Niobec Niobium Mine, Quebec

The Niobec Niobium mine is located in the municipality of Saint-Honore in Quebec. The site is situated 25km northwest of the Saguenay region. It is spread over 1,735ha and owned by IAMGOLD, a mining and exploration company.

The underground mine started commercial production of niobium pentoxide in 1976. It is one of the major sources of niobium in the world and North America’s only source of pyrochlore. It currently produces around 7%-8% of the niobium used globally.

In 2005, a new head frame and shaft were developed at the mine to increase its production capacity. In the third quarter of 2010, a paste backfill was constructed at the mine.

Expansion of the niobium mine

The company undetook a prefeasibility study in early 2012 and will continue with a feasibility study for the block caving mining method. It is expected to complete by mid-2013.

It is hoped that the block caving mining method will triple the reserve base of niobium production. The new processing facility will begin its operation in 2016 or 2017.

Geology and mineralisation

The Niobec deposit stretches into the southern part of the Saint-Honore carbonatite, which is located in the Grenville structural province of the Canadian Shield. The Grenville province is subdivided into three different litho-structural units, which include a gneiss complex, charnokite-magnerite batholiths and calc-alkaline intrusions.

The St- Honoré alkaline complex is covered with Trenton limestone. It contains a series of crescentic lenses of carbonate and the compositions are enhanced from calcitite through dolomitite to ferrocarbonatite. The complex is surrounded with magnetite diorite and hypersthene syenite.

Carbonate is an igneous rock which contains a minimum of 50% carbonate minerals. Reserves of some of the leading carbonate minerals are falling rapidly.

Open stoping underground mining method

The Niobec mine comprises of a headframe, a niobium pentoxide (Nb2O5) concentrator, a concentrate-to-ferroniobium converter, and ancillary surface installations.

Earlier, the mine used open stoping underground method, where stopes were designed and planned depending on the availability of geological information.

Each stope is about 200ft long, 80ft wide and 300ft in height. The dimensions vary with the distance between the development and production levels.

Explosives are placed in 6.5in diameter vertical holes drilled through the stopes, and blasted. The ore gets collected in the lowest level of the stopes. The collected ore is extracted and transported.

The transported ore is compressed up to a diameter of 3.5in before it is transferred to the concentration plant.

Paste backfill is used to increase the ore grade material and thus the quantity of reserves, thereby increasing resources from the same ore volume.

Processes for the extraction of niobium pentoxide

The extraction of pyrochlore concentrate involves a series of steps beginning with crushing and grinding of the ore in a crusher and roll ball mill. It is followed by a series of processing methods using 15 varieties of chemicals. The processing techniques include flotation, leaching, filtering and drying. The extracted pyrochlore concentrate contains 58% of niobium pentoxide.

Approximately 35,000kg of chemicals and around 6,700 gallons of water are being used to produce 30,000kg of concentrate daily. The concentrator currently has a capacity of 2.2mtpa.

The niobium concentrate is converted into ferroniobium with the help of an aluminothermic reaction in batch processing.

Production and further exploration

In 2009, the mine’s niobium mineral was increased by 32%, to 181.3mkg (199,849t) of niobium pentoxide. The increase in production was a result of infill drilling that increased the indicated mineral resources in blocks 5 and 6.

The company plans to further concentrate on infill drilling to convert more resources in the mining area into reserves.