Valorisation of iron ore tailing piles: utilisation of element-to-mineral conversion and association index to building mineralogical modal

Abstract

ABSTRACT The objective of this study is to employ the Element-to-Mineral Conversion (EMC) method for determining the mineralogical modal distributions of tailings from iron ore processing plants. Initially, mineralogical studies were conducted by sampling tailing piles to identify textural characteristics and chemical composition in each size fraction. Utilizing the obtained data, the EMC method (HSC-Chemistry software-V.9) was employed to determine the mineralogical modal. The results reveal an increase in the grade of iron oxide minerals, especially magnetite, with decreasing particle size. The highest magnetite grade is associated with the size fraction of −250 + 106 microns (26%). The gangue minerals in the tailings consist of the diopside/calcite phase with an average grade of 35% and the garnet/quartz phase with an average grade of 26%, while pyrite and chalcopyrite are identified as minor minerals. The calculated values for the Association Index (AI) indicate that, in all size fractions, magnetite exhibits the highest interlocking with the diopside/calcite phase, followed by the garnet/quartz phase. The ratio of AI to grade suggests that, in the size range of +1 mm, magnetite is preferred over pyrite, chalcopyrite, chlorite, and tremolite phases. Calcite/diopside and quartz/garnet phases are preferred in all size fractions, with magnetite identified as an accompanying phase.