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A new process for Al2O3 production from low-grade diasporic bauxite based on reactive silica dissolution and stabilization in NaOH-NaAl(OH)4 media
Alternative TitleAiche J.
Ma, Jiayu; Li, Zhibao; Xiao, Qinggui
2012-07-01
Source PublicationAICHE JOURNAL
ISSN0001-1541
Volume58Issue:7Pages:2180-2191
AbstractA new process of Al2O3 production from low-grade diasporic bauxite based on the reactive silica dissolution and stabilization in concentrated NaOH-NaAl(OH)4 solutions is proposed and proved feasible. NaOH and Al2O3 concentrations and leaching temperature were found to be the main factors affecting the leaching process of reactive silica. The A/S (mass ratio of Al2O3/SiO2) of diasporic bauxite was enhanced from 5.4 to 15 by reactive silica removal under the optimum operation conditions. Two obvious steps control the whole leaching process of reactive silica in NaOH-NaAl(OH)4 media: reactive silica dissolution and desilication products (DSPs) precipitation. The kinetics data of two controlling steps fit a shrinking core model based on the calculation of OH- activity with the aid of OLI platform and an empirical kinetic model well, respectively. Apparent activation energies of reactive silica leaching in the temperature range from 80 to 110 degrees C are 101.91 and 58.65 kJ mol-1 for the two steps, respectively. The stabilization mechanism of reactive silica in concentrated NaOH-NaAl(OH)4 solution was also elucidated based on the complexation of aluminum-bearing species and the calculation of supersaturation to DSP. It was found that the concentration of OH- sharply decreases due to the formation of Al(OH)?4- species with increasing aluminum concentration, suppressing greatly DSP precipitation. This proposed process paves the way for Al2O3 production from low-grade diasporic bauxite with high-reactive silica content. (C) 2011 American Institute of Chemical Engineers AIChE J, 2012; A new process of Al2O3 production from low-grade diasporic bauxite based on the reactive silica dissolution and stabilization in concentrated NaOH-NaAl(OH)4 solutions is proposed and proved feasible. NaOH and Al2O3 concentrations and leaching temperature were found to be the main factors affecting the leaching process of reactive silica. The A/S (mass ratio of Al2O3/SiO2) of diasporic bauxite was enhanced from 5.4 to 15 by reactive silica removal under the optimum operation conditions. Two obvious steps control the whole leaching process of reactive silica in NaOH-NaAl(OH)4 media: reactive silica dissolution and desilication products (DSPs) precipitation. The kinetics data of two controlling steps fit a shrinking core model based on the calculation of OH- activity with the aid of OLI platform and an empirical kinetic model well, respectively. Apparent activation energies of reactive silica leaching in the temperature range from 80 to 110 degrees C are 101.91 and 58.65 kJ mol-1 for the two steps, respectively. The stabilization mechanism of reactive silica in concentrated NaOH-NaAl(OH)4 solution was also elucidated based on the complexation of aluminum-bearing species and the calculation of supersaturation to DSP. It was found that the concentration of OH- sharply decreases due to the formation of Al(OH)?4- species with increasing aluminum concentration, suppressing greatly DSP precipitation. This proposed process paves the way for Al2O3 production from low-grade diasporic bauxite with high-reactive silica content. (C) 2011 American Institute of Chemical Engineers AIChE J, 2012
KeywordReactive Silica Kinetic Modeling Bayer Process Stabilization Dissolution Precipitation
SubtypeArticle
WOS HeadingsScience & Technology ; Technology
DOI10.1002/aic.12722
URL查看原文
Indexed BySCI
Language英语
WOS KeywordSPENT BAYER LIQUOR ; ALUMINOSILICATE SOLUTIONS ; DIGESTION CONDITIONS ; SOLUBILITY ; SYSTEM ; DESILICATION ; KINETICS ; MODEL ; BEHAVIOR ; ION
WOS Research AreaEngineering
WOS SubjectEngineering, Chemical
WOS IDWOS:000304900700019
Citation statistics
Cited Times:9[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Version出版稿
Identifierhttp://ir.ipe.ac.cn/handle/122111/6408
Collection研究所(批量导入)
AffiliationChinese Acad Sci, Key Lab Green Proc & Engn, Natl Engn Lab Hydromet Cleaner Prod Technol, Inst Proc Engn, Beijing 100190, Peoples R China
Recommended Citation
GB/T 7714
Ma, Jiayu,Li, Zhibao,Xiao, Qinggui. A new process for Al2O3 production from low-grade diasporic bauxite based on reactive silica dissolution and stabilization in NaOH-NaAl(OH)4 media[J]. AICHE JOURNAL,2012,58(7):2180-2191.
APA Ma, Jiayu,Li, Zhibao,&Xiao, Qinggui.(2012).A new process for Al2O3 production from low-grade diasporic bauxite based on reactive silica dissolution and stabilization in NaOH-NaAl(OH)4 media.AICHE JOURNAL,58(7),2180-2191.
MLA Ma, Jiayu,et al."A new process for Al2O3 production from low-grade diasporic bauxite based on reactive silica dissolution and stabilization in NaOH-NaAl(OH)4 media".AICHE JOURNAL 58.7(2012):2180-2191.
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