title: An active dealkalization of red mud with roasting and water leaching.
abstract: The research has focused on the dealkalization of red mud after active roasting and water leaching, which is obtained from bauxite during alumina production. The main factors such as roasting temperature, roasting time, water leaching stage, leaching temperature, leaching reaction time and liquid to solid ratio were investigated. The mechanism of dealkalization was in-depth studied by using ICP-AES, XRD, TG-DSC, SEM-EDS and leaching kinetic. The results show that the dealkalization rate reached 82% under the condition of roasting temperature of 700 °C, roasting time of 30 min, four stage water leaching, liquid to solid ratio of 7 mL/g, leaching temperature of 90 °C and reaction time of 60 min. The diffraction peak of Na6CaAl6Si6(CO3)O24 · 2H2O in red mud was decreased during the active roasting process, whereas the mineral phases of NaOH · H2O and Na2Ca(CO3)2 were appeared. The content of alkali obviously decreased and the grade of other elements increased during the process of active roasting and water leaching, which was in favor of next application process of red mud. The water leaching was controlled by internal diffusion of SCM and the apparent activation energy was 22.63 kJ/mol.
authors.affiliation: School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China; Henan Key Discipline Open Laboratory of Mining Engineering Materials, Henan 454000, China. Electronic address: zhuxiaobo0119@126.com.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhu
authors.affiliation: School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China; Henan Key Discipline Open Laboratory of Mining Engineering Materials, Henan 454000, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China; Henan Key Discipline Open Laboratory of Mining Engineering Materials, Henan 454000, China.
authors.forename: Xuemao
authors.initials: X
authors.lastname: Guan
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002681:China; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis; D007501:Iron; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008903:Minerals; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014873:Water Pollutants / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: D007220:Industrial Waste; D008903:Minerals; D014873:Water Pollutants; D014867:Water; D007501:Iron; D000537:Aluminum Oxide
keywords: Active roasting; Dealkalization; Leaching kinetic; Red mud; Water leaching