The formation characteristics of calcium aluminates in the CaO-Al2O3-SiO2 system with sodium oxide was investigated by XRD, SEM-EDS and DSC-TG technologies. The main phases in the clinker after sintering at 1350 °...The formation characteristics of calcium aluminates in the CaO-Al2O3-SiO2 system with sodium oxide was investigated by XRD, SEM-EDS and DSC-TG technologies. The main phases in the clinker after sintering at 1350 °C are 12CaO?7Al2O3, 2CaO?Al2O3?SiO2 and 2CaO?SiO2 when the mass ratio of Al2O3 to SiO2 is 3.0 and the molar ratio of CaO to Al2O3 is 1.0. The proportion of 12CaO?7Al2O3 increases with the increase of Na2O addition when the molar ratio of Na2O to Al2O3 is from 0 to 0.4, while the proportion of 2CaO?Al2O3?SiO2 decreases with the increase of Na2O addition. Na2O forms solid solution in 12CaO?7Al2O3, which increases the volume of elementary cell of 12CaO?7Al2O3. The formation temperature of 12CaO?7Al2O3 is decreased by 30 °C when the molar ratio of Na2O to Al2O3 increases from 0 to 0.4 determined by DSC. The alumina leaching property of clinker increases obviously with the increase of Na2O addition.展开更多
The phase transition,morphology,stability and pulverization performance of dicalcium silicate(C_(2)S)with different Na_(2)O additions during the high-temperature sintering process were studied using XRD,SEM-EDS,FT-IR,...The phase transition,morphology,stability and pulverization performance of dicalcium silicate(C_(2)S)with different Na_(2)O additions during the high-temperature sintering process were studied using XRD,SEM-EDS,FT-IR,and Raman spectra methods.When the CaO to SiO_(2) molar ratio is 2.0 and the Na_(2)O to SiO_(2) molar ratio is below 0.20,the crystalline calcium silicate compounds includeγ-C_(2)S andβ-C_(2)S.As the Na_(2)O addition increases,the proportion,crystallinity and grain size ofβ-C_(2)S in the sintered products increase,those parameters ofγ-C_(2)S decrease,and the content of amorphous phase increases.Na_(2)O mainly forms solid solutions inβ-C_(2)S and inhibits the transition ofβ-C_(2)S toγ-C_(2)S,resulting in the sintered products unpulverized.The stability of sintered products in alkali solution decreases significantly with the increasing Na_(2)O additions,and theβ-C_(2)S solid solution with Na_(2)O is less stable thanγ-C_(2)S.The mechanism that Na_(2)O affects the transition of C_(2)S as well as its stability was also discussed,which can give actual guidance for the treatment of low-grade alumina-containing resources by the sintering process.展开更多
基金Projects(51174054,51104041)supported by the National Natural Science Foundation of China
文摘The formation characteristics of calcium aluminates in the CaO-Al2O3-SiO2 system with sodium oxide was investigated by XRD, SEM-EDS and DSC-TG technologies. The main phases in the clinker after sintering at 1350 °C are 12CaO?7Al2O3, 2CaO?Al2O3?SiO2 and 2CaO?SiO2 when the mass ratio of Al2O3 to SiO2 is 3.0 and the molar ratio of CaO to Al2O3 is 1.0. The proportion of 12CaO?7Al2O3 increases with the increase of Na2O addition when the molar ratio of Na2O to Al2O3 is from 0 to 0.4, while the proportion of 2CaO?Al2O3?SiO2 decreases with the increase of Na2O addition. Na2O forms solid solution in 12CaO?7Al2O3, which increases the volume of elementary cell of 12CaO?7Al2O3. The formation temperature of 12CaO?7Al2O3 is decreased by 30 °C when the molar ratio of Na2O to Al2O3 increases from 0 to 0.4 determined by DSC. The alumina leaching property of clinker increases obviously with the increase of Na2O addition.
基金Project(2018YFC1901903)supported by the National Key R&D Program of ChinaProjects(22078055,52074083,51674075)supported by the National Natural Science Foundation of China。
文摘The phase transition,morphology,stability and pulverization performance of dicalcium silicate(C_(2)S)with different Na_(2)O additions during the high-temperature sintering process were studied using XRD,SEM-EDS,FT-IR,and Raman spectra methods.When the CaO to SiO_(2) molar ratio is 2.0 and the Na_(2)O to SiO_(2) molar ratio is below 0.20,the crystalline calcium silicate compounds includeγ-C_(2)S andβ-C_(2)S.As the Na_(2)O addition increases,the proportion,crystallinity and grain size ofβ-C_(2)S in the sintered products increase,those parameters ofγ-C_(2)S decrease,and the content of amorphous phase increases.Na_(2)O mainly forms solid solutions inβ-C_(2)S and inhibits the transition ofβ-C_(2)S toγ-C_(2)S,resulting in the sintered products unpulverized.The stability of sintered products in alkali solution decreases significantly with the increasing Na_(2)O additions,and theβ-C_(2)S solid solution with Na_(2)O is less stable thanγ-C_(2)S.The mechanism that Na_(2)O affects the transition of C_(2)S as well as its stability was also discussed,which can give actual guidance for the treatment of low-grade alumina-containing resources by the sintering process.
