This ore body extends over a length of about
4 km and a width of about 1.5 km striking
about 25°N. The largest potash deposit,
Musely, was extensively explored during the
1960s.
Within the thick sequence of halite, there
is a potash-rich interval consisting of sylvite
(upper¬most), carnallite and basal kainite.
This interval was explored by drilling with
300 m spacings, by shaft-sinking (90 meters)
and by underground work down to 800 m to
evaluate mineability.
Drilling indicated the presence of a 500 m
deep potash-bearing horizon similar to that
explored by the underground work and by
shallow drilling. The potash beds are shallowest in the western part of the basin and
dip to the east. At Musely, drill-hole information suggests that the potash-rich horizon
underlies an area at least 19 km long (northsouth) and nearly 11 km wide. However, the
full extent of this horizon is not yet determined.
Drilling and underground work resulted in
an ore reserve estimate for Musely of 66 million tonnes ‘proven’ and 32 million tonnes
‘probable’. Both reserves are averaging 33%
sylvite, with a cut-off grade of 25% sylvite
and a 2.1 m minimum mining thickness.
Reserves in the category ‘possible’ were estimated to around 62 million tonnes, resulting
in a total of 160 million tonnes of reserves.
Companies operating in the Danakil
Depression
The following companies are operating in the
Danakil Depression exploring for potash and
related salt minerals: Sainik Coal Mining plc,
Ethio-Gibe Canada Mining plc, G and B
Central African Resources Ltd, BHP Bilton
World Exploration inc, SB Management inc,
Forbs & Manhattan inc, Nova Potash plc and
Haro Petroleum Corporation. Sainik Coal
Mining plc also has an active mining license.
Ministry of Mines of Ethiopia
Dear Investors,
We take this opportunity to welcome you
to Ethiopia.
We promise to make every possible effort
to provide you with all required information on the mineral sector in Ethiopia.
If you require information on the mining
law, licensing conditions and the investment climate in Ethiopia, please contact
the Mineral Licensing and Administration
Department:
Ministry of Mines
Mineral Licensing and Administration
Department
P.O. Box 486
Addis Ababa, Ethiopia
Tel. +251 11 6461214
Fax +251 11 6463454
Email: [email protected]
www.mome.gov.et
If you require information on the geology
and mineral opportunities in Ethiopia,
please contact the Geological Survey of
Ethiopia (GSE):
Geological Survey of Ethiopia
P.O. Box 2303
Addis Ababa, Ethiopia
Tel. +251 6 463325
Fax +251 6 463326
Email: [email protected]
www.geology.gov.et
Drilling for potash in the Danakil Depression.
We are looking forward to your mining
investment in Ethiopia.
Prepared with assistance from GEUS.
December 2010