Recovery Improvement of Fine Iron Ore Particles by Multi Gravity Separation

ABSTRACT

Conventional gravity separation process of iron mineral fines is not very effective. In present work Multi Gravity Separation (MGS) process has been studied. This study was performed on a low-grade iron ore namely goethiticlateritic ore (GLO) from Eastern India. Detailed mineralogical, physical and chemical characteristics of a goethiticlateritic iron ore showed that the sample contained porous and friable oxides and hydroxides of iron. The ore sample had a feed grade of 54.43% total Fe, 9.27% SiO2 and 8.02% Al2O3. Hematite and goethite are main iron-bearing minerals while kaolinite and gibbsite are the major gangue mineral constituents. Considering the characterization data, these ores were ground separately to three size fractions, namely -300 μm, -250 μm and -150 μm sizes and subjected to flowing film concentration in Wilfley Table. As revealed by the liberation study, higher concentration was obtained by the processing of -150 μm crushed sample. The grade of the ore was improved from 54.43% Fe to 65.71% Fe. However, significant amount of fine iron ore particles were lost during the processing of -150 μm size ore, because it is not very effective for particles less than 15 μm. Thus, fine hematite and goethite particles are usually not recovered resulting in the loss of valuable iron ore fines. To recover this fine, Multi Gravity Separator was used in place of Wilfley Table and was found to be effective in reducing loss of fine iron particles and increasing the grade of the concentrate. The MGS process improved the Fe from 54.43% to 66.5% along with decreasing the alumina from 8.02% to 1.17%.

Keywords:

Comminution, fine particle processing, multi gravity separator, gravity concentration, grinding, liberation.