Abstract:Alkaline leaching conditions of niobium-rich red mud from Bayer Process were investigated. The effects of particle size of red mud, KOH concentration, leaching temperature, and L/S on niobium leaching rate were investigated. The results show that niobium leaching rate is 85% above under the optimum conditions including particle size of -80 μm, KOH concentration of 6 mol/L, reaction temperature of 260 ℃, and L/S=6︰1. Leaching process of niobium by alkaline corresponds with model of contractibility and unreacted core is controlled by solid-membrane diffusion process.