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Niobium and tantalum
NIOBIUM AND TANTALUM
NIOBIUM
Niobium is a soft silvery-grey metal that resembles fresh-cut steel. It neither
tarnishes nor oxidizes in air at room temperature because of a thin coating
of niobium oxide. It does readily oxidize at high temperatures (above 200ºC),
particularly with oxygen and halogens. Niobium is not attacked by cold acids but
is very reactive with several hot acids such as hydrochloric, sulphuric, nitric, and
phosphoric acids. It is ductile and malleable [23]. The European Union has recently
identified Niobium as critical raw material.
SHORT DESCRIPTION
FACTSHEET
Multi-Stakeholder Platform for a Secure
Supply of Refractory Metals in Europe
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Fig. 1. Niobium metal
TANTALUM
Tantalum (Ta) is a dense, tough and ductile element with very high melting point of
3017ºC. It is also highly corrosion-resistant to most acids below 150ºC and, in most
cases, chemically inert. It has good thermal and electrical conducting properties
and is easy to machine [16]. Tantalum has not been placed on the critical raw
materials list as of yet, but it is strategically important in several industries.
Fig. 2 Tantalum metal
APPLICATIONS
NIOBIUM
The main application of Niobium is in high-strength low-alloy steels (HSLA), where Niobium is added as Ferro-Niobium.
This market accounts for 90% of Niobium usage and is responsible for most of the increase in overall consumption. The
next table shows the main Niobium applications [1] [2]:
Table 1. Main Nb applications
Ferro-Niobium and Nickel-Niobium are applied in super-alloys used in the aerospace industry, particularly in commercial
aircraft engines, as well as in land-based gas turbines for electricity generation, and in corrosion-resistant alloys. Titanium
and Zirconium Niobium alloys are used in aeronautics, superconductors and nuclear energy.
Niobium chemicals are applied in many fields such as catalysts and functional ceramics, but information concerning the
Niobium grades that are employed in specific individual applications is scarce.
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Fig. 3 Niobium applications
TANTALUM
Tantalum is used in different sectors of the industry thanks to its corrosion-resistant qualities and its applicability as
capacitor, the latter being the most important application, with billions of units produced every year. Other applications
in electric and electronic equipment (EEE) are sputtering targets (Ta metal, Ta
2
O
5
, TaN) and surface acoustic wave filters,
of which the applications are cellular and wireless telephones, television sets, video recorders, tire pressure control and
keyless entry systems [5]. Tantalum is also used for high temperature applications, e.g. aircraft engines, in the form of
super alloys based on nickel and cobalt. Tantalum carbide is used for the fabrication of cemented carbides. Tantalum
oxide is used for manufacturing of special types of glass.
Fig. 4 Tantalum applications, Source: Roskill 2013 in Minor Metals Conference
NIOBIUM
90% of the world's Niobium is produced by three
mines, two of which are in Brazil (the Araxá and
Catalao mines) and the other in Canada (the
Niobec mine). The vast majority of the world's
Niobium reserves are in these countries and there
are currently no Niobium-mining operations in
Europe.
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EU SUPPLY AND DEMAND: CURRENT AND FUTURE
Fig. 5 Niobium production worlwide
Statistics on imports to the EU EU of Niobium and Tantalum-containing slags, ashes and residues from 2011 to 2015 are
shown in Fig. 6 [4].Exporting flows and importing and exporting wastes containing Niobium in this period were almost
zero.
Fig. 6 Imports to the EU of Nb- and Ta-containing materials
Niobium is mainly imported and exported as Ferro-Niobium:
Fig. 7. EU FeNb imports and exports, 2010-2015
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2008
2009
2010
2011
2012
2013
2014
Total production
85984
53520
83895
88918
57532
54574
59700
Total EU imports
22871
12107
20249
21902
21960
22774
43016
% EU
26.6
22.62
24.14
24.63
38.17
41.73
72.05
Table 2. EU import quantities as a percentage of total FeNb production
Fig. 8 EU FeNb imports 2000-2015 (BGS Statistics)
Ferro-Niobium imports to the EU have risen every year since 2009, after the decrease recorded between 2007 and
2009, which probably occurred as a result of the poor economic situation which led to a fall in demand for automobiles
and structural steel for the consturction industry. Ferro-Niobium imports to the EU rose considerably in 2014, mainly
as a result of the large quantities of Ferro-Niobium imported by Spain (20,093 tons). If Spain's imports had not been
taken into account, total EU demand would have been 22,923 (based on date from the previous years) and would have
increased in 2015.
Sharp growth in demand is expected between now and 2020 for Ferro-Niobium (over 8% per year), driven by a global
demand for steel in construction, infrastructure and automotive applications, and a trend towards increased use of
HSLA steels. Increasing demand for natural gas is also expected to result in increased demand for pipeline steel [26].
ArcelorMittal, whose headquarters are in Luxembourg, is the world's leading steel maker (96.1 million tonnes of crude
steel production in 2013). ThyssenKrupp in Germany is also among the world's leading steel makers (15.9 million tonnes
of crude steel production in 2013). Therefore, it is clear that, given the current economic situation, the demand for
Ferro-Niobium in the EU will remain high. The graph below shows annual Ferro-Niobium demand projections based on
an average increase in demand of 8% per year ([27]):
Fig. 9 Estimated FeNb demand from 2016 to 2025
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TANTALUM
Rwanda provided almost 50% of 2013 worldwide
production of concentrate. Other countries, such as
Congo and Brazil, played lesser but still significant roles
(16.56% and 12.58%, respectively). The European
Union's contribution to the world production of
Tantalum concentrate was low. The only primary
production of Tantalum came from the Echassières
kaolin quarry (in France), which in 2011 produced
55 tonnes of Sn-Ta-Nb concentrate at 10% Ta
2
0
5
, i.e
Fig. 10 Tantalum production worldwide
around 4.5 tonnes of Ta [5].
In 2014, 375 tons of capacitors were imported by the EU, and 415 tons were exported. The EU 28 export more wastes
and scraps than they import (+ 94 tons) but they import huge amounts (21,575 tons) of slag, ash and residues containing
mainly Tantalum and Niobium, mainly from Malaysia (20,862 tons in 2014).
There is currently no data available on EU production or transformation of Tantalum. Roskill does not make any assessment
for Europe in its market reviews and the Tantalum-Niobium International Study Center (TIC) states that there are no
figures for the EU market, as its members are “unable to provide this level of information”. This lack of transparency
could be related to the fact that Europe imports Tantalum extracted in conflict-affected countries in Central Africa, which
underscores the fact that it is a very fragile and small market with very few actors [27].
EU Tantalum consumption is roughly estimated to lie between between a quarter and a third of total worldwide
production, i.e. between 250 and 330 tons [Hocquard ,2016], if a global production figure of 1,000 tons is assumed for
2015 [27].
So far, Europe has not encountered any supply problems, but as demand for Tantalum is expected to grow, different
options could be studied to improve supply chain security [27], including:
• Improving recycling rates, focusing not only on old scraps (cemented carbides and alloys) but also on end-of-
life products containing high-grade Tantalum (electrolytic capacitors: 36.7%, wavefilters: 33%, semiconductors:
28.6%).
• Exploitation of old tin tailings containing Tantalum (or Niobium) in metal extraction procedures, using new
technologies.
• Exploitation of new deposits, especially in Australia which had 49% of estimated Tantalum reserves in 2015. There
are also resources to be exploited in the EU, among which Treguennec in France represents a potential source of
1,600 tons of Tantalum.
Substitution of Tantalum in the manufacture of capacitors is simple and could mitigate Tantalum supply-and-demand
issues in the future. There is no real supply risk for EU industries, but the situation could change if tighter regulations
are placed on importation of supplies from conflict-affected regions and countries with poor working conditions and if
environmental concerns are fully addressed. Finally, more transparency among EU processors will be required if the EU's
needs and weaknesses are to be properly assessed [27].
PRIMARY RESOURCES
Tantalum usually occurs together with Niobium in the same type of mineral deposits and in minerals of similar
characteristics. These metals are often found in solid solutions, as is the case with columbite-tantalite, represented by
the formula (Fe,Mg,Mn)(Nb,Ta)
2
O
6
, or minerals from the pyrochlore group. Mineral deposits from which Tantalum is
extracted are associated with specific igneous rocks: Carbonatites and associated rocks, alkaline with peralkaline granites
and syenites, and pegmatites. The weathering of these deposit types can result in other types of Niobium – Tantalum
MAIN PRIMARY AND SECONDARY RESOURCES
mineral deposits, as laterites concentrating pyrochlore, and alluvial deposits (placers). This is the case with the Araxá
deposit, which is managed by CBMM (major worldwide Niobium producer).
• Carbonatites and associated rocks: rarely contain profitable concentrations of Tantalum, neither as a by-product.
They are mainly sources of Niobium.
• Alkaline granite and syenites: Tantalum can occasionally be obtained as a by–product.
• Pegmatites: more widespread throughout the world. The main Niobium and Tantalum minerals in this type of
deposits are columbite-tantalite series.
Although the largest Tantalum reserves are located in Brazil and Australia, the combination of demand issues, lack of
control over production and sale, and small-scale mining has led to continued domination by the countries in Africa's
Great Lakes Region in recent years.
The main economical ores for Tantalum and Niobium production are:
Table 3 Main economical ores for Ta and Nb production
SECONDARY RESOURCES
Niobium
Niobium can be extracted as by-product of tin smelter waste or extracted from sludge from the cemented carbide tool
industry or from mill scrap from alloyed and unalloyed metal fabrication and scrap from industrial alloys and superalloys.
Concerning end-of-life products, Niobium is found in [3]:
• Waste electric and electronic equipment (WEEE). It was estimated that a computer can contain 0.0002% of
Niobium. The amount of Niobium recovered from collected IT and telecommunications equipment could be as
high as 1.2 tonnes, and the grade of Niobium in PCB is about 36 g/t.
• End-of-life Vehicles. The grade of Niobium in ELV can be estimated thanks to the grades of Niobium used in
stainless steels, which is in the range of 0.04-0.08%.
Potential sources for Niobium recovery are mostly steels, but the Niobium content is low (<0.5% in weight).
Among the companies in Europe that have been identified as Niobium recyclers are: Buss&Buss Spezialmetalle GmbH,
Innova Recycling GmbH, Jean Goldshmidt International SA, Metherma KG, ELG Utica Alloys Ltd, Metallum Metal Trading
AG (Minor Metal Trade Association, Ta-Nb international study centre).
Tantalum
Tantalum can be extracted as a by-product of tin smelter waste. Tin smelter waste typically contains 8 to 10 per cent
tantalum oxide, but can sometimes be as high as 30%. Low grade smelter waste can be upgraded by electrothermic
reduction yielding a synthetic concentrate with up to 50% Tantalum and Niobium. In the EU, potential tailings and slags
The natural co-occurrence of Tantalum and Niobium in Ta-bearing ores explains their co-production form primary resources.
Tantalite is the primary mineral for industrial production of Tantalum (being called ferrotantalite or manganotantalite
depending on the presence of Fe or Mn). Tantalum-free Niobium can be found the mineral pyrochlore (NaCaNb
2
O
6
F).
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can be found in Spain, Portugal, France, the UK,
Germany and the Czech Republic. Tantalum can also
be found in waste from uranium mining operations.
Tantalum can also be extracted from municipal
waste landfills, industrial landfills (WEEE recycling
companies) and incineration slags.
Other potential sources are scrap from manufacturing
of Tantalum powders and ingots as well as
manufacturing of Tantalum-containing products and
end-of-life scrap containing Tantalum. Fig. 4 shows
Tantalum sources in 2011 (%Ta
2
O
5
).
Fig. 6. Primary Tantalum Supply 2011
PRIMARY RESOURCES
Mining technology
The size and grade of the ore, the depth and the distribution of the ore minerals (disseminated or concentrated) and
the geotechnical properties of the rock, are the main factors taken into account for the type of mining: open pit or
underground. Almost all mines in carbonatites and other steeply-dipping intrusive rock structures are mined in open
pits. The Araxá mine starts mining in the most surficial weathered part of the deposit, whereas the Niobec mine employs
only underground mining techniques. Underground mining is restricted to deep deposits (the Tanco mine in Canada, the
Greenbushes mine in Australia, for example, for Tantalum extraction).
Processing technologies
Industrial beneficiation of the ores on an industrial scale relies upon the combination of:
• Crushing (jaw, cone or impact crusher) to say <15-20 mm
• Grinding (ball or rod milling) and classification (screens and hydrocyclones) in closed circuit to <1mm
• Conventional (jig, shaking table), centrifugal (spiral) and enhanced gravity separation (MGS, Falcon concentrator),
depending on the size of the liberated particles.
• Selective reverse flotation in order to concentrate the finest material, normally at controlled pH. The high
consumption of additives is a significant cost factor for the flotation processing of Ta-Nb fines, and represent a
pollution issue as well.
• Regular and high magnetic separation to remove companion magnetic phases.
• Thickening circuit to recycle the process water.
Extractive Metallurgy
• Hydro-metallurgy
o Leaching: Acid digestion of ores in a mixture of hydrofluoric acid with other mineral acids, generally sulphuric
acid.
o Fractional Crystallization: Separation should preferably be conducted at an acid concentration of about 1 to
7% HF, where the solubility of Niobium complex is nearly 10 to 12 times that of Tantalum. Apart from acidity,
many other factors, such as temperature and the presence of other ionic species, affect the solubility of the
complex species. The separation of Niobium and Tantalum by fractional crystallization is achievable due to their
double fluoride complexes with potassium.
MAIN PROCESSING AND EXTRACTING TECHNIQUES
As the solubility of potassium fluotantalate (K2TaF7) is low, it crystallizes out. The crystalline solid is redissolved
and recrystallized. The process is conducted in several stages. The process works quite satisfactorily and
relatively easily as far as the preparation of pure tantalum complex K2TaF7 is concerned. The process flow
sheet is shown to the right.
Fig. 11 Crystallization process for Nb and Ta production
o MIBK extraction: The key parameter is H+ concentration, which controls the degree of separation as well as
the recovery of the two metals. Normally, operated mixer-settlers are used. Niobium and Tantalum remain in
the organic phase, in which they are cleaned with concentrated sulphuric acid and re-extracted with water or
dilute sulphuric acid to obtain Niobium. Niobium oxide hydrate is then precipitated using gaseous or aqueous
ammonia and is subsequently filtrated, dried and calcined at up to 1100 ºC. The precipitation, drying and
calcination parameters can be modified to obtain different particle sizes of the oxides, depending on the
desired application. Impurities are not extracted and are left in the raffinate. Very pure Ta and Nb products are
obtained. The process flow sheet is shown to the right:
Fig. 12 MIBK extraction process for Nb and Ta production
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o Pyro-metallurgy: The pyrochlore concentrate obtained after physical beneficiation followed by chemical
leaching to remove impurities is of the right specification and it can be used directly for the production of
Ferro-Niobium through an aluminothermic reduction process.
One of the simplest methods for breakdown treatment of Niobium concentrates is direct reduction with
aluminium and carbon, with or without the addition of iron and iron oxides. In aluminothermy, all the oxides
that have free energy of formation which are less negative than that of alumina are reduced to the metallic
state and form ferroalloys, particularly Ferro-Niobium alloys. In carbothermic reduction, Niobium reacts with
excess carbon and forms carbides, which in turn form an alloy carbide. This process is usually performed in a
smelting electric arc furnace.
However, if the objective is to separate Tantalum from Niobium, a selective reduction of the chlorides can be
applied. Niobium pentachloride is more readily reduced by hydrogen (or by metals such as aluminium) to the
lower chlorides. NbCl
5
reduction is then performed at 450-550ºC to form a trichloride. TaCl
5
is not reduced
under these conditions.
Fig. 13 Pyro-metallurgy process for Nb and Ta extraction from concentrates
EXTRACTION OF TANTALUM FROM SECONDARY RESOURCES:
Mineral processing
• Municipal and Industrial Landfill waste: The first stages include crushing and separation of fines from larger particles
using a rotary screen, for example. The typical methods employed are the magnetic, density and ballistic separation
methods or, in some cases, the eddy current method is used.
• Incineration bottom ash: Usually the slag is treated at the incineration plant. Before treatment, the slag is stored at
least one day for integration of CO
2
and to make it less wet and sticky. Metal pieces and particles are separated
by several mechanical processing stages: sieving, crushing and mechanical separation (magnetic, eddy current).
Sensor separators are also used.
• Tin slags and silt-like tailings: Strong chemical digestion or electro-thermic reduction are usually required.
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Extractive metallurgy
• Hydrometallurgy: the organic solvents than can be used in Niobium and Tantalum extraction are of two categories:
1) neutral oxygen-containing extractants, such as ketones, TBP, TOPO or octanol, and 2) anion exchangers, such as
trioctylamine (TOA). Industrially, MIBK, cyclohexanone, TBP and 2-octanol are used. Generally, the extraction and
refining of Tantalum is accomplished through hydrofluoric and sulphuric acid leaching at high temperatures, which
produces complex fluorides. After filtration and solvent extraction (MIBK) or ion exchange (amine extractant in
kerosene), highly purified solutions of Tantalum and Niobium are produced. Tantalum values in the solution are
generally converted into potassium tantalum fluoride or tantalum oxide.
• Pyrometallurgy: Tantalum oxidizes easily and moves into the slag produced in pyro-metallurgical processes.
By using electrothermic reduction process, the slag is upgraded to a Tantalum-oxide content as high as 50%.
Carbothermic, metallothermic, and hydrogen reduction can be applied to extract Tantalum. Molten salt electrolysis
is is also applied. After being subjected to these processes, Tantalum metal can be refined by molten salt electro-
refining, vacuum sintering, electron beam or plasma processes.
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EXTRACTION OF NIOBIUM FROM SECONDARY RESOURCES:
Mineral processing
Tin smelting slags are generally upgraded by a pyrometallurgical process, involving the production of ferroalloy called
block metal, which acts as a collector for Niobium and Tantalum. The block metal is further upgraded through simple
acid leaching or by a combination of oxidative smelting followed by acid leaching of the slag derived from the second
smelting. The upgraded slag is used for the extraction of Niobium and Tantalum using hydrofluoric acid.
Extractive metallurgy
Well-classified metal scrap can be reused by pulverizing it after hydriding, applying acid leaching to remove iron conta-
mination, if there is any, and then reusing it in the fabrication stream. Similarly, well-classified scrap of cemented carbide
tools consisting primarily of a low carbide cemented with a cobalt binder can be reused in the fabrication plant after
separating the carbides from the cementing material. This can be achieved by a simple process involving treatment of
the scrap with molten zinc. Cobalt and zinc form an alloy which has a higher specific volume, which disintegrates the ce-
mented carbide shapes. The carbide powder can thus be reused and cobalt can be recovered through vacuum distillation
of zinc.
Niobium and Tantalum separation by solvent extraction is normally performed in the presence of fluorides. Sulphuric and
hydrochloric acid solutions are characterized by association and polymerization of complexes of these elements, which
prevent their selective isolation.
Niobium extraction processes from tin slags can be divided into the following process types:
1. Upgrading the Niobium content of the slag: separating some of the constituents by leaching (acid leaching of slag
with 2% sulphuric acid at 50ºC).
2. Preparing synthetic concentrate.
3. Recovering Niobium directly from medium-grade slags.
Recycling of iron and steel scrap
Scrap is collected by scrap dealers and processed into a physical form and chemical composition that can be consumed
by steel mills in their furnaces. Baling presses are used to compact the scrap into manageable bundles. Scrap dealers
sort scrap materials, and steelmakers carefully purchase scrap that does not contain undesirable elements that exceed
acceptable levels. The scrap is mainly melted in basic oxygen and electric arc furnaces (BOF and EAF). In the recycling
of high-strength low-alloy steel, one must be aware that about 0.05% of Niobium will most likely be oxidised to the slag
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phase and lost during recycling to EAF or BOF. In the fabrication of new steel products, new steel scrap with a known
chemical composition is produced. Preparation of the new scrap for recycling is usually limited to cutting, cleaning and
baling prior to shipment back to the steel maker [28].
Niobium and Tantalum do not represent any special risk. The solid forms of Tantalum and Niobium do not pose any
particular environmental problems. There is no reported information on toxicity of the metals and alloys, and the only
associated health hazards stem from the powders, which, like any other powder, can be irritants. Flotation reagents are
generally biodegradable and the tailings are not very hazardous, as occurs for example in mine drainage[29]. The life-
cycle analysis performed by Nuss & Eckelman in 2014 shows 260 kgCO
2
eq/kg of global warming potential for Tantalum
(considered to be a medium degree of impact), whereas for Niobium, the figure is 12.5 kgCO
2
eq/kg (lower impact).
However, Niobium has 133 MJ eq/kg of cumulative energy demand compared to 4,360 MJ eq/kg for Tantalum. As for
terrestrial acidification, Niobium would have low impact compared to other metals on the periodic table, while Tantalum
would be in the middle. The same occurs for freshwater eutrophication and human toxicity.
The minerals from which Nb and Ta are extracted are known for their significant content in naturally occurring radioactive
materials (NORMs), especially in the cases of 226Ra, 238Ru, 232Th and 40K. NORMs. Afterwards, the raw materials are
processed they are converted into TENORMs (technologically enhanced natural radiation materials). The environmental
hazard is extremely intense in the case of Nigeria, where large quantities of generated tailings rich in these radioactive
minerals are disposed of haphazardly into the environment. Radiation monitoring in the area and at some processing
mills has revealed high dose rates with values as high as 100 aSv per hour for processed zircon. The in situ dose rate
measurements for workers and the public at large indicated exposures significantly higher than the recommended values
of 1 and 20 mSv/year, respectively. Niobium ore deposits frequently contain a number of radionuclides at elevated
concentrations. The release of radionuclides such as uranium and thorium could have an important impact on the local
environment and on worker health.
Tantalum concentrates from pegmatites generally contain minute quantities of natural thorium and uranium, but
pose a very low radiological risk during transport, and the regulations are designed so that safety is provided through
passive safety inherent in the package. Moreover, generation concentrates, especially those produced from alkaline and
peralkaline deposits, will almost certainly have higher levels of these radioactive elements, and some type of on-site
processing prior to shipment may well be required [29].
Ferro-Niobium production is not hazardous as on-site safety precautions are adequate [29]. Pyrochlore concentrates
used to produce Ferro-Niobium also contain thorium and uranium, which are present in the Ferro-Niobium slag. This slag
contains elevated levels of thorium and uranium and is generally stored on site. Despite its thorium and uranium content,
FeNb is not included in the Best Available Techniques Reference Document for the Non-Ferrous Metals Industries, where
it is only commented that the dust generated from the furnace is discharged to a landfill except for a certain amount of
FeNb, and that 1.9 tons of slag is generated per ton of alloy.
As the key to increased Tantalum capacitor efficiency is the fineness of the powder, care must be taken to ensure a static
and ignition-free environment as, as in the cases of many other very fine powders, they are pyrophoric and may explode
if handled improperly. Comprehensive regulation of materials is now in place in the European Union, under a protocol
known as REACH (registration, evaluation, authorisation and restriction of chemicals). All companies wishing to produce
substances in the EU or import them into the EU must ensure they meet their registration obligations if they are to continue
with their activities; further guidance can be obtained from the European Chemical Agency website (ECHA, 2011) or
from national authorities [29]. A life cycle analysis was performed as part of the MSP-REFRAM EU Project, comparing
Tantalum primary extraction and the Ta secondary recovery. The results indicate that, in all categories considered, (global
warming, cumulative energy demand, terrestrial acidification, freshwater eutrophication and human toxicity) there is
an important gap between the impact of the secondary recovery process and the primary extractive process, with the
effects of secondary process representing only about 15 % of primary process activities. As there is currently no primary
production of Ta or Nb in Europe, secondary production is a good opportunity in terms of environmental impact.
ENVIRONMENTAL AND SOCIAL IMPACTS OF THEIR EXPLOITATION
Table 4 shows substitutability scores for Tantalum presented by Oakdene Hollins and Fraunhofer ISI in their report
entitled Critical Raw Materials at the EU Level in 2013. A score of “0” means the material is easily substitutable at no
additional cost or loss in performance, while a score of “1” represents substitutable, but with an increase in cost and loss
in performance:
SUBSTITUTION POSSIBILITIES
Material
Application
Share
Megasector
Substitutability
Tantalum
Capacitors
40%
Electronics
0.3
Tantalum
Superalloys
21%
Metals
0.7
Tantalum
Sputtering targets
12%
Electronics
1.0
Tantalum
Mill products
11%
MechEquip
0.7
Tantalum
Carbides
10%
MechEquip
0.3
Tantalum
Chemicals
6%
Chemicals
1.0
Table 4. Tantalum substitutability in different applications [30]
Thus, Tantalum substitutability according to the scores shown in Table 4, is quite simple due to the low costs of capacitors
and carbides. In superalloys and mill products, substitutability is possible, but at a higher cost and/or with a loss in
performance. In sputtering targets and chemicals, Tantalum is still not substitutable. Thus, Tantalum can be substituted
by other materials but most substitutes have either higher costs or adverse properties. Distribution of end-uses and
corresponding substitutability assessment for tantalum is presented in the figure below:
Fig. 14 Substitutability of Tantalum in its major applications [31]
Niobium was listed as one of the 21 critical raw materials for the EU in a December 2015 study conducted by Oakdene
Hollins Research & Consulting and Frauhofer ISI. Table 5 provides a breakdown of Niobium applications with their
respective substitutability levels:
Application
Share
Megasector
Value (GVA)
Substitutability
Steel: Structural
31
Construction
104.4
0.7
Steel: Automotive
28
Transport – Road
147.4
0.7
Steel: Pipeline
24
Oil
50.0
0.7
Superalloys
8
Metals
164.6
0.7
Others
6
Other
63.3
0.5
Steel: Chemical
3
Mechanical Eqpt.
182.4
0.7
Table 5 End uses, megasector assignment and substitution values [30]
MSP-REFRAM has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 688993.
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MSP-REFRAM has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 688993.
VISIT OUR WEBSITE!
http://prometia.eu/msp-refram
Figure 15 shows the distribution of Niobium uses and their substitutability levels. The manner and scaling of the
assessment is compatible with the work done by an ad-hoc group on the definition of critical raw materials (2010):
Fig. 15 Distribution of end-uses and corresponding substitutability assessment of Niobium [31]
As seen, the substitution of Niobium and Tantalum is possible depending on the applications they are used for. . The
following table outlines several possibilities [16-24][25]:
Metal
Application
Substitutes
Nb
HSLA Steels
Titanium, Vanadium, Molybdenum
Nb
Stainless Steels
Titanium, Tantalum, High Nitrogen
steels
Nb
Superalloys
Ceramic Matrix Composites, Molyb-
denum, Titanium, Tantalum
Nb
Superconductors
Vanadium-Gallium alloys, BSSCO
alloys
Ta
Capacitors
Niobium oxide, Aluminium, Ceramic
Ta
Cemented carbides
Niobium, Tungsten, Titanium car-
bides, Titanium nitride (some CRM)
Ta
Steels super-alloy
Vanadium, Molybdenum
Ta
Super-alloys for high T applications
Hafnium, Iridium, Molybdenum, Nio-
bium, Rhenium, Tungsten (some CRM)
Ta
Process equipment, resistance to
corrosion, high-T environment
Niobium (CRM), Glass, Platinum
(CRM), Titanium, Zirconium
Ta
SAW filters and SAW resonators in
electronic applications in cellphones,
TV sets, video recording
Lanthanum gallium silicate (CRM)
Ta
Orthopaedic applications
Titanium and ceramics in some cases
Ta
Surgical equipment
Chromium/Nickel steel alloys
Ta
Optic/lenses
Niobium in some cases
Ta
Hard disk drives
Niobium
Innovative improvements in hydrometallurgical technology for processing Niobium and Tantalum concentrates is
expected in the following areas [4]:
• The application of more robust extractants with higher stability and lower water solubility . A process for
extracting Nb and Ta from a fluorinated leach liquor with Alamine 336, using kerosene and xylene as diluents and
n-decanol as a modifier has been proposed. Ta extraction was higher than that of Nb [6]. High purity Tantalum and
Tantalum-free Niobium (99.99-99.99%) can be obtained using quaternary ammonium salts as extractants from
a hydrofluoric acid solution [12] containing various metallic impurities (alkaline or alkaline-earth metals such as
cobalt, manganese, iron, nickel, copper, etc.). This patented process can be applied to ore concentrates as well as
scrap containing Nb and Ta, or Ta-rich tin slags.
• Less HF or no HF used for the digestion of concentrates and metal separation using SX. Using ammonium
bifluoride as an alternative to hydrofluoric acid, the leaching process is performed with water and large amounts
of impurities are precipitated in the form of insoluble compounds that can be separated from the solution through
filtration. Optimum digestion conditions were determined: a tantalite-to-bifluoride mass ratio of 1:30, a reaction
temperature of 250 °C and a reaction time of 3 h. Under these conditions, the leach recoveries of Niobium and
Tantalum were 95% and 98.5% respectively [11].
• Recycling reagents used as much as possible to reduce liquid and solid wastes
More specifically, Niobium and Tantalum extraction techniques for secondary resources research has been done on:
• Extraction of Niobium and Tantalum from Tin slag: chlorination at 1000ºC has allowed the extraction of about
84% and 65% of the Nb and Ta compounds, respectively. Carbochlorination at 500ºC has allowed complete
extraction and recovery of both compounds [7].
• Niobium and Tantalum from Copper Smelting slag: physical separation by froth flotation is widely used.
Hydroxamates are powerful collectors in flotation due to their ability to selectively chelate on the surfaces of
minerals that contain Niobium [8].
• Tantalum extraction from concentrates: a novel hydrometallurgical process was developed to selectively extract
Nb and Ta from Nb–Ti–Fe raw concentrates, by forming a sodium hexaniobate through a reaction between the
initial concentrate and concentrated NaOH at atmospheric pressure [9]. After caustic conversion, the sodium
hexaniobates are selectively dissolved in water.
• Tantalum from alloy scrap: iodization of alloy scrap produces volatile tantalum (V) iodides that can be reduced in
a plasma furnace to produce high surface area tantalum metal powder precursors, which, after being annealed,
yield high-purity nano-powders with uniform particle size distribution, low oxygen content, and high surface area
and capacitance [10].
• Tantalum from electronic waste: use of ionic liquids at room temperature concurrently with the extractants,
containing either the chelating ligands or task-specific ionic liquids (TSILs) that have a strong affinity and/or
selectivity with the target metal and as purification agents through a selective electrodeposition process[13].
Also, oxidation in the air of the scraps followed by a mechanical collection of the sintered Ta electrodes inside the
scraps in combination with chemical treatment allows high purity Ta
2
O
5
recovery, by reducing the Ta
2
O
5
obtained
through magnesiothermic reduction [14].
• Niobium from steel scrap: Niobium has a recycled content higher than 50%. Niobium is eventually reintroduced
into the steel-making process, which makes the recycling of Niobium relatively easy [15].
HEADING TOWARDS THE FUTURE: RECENT RESEARCH ACTIVITIES
MSP-REFRAM has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 688993.
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EUROPEAN RELATED PROJECTS
• OptiMore: optimizes the crushing, milling and separation ore processing technologies for Tungsten and Tantalum
mineral processing, by means of improved, fast and flexible fine tuning production process control based on new
software models, advanced sensing and a more thorough study of the physical process, which increases by 7-12%
over the best current production processes, increasing energy savings by 5% compared to the best available
techniques.
• E4-CritMat (Marie Curie programme): Engineering of Energy Efficient Extraction of Critical Materials – Application
to the Processing of Niobium and Tantalum Minerals.
MSP-REFRAM has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 688993.
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[1] Roskill, THE ECONOMICS OF NIOBIUM, Eleventh Edition, 2009
[2] D. Arcos, AMPHOS 21, Nb_Ta_mining_state of the art D_Arcos-V1.pptx, presentation from WS1 in Barcelona, May, 30-31st , 2016
[3] S. Casanovas, AMPHOS, Mapping_of_secondary_Nb_resources_(EOL_products) S_Casanovas_V1.pptx, presentation
from WS1 in Barcelona, May, 30-31st, 2016
[4] Extraction from Eurostat databasis “EU Trade Since 1999 by HS2,4,6 and CN8 (daily updated) “ website, based on
CN8 codes, http://epp.eurostat.ec.europa.eu/newxtweb
[5] Audion A.S., Piantone P., Panorama 2011 du marché du tantale (in French), report BRGM/RP-61343-FR, 2012
[6 ]El hussaini O. M.; Rice N. M. (2004) Liquid-liquid extraction of niobium and tantalum from aqueous sulphate/
fluoride solutions by a tertiary amine, Hydrometallurgy, 72, 259-267.
[7] I. Gaballah, E. Allain, and M. Djona, Extraction of Tantalum and Niobium from Tin Slags by Chlorination and
Carbochlorination, Metallurgical and Materials Transaction B, volume 28B, June 1997—359-369.
[8] S. Roy, A. Datta et S. Rehani, Flotation of copper sulphide from copper smelter slag using multiple collectors and
their mixtures, International journal of mineral processing, vol. 143, pp. 43-49, 2015.
[9] Gauthier J.-P. Deblonde, Valérie Weigel, Quentin Bellier, Romaric Houdard, Florent Delvallée, Sarah Bélair, Denis
Beltrami, Selective recovery of niobium and tantalum from low-grade concentrates using a simple and fluoride-free
process, Separation and Purification Technology 162 (2016) 180–187
[10] Joseph D. Lessard, Leonid Shekhter, Daniel Gribbin, Larry F. McHugh. A new technology platform for the
production of electronic grade tantalum nanopowders from tantalum scrap sources. International Journal of Refractory
Metals and Hard Materials 48:408-413 · January 2015
[11] Kabangu, M. J. and P. L. Crouse (2012). "Separation of niobium and tantalum from Mozambican tantalite by
ammonium bifluoride digestion and octanol solvent extraction." Hydrometallurgy 129: 151-155.
[12] Niwa, K.; Ichikawa, I. ; Motone, M. (1987). “Method of separating and purifying tantalum and niobium-containing
compounds.” Patent JP82487/86; EP0241278.
[13] Matsuoka, R., Mineta, K., & Okabe, T. H. (2004). Recycling process for tantalum and some other Reactive Metal
Scraps. In the Minerals, Metals & Materials Society [TMS] (Ed.), Proceedings of the Symposium on Solid and Aqueous
Waste from Non-ferrous Metal Industries (pp. 689-696). Charlotte: TMS.
[14] http://www.agence-nationale-recherche.fr/?Projet=ANR-13-CDII-0010
[15] Worrel, E. & Reuter, M.,2014,"Handbook of Recycling: State of the art for Practitioners, Analysts and Scientists", Newnes, pp 74-75
[16] RPA, 2012. Study on data needs for a full raw materials flow analysis. Prepared for Directorate – General
Enterprise and Industry. London, UK Risk and Policy analysis limited.
[17] BGS 2011. Mineral profile: Tungsten
[18] Argus 2016. An overvirew of downstream Tungsten markets. Argus Metal Pages Forum, Tokyo.
[19] EUROSTAT DATABASE http://ec.europa.eu/eurostat/data/database
[20] European Commission 2014. Report on critical raw materials for the EU. Report of the Ad-hoc working group on
defining critical raw materials. European Commssion.
[21] BGS 2012. Risk list 2012- Current supply risk for chemical elements or element groups which are of economic value.
[22] BGS 2015. Risk list 2015- Current supply risk for chemical elements or element groups which are of economic value.
[23] Krebs, Robert E. The history and use of our earth's chemical elements: a reference guide. Greenwood Publishing
Group, 2006. ISBN: 9780313334382
[24] Chapman, A., et al. "Study on Critical Raw Materials at EU Level." Oakdene Hollins: Buckinghamshire, UK (2013).
[25] CRM_InnoNet: Substitution of Critical Raw Materials. “Critical Raw Materials Substitution Profiles”. September
2013. Revised May 2015. Accessed Online: October 2016. Link: http://www.criticalrawmaterials.eu/wp-content/
uploads/D3.3-Raw-Materials-Profiles-final-submitteddocument.pdf
[26] E. Commission, “Report on Critical Raw Materials for the EU,” European Commission, 2015.
[27] D1.1 “Current and future needs of selected refractory metals in EU” MSP REFRAM EU H2020 project
[28] D4.2 “State of the art on the recovery of refractory metals from urban mines” MSP-Refram project EU H2020.
[29] Critical Metal Handbook, First Edition, Edited by Gus Gunn. Chapter 15 “Tantalum and Niobium” by Robert
Linnen, Dave Trueman and Richard Burt. 2014
[30] Chapman, A., et al “Study on Critical Raw Materials at EU Level” Oakdene Hollins: Buckinghamshire, UK (2013)
[31] CRM_InnoNet: Substitution of Critical Raw Materials. “Critical Raw Materials Substitution Profiles”. September
2013. Revised May 2015. Accessed Online: October 2016. Link: http://www.criticalrawmaterials.eu/wp-content/
uploads/D3.3-Raw-Materials-Profiles-final-submitted-document.pdf
MSP-REFRAM has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 688993.
VISIT OUR WEBSITE!
http://prometia.eu/msp-refram
REFERENCES
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