Relevance of geological aspects and ore mineralogy in selecting beneficiation methods for processing of eastern Indian iron ores

Abstract

Geological aspects, particularly mineralogy and ore genesis of different iron ores have important roles to play in understanding their behaviour during processing and decide suitable beneficiation method for particular type of ore so to produce desired quality end products. The implications of different geological aspects and mineralogical characteristics specific to ore types in mineral beneficiation have been outlined in this paper. Experiments indicated that iron ores, such as massive hard ores, laminated hard ores, fine powdery ore and blue dust ore, do not require complicated processing, however at the other end; sub grade ores, such as flaky, friable, shaly, ochrous, powdery, lateritic and goethitic ores having low iron and high alumina content, require specific beneficiation treatments before their use as direct or as agglomerates in the blast furnace feed. While processing, different ore types need treatment differently for their up gradation. Hence, in addition to the conventional methods of processing such as crushing, screening and washing, advanced beneficiation techniques using concepts of gravity and magnetic separation have found their specific applications for beneficiation of different types of ores, based upon their physicochemical and mineralogical characteristics. Geological setup of the deposits and mode of occurrences of different ore types, physical, chemical and mineralogical characterisation and extensive beneficiation experiments conducted on Indian iron ores have established that quality of lumps can substantially be up graded through simple processing and log washing. On the other hand, for fines ores, Jigging has been found to be the best suitable method. Slime beneficiation requires combination of processes and treatment through hydrocyclones, multigravity separation, magnetic separation and sink float methods, etc. These applications would help not only to recover more values from the inferior grades of iron ores but also to conserve and preserve the natural resources too.