Process mineralogy and characteristic associations of iron and phosphorus-based minerals on oolitic hematite

Abstract

The chemical compositions, mineralogical characteristics, as well as dissemination of iron- and phosphorus-based minerals were studied for the E’xi oolitic hematite from western Hubei Province in China by using chemical analysis, optical microscope, electron probe micro-analyzer (EPMA) and energy dispersive spectroscopy (EDS). It is found that this kind of oolitic hematite ore contains 47.71% TFe, 10.96% SiO2, as well as 0.874% P, with hematite as the dominant Fe-bearing minerals, and quartz, chamosite, illite and cellophane as main gangue minerals. The microscope examination showed that the ore has an oolitic structure, with some ooids principally formed by a series of concentric layers of hematite collophanite around nucleus that is hematite in the association with collophanite. Based on the EPMA and EDS analysis, it can be known that some ooids are primarily composed of hematite and collophanite. The separation can be achieved through fine grinding for those collophanite laminae with a higher P content. However, the dissemination of two minerals at the interface will result in the difficulty in effective separation. Besides, some ooids are made of chamosite with some nucleus formed of quartz, which is principally finely disseminated with hematite. In view of the close association and dissemination of iron- and phosphorus-based minerals in the ooids, it is found that the process of stage-grindings and stage-separations can be adopted to effectively increase the iron recovery and decrease the P content in the concentrate to some extent.