研究了以氢氧化钠为助剂活化高铝粉煤灰的煅烧工艺。采用SEM扫描电镜观察了高铝粉煤灰显微状态下的形貌,X射线衍射表征高铝粉煤灰以及不同煅烧条件下所得产物的物相组成,得出高铝粉煤灰煅烧活化最佳工艺条件为:煅烧温度为850℃,保温时间...研究了以氢氧化钠为助剂活化高铝粉煤灰的煅烧工艺。采用SEM扫描电镜观察了高铝粉煤灰显微状态下的形貌,X射线衍射表征高铝粉煤灰以及不同煅烧条件下所得产物的物相组成,得出高铝粉煤灰煅烧活化最佳工艺条件为:煅烧温度为850℃,保温时间为2 h,粉煤灰与氢氧化钠的质量比为1∶1.2。煅烧后的产物主要为可溶性的硅铝酸钠(Na Al Si O4)和硅酸钠(Na2Si O3),原高铝粉煤灰中的石英、莫来石相基本消失,粉煤灰得到充分活化。展开更多
In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream proces...In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.展开更多
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 pro...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.展开更多
文摘研究了以氢氧化钠为助剂活化高铝粉煤灰的煅烧工艺。采用SEM扫描电镜观察了高铝粉煤灰显微状态下的形貌,X射线衍射表征高铝粉煤灰以及不同煅烧条件下所得产物的物相组成,得出高铝粉煤灰煅烧活化最佳工艺条件为:煅烧温度为850℃,保温时间为2 h,粉煤灰与氢氧化钠的质量比为1∶1.2。煅烧后的产物主要为可溶性的硅铝酸钠(Na Al Si O4)和硅酸钠(Na2Si O3),原高铝粉煤灰中的石英、莫来石相基本消失,粉煤灰得到充分活化。
基金support from the National Natural Science Foundation of China(21978128,91934302)partial support from the State Key Laboratory of Materials-oriented Chemical Engineering(ZK202006)also acknowledged.Additionallysupported by the“Cultivation Program for The Excellent Doctoral Dissertation of Nanjing Tech University(3800124701)”.
文摘In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.
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).
文摘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.
