Abstract: The flotation recovery of tin minerals in copper tailings with a tin grade of 0.47% was investigated through an experiment conducted in Inner Mongolia. Cassiterite, the primary form of tin, predominantly occurred in the fine grain size range of −0.043+0.005 mm and exhibited significant recovery potential. In order to improve the flotation recovery rate of cassiterite, a novel combined collector named KDK−1, composed mainly of hydroxamic acid and synthesized in the laboratory, was employed for conducting flotation experiments on the tailings. The tailings were first deslimed, followed by sulfur removal and subsequent tin flotation processes. Using 120 g/t sodium hexametaphosphate as a regulator, 2000 g/t KDK−1 as a collector, 50 g/t PBL as an auxiliary collector, and 10 g/t pine oil as a frother, closed circuit flotation experiments using "one rougher−three cleaners−two scavengers" process resulted in a tin concentrate with a grade of 6.07% and a recovery rate of 73.10%. The combined collector has a good collection effect on cassiterite, which is better than ammonium butyrate black, and can efficiently recover tin resources in copper tailings. It also provides a reference for the efficient recovery of low−grade fine cassiterite and the development of new collectors in the future.