Abstract: The high sulfur content in some batches of iron concentrate in Jianshan Iron Mine not only seriously affects the product quality，but also causes environmental pollution. In order to effectively control the sulfur content in iron concentrate powder，the occurrence state and process mineralogical properties of sulfur in Jianshan iron ores are systematically studied by means of electron probe，scanning electron micro⁃ scope and automatic quantitative analysis of minerals.The results show that the sulfides in iron ore are main⁃ ly in four types: disseminated，banded，fine veined and agglomerated，mainly pyrite，with a small amount of chalcopyrite and trace pyrrhotite. Some sulfides are in contact with or enwrapped with magnetite minerals. Most of the sulfur-containing minerals in the beneficiation process products are pyrite，with trace chalcopy⁃ rite and few other minerals. The monomer dissociation degree of sulfides is relatively high，and the sulfides entering the iron concentrate products are mainly produced in the form of monomers. The minerals most closely embedded with sulfides are magnetite，followed by quartz，hornblende，chlorite，etc.In each stage of the beneficiation process，the dissociation degree of sulfide in the concentrate product tends to increase，and the proportion of sulfide and magnetite intergrowth is high，showing a close relationship，while the propor⁃ tion of non-metallic minerals such as quartz gradually decreases. It shows that the embedded minerals such as quartz can be well removed by the beneficiation process，while it is difficult to effectively remove the mag⁃ netite intergrowth.

Key words: Jianshan iron ores, sulfide, dissociation degree, mineral parameters, automatic analysis system