Suspension calcination and alkali leaching of low-grade high-sulfur bauxite:Desulfurization, mineralogical evolution and desilication  

作　　者：Hong-fei Wu Jun-qi Li Chao-yi Chen Fei-long Xia Zhen-shan Xie 

机构地区：[1]Department of Metallurgical Engineering,College of Materials and Metallurgy,Guizhou University,Guiyang 550025,China [2]Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving,Guiyang 550025,China

出　　处：《International Journal of Minerals,Metallurgy and Materials》2020年第5期602-610,共9页矿物冶金与材料学报（英文版）

基　　金：This work was financially supported by the National Natural Science Foundation of China(Nos.U1812402,51664005,and 51774102);Talents of Guizhou Science and Technology Cooperation Platform(Talent Team Giant[2015]4005,Platform Talent[2017]5788,[2017]5626,and KY(2015)334).

摘　　要：To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.

关 键 词：LOW-GRADE BAUXITE sulfur SUSPENSION CALCINATION ALKALI-SOLUBLE DESILICATION Bayer process 

分 类 号：TQ133.1[化学工程—无机化工]