Cement Preparation By Using Red Mud After Calcification-Carbonization Treatment

With the rapid development of aluminum industry,bauxite grade reduces year by year and the discharge amount of red mud continue to increase,which causes great harm to the environment.At present,the comprehensive utilization of red mud has become a worldwide problem.In this paper,the preparation process of Portland cement and aluminoferic cement produced from calcification-carbonization red mud was studied.The main research contents and results are as follows:(1)The mineralogical analysis shows that the main mineral phases of calcification-carbonization red mud are calcium carbonate,silicate,ferric oxide,and a small amount of almandine.The chemical composition of calcification-carbonization red mud is similar to that of cement raw materials.It is suitable for cement preparation from the perspective of composition.(2)According to the composition of calcification-carbonization red mud,pure substance is used to prepare cement and eventually the appropriate material proportion is 66.28%CaO,22.52%SiO2,6.15%Al2O3 and 3.56%Fe2O3.The materials were calcined and kept at 1500? for 1 h.Quenching cooling was performed and the clinker was ground until the specific surface area reaches 350 m2/kg.The prepared clinker basically achieves the strength requirement of national 525 grade cement.(3)Based on the research of pure material synthesis,the calcification-carbonation red mud was used as raw materials to prepare cement.The raw materials were blended in the proportion of 66.33%CaO,22.66%SiO2,5.33%Al2O3 and 3.71%Fe2O3.The materials were calcined at 1450?,kept for 1 h,air cooled and ground to the specific surface area of 264 m2/kg.The strength of clinker is more than 425 cement,very close to the strength of 525 cement.The additive proportion of red mud can reach 42.37%,increased by 20%compared with the current method.(4)Finally,an exploratory study on the preparation of aluminoferic cement cement with calcification-carbonization red mud was conducted.It can be found that in the compositions of 43.2%CaO,10.47%SiO2,26.8%Al2O3,7.9%Fe2O3,8.4%SO3 and under the conditions of calcination temperature 1300?,holding time 1 h,air cooled,and specific surface area 228 m2/kg,the strength of clinker achieves the requirement of national 325 grade cement and the additive proportion of red mud reaches 65%.