Mineralogical characteristics of a high-grade magnetite concentrate in Sichuan Province
Ultra-pure iron concentrate(w(TFe)≥72.0％) is widely used in the preparation of high-performance iron-based materials. Different analytical methods such as chemical analysis,X-ray fluorescence(XRF) analysis,laser particle size analysis,optical microscopy,scanning electron microscopy with X-ray energy dispersive spectroscopy(SEM-EDS) and mineral liberation analysis(MLA) were used to study the sample's chemical composition,mineral composition,mineral embedding characteristics and intergrowth relationships,mineral liberation degree and mineral isomorphous substitution. The results show that the TFe grade of the magnetite concentrate is 69.49％,with Al2O3 and SiO2 contents of 0.85％ and 1.95％,respectively. The primary iron-bearing mineral is magnetite,accounting for 94.69％,while the secondary iron-bearing minerals include hematite,siderite,ilmenite and pyrrhotite. Magnetite mainly occurs in subhedral or irregular granular forms,with a coarse grain size ranging from 0.02 mm to 0.30 mm,mostly as monomers with a liberation degree of 97.17％. Gangue minerals,primarily quartz,chlorite,mica and pyrrhotite have coarse grain sizes and low liberation degrees,requiring grinding in subsequent beneficiation. Pyrrhotite,which is similar in nature to magnetite,is difficult to separate,and its sulfur content negatively affects concentrate quality. Additionally,Fe-Al isomorphous substitution in magnetite makes Al difficult to remove by conventional physical separation methods. Magnetite contains 72.09％ Fe,theoretically meeting the conditions for producing ultra-pure iron concentrate.
magnetiteultra-pure iron concentrateprocess mineralogydisseminated characteristicliberation degree
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