Egyptian tantalum niobium and tin deposits

Egyptian Tantalum- Niobium deposits

by Hassan Z. Harraz

[email protected]

OUTLINE OF TOPIC:

Definitions and characteristics

Mineralogy

Deposits

EXTRACTION METHODS

Processing

Artisanal mining of coltan

Tantalum Industry Overview

Tantalum Applications

Tantalum Sources

Tantalum Market

World Demand

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Prof. Dr. H.Z. Harraz Presentation 16 April 2013

Egyptian Ta-Nb Deposits

Abu Rusheid

Abu Dabbab (Tantalum, Niobium, Feldspar)

Introduction

Previous exploration

Geological setting

Resources and Reserves

Bankable Feasibility Study

Tantalum Off-Take Agreements

Fast-Track Start-Up

Abu Dabbab Alluvial Tin

Nuweibi (Tantalum, Niobium, Feldspar)

Location


Geological setting

Exploration

Resources

Prof. Dr. H.Z. Harraz Presentation 16 April 2013 3

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Niobium (Nb) and tantalum (Ta) are transition metals with very similar physical and chemical properties, and are thus commonly grouped together (Table 1). Niobium was discovered in 1801 by Charles Hatchett, and was originally named 'columbium'; it was subsequently also recognized by a German chemist, Heinrich Rose, who named it 'niobium'. The names were used interchangeably for some time, before 'niobium' was finally accepted in 1949. Tantalum was discovered in 1802 by a Swedish scientist, Anders Ekeberg.

Definitions and characteristics

Niobium (Nb) Tantalum (Ta)

Atomic number 41 73

Atomic weight 92.90638 180.9479

Density at 293k (g/cm3) 8.581 16.677

Melting point oC 2468 2996

Boiling point oC 4930 5425

Vickers hardness (MPa) 1320 873

Electrical resistivity (nano ohm-metres) 152 at 0oC 131 at 20oC

Crystal structure Body centred cubic Body centred cubic

Niobium is a shiny, ductile metal with a white luster. Naturally-occurring niobium consists almost exclusively of the isotope 93Nb; natural tantalum is mainly 181Ta, with 0.012 per cent 180Ta. A number of other radioactive isotopes of both elements have been synthesised.

The overall abundance of niobium and tantalum in the average continental crust are relatively low, niobium having an abundance of eight parts per million (ppm) and tantalum of 0.7 ppm (Rudnick and Gao, 2004. Compared to other metallic elements such as the light rare earths, niobium and tantalum are rather depleted in the continental crust. This can be attributed to the fact that much of the continental crust was formed at convergent margins above seduction zones, and that magmas formed in this setting are typically depleted in both niobium and tantalum.


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Mineralogy Niobium and tantalum do not occur naturally as free metals, but are

essential components in a range of mineral species (Table 2). The majority of these are oxide minerals; silicates of niobium and

tantalum do exist, but are relatively rare. Niobium and tantalum also substitute for major ions in a number of

other minerals, in which they typically have low concentrations. The vast majority of the economically important species are oxides.

The columbite-tantalite mineral group (Fig.1) is the most common group of tantalum - and niobium – bearing minerals.

Wodginite is also an important source of tantalum. The pyrochlore group (Fig.2) is of great economic importance,

particularly for niobium. This group has a wide compositional range, including some species rich in both niobium and tantalum. Pyrochlore is typically found as a primary mineral in alkaline igneous rocks.

Other, less common oxides of niobium and tantalum include tapiolite, ixiolite, and minerals of the perovskite group.

Niobium and tantalum also substitute for major ions in some common oxide groups such as cassiterite, rutile, and ilmenite. Contents of niobium and tantalum in these minerals are rarely high enough to make them of economic interest.

Similarly, niobium and tantalum occur those found in alkaline igneous rocks such as eudialyte (Na4(Ca,Ce)2(Fe++,Mn,Y)ZrSi8O22(OH,Cl)2).

Fig. 1 Dark coloured tantatlite with pale coloured albite.

Fig.2: Pyrochlore, Source: Rob Lavinsky (iRocks. Com)


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Table 2: selected niobium and tantalum minerals and indicative contents of Nb2O5 and Ta2O5.

Mineral

name

Mineral group Formula Nb2O5

(%)

Ta2O5

(%)

Columbite Columbite-tantalite (Fe,Mn)(Nb,Ta2)O6 78.72 n.a.

Tantalite Columbite-tantalite (Fe,Mn)(Nb,Ta2)O6 n.a. 86.17

Pyrochlore Pyrochlore (Na,Ca)2Nb2O6(O,OH,F) 75.12 n.a.

Microlite Pyrochlore (Na,Ca)2Ta2O6(O,OH,F) n.a. 83.53

Tapiolite Tapiolite (Fe,Mn)(Ta,Nb)2O6 1.33 83.96

Ixiolite Ixiolite (Ta,Nb,Sn,Mn,Fe)4O8 8.30 68.96

Wodginite Wodginite (Ta,Nb,Sn,Mn,Fe)O2 8.37 69.58

Loprite Perovskite (Ce,La,Na,Ca,Sr)(Ti,Nb)O3 16.15 n.a.

Lueshite Perovskite NaNbO3 81.09 n.a.

Euxenite Euxenite (Y,Ca,Ce,U,Th)(Nb,Ti,Ta)2O6 47.43 22.53

Struverite Rutile (Ti,Ta,Fe)O2 11.32 37.65

IImenorutile Rutile Fex(Nb,Ta)2x4Ti1-xO2 27.9 n.a.

Prof. Dr. H.Z. Harraz Presentation

Deposits Niobium and tantalum mineral deposits are most commonly associated

with igneous rocks3, including granites, pegmatities4, syenites5 and carbonatities6. Some secondary deposits, where niobium – and tantalum – bearing minerals have been concentrated by weathering and sedimentary processes, are also known (see Table 3 and Fig. 3). In general, these secondary deposits occur in relatively close association with their primary sources, and so they are not considered separately in the descriptions below.

Primary Niobium and Tantalum deposits can be divided into three main types, on the basis of the igneous rocks with which they are associated (Küster, 2009).

1) Carbonatites and associated rocks. 2) Alkaline to peralkaline granites and syenites. 3) Granites and pegmatities of the LCT family (enriched in lithium (Li),

caesium (Cs), tantalum) (Cerný and Ercit, 2005). Moderately high contents of niobium and tantalum may be found in some

granites and pegmatites that do not fall into the categories given above, but economic examples are not known.

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• Niobium and Tantalum Deposit Types Include: 1) Nb>Ta: Lateritic regolith (residual supergene enrichment blankets) above

carbonatite intrusions (Araxá/Brazil, potentially Mt. Weld/Australia) 2) Nb>Ta: Hard rock carbonatite or nepheline syenite with pyrochlore

(Niobec mine Quebec/Canada) 3) Ta>Nb: Rare-element granites ("tantalum granite") with tantalum-rich

magmatic columbite and cassiterite (Yichun/South China: Yin et al. 1995; Fig. 1.15; potential future mines include Ghurayyah in Saudi Arabia, Abu Dabbab in Egypt)

4) Ta>Nb: Rare-element pegmatites of the Li-Cs-Ta type with tantalum-rich magmatic columbite and magmatic to hydrothermal cassiterite (examples are today's largest tantalum mine Wodgina and, until closure in 2006, Greenbushes in Australia: compare chapter „Lithium“ and Fig. 2.41)

5) Ta>Nb: Eluvial, alluvial and coastal tin placers (Malaysia, Nigeria, Central Africa).

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Fig.3: Map showing the global distribution of niobium and tantalum mines, deposits and major occurrences.


1. Carbonatites and associated rocks • Carbonatites are igneous rocks that consist of more than 50 per cent primary carbonate minerals. They are almost exclusively found in areas of continental extension and rifting7, and their source magmas

are thought to be derived directly from the mantle with very little crustal influence. Carbonatites are most commonly found as dykes, sills and small plugs (less than one kilometer in diameter), more rarely occurring as large plutons or as extrusive8 volcanic sequences. They rarely occur in isolation, being more commonly associated with alkaline9 silicate rocks, either nepheline syenite and other feldspathoid-bearing10 igneous rocks, or mafic11 to ultramafic12 alkaline rocks (Woolley and kjarsgaard, 2008). Many carbonatite bodies are surrounded by a metasomatised13 or 'fenitised' zone, ypically rich in sodium (Na) and/or potassium (K), formed through alteration of the counry rocs by fluids derived from the carbonatite. Some carbonatite bodies are considered to be carbohydrothermal14 – formed from carbon dioxide – rich and water – rich fluids rather than magmas.

• Carbonatites are typically enriched in a range of elements, including the rare earth elements (REE), barium (Ba), strontium (Sr), fluorine (F), phosphorus (P), niobium (Nb), zircronium (Zr), uranium (U) and thorium (Th). Niobium is preferentially enriched over tantalum in carbon dioxiderich melts, and so carbonatites do not generally have high tantalum contents (Moller, 1989). Common niobiumbearin minerals found in carbonatites inclde members of the perovskite and pyrochlore mineral groups, as well as niobium-rich silicates such as titanite (Mitchell, 2005).

• In general, bulk rock niobium contents for carbonatite bodies are moderately high (commonly 0.01 – 0.1 per cent, rarely up to 1.0 per cent), but not org-grade. However magmatic differentiation15 processes such as crystal settling may concentrate niobium-bearing minerals such as pyrochlore. Weathering processes16 may also concentratre these minerals in the shallow subsurface. Late-stage veins and areas of metasomatism, formed through carbohydro-thermal activity, are a third potential source of niobium mineralisation.

• Much of the world's niobium supply comes from Brazil, where the main niobium deposits occur in alkaline ultramafic-carbonatite complexes of the late Cretaceous17. Alto Paranaiba igneous province, intruded into Neoproterozoic18 metasedimentary rocks. The largest currently worked niobium deposit is at Araxá, and is owned and exploited by the Companhia Brasileira de Metalurgia e Mineracao (CBMM). A second major niobium mine, at catalão, is operated by Anglo American. These deposits are hosted in rather unusual intrusions consisting of carbonatite - and phoscorite19 - series rocks with no associated syenites. In both deposits, pyrochlore is the main nibium ore mineral. The Araxá deposit lies within the Barreiro Carbonatite Complex, a roughly circular intrusion approximately 4.5 kilometre in diameter (Nasraoui a Waerenborgh, 2001). Dominated by dolomite carbonatite with subordinate calcite carbonatite, glimmerite20 and phoscorite. The central part of the intrusion has been weathered under tropical conditions to form a thick (>200 metres), lateritic21 cover in which pyrochlore has become concentrated at a reported mean grade of 2.5 per cent niobium oxide, and which is exploited by open-pit mining. The country rocks to the carbonatite have been metasomatised in an aueole22 up to 2.5 kilometre wide (Nasraoui and Waerenborgh, 2001). The main worked deposit at Catalão is in the Catalão I alkaline-carbonatite complex, but a similar deposit occurs in the nearby Catalão II complex. Catalão I is a steep-sided, zoned intrusive body with a diameter of approximately six kilometers at the surface. It is dominated by glimmerite (phlogopitite) at the margins of the complex, with sheets and plugs of decolomite-carbonatite and phoscorite-series rocks that become increasingly common towards the centre of the complex (Cordeiro et al., 2010). As at Araxá, the mined deposit is in the weathered lateritic zone above the centre of the complex.

• The largest active niobium mine outside Brazil is the Niobec mine in Quebec, Canada, operated by the lamgold corporation. This mine lie in the southern part of the Neoproterozoic-age saint-Honoré carbonatite complex; which has an elliptical shape and is approximately four kilometers across at the surface. It consists of a series of crescentic lenses of carbonatite, younging inwards from calcite carbonatite through dolomite carbonatite to ferrocabonatite (Belzile, 2009).

• The carbonatite body is surrounded by a ring of syenites and diorites, and is almost entirely covered by palaeozoic23 limestones. Pyrochlore is the main niobium mineral in the saint-Honore' complex. It is disseminated through the carbonatite, but is particularly abundant in mineralized lenses that are 50-150 meters wide and up to approximately 750 meters long, with grades of 0.44-0.51 per cent niobium oxide (Belzile, 2009).

• These mineralized zones occur at depths of over 100 meters beneath the surface, and the Niobec mine is the only underground niobium mine in the world. On the same structural lineament, the nearby Crevier syenitecarbonatiye complex contains a niobium-tantalum deposit which is currently being evaluated.

• Numerous other carbonatite-hosted niobium deposits are known across the world, but are not currently being exploited. The most significant of these are the Tomtor deposit in Siberia Russia and the Morro dos Seis Lagos deposit in Brazil (Pollard, 1995). The Neoproterozoicage Tomtor alkaline complex comprises an outer ring of nepheline-syenites, with a central stock24 of carbonatite, having a surface area of approximately 12 square kilometers (Kravchenko and Pocrovsky, 1995). Pyrochlore is disseminated throughout the carbonatite, but is particularly concentrated in two ore horizons. The lower ore horizon, which is up to 300 metres thick, represents the weathered and altered top to the carbonatite body, whilst the upper ore horizon is a buried placer deposit25 formed in an ancient lake, associated with Permian26 sedimentary rocks. The upper ore horizon contains more than 12 percent niobium (Kravchenko and Pokrovsky, 1995). The Morro dos Seis Lagos deposit is poorly known, to the extent that even its age is uncertain (Bwerger et al., 2009), but it is thought to represent the largest single niobium deposit in the world with 2897 million tones niobium (Pollard, 1995).

• A total of 58 carbonatite bodies containing niobium and rare earth element mineral deposits have been recorded in published work (Berger et al., 2009) and other such deposits may remain to be found. The smaller deposits include well-studied examples from Lueshe (Democratic Republic of Congo), Oka (Quebec, Canada), and Sökli (Finland). The Lueshe syenite-carbonatite complex, which is Cambrian27 in age, has a central core of syenite some 800 metres in diameter, bordered by a ring dyke of calcite carbonatite and dolomite carbonatite (Nasraoui and Bilal, 2000). Intense weathering of the carbonatites has formed a laterite horizon which is enriched in pyrochlore, and has been mined for niobium. The Cretaceous28 Oka carbonatite complex is an elongate pulton, about seven kilometers long, comprising carbonatites and feldspathoid-bearing silicate rocks. It includes three separate niobium-mineralised deposits containing minerals of the perovskite and pyrochlore groups (Zurevinski and Mitchell, 2004). The Sokli carbonatite-phoscorite comples is Devonian29 in age, with an area of aobut 20 square kilmetres, and comprise metasomatised ultramafic rocks, carbonatites and phoscorites, with abundant pyrochlore in the younger units of the complex (Lee et al., 2006). The major Bayan Obo rare earth element deposit in China, which is also enriched in niobium, is associated with carbonatite magmatism and may have been formed by the interaction of carbonatite-derived fluids and sedimentrary host rocks (Yang et al., 2009).

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2. Alkaline to peralkaline granites and syenites The alkaline igneous rocks are classified, on the basis of mineralogy, as those rocks containing certain sodium or potassium-rich minerals (feldspathoids, alkali

amphiboles, or alkali pyroxenes). Peralkaline rocks are a subset in which the molecular amount of Na2O+K2O xceeds Al2O330. Alkaline rocks are most commonly

found in intraplate settings such s zones of continental rifting, but they may also be formed in post-collisional31 to post-orogenic32 environments. The most evolved alkaline igneous rocks, such as alkali granites and syenites, are characterized by high contents of iron (Fe), fluorine, niobium, zirconium, rubidium (Rb), uranium, throum and rare earth elements but low niobium and tantalum (Pollard, 1989, Küster, 2009). Mineral deposits in alkaline igneous rocks typically contain high contents of zirconium, yttrium (Y), niobium and the rare earth elements, but are less commonly enriched in tantalum.

Several factors contribute to the enrichment of High Field Strength Elements33 (HFSE), such as niobium and zirconium, in alkaline igneous rocks such as alkaline granites and syenites. Alkaline magmas are most commonly considered to be derived from the enriched sub-continental lithospheric34 mantle, and are enriched in the HFSE from their formation. The HFSE are incompatible35 and thus they become enriched in the most evolved, granitic and syenitic magmas; in some localities, ore minerals are found disseminated throughout highly evolved granites and syenites. Further concentration can occur because the HFSE typically form relatively dense minerals, which may be accumulated through crystal settling into layers. The most famous example of a niobium deposit formed in this way is in the llímaussaq Complex of south-west Greenland. However, many minerlaised deposits within alkaline rocks, such as the Motzfeldt deposit in Greenland, have undergone further concentration of elements such s the HFSE and REE through hydrothermal36 processes (Salvi and Williams-Jones, 2005). The HFSE and REE appear to be highly mobile in fluids associated with peralkaline magmas that are enriched in fluorine, chlorine (Ci) and/or carbon dioxide (Goodenough et al., 2000, Salvi and Williams-Jones, 2005).

At the time of writing, there are few niobium or tantalum mines operating in alkaline granite and syenite complexes, although exploration is under way in some areas. One major area of interest lies in the mesoproterozoic37 Gardar Igneous Province in south-west Greenland, including the llímaussaq and Motzfeldt complexes. The llímaussaq complex is elliptical, 8×17 kilometres at the surface, and comprises a range of mineralogical unique syenites and alkaline granites which are spectacularly layered in places (Larsen and Sorensen, 1987). The main mineral deposits occur in a unit of layered syenites known as kakortokites, which contains twenty-nine separate layers that are rich in eudialyte, with high contents of zirconium, yttrium, niobium and the REE. The average grade of niobium in these layers is 0.1 weight per cent niobium oxide (Salvi and Wiliams-Jones, 2005). In the Kvanefjeld area of the llímaussaq Complex, hydrothermal veins in the syenites and their country rocks contain significant uranium-niobium minerlasiation. Zones of hydrothermally altered syenite also host the niobium-tantalum-REE pyrochlore minerlaisation in the Motzfeldt intrusion (Steenfeld, 1991) which is the subject of an ongoing exploration programme.

In Russia's Kola Peninsula, the Devonian-age Lovozero syenite massif contains layered syenites with layers that are rich in eudialyte, loparite and apatite. Laparite has been mined on and off for many years, and the loparite concentrates have average grades of eight weight per cent niobium oxide and 0.7 weight per cent tantalum oxide (Salvi and Williams-Jones, 2005). The Mesoproterozoicage Pilanesberg Complex of South Africa is another large (>500 square kilometers) alkaline complex with eudialyterich syenites that are enriched in zirconium, niobium and the REE.

In eastern Canada, the Strange Lake peralkaline granite pluton, which is Mesoproterozoic in age, outcrops over an area of about 36 square kilometres. It has a central ore zone where the granite has undergone extensive haematisation38 and calcium metasomatism, producing a range of secondary HFSE-bearing minerals, including gittinsite39 and pyrochlore. Ore from this zone has an average grade of 0.56 weight per cent niobium oxide (Salvi and Williams- Jones, 2005, Salvi and Williams-Jones, 2006). In Canada’s Northwest Territories, the Palaeoproterozoic Blatchford Lake igneous complex comprises syenites and peralkaline granites with a number of hydrothermally altered mineralized zones, known as the Thor Lake deposits. These deposits are enriched in beryllium (Be), yttrium, REE, niobium, tantalum and zirconium, with columbite-tantalite minerals hosting the majority of the niobium and tantalum, and average grades up to 0.4 weight per cent niobium (Salvi and Williams-Jones, 2005). The Thor Lake deposits are currently owned by Avalon Rare Metals Inc, which intends to develop them for REE, niobium and tantalum.

In Mongolia, the Devonian-age Khaldzan-Buregtey zirconium-niobium-REE deposit is formed by the hydrothermally altered late phase intrusions of a peralkaline granite massif (Kovalenko et al., 1995). Pyrochlore is the main niobium ore mineral. In Malawi, exploration is ongoing at the Kanyika niobium-tantalum deposit, which comprises an elongate body of nepheline syenite over 3.5 kilometres long with numerous mineralised, pyrochlore-bearing veins (BGS, 2009). In Saudi Arabia, the Ghurayyah alkaline granite stock is about 800 metres in surface diameter and contains disseminated tantalum and niobium ore minerals, chiefly columbite-tantalite and pyrochlore. The distribution of these ore minerals appears to be remarkably consistent throughout the granite (Küster, 2009). In Brazil, niobium and tantalum are extracted along with tin from a Palaeoproterozoic-age albite-rich peralkaline granite at the Pitinga mine (Bastos-Neto et al., 2009). Alkaline to peralkaline intrusions with the potential for nioium and/or tantalum deposits occur in many other countries, including Morocco, Nigeria, and Namibia.

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3. Granites and pegmatites of the LCT family (enriched in lithium, caesium, tantalum)

Granites and pegmatites of the LCT family are LCT family are typically peraluminous40 and enriched in lithium, rubidium, caesiu, beryllium, tin(Sn), tanalum and niobium (tantalum greater than niobium) (Černý and Ercit, 2005). These magmas are formed by melting of pre-existing crustal rocks, and were most commonly emplaced as post-orogenic plutons in zones of continental collision. Granites and pegmatites of this type are the main hosts for tantalum deposits across the world. These intrusions typically take the form of a large peraluminous leucogranitic41 pluton surrounded by a halo of pegmatites, with the most mineralized pegmatites at the greatest distance from the granite (Černý, 1989), although in some areas swarms of pegmatites are not associated with exposed granitic plutons.

The granite bodies contain minerals such as biotite, muscovite, topaz and tourmaline, and are typically rather heterogeneous, showing extensive albitisation42 and alteration by late-stage fluids. These granites may contain disseminated tantalum ore minerals, particularly concentrated in the uppermost parts of the granitic body (Linnen and Cuney, 2005).

Many of the largest tantalum deposits occur in pegmatite swarms. LCT pegmatites can be divided into five types: the beryl type; the complex (spodumene-petalite-amblygonite) type; the complex lepidolite type; the albite-spodumene types; and the albite type (Černý, 1989). Many of pegmatites falling into the first three types are zoned. All types can contain a range of tantalum minerals, of which the most important are generally columbite-tantalite, microlite, ixiolite and wodginite. Tantalum-rich cassiterite tin oxide) is also an important ore mineral in some bodies. Many of the pegmatites have been highly affected by latestage alteration, such as kaolinisation43.

In recent year, much of the world's production of tantalum has come from the Greenbushes and Wodgina mines in Australia, although production from these mines ceased between 2008 and 2011. Both mines are owned by Global Advanced Metals (previously Talison). The Greenbushes mine in south-western Australia is hosted in a giant (greater than three kilometre long) syn-tectonic44, zoned, complex-type pegmatite body of Archaean45 age, which contains large resources of both tantalum and lithium, associated with tin mineralisation. This pegmatite does not appear to be genetically associated with a larger granitic body (Partington et al., 1995). Three phases of tantalum mineralisation are recorded within this pegmatite: earlyformed minerals such as wodginite and ixiolite, which form inclusions in cassiterite and tourmaline; tantalites and tapiolites in fractures within early silicate phases; and later hydrothermal mineralisation, where microlite is the main tantalum mineral (Partington et al., 1995). The Greenbushes pegmatite has been exploited by both open pit and underground mining. In north-western Australia, a large number of pegmatite swarms occur within the Archaean rocks of the Pilbara Craton, and many of these include some tantalum-mineralised examples. The most important area here is the Wodgina pegmatite district, which includes the Wodgina Main Lode and Mount Cassiterite tantalum-mineralised pegmatites. The Wodgina Main Lode is a dyke-like pegmatite about one kilometre long, of albite-type, with manganese-rich tantalite as the main tantalum mineral, together with some manganese-rich columbite and wodginite. At Mount Cassiterite the deposit is formed by a series of pegmatite sheets of albite-spodumene type, and wodginite is the main tantalum mineral (Sweetapple and Collins, 2002). Tantalum from these pegmatites is extracted by open pit mining.

An Archaean pegmatite body also forms the host for the tantalum mineralisation at Tanco, in Manitoba, Canada, owned by Cabot Corporation. It is part of the rare-metal bearing Bernic Lake pegmatite group, which intrudes metavolcanic46 Archaean rocks. The Tanco pegmatite forms a shallowly dipping sheet, up to about 100 metres thick and 1600 metres along strike, which is exploited in a room-and-pillar underground mine. It is of the complex pegmatite type, and is strongly zoned; tantalum ore minerals are found throughout, though concentrated at higher grade in certain zones. A wide range of tantalum minerals occur (14 in all) and they are generally fine-grained, meaning that processing of Tanco ore is rather difficult (Cˇern‎, 1989). Caesium and lithium are also produced from the Tanco pegmatite. In addition, numerous other tantalummineralised pegmatites are known from the Superior Province of Ontario and Manitoba (Selway et al., 2005). In Brazil, a large (about one kilometre long), zoned, Proterozoic47 pegmatite body of albite-spodumene type is mined for tantalum, niobium and lithium at the Volta Grande mine at Nazareno, in the Minas Gerais district (Lagache and Quemeneur, 1997).

In Egypt, the Abu Dabbab and Nuweibi prospects are currently being developed towards production. These deposits are unusual in that the mineralisation is found in stock-like granite intrusions, rather than in pegmatites. Columbite-tantalite minerals are disseminated throughout these intrusions, and although the granites show significant evidence of later metasomatic alteration, the tantalum minerals are considered to be magmatic in origin (Küster, 2009). Abu Dabbab is a small conical mountain (Fig./Plate 2.18) built of the apical part of a granite cupola (therefore called an apogranite in

Russian terms). The host rock is fine-grained leucogranite consisting mainly of albite, some nologymicrocline, quartz and muscovite. Ore minerals are disseminated in the uppermost 130 m of the granite beneath the roof. The paragenesis comprises Ta-rich columbite, cassiterite, pyrochlore, monazite, rutile, zircon, magnetite, galena and sphalerite. Total resources are estimated as comprising 40 Mt of ore at 252 ppm Ta2O5, 116 ppm Nb2O5 and 0.01% Sn. A bankable feasibility study proposed to produce mainly Ta2O5, cassiterite and ceramic-grade feldspar. Similar are the nearby measured resources at Nuweibi in Egypt (Helba et al. 1997).

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Table 3: Key characteristics and examples of the major types of niobium and tantalum deposits (grades and tonnages are very variable between deposits and figures given are indicative only).


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In Central Africa, a zone of Neoproterozoic-age tantalum mineralised pegmatites cuts the Mesoproterozoic Kibaran belt which extends through Burundi, Rwanda, Uganda and the Democratic Republic of Congo (Romer and Lehmann, 1995). Columbite-tantalite minerals are mined both from deeply weathered pegmatites and from secondary placer deposits derived from the pegmatites.

Several regions of China have tantalum-mineralised granites and pegmatites. The most well-known is the Yichun deposit, which is hosted in a small (less than 10 square kilometres) granitic batholith of Jurassic age. The uppermost part of this batholith is a highly fractionated topaz lepidolite granite, which contains tantalum mineralization in the form of disseminated columbite-tantalite, tantalum-rich cassiterite, and minor microlite (Yin et al., 1995). Elsewhere in China, the Altai pegmatites (north-western China) and the Nanping pegmatites (south-eastern China) have been mined for columbite-tantalite in the past. In Malaysia and south-western Thailand, tin is produced from weathered tin-mineralised granites and pegmatites, and from secondary placer deposits. The tin slags are being reprocessed to produce tantalum.


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EXTRACTION METHODS The mining methods employed to extract niobium and tantalum are similar to

other metals of comparable occurrence. Factors that dictate the selection of mining methods include: the physical and

chemical properties of the ore mineral; the tonnage and grade; and the shape, geometry and depth of the orebody.

The most common methods of extraction are surface (or open-pit) and sub-surface (or underground) mining, or a combination of both.

Significant amounts of niobium and tantalum are also extracted by artisanal and small scale mining (ASM).


1. Surface mining

Massive, or steeply-dipping, low-grade near-surface ore bodies are amenable to open-pit mining techniques. Open-pit methods commonly involve removing overburden, digging or blasting the ore, followed by removal of the ore by truck or conveyor belt for stockpiling prior to processing. Open-pit mining may reach depths of several hundred metres but seldom exceeds 100 metres. Heavily weathered ore bodies, such as the Araxá carbonatite deposit in Brazil, are also mined using open-pit methods.

Land-based placer deposits are amenable to strip mining involving scrapers, bulldozers and loaders.

Placer deposits can be poorly consolidated, and only require drilling and blasting where materials have become cemented. For example, tin-tantalum placers in Malaysia are mined using simple stripping methods, whilst hard-rock surface operations, such as Wodgina Mine, are mined using drilling and blasting techniques.

Capital and operating costs for open-pit techniques are far less than those for underground operations.

Underground mining

Underground mining methods are usually employed when surface methods are, or become prohibitively expensive, for example if the deposit becomes too deep. Another major factor in the decision to use underground methods is the waste to ore ratio, or strip ratio. Once the ratio becomes large, open-pit mining methods become uneconomic.

Underground operations commonly require extensive mine development including shaft sinking, de-watering, ventilation, geo-technical support and ore handling.

Room and pillar is an underground mining technique where mining progresses in a horizontal direction by developing numerous stopes49, or rooms, leaving pillars of material for roof support. Ore is blasted and then transported by rail, conveyor or dump truck to the processing plant. Room and pillar mining methods were used at the Tanco pegmatite in Manitoba, Canada. The mine is located under Bernic Lake and is accessed via a 60-metre shaft and via a 20-degree decline50 from the surface (Cabot, 2001).

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3. By-product production

Niobium and tantalum can also be extracted as a by-product of tin smelter waste. Niobium produced in this way accounts for less than two per cent of total global niobium production. However, the percentage is much higher for tantalum at around 14 %. Tantalum is extracted from cassiterite51 placer middlings52 using shaking tables, and magnetic53 and electrostatic54 separation methods.

Tin smelter waste typically contains 9 to 10 % tantalum oxide, although exceptionally this may rise to 30 %. Low-grade smelter wastes can be upgraded by electrothermic reduction55 yielding a synthetic concentrate with up to 50 % tantalum and niobium oxides (Roethe, 1989).

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Processing After mining the ores are processed to increase their niobium and tantalum contents. Initial concentration is normally

undertaken at, or close to, the mine site and involves crushing the ore followed by separation of niobium and tantalum ore from gangue56 material, using a combination of physical and chemical methods. Although niobium and tantalum are geochemically similar each requires a different processing route.

Ore beneficiation Niobium ore is first crushed in jaw, cone or impact crushers and milled in rod or ball mills operating in closed circuits with

vibrating screens and screw classifiers57 to liberate niobium mineral particles. The slurry containing niobium and waste rock is further concentrated to around 54 per cent niobium oxide using a number of methods in multiple stages: gravity separation58, froth flotation59, magnetic and electrostatic separation, and acid leaching60 may be used, depending on the physical and chemical characteristics of the ore.

At the Niobec operation in Canada niobium ore is screened and classified, after which the resultant slurry is sent for desliming61. Carbonate material is removed by two stages of froth flotation, followed by an additional desliming stage. Magnetite is removed from the slurry, by low intensity magnetic separation, and sent to waste. The sought-after pyrochlore is collected from the slurry by froth flotation using diamine collectors62. A final stage of froth flotation is used to remove sulphides, such as pyrite. Residual impurities are leached by hydrochloric acid, leaving a final concentrate that contains around 54 per cent niobium oxide (Fig.4) (Iamgold, 2009).

Tantalum ores are initially treated in a similar manner to niobium ores; they are crushed, milled and screened to liberate tantalum mineral particles. The slurry containing tantalum and waste material is concentrated to around 30 per cent tantalum oxide using predominantly gravity and magnetic separation techniques, again depending upon the characteristics of the ore.

At the Greenbushes mine in Australia tin-tantalum ores are processed using a circuit of shaking tables, spirals and jigs63. The rough concentrate is de-watered and dried producing a tantalum concentrate containing about four to six per cent tantalum oxide. High intensity magnetic separation is used to separate the paramagnetic64 tantalum grains from the non-magnetic tin-tantalum grains; the paramagnetic fraction is further concentrated to around 30 % tantalum oxide by roasting. The non-magnetic fraction is further processed using a combination of froth flotation and roasting to remove sulphides, and smelting to separate tantalum from tin (Fig.4) (Fetherston, 2004).

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Fig. 4: Generalised beneficiation flow diagrams, based upon the Niobec and Greenbushes operations.


Conversion to Metal Tantalum and niobium metal can be produced from three different compounds -

fluorides, oxides and chlorides (Albrecht, 1989). The tantalum and niobium compounds are reduced to form pure metals and metal powders by two main methods. A mixed niobium-tantalum concentrate is digested using a mixture of hydrofluoric and sulphuric acids. The niobium-tantalum- bearing acid solution is then treated using liquid-liquid separation methods, involving solvent extraction or ion exchange, to separate niobium from tantalum. Niobium and tantalum can be extracted from the hydrofluoric -sulphuric acid mixture by using organic solvents, such as cyclohexanone, tributyl phosphate (TBP) or methyl-isobutyl-ketone (MIBK), whilst leaving behind impurities such as iron, manganese, tin and titanium (Fig.5). Ion exchange is used to produce high-purity solutions of niobium and tantalum and is usually performed using an amine extractant in kerosene.

Niobium and tantalum are precipitated as hydroxides from the mixed organic solvent solution by the addition of ammonia (NH3). The resultant hydroxides are calcined65 in a furnace to form niobium and tantalum oxides. The process of sintering66 the oxide products, with carbon, at high temperature is used to produce niobium and tantalum carbides. Niobium oxide is also the starting point for niobium metal production. The addition of potassium fluoride to the mixed organic solvent solution results in the crystallization of potassium tantalum fluoride (K2TaF7), the pre-requisite for tantalum metal production (Fig. 5).

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Fig.5: Chemical processing of niobium and tantalum concentrates


Two slightly different production routes are available for the production of niobium metal: one is used to produce pure niobium metal and the other is used to produce ferro-niobium. High-purity niobium metal is produced by aluminothermic reduction67 of high-purity niobium oxide with aluminium, lime and fluorspar. Electron beam melting is commonly used to increase the purity of niobium. To produce ferro-niobium, containing about 60 % niobium, iron oxide powder is added to the mixture prior to reduction (Albrecht, 1989).

The reduction of potassium tantalum fluoride by reaction with sodium is the most common method of producing tantalum metal. Potassium tantalum fluoride is blended with liquid sodium and inert salts to form a paste. The paste is then roasted in a continuous furnace to produce tantalum metal powder, potassium fluoride and sodium fluoride. To ensure a high degree of purity, as required by the electronics industry, the conversion process is performed using tantalum vessels under low-oxygen conditions. Further purification is achieved by vacuum arc furnace or electron beam melting68 of tantalum powder (Albrecht, 1989).

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Artisanal mining of coltan Although niobium and tantalum are extracted and processed conventionally, significant amounts are

also extracted by artisanal and small scale mining (ASM). Artisanal and small scale mining (ASM) is believed to provide a livelihood for over 100 million people worldwide and is defined as mining activities that are labour-intensive but capital-, mechanisation- and technology-poor. ASM is characterised by: Poor occupational safety.; Poorly qualified and trained personnel.; Inefficiency in extraction and processing.; Low salaries.; and Insufficient consideration of environmental issues.

Additionally, ASM is often unregulated with many activities falling outside the host countries’ legal

framework (Hentschel et al., 2003).

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Fig.6: Coltan (columbite-tantalite). Source: Sasha Lezhnev (© Enough Project)69

Coltan

• An abbreviation used only in Africa for the “columbo-tantalite” mineral, containing both Columbium (niobium) and Tantalum.

• There is controversy over the mining of Coltan in Africa, the UN reports it has been used to finance war in Rwanda and the Democratic Republic of Congo, much like “blood diamonds”, of the 1990’s and 2000’s.

Tantalum Industry Overview • When Swede Anders Gustaf Ekeberg (1767-1813) discovered tantalum in 1802, it was initially

thought that niobium and tantalum were the same element. He called it tantalum after Tantalus, the son of Zeus, who was condemned to eternal frustration and could not drink even though he was standing in water up to his neck. The isolation of this new element was a ‘tantalizing’ experience, hence the name.

• Elemental tantalum is metallic, heavy, grey and very hard. At temperatures below 150oC tantalum is almost completely immune to chemical attack. Only hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulphur trioxide affect the metal at these temperatures. Only tungsten and rhenium have higher melting points than tantalum.

Tantalum applications Tantalum is a grey metal, classed as a refractory metal because it is resistant to chemical attack. For industrial use, its important properties are a high melting point, ductility which allows it to be drawn

into wire, and malleability which allows sheets and tubes to be made. Once exposed to air, the metal is covered with a thin layer of oxide which allows it to resist fluids in the

human body, and also acids and other corrosive liquids, in the chemical industry. It has a high dielectric, which makes it so valuable in capacitors for the electronics industry. Tantalum

capacitors form an integral component in the production of mobile telephones, telecommunication infrastructure, laptop computers, auto-electrics plus still and video digital cameras.

Because of the metal’s resistance to corrosion it is used in chemical plant and equipment. Its high melting point (2,997°C) and low thermal coefficient of expansion make it a crucial component of jet

engine turbine blades. As tantalum carbide, one of the hardest substances known to man, it is used for cutting tools.

16 April 2013 24 Prof. Dr. H.Z. Harraz Presentation 16 April 2013

Tantalum Sources Tantalum ores are found primarily in Australia, Africa, Canada and Brazil with some additional quantities located in

Southeast Asia. Tantalum is typically hosted in relatively small pegmatites (1 – 100 million tonnes) and the generally larger apogranite bodies (100 – 1,000 million tonnes). The mineralization in pegmatite deposits typically has a tantalum pentoxide (Ta2O5) content of 100 – 1,000 g/t however the mineralization is usually found to be quite variable throughout the deposit and often requiring high-cost underground mining. Conversely, the usually larger apogranite deposits tend to be of a lower grade, however this can be off-set by mineralization which is uniformly distributed through the deposit, thus being ideal for low-cost open-pit bulk mining.

Both types of deposits can be either simple or complex, and thus difficult to process. Tantalum usually occurs with its relatively low value sister metal niobium plus tin. Deposits in which the tantalum is dominated by niobium are less economically viable while the development of tantalum resources containing excessive levels of uranium and thorium may be prevented due to international transport regulations pertaining to the transport of radioactive substances.

Tantalum Mineral Processing Tantalum ores are typically processed by careful milling of the ore to liberate the ne tantalum

minerals. Following this initial stage, the milled ore is subjected to a series of physical or non-chemical

processes involving the use of gravity separation techniques. The gravity techniques utilize the earth’s natural gravitational (1G) force to separate the heavy

tantalum (plus tin and niobium) minerals from the lighter host rock or waste. The separation process also typically employs enhanced gravity equipment by applying

centrifugal forces of up to 300G to separate heavy and light fractions. The tantalum concentrate produced then undergoes a series of complex chemical processes to

separate the tantalum from niobium and tin whilst also removing certain impurities to produce a saleable concentrate containing between 10% and 30% Ta2O5


Tantalum Market

The majority of the world’s tantalum is sold by way of long-term offtake agreements between the miner and the tantalum refiner/metal producer.

Tantalum is not sold via a regulated market as is for gold, copper, zinc and tin.

The global tantalum Ta2O5 market is estimated to be in the order of 5 - 7 million pounds per annum. Industry commentators suggest that the market is growing at a rate of about 7% per annum.

HC Starck GmbH, is generally considered to be the world’s leading tantalum concentrate consumer/processor followed (not in order) by:- Cabot Corporation (USA), Ulba OJSC (Kazakhstan), Mitsui-Kinzoku (Japan) and Ningxia Non-Ferrous Metals (China) plus various other Chinese groups.

Property Applications Market %

high dielectric (High coefficient of capacitance)

production of electronic capacitors used in:

Mobile telephones

Telecommunication infrastructure

Still and video digital cameras.

Laptop computers, servers and PCs

Auto-electrics

Processed in powder form for use in the

50

Resistance to corrosion construction of chemical

plant and equipment

Milled tantalum metal products are used in 15

High melting point (2,997°C) and low coefficient of

thermal expansion

Manufacture of super-alloys for power generation and a crucial

component of jet engine turbine blades 10

High density hard metal Production of tantalum carbide, one of the hardest substances

known to man, it is used for cutting tools. 10

Other Medical prosthetics, specialty chemicals production 15



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Tantalum Supply and Demand Forecast Figure shows our production and demand forecast for tantalum under three scenarios: low growth (6% CAGR), medium growth (9% CAGR) and high growth (12% CAGR).

• Estimates indicate that tantalum demand has grown by 6% between 1995 and 2002, but had a one-year decline of 31% in 2009 due to the recent global economic slowdown.

• Tantalum demand expected to grow by 9% in the next 4 years.

World Demand

Projects Under Development

16 April 2013 28

In Egypt, Gippsland Ltd. Is developing the Abu Dabbab mine scheduled for production in 2013, with a production target of 650,000 pounds per year.


Egyptian Ta-Nb Deposits

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This type of mineralization was identified for the first time in Egypt in the late sixties during the ground verification of the most pronounced airborne radiometric anomaly recorded in the Eastern Desert.

Main Occurrences

1) Abu Rusheid (24o 37/ 09// N, 34 o 46/ 04// E)

2) Abu Dabbab (25 o 20/ N, 34 o 32/ E)

3) Nuweibi (25 o 12/ N, 34o 30/ E)

4) Minor Occurrences:

Locality Lat Long

Um Naggat 25° 30'N 34° 15'E

El-Shalul 25° 27'N 33° 40'E

EI-Backriya 25° 18'N 33°41'E

Um Bisilla 25°21'N 34° 00/E

Um Salim - -

Rod Ishab 25° 08'N 34° 06'E

Muelha mine 24° 54' N 330 55'E

Um Dubr 22° 40'N 35° 50'E

30 16 April 2013 Prof. Dr. H.Z. Harraz Presentation


1) Abu Rusheid (24o 37/ 09// N, 34 o 46/ 04// E)

The causative body was found to be a rock formation anomalously rich in rare metals and containing abnormally high concentrations of economically interesting accessory minerals, with visible columbite and zircon in hand specimens.

The ore minerals present are columbite (Nb2O5 : Ta2O5 ratio 51 to 81), cassiterite, monazite, xenotime, fluorite, zircon, thorite-thorogummite, and sulfides of iron zinc, copper, lead and molybdenum.

This mineralized rock formation may represent an apogranite tongue or silk 50 m thick, intruded concordantly along the contact between the psammitic gneiss and the overlying schists This sill is an offshoot of a hidden granitic intrusion somewhere below Wadi Abu Rusheid

This radioactive mineralized rock formation is the uppermost part of the psammitic gneiss sequence that was subjected to metasomatic alterations and introduction of ore components by emanations coming probably from an underlying granite body. The volatiles were trapped by the impervious schist and hence had the chance to alter and mineralize the uppermost parts of the gneiss formation. This dispute has not been settled.

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1) Abu Rusheid (cont.)


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Thus it was concluded that, in this area, the deposit contains Ta (Ta2O5, up to 0.0328%), Nb (Nb2O5, up to 0.3%), Sn (up to 0.3%), Li (Li2O, up to 0.25%), Zr (1%), U (up to 0.86%), Th (up to 1.43%), and traces of Cu. Zn, Pb and Mo.

Of these, the Nb and Ta are the most interesting. Abu Rusheid is therefore an ore body containing 90.000 tons of Nb2O5 and 13.000 tons of Ta2O5 at a cutoff grade of 0.02% Ta2O5.

If and when worked, some Sn, Zr, Li and other elements will be obtained as by-products

1) Abu Rusheid (cont.)

2) Abu Dabbab (25 o 20/ N, 34 o 32/ E) A country rock of paraschists that include quartz-biotite and quartz-chlorite

schists with intercalated beds of tuffs and agglomerate, with an intruded stock of apogranite with Ta-Nb-Sn mineralization.

Quartz veins bearing cassiterite and wolframite are associated with this stock.

The mineralized stock covers an area of 3.2 km2 and is made up of quartz-albite or quartz-albite-amazonite lithionite Mineralization is most intensive in the northeastern endocontact zone of the mass, which is 30 m wide.

This mass has been studied in detail, drilled and assayed. Ta2O5, ranged from 0.0095 to 0.075%, with an average of 0 028% (cutoff grade. 0.01% Ta2O5). Nb2O5 values varied from 0.002 to 0.029% (average 0.008%)

Abu Dabbab is thus primarily a tantalum deposit, as the Ta2O5 : Nb2O5, ratio averages 3:1.

Proven ore reserves were calculated at ten million tons containing 2600 tons Ta2O5 and 800 tons Nb2O5.

16 April 2013 Prof. Dr. H.Z. Harraz Presentation Economic Geology, Introduction

34

Abu Dabbab location

Abu Dabbab project infrastructure

(Gippsland Limited Annual Report 2004)



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Gippsland has a controlling 50% interest in the Egyptian Abu Dabbab and Nuweibi tantalum-tin-feldspar deposits having a combined resource of 138 million tonnes.

The Company’s Abu Dabbab and Nuweibi tantalum deposits will be developed to establish Gippsland as a leading global tantalum producer for several decades.

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Abu Dabbab (tantalum-tin-feldspar)

Introduction The (40 Mt April - June 2004) 44.5 Mt Abu

Dabbab Tantalum-Tin-Feldspar deposit is located within the Central Eastern Desert in Egypt.

The deposit is located about 16 km inland from the western shore of the Red Sea.

The deposit is covered by two Exploitation Leases (1658 & 1659) granted in the name of Tantalum Egypt JSC, a company incorporated in Egypt and owned 50% by the Egyptian Government via the Egyptian Mineral Resources Authority (EMRA) and 50% by Tantalum International Pty Ltd which is a 100% owned subsidiary of Gippsland Ltd.

The Abu Dabbab plant site 14 km in area is located 6 km from the Red Sea coast has been secured under Ministerial Decree No 11/2003.

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Previous exploration • Tin-tungsten mineralization at Abu Dabbab has been known since the 1940s

but it was not explored until the early 1970s when a joint Soviet-Egyptian team, completed an extensive exploration programme.

• In the early 1990s the project was further explored by a joint venture between the Egyptian Government and Italian company Geominera Italiana. The previous work included 28 diamond drill holes, three adits, one crosscut, numerous trenches, surface sampling, bulk sampling and metallurgical tests.

• Gippsland carried out some re-sampling of the adits to verify the previous results, collected bulk samples totalling 43 tonnes which were used to conducted additional detailed metallurgical test work in Australia. Encouraged by the results of the test work, Gippsland commenced a Bankable Feasibility Study which was completed in October 2004 and updated in September 2008 by the international engineering Group Lycopodium Pty Ltd.

16 April 2013 40 16 April 2013 Prof. Dr. H.Z. Harraz Presentation

16 April 2013 41 16 April 2013

Abu Dabbab tantalum mineralization outcrop

Abu Dabbab summit

Abu Dabbab field camp


Geological setting The Ta-Nb-Sn mineralisation of Abu Dabbab is represented by

disseminated cassiterite and niobio-tantalite, hosted in a stock of apogranite. The apogranite at Abu Dabbab is leucocratic, holocrystalline, white grey to greenish blue and with manganese oxide spots and dendrites. It is mostly fine to medium grained and occasionally has a porphyritic texture.

The characteristic alteration processes in the apogranite are greisenisation, microclinization, silicification and albitization.

The shape of the host apogranite intrusion is generally ellipsoidal except in the north-western part where there is a narrow off-shoot, about 150m in length. The apogranite mass is elongate in an east-west direction with a maximum length of about 400m. Maximum width in a northeast-southwest direction is nearly 200m. The body extends about 130m above the level of the adits and has been intersected in drilling at a depth of 350m below the adits.

No significant disseminated mineralization is present in the country rocks surrounding the intrusive mass, therefore the ore deposit limits correspond to the limits of the apogranitic body.


Interpreted geology

Abu Dabbab geological cross section through tin-tantalum deposit (Gippsland Limited Annual Report 2004)

Abu Dabbab geological map (Gippsland Limited Annual Report 2008)


OBLIQUE AERIAL VIEW OF ABU DABBAB LOOKING TO THE SOUTHEAST (Gippsland Limited Annual Report 2006)


Pit optimization and Ore Reserve up-grade Subsequent to the highly successful RC and diamond drilling programme described

above, the Abu Dabbab Ore Reserves were increased from 14.60 million tonnes to 30.24 million tonnes, grading 255g/t Ta2O5and 0.109% Sn, an overall 107% increase in total Ore Reserves.

The new Ore Reserves were based on a number of Whittle open pit optimization runs using the wireframe constrained Mineral Resources for a range of tin prices to test the sensitivity of the optimization. The pit optimization showed little sensitivity to the tin price. The tantalum price used in the optimization is determined by an Off-take Agreement, the terms of which stipulate that the price is confidential.

The optimal 15 year pit shell contained an undiluted mineral resource of 29.09 million tonnes grading 270g/t Ta2O5 and 0.113% Sn, with 22.8 million tonnes of waste. From this Whittle shell, the revised open pit mine design included no ore loss and 5% dilution at zero grade at a production rate of 2 million tonnes per year. There were no Inferred Resources contained in the open pit mine design.

Abu-pit shell-15 cut-1


3D Image of proposed Abu Dabbab (Gippsland Limited Annual Report 2005)

Mining operation plant site reserve infrastructure (Gippsland Limited Annual Report 2005)


Resources Abu Dabbab Mineral Resources (100 g/t Ta2O5 cut-off) (Gippsland Limited Annual Report 2012)

Category Million Tonnes Ta2O5 (g/t) Sn grade(%)

Measured Mineral Resource 15.2 290 0.143%

Indicated Mineral Resource 17.3 250 0.078%

Inferred Mineral Resource 12 200 0.03%

Total Mineral Resource 44.5 250 0.09%

• The original pit optimization and open pit mine design for the bankable feasibility study for the Abu Dabbab project was based on prices of US$42.00 per pound for Ta2O5 and US$7,000 per tonne for tin. In light of the recent significant lift in the prices for both commodities, the Company decided to re-optimize the open pit design with the aim of better utilizing the total Abu Dabbab resource.

• With this in mind, the pit re-optimizations were run at both 2 Mtpa and 3 Mtpa production rates with the following metal prices: Ta2O 5 US$75.00 per lb and tin US$25,000 per tonne. The results of the re-optimizations pointed to improved overall project economics stemming both from the increased production rate and metal prices. Accordingly, an updated 3 Mtpa open pit mine design was prepared.

• The revised open pit mine design and associated production schedule supports the following updated Ore Reserves statement, based on a 100 g/t Ta2O5 cut-off.


Reserves Abu Dabbab Ore Reserves (100g/t Ta2O5 cut-off) (Gippsland Limited Annual Report 2012)

Category

Million

Tonnes

Ta2O5

(g/t)

Sn grade

(%)

Proved Ore Reserve 15.20 260 0.1695%

Probable Ore Reserve 17.98 245 0.0989%

Total Proved & Probable Ore Reserves 33.18 252 0.1312%

Category Tonnes

(Mt)

Ta2O5

(g/t)

Nb2O5

(g/t)

Sn

(%)

Abu Dabbab (0.1 % Ta2O5 cut-off)

Measured 12 274 126 0.130

Indicated 2.1 260 90 0.160

Inferred 26 240 110 0.060

Total all categories 39.9 252 116 0.089

Abu Dabbab mineral resources at 30 June 2004


Feasibility Study • The utilization of seawater eliminates the need to produce 6,000 cubic metres per day of potable water by way of a reverse

osmosis (RO) plant and enables the plant site to be conveniently relocated to within one kilometre of the open pit mine.

• This change will reduce the distance by some 19 km over which 2 million tonnes per year of ore will need to be hauled.

• This will result in a capital cost saving of approximately US$4 million and an operating cost saving of approximately US$900,000 per year, equating to US$18 million over the likely 20 year Abu Dabbab mine life.

• The relocation of the plant-site will also shorten the ore haul distance from the Company’s 98 million tonne Nuweibi tantalum deposit, located some 16 km to the south of the Abu Dabbab plant-site, by approximately 16 km.

• One major improvement in the flowsheet process has been the identification that the plant process can be successfully operated using raw seawater which provides direct and very important benefits to the project.

• The utilization of seawater in the majority of the plant process eliminates the need to produce 6,000 cubic metres per day of potable water by way of a reverse osmosis (RO) plant. It has been calculated that the modified process route will consume less than 600 cubic metres per day of potable water which will be used in the final stages of the process.

• The reduced size of the RO plant will result in a capital cost saving of approximately US$4 million and an operating cost saving of approximately US$900,000 per year or US$18 million over the likely 20 year Abu Dabbab mine life.

• The use of seawater eliminates the need to inject waste RO brine into 200m deep saline aquifers immediately adjacent to the Red Sea, which in turn enables the plant site to be conveniently relocated to within one kilometre of the open pit mine.

• This change will reduce the distance by some 19km over which 2 million tonnes per year of ore will need to be hauled, thereby eliminating the need for a heavy haulage road fleet, whilst reducing haulage costs by approximately US$4 million per year. The road between the mine and the Red Sea coast will now become an access road that does not need to be engineered for use by heavy ore haulage vehicles.

• The relocation of the plant site will also shorten the ore haul distance from the Company’s 98Mt Nuweibi tantalum deposit located some 16km to the south of the Abu Dabbab plant-site. However, as Abu Dabbab will have a mine life of approximately 20 years, Nuweibi will not be utilized in the immediate future.

Bankable Feasibility Study • Following detailed evaluation of alternative production profiles for the Abu

Dabbab Project, the Company has proceeded with a change of scope for the Abu Dabbab Project from 2 million tonnes per annum (“Mtpa”) of Run-of-Mine ore (“ROM”) to 3 Mtpa of ROM.

• Revised pit optimization studies suggest a mine life of 13.5 years. The Company has completed Whittle pit re-optimizations at both 2 and 3 Mtpa based on both Measured and Indicated Mineral Resources and Measured, Indicated and Inferred Mineral Resources. In each case a number of scenarios over a range of metal price assumptions were performed. The results indicate that the 3 Mtpa ROM option is superior to the 2 Mtpa ROM case on technical, economic and commercial (marketing) grounds.

• At this expanded rate of production, the average annual output of products is estimated to be approximately:

925,000 pounds of tantalum oxide (Ta2O5) in slag; 2,200 tonnes of tin as tin metal; and up to 2.4 Mtpa of feldspar.

Environmental and Social Impact Assessment • The Abu Dabbab Environmental Impact Assessment (EIA) completed by the

Company to World Bank standards has been approved by the Egyptian Environmental Affairs Agency.


Bankable Feasibility Study • During the year the Company completed a BFS which confirmed that

the world-scale 40Mt Abu Dabbab deposit has the potential to become a major global supplier of tantalum whilst operating from a Low cost base.

• The BFS and subsequent test work determined that the Abu Dabbab is scheduled to produce in excess of 720,000 pounds of tantalum pentoxide (Ta2O5) thus firmly establishing the project as the world’s second largest tantalum supplier.

• The Abu Dabbab project is also scheduled to produce 1,680 of tin metal per year.

• The BFS determined that the project has the capacity to generate a net cash flow in excess of US$170 million during its estimated 20-year mine life.

• Granting of Abu Dabbab free trade zone providing Tax-Free Status, Exemption from customs Import Duty and Sales Tax for life of project.

• Excellent timing for company to be positioned to become major long-term supplier to expanding Global Tantalum Market.


Tantalum Off-Take Agreements • A pivotal event during 2008, was the announcement of a ten year Off-take Agreement with the

German tantalum major HC Starck GmbH for the supply of six million pounds of tantalum pentoxide from the Abu Dabbab project.

• This Agreement represents 92% of the project’s initial projected annual tantalum pentoxide production.

• Recent increases in the price of tin metal further enhance the project with tin production likely to approach tantalum pentoxide in terms of cash value. Additionally tin can be sold on the spot metal market.

• The Company has now entered into a sale and purchase off-take agreement for 480,000 pounds of tantalum per year for a fixed period of 5 years. The price of the tantalum, which has been fixed for the whole of the contract period, will remain confidential for commercial reasons. The agreed price is consistent with that used in the Abu Dabbab BFS completed during November 2004.

• Additionally, over the 5-year period, the same purchaser has been granted the first right of refusal for an additional 70,000 pounds of tantalum per year subject to such quantities being available for sale, at the same price.

• The Company has also entered into a heads of agreement with a major Asian tantalum consumer for the off-take of 100,000 pounds of tantalum per year.

• The 1,680 tonnes of tin per annum will be sold direct to industry and/or via the London Metal Exchange.

• The Abu Dabbab project has the potential to produce approximately 1.5 million tonnes per annum of ceramic grade feldspar. Consideration of this additional phase of the project will be undertaken following commissioning of the Abu Dabbab tantalum/tin operation.

• Gippsland has entered into Heads of Agreement with a major Italian group for the off-take of 2.65 million tonnes of feldspar delivered over a 4-year period.


Ten year tantalum Off-take agreement • On 12 November 2007, the company announced that its 50% owned subsidiary Tantalum Egypt,

had secured a 10 year Off-take Agreement with the German tantalum major HC Starck GmbH for the supply of six million pounds of tantalum pentoxide (Ta2O5) from its 44.5 million tonne Abu Dabbab project in Egypt.

• This milestone Off-take Agreement covers the delivery of a minimum of 600,000 pounds of Ta2O5 per annum – almost the entire expected initial annual production of 650,000 pounds of Ta2O5 from the project. As is traditional for the tantalum industry, the Ta2O5 Off-take Agreement prices are confidential, however based upon present Ta2O5 spot prices the Abu Dabbab project is expected to generate Ta2O5 revenue in excess of US$280 million over the initial 10 years of its estimated 20 year mine life. The Off-take Agreement signed on 12 November 2007 replaces the smaller Ta2O5 off-take agreement between Gippsland and HC Starck announced on 13 January 2005 for the supply of 480,000 pounds of Ta2O5 per annum for a period of 5 years.

• Importantly, the Ta2O5 Off-take Agreement contains price escalation clauses tied to production cost increases and a floor Ta2O5 price which will largely underpin the on-going viability of the project.

• The Off-take Agreement also contains a formula for the Ta2O5 Off-take price to be varied to reflect a premium to spot market prices. The Off-take Agreement largely protects Gippsland shareholders from production cost escalations, significantly reducing the market risk.

• In addition to Ta2O5, the Abu Dabbab project will produce approximately 1,530 tonnes of tin metal per annum which will be sold on the open market or via the London Metal Exchange (LME). Based upon the present LME tin price, the Abu Dabbab project is expected to generate tin revenue of approximately US$300 million over the initial 10 years of its estimated 20 year mine life

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Fast-Track Start-Up • In order to fast-track the commencement of operations,

the project will proceed based upon the production of tantalum and tin alone. While the project has the potential to produce approximately 1 million tonnes ceramic grade feldspar per annum, the BFS and thus the project will progress independent of feldspar production.

• The project's viability is not dependent upon feldspar revenue and production of feldspar will be considered as a separate issue following commissioning of the tantalum and tin production facilities.

• As the BFS progresses, the Directors are becoming increasingly confident that the 40Mt Abu Dabbab operation

has the potential to become the world's largest and lowest cost tantalum producer.


Abu Dabbab Alluvial Tin During the early 1970s a joint Egyptian‐Soviet expedition explored and evaluated two placer tin

deposits at Abu Dabbab. The placers are known as Wadi Mubarak and Wadi Quaria and are located adjacent to the large Abu

Dabbab tantalum-tin deposit. The sampling data produced by the Soviets was re‐evaluated and a new resource estimation

completed by Gippsland in 2008 identified an Inferred Resource containing 759 tonnes of tin metal.

Placer Overburden

(m 3)

Mineralized layer

(m 3) Cassiterite

Tin

(tonne)

Wadi Mubarek 146,290 175,120 247.6 193.5

Wadi Quaria 293,630 262,770 724.0 566

Totals 439,920 437,890 971.6 759

(Gippsland Limited Annual Report 2012)


In April 2011 a programme of trial mining of the alluvial material and on‐site processing using a HPC‐15 alluvial separator commenced with bulk sample feed being mined by excavator from selected profiles representing the range of alluvial material and cassiterite grades expected to be encountered during full scale mining. The trial mining to date has focussed on characterizing the placer deposit material to determine metallurgical behaviour and to confirm the cassiterite content of the deposit, cassiterite content of the waste material and the mineralogy of the cassiterite in the concentrate and tailings.

Following the completion of a comprehensive engineering study and economic evaluation of the Abu Dabbab alluvial tin deposits and the sufficiently robust results of the trial mining, the Directors formally approved implementation of the Abu Dabbab Alluvial Project at the earliest opportunity.

Two modular IE‐TEC HPC‐30 alluvial separator units will be utilized to process high grade alluvial material with the smaller HPC-15 unit that was used for the trial mining used as a cleaning unit. The final concentrate product will be produced from a Wilfley Table.

Site preparation is currently in progress. The main plant and equipment has arrived on site in Egypt and is due to be on site at Abu Dabbab in early February 2012. Commissioning of the plant is due in early March 2012.


Trenching for alluvial Tin trial mining samples

Alluvial separator used for trial mining of cassiterite


Location Plan of Abu Dabbab tin placer deposits (Gippsland Limited Annual Report 2012)

Construction of mining contractors camp


Installation of screening plant Marking out grade control blocks for mining

Construction of waste water settling ponds Mining of alluvial material


Abu Dabbab –tantalum tin project infrastructure (Gippsland Limited Annual Report 2008)

Abu Dabbab project mine area (Gippsland Limited Annual Report 2008)

RC drilling at Abu Dabbab (Gippsland Limited Annual Report 2008)


Abu Dabbab 3D topographic image showing ore block, waste dump, haulage road and final pit outline (Gippsland Limited Annual Report 2008)



3) Nuweibi – Tantalum, Niobium, Feldspar Projects

Location The Nuweibi tantalum-niobium deposit (or the 98 million tonne Nuweibi) is

located 17 km to the south-southwest of Gippsland's Abu Dabbab Tantalum-Tin-Feldspar Project and 30 (25) km inland from the western shore of the Red Sea.


Tin mineralization was first discovered at Nuweibi in 1944 and it was not until 1970 that the more valuable tantalum mineralization was recognized.

The deposit was the subject of detailed exploration by the same joint Soviet-Egyptian team that explored Abu Dabbab.

The previous work has included 23 diamond drill holes totalling 2,746 m, four surface trenches and four bulk samples which were used for detailed metallurgical testwork undertaken in Moscow in the then Soviet Union.

There is the potential for a significant increase in Nuweibi resources to the east as most of the eastern diamond drill holes bottomed in mineralization.

The Nuweibi deposit presents the opportunity for the Abu Dabbab process plant to be utilized for several decades beyond the estimated 20-year Abu Dabbab mine life.

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Geological setting The country rocks are mainly quartz-biotite schists The Nuweibi mineralization is hosted by an apogranite intrusive within a sequence of

schists, gabbro, serpentinite older granites and dykes of varying composition. The apogranite that hosts the mineralization is comprised of three main facies, an upper,

middle and lower, each separated by transition zones. Nb-Ta mineralization occurs as disseminations in the apogranite part of the Nuweibi mass. Quartz-cassiterite veins with greisen selvages characterize the exocontact zone. Mineralogical analysis of apogranites from the most intensively albitized and mineralized

parts of the mass revealed the presence of columbite, cassiterite, magnetite, ilmenite, zircon, topaz, barite, and trace amounts of apatite, rutile and monazite.

Exploration Analyses show that Ta2O5 contents vary from 0.018 to 0.024%, and Nb2O; from 0.005 to 0.009%, with the

Ta2O5: Nb2O5 ratio ranging from 5 1 to 2:1. Drilling and assay of cores indicate that the lower levels of the mass show a sharp decrease in Ta and Nb

contents, to 0.004% Ta2O5 and 0.002% Nb2O5 The eastern part of the apogranite mass is potentially important. There is a zone 1000 m long, 450 m

maximum width, with mineralization down to 50 m. Average Ta2O5 and Nb2O5 are 0 018% and 0.009% respectively, and the Ta2O5: Nb2O5 ratio is 2: 1

The nearby Abu Dabbab deposit has adequate resources for at least a decade of mining such that immediate exploitation is not warranted.

Current exploration will focus on infill drilling to upgrade the resource categories.

This will involve the completion of diamond drilling to 150m. 16 April 2013 65

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Nuweibi project - drill hole location plan (Gippsland Limited Annual Report 2007, 2008)

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Nuweibi geology (Gippsland Limited Annual Report 2012)

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Nuweibi geological plan and cross section (Gippsland Limited Annual Report 2004)

Exposed Nuweibi tantalum mineralization

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Loader works at little wadi at Nuweibi area

General view of the Nuweibi deposit (light coloured rocks)

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CONSTRUCTION OF THE ABU DABBAB MINE ACCESS ROAD

PREPARING THE LAYDOWN AREA ON THE 440RL

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Resources The resources at Nuweibi have been estimated by Gippsland using the ore block modelling method at a 0.01% Ta2O5 cut-off.

Table shows the Nuweibi resources estimation with the ore block model method using 5 m square blocks at a 0.01% Ta2O5 cut-off (Gippsland Limited, Annual Report 2004, 2008, 2012).

Category Million Tonnes Ta2O5 (g/t) Nb2O5 (g/t)

Indicated Resource 48 147 90

Inferred Resource 50 138 95

Total Resource 98 143 95

There is the potential for a significant increase in the Nuweibi resources to the east as most of the eastern diamond drill holes bottomed in mineralization (Gippsland Limited, Annual Report 2006).

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4) Minor Occurrences

Locality Lat Long Remarks

Um Naggat 25° 30'N 34° 15'E Albite-microcline- quartz apogranite in marginal zone of the Um

Naggat mass (0.02% Ta and 0.03-0.15% Nb)

El-Shalul 25° 27'N 33° 40'E Altered muscovite granite (traces of Ta and 0.01% Nb)

EI-Backriya 25° 18'N 33°41'E Altered zone in the N endocontact of EI-Backriya granite (0.01 %Nb,

traces of Ta)

Um Bisilla 25°21'N 34° 00/E Muscovite-albite- quartz apogranite (0.005% Nb)

Um Salim - - Muscovite-microcline- albite-quartz apogranite, 5 m wide endocontact

zone (0.005% Nb, traces of Ta)

Rod Ishab 25° 08'N 34° 06'E Sheet-like pegmatite body (0.001-0.008% Nb)

Muelha mine 24° 54' N 330 55'E Greisen with disseminated cassiterite (0.01% Ta and 0.01 % Nb)

Um Dubr 22° 40'N 35° 50'E

Zones of amazonite granite (panning yielded columbite and xenotime;

radioactive zones associated with quartz amazonite pegmatites and

altered zones in granites; sampled pegmatites and altered zones (~0.1

% Ta2O5 and 0.5-1.1% Nb2O5

In addition to the three deposits described above, Nb-Ta mineralization has been identified in a number of localities, some of which also contain Sn or W. The main occurrences are listed in table .

Table : Localities with Nb-Ta mineralization.

Profiled Company (Gippsland Limited)

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Egypt‎


REFERENCES ALBRECHT, W W. 1989. Production, Properties and Application of Tantalum, Niobium and Their Compounds. In: Möller, P, Černý‎, P and Saupé, F. (eds.) Lanthanides,

Tantalum and Niobium. Berlin Heidelberg: Springer-Verlag.

ANGLO AMERICAN. 2011. Fact Book 2009/10 [Online]. Anglo American plc. Available: http://www.angloamerican. com [Accessed January 2011].

Bastos-Neto, A C, pereira, V P, ronchi, L H, lima, E F and frantz, J C. 2009. The World-Class Sn, Nb, Ta, F, (Y, Ree, Li) Deposit and the Massive Cryolite associated with the Albite-Enriched facies of the Madeira A-type Granite, Pitinga Mining District, Amazonas State, Brazil. The Canadian Mineralogist, 47, 1329–1357.

Bevins, R E and Mason, J S. 2010. Wales. In: Bevins, R E, Young, B N, Mason, J S, Maning, D A C and Symes, R F. (eds.) Mineralization of England and Wales. Peterborough: Joint Nature Conservation Committee.

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Černý‎, P. 1989. Characteristics of Pegmatite Deposits of Tantalum. In: M‎ ِ ller, P, Černý ‎, P and Saupé, F. (eds.) Lanthanides, Tantalum and Niobium. Berlin Heidelberg: Springer-Verlag.

Černý ‎, P and ERCIT, T S. 2005. The Classification of Granitic Pegmatites Revisited. The Canadian Mineralogist, 43, 2005–2026.

CORDEIRO, P F O, BROD, J A, DANTAS, E L and BARBOSA, E S R. 2010. Mineral chemistry, isotope geochemistry and petrogenesis of niobium-rich rocks from the Catalão I carbonatite-phoscorite complex, Central Brazil. Lithos, 118, 223-237.

DEPARTAMENTO NACIONAL DE PRODUاأO MINERAL (DNPM). 2009. Sumário Mineral Brasileiro 2008 [Online]. DEPARTAMENTO NACIONAL DE PRODUÇÃO MINERAL BRASIL. Available: www.dnpm.gov.br [Accessed February 2011].

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FETHERSTON, J M. 2004. Tantalum in Western Australia, Perth, Geological Survey of Western Australia FOWLER, M B, KOCKS, H, DARBYSHIRE, D P F and GREENWOOD, P B. 2008. Petrogenesis of high Ba-Sr plutons from the Northern Highlands Terrane of the British Caledonian Province. Lithos, 105, 129-148.

GIPPSLAND. 2011. Abu Dabbab Tantalum [Online]. Available: www.gippslandltd.com [Accessed March 2011].

GOODENOUGH, K M, UPTON, B G J and ELLAM, R M. 2000. Geochemical evolution of the Ivigtut granite, South Greenland: a fluorine-rich ‘A-type’ intrusion. Lithos, 51, 205-221.

GRAUPNER, T, MELCHER, F, GABLER, H-E, SITNIKOVA, M, BRATZ, H and BAHR, A. 2010. Rare earth element geochemistry of columbite-group minerals: LA-ICP-MS data. Mineralogical Magazine, 74, 691-713.

KـSTER, D. 2009. Granitoid-hosted Ta mineralization in the Arabian-Nubian Shield: Ore deposit types, tectonometallogenetic setting and petrogenetic framework. Ore Geology Reviews, 35, 68-86.

LAGACHE, M and QUEMENEUR, J. 1997. The Volta Grande Pegmatites, Minas Gerais, Brazil: an example of rare-element granitic pegmatites exceptionally enriched in Lithium and Rubidium. The Canadian Mineralogist, 35, 153-165.

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Egyptian tantalum niobium and tin deposits