Often associated geologically, but with different end-uses, tantalum and niobium have had to weather tough economic times over the past year or so. With demand in the principal market for tantalum – electronic capacitors – having slumped during the downturn, producers of the metal have cut back their output, leading to fears of significant production shortfalls once demand returns.
Meanwhile, demand for specialist steels, which make up the largest proportion of annual niobium production, has also been reduced, although the impact on the world’s leading producers has been much less dramatic.
A common feature for both metals is the limited number of major producers worldwide.
According to recent data from the British Geological Survey, Brazil and Australia contributed by far the greatest proportion of the estimated 900t of tantalum produced in 2007, with Canada, China, Mozambique and Ethiopia making up much of the rest.
Since then, Talison has suspended production at its Wodgina mine in Australia, while Noventa’s Marropino operation in Mozambique has gone the same way. To put this into perspective, Wodgina has an annual nameplate capacity of nearly 600t of tantalum oxide, while Talison’s Greenbushes mine, also suspended, could add a further 450t. Little wonder then that the markets quickly fell into disarray once electronics manufacturers stopped buying new material and began running on their internal stocks.
For niobium, the leading producers are concentrated in Brazil and Canada with just three companies - Companhia Brasileira de Metalurgia e Mineração (CBMM), Anglo American and Iamgold Corp - dominating the market with a combined 85% share.
Iamgold’s Niobec mine in Québec produced some 4,400t of niobium as ferro-niobium in 2008, while Anglo’s Catalão de Goiás added a further 4,600t. These tonnages, however, are dwarfed by CBMM’s output, with the company having announced its intention to increase ferro-niobium capacity at its Araxá operations from 85,000 t/y in 2008 to 150,000 t/y by 2013. With standard-grade ferro-niobium containing around 66% niobium, this equates to a niobium capacity upgrade from 56,000 to 99,000 t/y.
Unlike many other metals, tantalum and niobium are sourced from two main ores: tantalite in the case of tantalum, and pyrochlore for niobium. Both are associated with igneous intrusive rocks, although tantalite is found in pegmatites, while the world’s pyrochlore deposits occur in alkaline intrusives – carbonatites.
Tantalite contains some niobium, with the mineral being referred to as niobite or columbite when the niobium content is greater than that of tantalum. Indeed, until the discovery of the world’s pyrochlore deposits in the 1950s, niobium was a by-product of tantalum mining, with increasing demand ensuring that it was highly valued and highly priced.
All of the world’s main tantalite mines are hosted in pegmatite ore bodies, including Wodgina, Greenbushes, Marropino and Bernic Lake in Canada. The Araxá and Niobec operations work carbonatite-hosted pyrochlore deposits, with CBMM reporting that reserves at Araxá alone are sufficient to satisfy world demand for some 500 years.
A word should also be made about coltan, the pariah of the global tantalite industry. Essentially mixed tantalite and columbite (the name stemming from the previous use of ‘columbium’ for niobium), the principal sources are found in pegmatite ore bodies in countries such as the Democratic Republic of Congo, Rwanda, Burundi and other central African countries. Concerned by the reported sale of illegally mined coltan to fund insurgent militias in the region, the world’s main tantalum and niobium users have embargoed its use since the turn of the century, with most sales apparently being made into China.
Despite its chemical properties of extreme durability, tensile strength and corrosion resistance, and its high melting temperature, tantalum is mainly used in the manufacture of electronic capacitors. Widely used in equipment such as mobile phones and laptops, tantalum-based capacitors have significant advantages over competitive materials in terms of their response times and light weight.
Other applications include the production of high-quality optical glass for camera lenses, in X-ray phosphors and in ink-jet cartridges as well as in more traditional products such as cutting tools and high-temperature alloys. Tantalum is also used in medicine in situations where bio-compatibility is essential, such as prosthetics and bone repair materials.
By far the greatest part of world niobium production ends up in high-strength, low-alloy and stainless steels, with the discovery in the 1950s that the addition of tiny amounts of niobium to carbon steel increases its strength and toughness characteristics having opened a major market for the metal.
End uses include the production of steels for gas pipelines, construction and the automotive industry, as well as high-specification alloys for aerospace, nuclear and turbine-blade applications.
CBMM recently reported an interesting new end-use, with a solid niobic acid catalyst included in the conversion of palm oil to bio-diesel. Given Brazil’s current enthusiasm for bio-fuels, this could indeed constitute a significant future market.
With existing producers more than capable of fulfilling market demand for the foreseeable future, there seems little prospect of any investment in new niobium mines. CBMM has already showed its capability to expand its existing operations, while Niobec has a reserve base adequate for at least ten more years and is increasing its own plant throughput. In its recent report on niobium, Roskill Information Services predicted that healthy demand growth will soon resume as end-users bring back suspended capacity.
For tantalum, the prognosis is markedly different. Roskill believes that recent mine closures have cut primary supply by some 40%, and that if demand begins to increase even modestly, there could be major supply shortfalls. That is not to say that there are no alternatives but they are being developed by junior companies that have struggled to raise funding over the past 18 months.
As Roskill points out, the leading contenders such as Gippsland’s Abu Dabbab project in Egypt are already years behind their original commissioning dates, while the suspension of Noventa’s Marropino mine in Mozambique has delayed development of the company’s Morrua deposit there.
While niobium producers can look forward to an assured future, recent oversupply is likely to overshadow the tantalum market for some time to come. Consumers are increasingly looking to scrap and secondary sources, while running on inventories. Until the next generation of producers can bring their operations on stream, playing the tantalum game will not be for the faint-hearted.