Abstract: Apparent viscosity is a fundamental property of fluids and a crucial factor influencing particle motion behavior in gas-solid fluidized dry separation processes. The apparent viscosity of binary mixed heavy media formed by magnetite powder and coal powder with varying content was studied using the falling sphere method. Furthermore, separation experiments were conducted to explore the coal separation efficiency and effectiveness under different viscosity conditions. The results indicate that the apparent viscosity of the fluidized bed decreases as the mass fraction of magnetite powder in the binary mixed heavy media decreases, with an average reduction of 0.12 Pa·s for every 2% increase in coal powder content. As the operating gas velocity increases from 9.5 cm/s to 12.2 cm/s, the apparent viscosity drops by approximately 55%. Based on the experimental results, the apparent viscosity model for binary mixed heavy media was modified. At a constant bed density, differences in apparent viscosity exist under various operating conditions. An increase in apparent viscosity not only prolongs the settling time of coal particles of various sizes but also enlarges the potential deviation in separation. In summary, regulating the viscosity characteristics of binary heavy media during gas-solid fluidized bed separation can enhance separation effectiveness and efficiency, achieving efficient dry separation of minerals.