Two significant niobium deposits have been defined to date and are named Boa Vista and Morro de Padre deposits. These deposits are hosts by igneous rocks which occur as swarms of thin dikes, forming a stockwork of crosscutting dikes in the upper zone and varying to individual mineralised thicker dikes at depth.

Niobium mineralisation is associated with nelsonite vein which vary in thickness and orientation forming stock work style deposits. Containing magnetite-apatite-carbonate composition economic mineralisation is exclusively associated with the mineral pyrochlore. The nelsonite veins are hosted within a variety of pre-existing lithologies including amphibolite and fenite, a metasomatically altered rock believed to originally comprise phyllite. Phlogopite alteration may also be associated with the carbonatite veins, where it commonly occurs as haloes surrounding the veins and overprinting the fenite. To a lesser extent phlogopite occurs as selvages to the nelsonite veins.

Both the Boa Vista and Morro de Padre deposits occur as pipe-like bodies consisting of sub vertical major feeder structures that permit vertical passage of the deep-seated carbonatite magmas to shallower depths where the dykes split into a complex stockwork of veins and veinlets. The stockwork zones are approximately 270m (N-S) by 350m (E-W) and are considered to be a result of magma degassing in response to reducing confining pressures and the formation of multiple sets of tensional fractures by the expanding gas exsolving from the ascending magma. A direct consequence of this model is the higher density of veins close to the central feeder zones, with decreasing vein abundance with increasing distance from the feeder zones. The vertical extent over which niobium mineralisation has been identified to a depth approximately 600m, however the drilling density is significantly higher in Boa Vista.

The niobium ore from the Boa Vista mine is mined using conventional open-pit mining methods in multiple benches in a confined mine. Operations commence with waste stripping, or the removal of the organic waste soil layer, which covers the economically viable ore to be explored. It is carried out by backhoe loaders, which remove the material and load the waste onto the trucks, which transport and unload the material in the waste dump. The Boa Vista LOM schedule was developed targeting an approximate ore production rate of 2Mtpa, and the mine is expected to be depleted in 2028.

The mined niobium ore is processed in two plants, being the BV plant and the BVFR plant. The BV plant, which processes oxidized ore from the Boa Vista mine, will later be modified to handle material from Mina II and I. The second, recently constructed, plant is the BVFR plant, which processes fresh rock ore from the Boa Vista mine. In addition, there is the Tailings Plant which treats the phosphate plant tailings to produce a niobium concentrate. The niobium concentrate from all three plants are further processed through an alkaline and acid leaching process to remove other impurities. The leached products are combined and sent to the kiln in order to remove water. The last stage of the niobium processing circuit is an aluminothermic reaction by batch that produces a ferroniobium alloy with a grade of 65% Nb, in conformity with international standards.

The BVFR plant was recently brought online with completion of construction in November 2014. It is expected to add concentrate capacity of 8.6ktpa of Nb2 O5 , increasing total Nb production capacity to 9.0ktpa Nb later in 2016, combined with debottlenecking and scalping activities now in ramp-up.

The investment in constructing the BVFR plant totaled approximately USD380 million. In 2011, construction commenced and in 2014 construction was completed, and trial operation was commissioned in November of the same year. The BVFR plant mainly covers the following processing steps: crushing, scalping, concentration, leaching and smelting. The plant processes and handles the fresh rock from Boa Vista mine.

The BV plant is expected to have processing capacity of 600ktpa ore and production capacity of 2.7ktpa pure Nb2 O5 with concentrate grade of 55%. The BV plant currently processes oxidized ore from the Boa Vista mine, and is expected to be modified to process ore from Mina II starting in 2019. Ore undergoes crushing, scalping, homogenization and grinding before reaching the concentration stage, where desliming, silica flotation, carbonate flotation, magnetic separation and niobium flotation are performed. Acid leaching and alkaline leaching are used to reduce phosphates content.

The Tailings Plant is expected to have processing capacity of 1.1Mtpa ore and production capacity of 2.3ktpa pure Nb2 O5 with concentrate grade of 44%. The apatite flotation tailing from phosphates plants is used as feeds, which then undergoes classification, magnetic separation, grinding, desliming, silica flotation, niobium flotation at the Tailings Plant. Pyrochrore concentrate is produced and sent to a leaching step located in the BV plant.

The leaching products from all the three plants (BV, BVFR and Tailings) come together and are sent to the calcining stage. The main objective of calcination is to remove the crystalized water associated with some minerals and drying the concentrate for pyrometallurgy.

At the pyrometallurgy stage, the product of calcination undergoes aluminothermic reactions. The final concentrate is mixed with fine aluminium and other inputs, then discharged into the crucible, which is then lit and the reaction occurs. After the reaction, the crucible is transferred to the slag tapping area, then the
cooling area, and the alloy button is removed.

The resulting FeNb alloy moves to the alloy crushing stage, composed of jaw crushers and screeners for classification of the material according to particle size, which will be packed in line with client specifications.