Effect of microwave pre-treatment on the magnetic properties of iron ore and its implications on magnetic separation

The use of microwave heating is a potential means of energy savings and is a more effective alternative to the conventional thermal processing of minerals. The effect of microwave treatment on Egyptian iron ore samples was investigated. Changing the microwave exposure time and power as well as their reflection on the magnetic properties of iron ore before and after microwave pretreatment was analyzed using different techniques. Microwave treatment was found to be more efficient at larger particle sizes and longer exposure times for a fixed value of the applied power intensity. Magnetic separation of microwave treated and untreated iron ore indicated that iron recovery increased from 39.54% in the untreated sample to 97.95% in the microwave-treated sample. The results indicated that microwave radiation has a significant effect on the magnetic properties of hematite through the formation of new and more magnetic phases that facilitate their separation from non-magnetic minerals, thereby obtaining high recovery, reaching ca. 98%. (C) 2014 Elsevier B.V. All rights reserved.