Abstract: Taking the third-stage magnetic separation concentrate obtained by the suspension roast⁃ ing-magnetic separation process in the concentrator of Jiuquan Iron and Steel Co.，Ltd. as the research ob⁃ ject，the process mineralogy characteristics were systematically analyzed by means of chemical analysis， optical microscopic observation，automatic mineral analysis，X-ray diffraction（XRD）and infrared spec⁃ troscopy（FTIR）. The results show that the iron grade of the roasted magnetic concentrate is 53.62%，and the iron element mainly exists in magnetite and roasted siderite. The monomer dissociation rate of magne⁃ tite/hematite is 39.14%，which shows the characteristics of wide distribution of fine particles and complex embedding relationship. As the main gangue mineral，quartz is mostly produced in the form of granular ag⁃ gregates and is closely associated with iron minerals. In the +0.038 mm fraction，iron minerals and quartz form a complex symbiotic structure，which hinders the effective adsorption of beneficiation reagents on the mineral surface，resulting in difficult surface modification. In the −0.038 mm fraction，although the disso⁃ ciation degree of iron minerals is high，the ultrafine particles are easily entrained by flotation foam due to the increase of surface energy，resulting in metal loss and affecting the separation index.

Key words: roasted magnetic concentrate, process mineralogy, dissociation