The effect of lime on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hem...The effect of lime on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz, and minor boehmite. Lime increases the desilication efficiency of the bauxite during the pre-desilication process by promoting the conversion of sodalite and cancrinite to hydrogarnet. Desilication reactions during the digestion process promoted by lime result in the loss of Al2O3 entering the red mud, but the amount of aluminogoethite-to-hematite conversion promoted by lime leads to the increase of aluminogoethitic Al2O3 entering the digested liquor. The alumina digestion rate at 245°C is higher than that at 145°C due to the more pronounced conversion of aluminogoethite to hematite. The soda consumption during the digestion process decreases due to lime addition, especially at higher temperatures.展开更多
AIM: To investigate the clinical features of Crohn's disease(CD) and intestinal tuberculosis(ITB) with a scoring system that we have developed.METHODS: A total of 25 CD and 40 ITB patients were prospectively enrol...AIM: To investigate the clinical features of Crohn's disease(CD) and intestinal tuberculosis(ITB) with a scoring system that we have developed.METHODS: A total of 25 CD and 40 ITB patients were prospectively enrolled from August 2011 to July 2012.Their characteristics and clinical features were recorded. Laboratory, endoscopic, histologic and radiographic features were determined. The features with a high specificity were selected to establish a scoring system. The features supporting CD scored +1, and those supporting ITB scored-1; each patient received a final total score. A receiver operating characteristic(ROC) curve was used to determine the best cut-off value for distinguishing CD from ITB.RESULTS: Based on a high specificity of differentiating between CD and ITB, 12 features, including longitudinal ulcers, nodular hyperplasia, cobblestone-like mucosa, intestinal diseases, intestinal fistula, the target sign, the comb sign, night sweats, the purified protein derivative test, the interferon-γ release assay(T-SPOT.TB), ring ulcers and ulcer scars, were selected for the scoring system. The results showed that the average total score of the CD group was 3.12 ± 1.740, the average total score of the ITB group was-2.58 ± 0.984, the best cutoff value for the ROC curve was-0.5, and the diagnostic area under the curve was 0.997, which was statistically significant(P < 0.001). The patients whose total scores were higher than-0.5 were diagnosed with CD; otherwise, patients were diagnosed with ITB. Overall, the diagnostic accuracy rate and misdiagnosis rate of this scoring system were 97% and 3%, respectively. CONCLUSION: Some clinical features are valuable for CD and ITB diagnosis. The described scoring system is key to differentiating between CD and ITB.展开更多
The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during the hightemperature sintering process were systematically investigated using DSC-TG,XRD,SEM-EDS,FTIR,and Ra...The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during the hightemperature sintering process were systematically investigated using DSC-TG,XRD,SEM-EDS,FTIR,and Raman spectra,and the crystal structure of Na4Ca3(AlO2)10 was also simulated by Material Studio software.The results indicated that the minerals formed during the sintering process included Na4Ca3(AlO2)10,CaO·Al2O3,and 12 CaO·7 Al2O3,and the content of Na4Ca3(AlO2)10 could reach 92 wt%when sintered at 1200°C for 30 min.The main formation stage of Na4Ca3(AlO2)10 occurred at temperatures from 970 to 1100°C,and the content could reach82 wt%when the reaction temperature increased to 1100°C.The crystal system of Na4Ca3(AlO2)10 was tetragonal,and the cells preferred to grow along crystal planes(110)and(210).The formation of Na4Ca3(AlO2)10 was an exothermic reaction that followed a secondary reaction model,and its activation energy was 223.97 kJ/mol.展开更多
Various characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface-area measurements, thermogravimetry–d...Various characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface-area measurements, thermogravimetry–differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy, were used to study the mineral structure and surface characteristics of high-iron hydrargillite. Gibbsite, goethite, and hematite were found to be the main mineral components of hydrargillite, whereas the goethite and hematite were closely clad to the surface of the multilayer gibbsite crystals. Compared with the synthetic gibbsite, the hydrargillite contained more structural micropores generated by the mineral evolution during the mineralization process. The gibbsite in hydrargillite contained less crystal water compared with the synthetic gibbsite, and it was a typical polymorphic structure. The isomorphous substitution of Al and Fe was observed in goethite. The dissolution-controlling step of hydrargillite was the ionic diffusion speed because of the goethite and hematite that closely covered and encapsulated the gibbsite crystals.展开更多
The sintering characteristics at 1 350℃and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2(C-A-S)system with different additions of FeO and Fe2O3 were investigated.FeO inhibits the conve...The sintering characteristics at 1 350℃and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2(C-A-S)system with different additions of FeO and Fe2O3 were investigated.FeO inhibits the conversion ofβ-Ca2SiO4toγ-Ca2SiO4 and makes the clinker not pulverizable.FeO and Fe2O3 inhibit the formation of CaAl2O4,but promote the formation of Ca12Al14O33.The interplanar spacing at(2 1 1)crystal face of Ca12Al14O33 in the clinker increases with the increase of FeO addition,which indicates that FeO forms solid solutions in Ca12Al14O33.The clinkers with Fe2O3 addition form a new phase Ca2Fe2O5,and the amount of Ca2Fe2O5 increases with the increase of Fe2O3 addition.Both FeO and Fe2O3 do not affect the Al2O3 leaching rate of calcium aluminate clinker in sodium carbonate solution,but they increase the molar ratio of caustic Na2 O to Al2O3 in the leached liquor.展开更多
The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650 ℃ in a V-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transm...The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650 ℃ in a V-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electron microscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at different nucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoid and pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the c/a interface, and the fine needles of interphase precipitates are perpendicular to the c/a interface. The vanadium carbides of long or short fibers, coarse particles and fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions and orientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modes were proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.展开更多
基金the financial supports from the National Key R&D Program of China(No.2022YFC2904401)the National Natural Science Foundation of China(Nos.22078055,52074083,51774079)the Fundamental Research Funds for the Central Universities,China(No.N2225002)。
基金Project(2018YFC1901903)supported by the National Key R&D Program of ChinaProjects(51774079,51674075)supported by the National Natural Science Foundation of ChinaProject(N182508026)supported by the Fundamental Research Funds for the Central Universities,China
基金the National Natural Science Foundation of China(Nos.51104041 and 51174054)
文摘The effect of lime on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz, and minor boehmite. Lime increases the desilication efficiency of the bauxite during the pre-desilication process by promoting the conversion of sodalite and cancrinite to hydrogarnet. Desilication reactions during the digestion process promoted by lime result in the loss of Al2O3 entering the red mud, but the amount of aluminogoethite-to-hematite conversion promoted by lime leads to the increase of aluminogoethitic Al2O3 entering the digested liquor. The alumina digestion rate at 245°C is higher than that at 145°C due to the more pronounced conversion of aluminogoethite to hematite. The soda consumption during the digestion process decreases due to lime addition, especially at higher temperatures.
文摘AIM: To investigate the clinical features of Crohn's disease(CD) and intestinal tuberculosis(ITB) with a scoring system that we have developed.METHODS: A total of 25 CD and 40 ITB patients were prospectively enrolled from August 2011 to July 2012.Their characteristics and clinical features were recorded. Laboratory, endoscopic, histologic and radiographic features were determined. The features with a high specificity were selected to establish a scoring system. The features supporting CD scored +1, and those supporting ITB scored-1; each patient received a final total score. A receiver operating characteristic(ROC) curve was used to determine the best cut-off value for distinguishing CD from ITB.RESULTS: Based on a high specificity of differentiating between CD and ITB, 12 features, including longitudinal ulcers, nodular hyperplasia, cobblestone-like mucosa, intestinal diseases, intestinal fistula, the target sign, the comb sign, night sweats, the purified protein derivative test, the interferon-γ release assay(T-SPOT.TB), ring ulcers and ulcer scars, were selected for the scoring system. The results showed that the average total score of the CD group was 3.12 ± 1.740, the average total score of the ITB group was-2.58 ± 0.984, the best cutoff value for the ROC curve was-0.5, and the diagnostic area under the curve was 0.997, which was statistically significant(P < 0.001). The patients whose total scores were higher than-0.5 were diagnosed with CD; otherwise, patients were diagnosed with ITB. Overall, the diagnostic accuracy rate and misdiagnosis rate of this scoring system were 97% and 3%, respectively. CONCLUSION: Some clinical features are valuable for CD and ITB diagnosis. The described scoring system is key to differentiating between CD and ITB.
基金Project(2018YFC1901903) supported by the National Key Research and Development Program of ChinaProjects(51774079,51674075) supported by the National Natural Science Foundation of ChinaProject(N182508026) supported by the Fundamental Research Funds for the Central Universities,China
基金financially supported by the National Key R&D Program of China(No.2018YFC1901903)the National Nature Science Foundation of China(Nos.51674075 and 51774079)the Fundamental Research Funds for the Central Universities,China(No.N182508026)。
文摘The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during the hightemperature sintering process were systematically investigated using DSC-TG,XRD,SEM-EDS,FTIR,and Raman spectra,and the crystal structure of Na4Ca3(AlO2)10 was also simulated by Material Studio software.The results indicated that the minerals formed during the sintering process included Na4Ca3(AlO2)10,CaO·Al2O3,and 12 CaO·7 Al2O3,and the content of Na4Ca3(AlO2)10 could reach 92 wt%when sintered at 1200°C for 30 min.The main formation stage of Na4Ca3(AlO2)10 occurred at temperatures from 970 to 1100°C,and the content could reach82 wt%when the reaction temperature increased to 1100°C.The crystal system of Na4Ca3(AlO2)10 was tetragonal,and the cells preferred to grow along crystal planes(110)and(210).The formation of Na4Ca3(AlO2)10 was an exothermic reaction that followed a secondary reaction model,and its activation energy was 223.97 kJ/mol.
基金financially supported by the National Natural Science Foundation of China (No.51104041)
文摘Various characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface-area measurements, thermogravimetry–differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy, were used to study the mineral structure and surface characteristics of high-iron hydrargillite. Gibbsite, goethite, and hematite were found to be the main mineral components of hydrargillite, whereas the goethite and hematite were closely clad to the surface of the multilayer gibbsite crystals. Compared with the synthetic gibbsite, the hydrargillite contained more structural micropores generated by the mineral evolution during the mineralization process. The gibbsite in hydrargillite contained less crystal water compared with the synthetic gibbsite, and it was a typical polymorphic structure. The isomorphous substitution of Al and Fe was observed in goethite. The dissolution-controlling step of hydrargillite was the ionic diffusion speed because of the goethite and hematite that closely covered and encapsulated the gibbsite crystals.
基金Item Sponsored by National Natural Science Foundation of China(51174054,51104041,51374065)
文摘The sintering characteristics at 1 350℃and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2(C-A-S)system with different additions of FeO and Fe2O3 were investigated.FeO inhibits the conversion ofβ-Ca2SiO4toγ-Ca2SiO4 and makes the clinker not pulverizable.FeO and Fe2O3 inhibit the formation of CaAl2O4,but promote the formation of Ca12Al14O33.The interplanar spacing at(2 1 1)crystal face of Ca12Al14O33 in the clinker increases with the increase of FeO addition,which indicates that FeO forms solid solutions in Ca12Al14O33.The clinkers with Fe2O3 addition form a new phase Ca2Fe2O5,and the amount of Ca2Fe2O5 increases with the increase of Fe2O3 addition.Both FeO and Fe2O3 do not affect the Al2O3 leaching rate of calcium aluminate clinker in sodium carbonate solution,but they increase the molar ratio of caustic Na2 O to Al2O3 in the leached liquor.
文摘The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650 ℃ in a V-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electron microscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at different nucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoid and pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the c/a interface, and the fine needles of interphase precipitates are perpendicular to the c/a interface. The vanadium carbides of long or short fibers, coarse particles and fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions and orientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modes were proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.
