[China Aluminum Network] There are three kinds of alumina production methods: sintering method, Bayer method and joint method. According to China's production practice experience, different alumina production methods have different requirements for ore quality. The sintering method is suitable for the treatment of low-grade ores with high silicon content. The Al/Si ratio (Al2O3/SiO2) is required to be 3-5 and Fe2O3 is less than 10%. The Bayer process is suitable for the treatment of high ores with low Al2O3 and low SiO2, and generally requires Al2O3. >65% Al/Si ratio >7: The combined method is suitable for handling medium-grade bauxite. China's bauxite in the Al2O3 grade is generally 40 to 65%, aluminum to silicon ratio (Al2O3/SiO2) is generally 5 to 7, so in our country, the production of alumina using the joint method.