Abstract

Vanadium mineralization occurs in oxide-rich horizons within the layered gabbro zones of the upper parts of the Bell River Complex, Matagami, Quebec and the Lac Dore Complex, Chibougamau, Quebec. The vanadium-rich horizons are well defined on the ground and in aeromagnetic surveys by their high magnetic susceptibility; consequently, magnetic susceptibility can be an indicator of vanadium mineralization. The main oxide minerals are ilmenite and titanian magnetite, containing 20% to 70% of volume and the ratio of titanian magnetite to ilmenite is relatively constant, ranging from about 1:1 to 2:1. Their sizes are less than 5 mu m to greater than 1 mm to 2 mm, occurring as coarse- to medium-grained subhedral crystals intergrown with cumulate silicate minerals (plagioclase, pyroxene, etc.). Electron microprobe analyses indicate that the ilmenite grains are mineralogically and compositionally homogeneous and have low V contents (average 0.18% equivalent V 2 O 5 ). In contrast, the titanian magnetite grains are inhomogeneous, consisting of trellisworks of ilmenite lamellae in Ti-poor, V-rich magnetite [less than 2 wt% TiO 2 , and 1.41% equiv. V 2 O 5 (1.16% V 2 O 3 ) for 20 analyses]. Thus, the magnetite is the principal ore mineral of vanadium; it hosts vanadium in the form of V (super 3+) , not V (super 5+) , as is commonly and erroneously reported. We have also devised a flowchart for the beneficiation of vanadium-titanium ores.

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