Unlike banded iron hosted magnetite deposits (taconites) where the magnetite mineralization is finely disseminated in siliceous bedding planes, the Buena Vista ore is of magmatic origin and as a consequence is coarser grained in association with the siliceous host rock.
The prime benefit of this is that metallurgical test work has shown that the primary crush of the Buena Vista ore on average increases the mill grade to +45% irrespective of the primary ore grade. This is an important distinction to taconites and results in reduced energy usage for the subsequent crushing and grinding upgrade to the concentrate grade of +67.5%.
The Buena Vista concentrate contains no deleterious concentrations of impurities with silica typically 1.4-1.5%, alumina less than 1% and negligible sulphur and phosphorous content (around-0.003% respectively).
In addition titanium and vanadium levels are low in the Buena Vista concentrate, typical levels are around 0.2% TiO2 and 0.3% V.
Buena Vista Composite Concentrate -150 mesh (106 microns) (After GR Engineering 2011)
Surface grade distribution (2011 feasibility study)