SEIS LAGOS THE LARGEST NIOBIUM RESERVE IN THE WORLD IS STILL WAITING TO BE DEVELOPED
By Pedro Jacobi
In the middle of the Amazon, 60km away from the Venezuelan border and 2km from a local road is the location of the largest Niobium deposit on the Earth.
It is called Seis Lagos and, believe it or not, is still waiting for the Brazilian Government’s decision to let miners extract and redistribute its enourmous wealth.
In 1975, during a geological mapping program, CPRM's geologists discovered the remarkable structures of Seis Lagos Alkaline Complex intruded in gneissic terrain. It comprises three different intrusive bodies.
Seis Lagos Property at the Amazonas State is the world’s largest niobium reserve of 2,897Mt @ 2.81% Nb2O5 or 81Mt of Nb2O5 and, possibly, a very large titanium and rare earths deposit.
click the picture to enlarge
The company that acquires this property will be in a position to control the largest niobium reserves in the world, and, likely become the main player in a very important, fast growing, industrial mineral market.
The element niobium (Nb), also named columbium, was discovered in 1802. Niobium is quite abundant in nature being present in the earth’s crust at the level of 24ppm. Its fusion point is high at 2468oC.
Due to its favourable high-temperature strength and good low temperature ductility, niobium has been used as a prime material for the aerospace industries.
This metal is mostly used in special steels, microalloys and superalloys, automobile industry, nuclear reactors, catalizers, acoustics, electrooptics, high temperature applications, glass manufacture and superconductors. It is a versatile element which is considered to be the best way of accomplishing many technological goals in a most cost effective way. Modern niobium technology is replacing the use of several metals such as molybdenum, vanadium, nickel, chromium, copper and titanium in many industrial applications.
CBMM’s main product is the iron-niobium (65%Nb) alloy which is used as an important element in the high-strength low alloy steels, stainless steels and niobium pentoxide. Metallic niobium is used together the titanium in a NbTi alloy which is used in an important superconductor material.
Pyrochlore (A2-mB2O6(O,OH,F)1-n.pH2O), probably the most abundant niobium mineral, has a extremely variable composition and occurs mainly in carbonatites. The pyrochlore group also includes betafite (2Ti>Nb+Ta), microlite (Nb+Ta>2Ti) and bariumpyrochlore which is the ore mineral at Araxá. Columbite is the second most important mineral of niobium and is, mainly, associated to pegmatites and tin bearing granites.
THE HOST ROCKS
Carbonatites are specialised intrusive magmatic rocks which are important sources of niobium, rare earths, titanium, copper, vermiculite and phosphates.
In Brazil the extremely high grades of niobium and titanium in the deposits is a result of an intense leaching of the carbonatite which caused a well developed lateritic profile that can be as deep as 300m.
Total world reserves of Nb2O5 are estimated at 5.4Mt (excluding the Seis Lagos deposit) being 88% in Brazilian soil.
Known ore reserves, at the most important producing mines, are 464Mt @ 2.5% Nb2O5 at Araxá (Brazil) and 16Mt @ 0.68% Nb2O5 at St-Honoré (Canada). Other niobium resources are reported from Tapira (179Mt @ 0.67% Nb2O5), Catalão (1.4Mt @ 2.19% Nb2O5) and Salitre (Brazil), Lueshe Lake, Panda Hill, Chilwa Island and Kalubwe (Africa), James Bay, Nemegosenda, Lackner Lake, Oka (6.3Mt @ 0.32% Nb2O5) and Manitou Island in Canada.
The St Honoré carbonatite complex (Cambior) hosts the most important niobium mine outside Brazil. This is an underground deposit of low grade (0.67% Nb2O5 ) where mining is executed by means of open stope and pillar. The mine depth surpasses 400m.
On the other hand, on the Araxá deposit, which belongs to CBMM, and combines the world’s largest reserve (excluding Seis Lagos) and highest grade (2.5% Nb2O5) , the ore is mined by open pit methods.
In Brazil, due to the deep weathering of the carbonatite, blasting is not required and mining costs are much lower than Canada.
Brazil has a leading position in technological development of special niobium alloys. The ore, at Araxá, is crushed, concentrated through grinding, magnetic separation, desliming and flotation to 60% Nb2O5 . The flotation concentrates are then treated in a calcining and leaching plant. The standard ferroniobium is produced by means of a new metallurgical process improved by CBMM, the aluminothermic reduction.
The Niobium price is been stable around 3-7US$/pound as can be seen on the graph.
There are more than 300 smelters world wide that use niobium in their production:
The main buyers of CBMM’s production are Nippon Steel, Mannesman (Germany), Ilva Spa (Italy), LVT steel (US), Usiminas, Cosipa and Gerdau.
Cambior (Canada) sells to Canada, US and Japan. while Mineração Catalão (Anglo American Corporation) sales are directed mostly to US and Germany.
FUTURE TRENDS AND USES
Niobium has been promoted, during the last 20 years into a very important component of the world steel industry. Forecasters are predicting that the consumption will continue growing at the rate of 8-10%.
SEIS LAGOS, THE LARGEST RESOURCE
In 1975, during a geological mapping programme CPRM’s geologists discovered the remarkable structures of Seis Lagos Alkaline Complex intruded in gneissic terrain. It comprises three different intrusive bodies. Only in 1982 that company started a detailed exploration programme.
The main carbonatite is an outstanding topographic feature which stands 300m above the local surface (see picture).
Seis Lagos main structure has a 5km diameter and is situated at the São Gabriel da Cachoeira municipality at the Amazonas State, only 60km away from the Venezuelan border and 2km from a local road. Seis Lagos is 97km from S. Gabriel port by the Negro River 900km upstream from Manaus.
The carbonatite is, also, characterized by its strong thorium anomaly which peaks at 35.344cps against a 1.300cps local background.
An intense supergene leaching process developed a 250m deep weathering profile. This is the main reason why this deposit is so rich in niobium (2.81% Nb2O5), titanium and rare earths.
At Seis Lagos the niobium is present in minerals such as niobium-rutile and niobium-brookite together with florencite and crandalite (rare earths).
This unusual mineralogy is a result of the destruction of pyrochlore during the supergene process causing the free niobium to combine with oxigen, forming these oxides. Niobium may be, also, in the structure of other supergene minerals such as goethite and hematite.
Technological studies have been made by CPRM and, apparently, the ore is amenable to treatment using known technology. A technical report done by INBRACEL confirms that the use of SAM for direct reduction of Seis Lagos ore will allow the introduction of niobium in common low carbon steels, at a very low price, which may change all the economicity of this metal.
Reserves, calculated by CPRM, after a preliminary drilling programme, are listed below.
Since niobium is associated to titanium it is possible that titanium reserves may be as large as the niobium ones.
CBMM, THE LARGEST PRODUCER
CBMM is the leading niobium producer of the world and is controlled by the, Brasil Warrant Adm. De Bens e Empresas LTDA (Moreira Salles Group) with 55% and Molybdenum Corporation (Molycorp) with 45%.
CBMM produces about 65% of the world’s market and 100% of the Brazilian market with annual sales amounting to $150M. This is one of the most profitable mining companies in Brazil today.
ABREU, Sylvio Fróes - Recursos Minerais do Brasil, Vol. II, EUSP, Ed. Edgar Blücher Ltda., São Paulo, 1973.
NIOBIUM : proceedings of the International Symposium - International Simposium, Niobium’81, Edited by Harry Stuart, New York, 1984.
CBMM : O Mercado do Nióbio e suas Características, 1985.
ROSKILL Information Services - The Economics of Niobium, fourth edition, London 1983
Revista - Minérios Minerales Extração & Processamento, Ano 18, nº 210, April 1996
ALVES, Benedito Paulo - Distrito Nióbio-Titanífero de Tapira, Boletim nº 108, Ministério da Agricultura, Rio de Janeiro, 1960.
GUIMARÃES, Djalma - Relatório sobre a Jazida de Pirocloro de Barreiro, Araxá, Minas Gerais, Boletim nº 103, Ministério da Agricultura, Belo Horizonte, 1957.
PENA, Fernando Ernesto - Perfil Analítico do Pirocloro (nióbio), Boletim nº 18, Ministério das Minas e Energia, DNPM, Brasília, 1989.
seis lagos ---> 4480
seis lagos ---> 4480
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