Beneficiation of iron ore fines by conventional flotation, flotation column and dual extraction column – A pilot scale study

Goa state in India is endowed with large deposits of low-grade iron ores, geologically formed from lower Dharwar super group of Archaean rocks. Petrological studies have revealed that silica and alumina are the main gangue minerals where alumina exists as fine clay and adherent material interspersed in the ore body and in some cases both silica and alumina interlocked with iron ore particles. Efficiency of conventional flotation, column flotation and dual extraction column for separation of gangue was studied on a pilot scale at Greater Ferromet Beneficiation Plant of M/s. Sociedade De Fomento Industrial Ltd., Goa. Reverse flotation process was adopted wherein gangue minerals silica and alumina were floated using cationic amine collector. Sodium hydroxide and starch were used to regulate the slurry pH and to depress iron ore, respectively. Various iron ore samples drawn from different mines and their mixtures were subjected to the test work. Results of pilot scale tests clearly indicate the superiority of flotation column vis-a-vis conventional cells and dual extraction column. Iron ore concentrate assaying 67 % Fe and 2 % Si02 and AI203 with a recovery of 85 - 90 % could be obtained by single stage flotation column operation.