Journal of Minerals & Materials Characterization & Engineering, Vol. 6, No.1, pp 69-77, 2007 Pr inted in the US A. A ll rights reserved
Adaptable Technologies for Life – Cycle Processing of
Tantalum Bearing Minerals
Amuda, M. O. H., Esezobor, D. E., and Lawal, G. I.
Department of Metallurgical and Materials Engineering
University of Lagos, Lagos, Nigeria.
Corresponding Author:
Nigeria is richly endowed in convertible natural resources of which solid minerals are a
member of the endowments. However, the country is basically a mono-product economy
based on its vast oil deposit accounting for over 84% of foreign earnings and 25% of GDP.
The triple challenges of the volatile nature of global oil politics, achieving the objectives of
the millennium development goals and the national economy empowerm ent and development
strategies calls for diversification into hitherto neglected solid mineral deposits to open a
window of opportunities. One of the widely reported mineral deposits in the country with
strong international influence is tantalum-bearing mineral. The mineral had in the past few
decades experienced a strong growth in demand averaging 10% per annum since 1992 with
total world consumption estimated at over 38 thousand tonne in 2005. The total annual
supply of the ore concentrate in 2001 was 720 tonnes when demand was 26 thousand tonnes.
Thus, pushing the price of the concentrate to an all time high of $165 / kg in 2001.
This paper outlines the characteristics of the Nigerian tantalum reserves. It also presents the
evaluation of the competing technologies for complete cycle processing of tantalum bearing
minerals for adoption in the Nigeria solid mineral industry.
Keywords: Adaptable technologies, life-cycle processing, tantalum bearing minerals.
Nigeria’s endowments in fluid and solid minerals are extensive. The country’s mineral
development in terms of prospecting and exploitation has been largely focused on its oil and
gas industry. The solid minerals sector has been neglected. Solid minerals constitute a wide-
range of natural resources that provide a high developmental potential for a given country.
They provide the bulk of raw materials for industry and have a high content of technological
development input. The list of known minerals in Nigeria is impressive [1]. Unfortunately,
knowledge is available for only about a third of the mineral [2]. Nigeria is Africa’s largest oil
producer and contributes about 3% to global production. Crude oil is therefore the bedrock of
the country’s economy. Oil production averages 84% of the annual foreign earnings of
government and constitutes about 25% of GDP [3]. As a consequence of this, mining and other
earth based economic activity has been neglected. Currently, prospecting and mining of solid
minerals contribute just 1% to the country’s GDP [4].
70 Amuda, M. O. H., Esezobor, D. E., and Lawal, G. I. Vol.6, No.1
The volatile nature of global oil politics and economics calls for diversification into the
hitherto neglected vast solid mineral deposit not only to widen the scope of the financial well
being of the state but also to open a window of opportunities. Besides, the current structural
reforms of the Federal Government as anchored in the National Economic Empowerment and
Development Strategy (NEEDS) policy and the millennium development goals emphasize
capacity building and self reliance in areas of comparative advantage in natural and national
endowments in order to improve standard of living.
Nigeria tantalite endowment is impressive. The mineral is currently experiencing global
Tantalite / Columbite – tantalite ore groups are the major sources of metal tantalum which is
a refractory metal with distinct electrical, chemical and physical properties. The metal is used
essentially as tantalum powder in a number of applications [5]. Some of the applications
include but not limited to electronic capacitor, metal cutting tools, important addition to super
alloys, camera lenses, chemical equipment. The use of tantalum has, for instance, been
instrumental in reducing the size of mobile phones.
The upsurge in the application of systems and devices that uses tantalum bearing component
as a unit has increased the demand for the primary tantalum ore concentrate. The mineral had
in the past few decades experienced a strong growth in demand averaging 10% per annum
since 1992 with total world consumption estimated at 38 thousand tonne in 2005[6]. The total
annual supply of ore concentrate in 2001 was 720 tonnes when demand was 2,600 tonne.
Thus, pushing the price of the concentrate to an all time high of $165/kg in 2001 compared to
$14/kg in 1990. The supply has not kept pace with the demand.
The clear gulf in the supply-demand market situation of tantalum ore concentrate due to
increase in devices, instruments and systems that uses capacitors to regulate voltage surge in
high temperature and similar environment, particularly in the electronic, aviation and medical
industries has made investment in prospecting, mining and beneficiating tantalite bearing
mineral a worthy investment. The high premium in tantalum ore concentrate at the moment
($165/kg) gives a high rate of return on investment.
The wining of tantalum from tantalite ore concentrate via industrial extraction requires the
establishment of tantalite processing plant adopting the best combination of production
technology, competitive economic and environmental safety. The decision to invest in a
tantalite processing plant is a function of many variables. Key element in these variables are
investment cost in relation to industrial uses, evaluation of market trends and return on
The paper characterizes the Nigerian tantalite reserves and evaluates competing technologies
for complete cycle processing of tantalum bearing minerals for adoption in the Nigerian solid
minerals industry.
Tantalum bearing minerals occur in pegmatite and other related mineral rock deposits as
tantalite and microlite, nodgnite, columbite and struvenite. It is naturally discovered in
pegmatite in conjunction with other economic minerals. Some of these are beryl, spodumene,
feldspar, mica, scheelite, cassiterite, uraninite and monazite. Also, weathering and erosion of
Vol.6, No.1 Adaptable Technologies for Life 71
tantalite bearing primary deposits can mechanically enrich the tantalite into secondary
alluvial deposits. The tantalum, tin and lithium minerals are derived from rare metal
pegmatites dated radiometrically at 2.6 billion years[7]. The two main ore zones within the
pegmatite are the albite (feldspar) zone containing tantalum/tin minerals and the spodumene
zone containing high grade lithium minerals which generally occurs in enriched zone on the
hanging wall of the principal pegmatite. The main pegmatite ore bodies occur along a strike
length of 3.15km and generally dip to the west at 45-50 degrees.
Pegmatites bodies are complex in their composition and continuity. The distribution of the
economic minerals in them is very erratic with the result that large amount of rock must be
mined for a relatively small recovery of mineral. Most pegmatites consist of quartz, potash,
soda feldspar and muscovite. Mineralization is chiefly associated with lenticular quartz
bodies surrounded by alteration zones containing minerals such as kaolin, sericite,
tourmaline, flurvite, beryl etc. The tantalite mineralization is usually concentrated in the
quartz-rich part of the pegmatite. The highest grade of tantalum deposit occurs in pegmatite
that contain relatively high concentrations of the tin mineral cassiterite and lithium mineral
spodumene and anomalous concentration of beryl.
The mineral grain size in the pegmatite varies widely, ranging from less than 1mm up to
100mm. The economic minerals tantalite and cassiterite are normally very fine-grained and
not visible in hand specimens. Spodumene occurs as microscopic grains through to lathes 2
millimetres long.
Tantalite is a compound of tantalum, iron and manganese and is often in association with
columbite (a niobate of iron and manganese). However, tantalite minerals with over 70
different chemical compositions have been identified. Those of greatest economic value are
tantalite, microlite, wodginite; though, it is common practice to name any tantalum –
containing mineral concentrate as “tantalite” primarily because it is processed for the
tantalum content and traded on that basis.
The general mineral composition of tantalite is (Fe, Mn) Ta2 O6, an oxide of iron, manganese
and tantalite. Niobium substitutes for tantalum in all proportions; a complete series extends to
columbite (Fe, Mn) Nb2 O6. Pure tantalite is rare. Iron and manganese vary considerably in
their proportions [8].
Tantalite mineral varies between black and red-brown color, hardness of 6 on the Moh’s
scale, specific gravity 5.2-8.0. It fractures uneven and luminescence varies from opaque to
translucent or transparent.
Tantalum bearing minerals are sourced primarily from Australia, Canada, Brazil and Central
Africa with some additional quantities from South East Asia, China, CIS countries, South
America and sparingly Egypt and Saudi-Arabia. Nigeria is just about making entry into the
supplying nations league and is reported as being the 7th tantalite (25metric tons) resource
country in the world[9].
Figure 1 is the illustration of the base and economic reserves of some tantalite producing
nations. The figure revealed that Australia and Brazil accounts for over 90% of the world’s
base reserve. The economic reserve describe the actual production capacity while the base
reserve is the total estimated tantalite endowments. The world acclaimed supplier of tantalite
72 Amuda, M. O. H., Esezobor, D. E., and Lawal, G. I. Vol.6, No.1
from Australia is Sons of Gwalia incorporated. The firm alone account for over 75% world
production capacity.
Tantalum economic and base reserve rate for ten (10) year periods is presented in Figure 2. It
is apparent from the figure that the rates have respectively increased from 35,000 and 22,000
ton in 1995 to 43,000 and150,000 ton in 2004 respectively.
There has been an average yearly growth rate of about 8-12% in tantalum demand since 1995
and this has caused a significant increase in exploration for the element (Figure 2). This
yearly growth rate has put a pressure on the spot price tags for tantalum ore. The combined
production capacity of the global producers and suppliers of tantalum cannot match the
demand. There are ready recipients of processed tantalum concentrates. These are Brazil,
Germany, Israel, Mexico and the United Kingdom [10] .
The Nigeria tantalum reserve spreads across ten states comprising Niger, Nasarawa, FCT
Abuja, Oyo , Gombe, Kaduna, Kwara, K ogi, Zamfara and Ekiti. The reserve is estimated at 25
metric tons. The deposits are both alluvial and primary pegmatites. Current production
statistics is put at 80 tons in 2000 rising from 60 tons in 1997[11]. However, it is one of the
solid minerals being aggressively marketed to both local and foreign investors for exploration
and exploitation owing to its unique potential economic value [12].
Several works [14-16] had been carried out on the mineralogical and compositional
characterization of major tantalum bearing mineral deposits in the country. These works
revealed the extensive abundance of elemental tantalum in association with niobium as the
respective oxides. The mineralogical characterization as studied by Adetunji et al16, being the
most recent and extensive in terms of number of deposits investigated is re-presented in Table
Australia BrazilCanadaWorld
F ig. 1: T he rate o f base & eco no mic reserve o f
tantalum in the Wo rld in 2004 (USGS)
[ 13]
Base Reser ve
Vol.6, No.1 Adaptable Technologies for Life 73
F ig. 2: T he rate of base & eco nomic
reserve o f tantalum in the Wo rld fo r
ten year period (1999-2004) (USGS)
[ 13]
Table 1: Mineralogical Analysis of Tantalum Ore Samples Form 8 Different
Locations in Nigeria[16]
Oxide Egbe Komu Nasarawa Agunrege Baba
Ode Ofiki Igbo
Ijaye Otu
TiO2% - - 3.81
±0.42 1.64
±0.37 2.34
±0.42 1.05
±0.33 20.36
±0.58 33.38
MnO% 4.15
±0.10 9.03
±0.17 5.80
±0.13 6.69
±0.14 8.62
±0.17 10.10
±0.18 3.46
±0.12 0.74
Fe2O3% 7.76
±0.18 3.51
±0.14 10.69
±0.23 7.37
±0.18 4.69
±0.16 2.86
±0.13 9.66
±0.21 9.70
Ta2O5% 59.58
±0.62 49.57
±0.54 46.15
±0.52 45.42
±0.49 42.00
±0.46 36.63
±0.42 23.64
±0.40 8.00
Nb2O5% 19.74
±0.17 29.18
±0.23 24.86
±0.20 31.18
±0.26 32.90
±0.26 37.48
±0.29 28.90
±0.29 22.43
WO3% - 0.38
±0.13 1.80
±0.14 - - - 0.32
±0.09 0.17
SnO2% - - 8.43
±1.97 - - - -
Hf% 0.22
±0.05 0.26
±0.05 0.31
±0.05 0.18
±0.05 0.17
±0.05 0.11
±0.04 0.13
±0.04 -
Zn% - 0.22
±0.03 0.09
±0.03 - 0.09
±0.03 0.07
±0.02 - -
Zr% 0.31
±0.01 0.12
±0.01 0.26
±0.01 0.15
±0.01 0.22
±0.01 0.17
±0.01 0.06
±0.01 0.06
Pb(ppm) 489
±146 570
±146 1720
±195 - 1010
±168 720
±146 - -
Rb(ppm) - 120
±47 - - - - -
Y (ppm) - - 333±51 - - - - -
ThO2% 0.34 0.03 0.15 0.02 0.02 0.05 0.03
U3O8% 0.17 0.37 0.65 0.42 0.94 1.57 0.28 0.27
74 Amuda, M. O. H., Esezobor, D . E., and Lawal, G. I. Vol.6, No.1
The analysis of Table 1 revealed that the tantalite constituent in the various deposits range
between 8.00-59.58% and niobium between 19.74-37.48%. The relative distribution of these
two important constituents did not follow a rhythmic pattern. However, the combined
distribution of these concentrates approximately range between 30.43-79.20%. Generally,
concentrates exceeding 25% Ta2O5 do not require any pre treatment before concentration for
tantalum recovery[17]. Since all the investigated deposits except Otu deposit contains more
than 25% Ta2O5, they may be concentrated through clean-up concentrations while the Otu
deposit will require pre-concentration before economic beneficiation could be embarked
The titanium ore concentrate in two of the eight deposits is appreciable; Igbo Ijaiye – 20.36%
and Otu 33.38%. The manganese ore and iron ore assays range 0.74% in Otu – 10.10% in
Ofiki deposit and 10.69% in Nasarawa – 3.51% in Komu respectively. Impurity trace
elements such as Hafnium (Hf), Zinc (Zn), Zirconium (Zr), Lead (Pb), Rubium (Rb) and
Yttrium (Y) were present in their relative insignificant amount as presented in the table.
The implication of the characterization of the tantalite deposit is that during the planning of
the beneficiation process for the primary concentration of the deposits for tantalite and/or
niobium concentrate, adjunct process could be coupled to the main plant for secondary
beneficiation of such constituents as TiO2, MnO2 and Fe2O3 depending on the quality of the
deposits in terms of these secondary constituents. This is the underlying concept for the
complete-life cycle processing techniques or what could be conveniently referred to as
wasteless beneficiation technologies.
The beneficiation process adopted in concentrating a particular ore is a function of the nature
of the ore in terms of physico-mechanical and chemical characteristics of the ore. Basically,
there are three stages that are involved and these are pre-concentration, primary concentration
and concentration clean up[18]. The choice of any or all of these depends on the characteristics
of the ore (particularly the content of the principal concentrate) relative to associated minerals
and impurities. The beneficiation process may be carried out by any or combination of the
mineral beneficiation techniques. These techniques include wet gravity, magnetic, electro
static and flotation and the associated contending technologies are pyrometallurgy,
chlorination and hydrometallurgy. The correlation existing among the three variables of
grades of tantalite, beneficiation and chemical extraction routes is provided in Table 2.
Table 2: Correlation between different Grades of Tantalite Ores, Beneficiation Routes
and Chemical Extraction (milled from Adetunji et al16)
Grades of
Tantalite % Raw-material input Beneficiation Routes Chemicaal
2-10 Low-medium grade tin
slags Pre concentration (sizing,
gravity separation) Pyrometallurgy
40-100 Alloys, scraps Chlorination
Natural ores
Synthetic concentrates
> 15 High grade tin slags
Floatation, leaching, magnetic,
electro-static separation.
Primary concentration
classifications, stage treatment
Vol.6, No.1 Adaptable Technologies for Life 75
Table 2 displays the beneficiation route and chemical extraction route suitable for different
grades of tantalite ore assay. The very low-grade deposit (2-10%) is preferably beneficiated
through preconcentration and pyrometallurgy technology. The concentrate in alloys and
scraps containing between 40-100% primary metal are best recovered through chlorination.
The natural tantalite ores, sy nthetic concentrates and high grade tin slags are best beneficiated
through flotation, leaching, magnetic separation, electrostatic separation, classifications etc.
deploying the hydrometallurgy technology.
The tantalite ore reserves investigated by [16] had 38.87% tantalite ore concentrate except for
the Otu deposit (see Table 1) which had an assay of 8.00% Ta2O5. This average tantalite
assay in relation to Table 2, implies that the Nigerian tantalite deposits are candidates for
hydrometallurgical beneficiation; except for the Otu deposit which needs to be pre
concentrated to upgrade the ore to assay grade suitable for hydrometallurgical beneficiation.
The conventional method for the beneficiation of tantalite mineral is the gravity separation
technique [18-19] due to the d ensity of Ta – Nb minerals which allows concentration with other
heavy metals. However, in the present effort, the focus is the concentration of multi-
constituents of tantalum bearing minerals with a view to generating economic value for the
secondary ore concentrates in the tantalum bearing minerals.
Our beneficiation effort proposed a model that combines the traditional gravity method of
beneficiation of tantalite and niobium minerals with techniques that are capable of equally
beneficiating TiO2, MnO2 and Fe2O3 as adjunct recovered concentrates.
A scheme of the proposed model is presented in Figure 3. The figure incorporates mainly
gravity, magnetic and electrostatic separation techniques with leaching as adjunct
beneficiation technique to generate the various secondary ore concentrates.
In the proposed model, as-mined tantalite ore is crushed, ground and sieved to 125 micron
size in appropriate system. The screened ore is subjected to gravity separation technique
where Ta2O5 / Nb2O5 and other associated minerals are concentrated. The Ta2O5 / Nb2O5 is
separated from associated heavy metals such as wolframite, ilmenite which are electrically
conducting through electrostatic separation.
The other heavy metals such as hematite, manganese oxide and rutile are roasted, dried and
subsequently subjected to magnetic separation where the hematite transformed to
ferromagnetic magnetite is concentrated from paramagnetic manganese and titanium ore
minerals. The titanium/manganese ore are subsequently beneficiated through
hydrometallurgy using leaching. This based on the work of Adetunji et al [16] in terms of
labour cost and simplicity of the process is best facilitated by direct dissolution in hydrogen
fluoride (HF).
The effectiveness of the model is to be evaluated by optimizing the dissolution of the
important metallic ore concentrates through the analysis of the chemical equilibria parameter.
The result of this analysis will be a basis for the design and development of a pilot multi-
constituent tantalite ore beneficiation technology.
76 Amuda, M. O. H., Esezobor, D. E., and Lawal, G. I. Vol.6, No.1
Figure 3: Proposed Multi-Ore Constituent Concentration Model
Previous studies on the Nigerian tantalite deposits had revealed that the deposits contains
other important constituents other than the Ta2O5 and Nb2O5 ore concentrates in appreciable
proportion that can stimulate secondary recovery process. These important constituents are
TiO2, MnO2 and Fe2O3. The present work reviewed the conventional beneficiation routes vis-
à-vis the mineralogical characterization of Nigerian tantalite deposits and that the
hydrometallurgical route is the most economically feasible option.
A scheme has been proposed for multi-ore beneficiation to generate secondary ore
concentrates from the primary tantalite beneficiation process. The scheme incorporates
combined gravity, magnetic and electrostatic separation techniques. The effectiveness of the
model is to be evaluated by optimizing the dissolution of the important metallic ore
concentrates through the analysis of the chemical equilibria parameter. The result of this
analysis will be a basis for the design and development of a pilot multi-constituent tantalite
ore beneficiation technology
Secondary TiO2
Fe304 + Ti02
+ Mn02
Gravity Separation
Crushing &
Grinding Magnetic Separation Electrostatic Separation Final Products
Drying +
of hematite
with HF
SnO + WO2
SnO +
Vol.6, No.1 Adaptable Technologies for Life 77
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