Abstract: Addressing the issue of poor flotation desulfurization performance in a certain mine’s iron concentrate, process mineralogy research, laboratory small-scale tests, and industrial tests are conducted focusing on magnetic separation concentrate and iron concentrate. The process mineralogy analysis of magnetic separation concentrate reveals that sulfur primarily exists in the forms of pyrite and pyrrhotite, with pyrrhotite predominantly being monomeric and pyrite mainly being interconnected. The screening analysis of iron concentrate indicates that the flotation performance of coarse-grained sulfur-containing minerals during on-site production is suboptimal. Through small-scale tests, modification measures such as adding oxalic acid as an activator, segmented addition of collectors and frothers, and increasing the stirring speed are identified. The effectiveness of these measures is verified in industrial tests. The results of the industrial tests show that the technical modifications effectively reduces the content of sulfur-containing minerals in the coarse-grained iron concentrate, with the average sulfur content of iron concentrate across 19 shifts decreasing from 0.54% to 0.33%.