Abstract: To fully understand the ore properties of a certain lean and impure iron ore and facilitate the determination of a reasonable beneficiation process，chemical multi-element analysis，MLA and other techniques were employed to systematically investigate the mineral composition，dissemination characteris⁃ tics，particle size distribution，as well as the monomer dissociation degree and intergrowth relationships of the major minerals. The results show that the ore is a low phosphorus，sulfur bearing，single acidic，medi⁃ um grade primary magnetite ore，with an iron grade of only 32.80% and a SiO₂ content of 43.38%，which is the main gangue component to be removed. The ore exhibits disseminated or disseminated banded struc⁃ tures. The iron mineral is predominantly magnetite (accounting for 35.92% of the total minerals)，occasion⁃ ally with sporadic hematite and limonite；sulfide minerals are present in low contents，and the gangue min⁃ erals are mainly quartz，amphibole and mica. Magnetite is disseminated in the gangue in dense，moderate⁃ ly dense to sparse scattered forms or as disseminated bands，with a grain size generally ranging from 0.005 to 0.3 mm. It is mainly embedded along the edges and intergranular spaces of amphibole，mica and chlorite，which favours liberation；therefore，the grinding fineness can be appropriately coarsened based on -0.019 mm. At grinding finenesses of -0.074 mm 85%，-0.043 mm 75% and -0.038 mm 90%，the combined distribution rates of iron mineral monomers and rich intergrowths reach 87.55%，91.38% and 97.23%，respectively. The main intergrown minerals are quartz，amphibole，mica and chlorite，followed by feldspar，pyrrhotite and apatite. These findings provide a systematic fundamental basis for determining the beneficiation process for this ore.

Key words: magnetite, process mineralogy, monomer dissociation degree