Mineralogical Characterization of Iron Ores

Abstract

Mineralogical characterization of iron ore is a very important and basic aspect that has to get due attention before any attempt for its processing and has become almost inevitable these days because of the increasing demand of the ore. Mineral processing technology is evol-ved to separate and recover ore minerals from gangue in a commercially viable method and is mainly based on the process of mineral liberation and the process of mineral separation. Therefore, it is important to first get a clear understanding about ore- and gangue minerals. A mineral is a natural inorganic substance having definite chemical composition and atomic structure. If the internal atomic arrangement is lacking, then it is an amorphous substance. A rock is generally composed of various mine-rals and if the rock contains valuable minerals from which metals can be extracted at a profit, it is called n 'ore'. The unwanted mineral in an ore is called gangue (i.e., generally rock forming minerals). For example, hematite (Fe203) and magnetite (Fe304) are oxides of iron and are ore forming minerals. In iron-ore, these minerals gene-rally dominate but other unwanted minerals that occur are quartz (Si02), kaolinite (clay) etc., are gangue minerals. The terminologies `ore' and 'gangue' are subjective. For example in a mine, when the ore/rock is mined with an objective to extract iron, hematite is the desired mineral and is called ore. The same mineral hematite if found in a sulfide ore (that is being mined to extract Pb, Zn or Cu) is called gangue. Therefore, `ore' and `gangue' terminologies can broadly be assumed as the desired and `undesired' material in a rock mass respectively. Even though ore is mined with the highest efficiency of the technology, the excavated ore gets partly contaminated by the surrounding host rock (overburden) and the geol-ogical material closely associated with the ore during mining. Both the materials are undesirable and hence form the gangue.