The Blaine number is a measure of specific surface area derived from a material’s air permeability. It was originally developed for the cement and aggregates industry to quantify a powder’s fineness which has implications for Portland cement’s key characteristics. It has long been borrowed by the iron ore industry as this same measure of fineness has equally relevant implications for the filtering and sintering of iron concentrate during the pelletisation process. To this day, the industry utilises particle size (cumulative % passing 45 µm) as the prevailing factor that determines a concentrate’s Blaine number and the effects of feed characteristics and mineralogy has been given little consideration.