Abstract: A high-silicon low-grade bauxite ore in Guizhou contains 57.62% Al₂O₃，SiO₂ content is 9.54%， mole ratio of aluminum to silicon is 6.04. To high efficiently dissolve alumina， alumina dissolution by Lime Bayer Process test was conducted on bauxite ore. Results indicated that， with leaching temperature 265 ℃， leaching time 65 min， grinding particle size -0.074 mm content 90%， lime addition 1.4 according to mole ratio of calcium to silicon， slurry liquid to solid ratio 4， and agitation speed 500 r/min， the leaching index of alumina over 83% and red mud average aluminum to silicon ratio 1.33 were obtained. The test results can provide reference for the rational development and utilization of this kind of bauxite resources with low bauxite-silicon content.

Key words: Bauxite, Lime Bayer process, Red mud, Dissolution rate