A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring sp...A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring speed on vanadium and chromium extraction were studied. The results suggest that the reaction temperature and KOH-to-ore mass ratio are more influential factors for the extraction of vanadium and chromium. Under the optimal reaction conditions （temperature 180 °C, initial KOH-to-ore mass ratio 4：1, stirring speed 700 r/min, gas flow 1 L/min, and reaction time 300 min）, vanadium and chromium extraction rates can reach up to 95% and 90%, respectively. Kinetics analysis results show that the decomposing process of vanadium slag in KOH sub-molten salt can be well interpreted by the shrinking core model under internal diffusion control. The apparent activation energies for vanadium and chromium are 40.54 and 50.27 kJ/mol, respectively.展开更多
The volatilization kinetics of senarmontite（Sb_2O_3） was analyzed in a neutral atmosphere in two temperature ranges： 550-615 °C（roasting temperature） and 660-1100 °C（melting temperature） by using a th...The volatilization kinetics of senarmontite（Sb_2O_3） was analyzed in a neutral atmosphere in two temperature ranges： 550-615 °C（roasting temperature） and 660-1100 °C（melting temperature） by using a thermogravimetric analysis method under various gas flow rates and using a 1.3 m L ceramic crucible（11 mm in internal diameter and 14 mm in height）. The effect of particle size was also analyzed. The experimental results of mass loss data, X-ray diffraction（XRD） analysis of partially reacted samples and thermodynamic studies indicate that the senarmontite becomes volatile in the form of Sb_4O_6（g） without the formation of any intermediary compound in the entire temperature range. At roasting temperatures, the volatilization kinetics of Sb_2O_3 was analyzed using the model X=kappt. The volatilization reaction was controlled by the surface chemical reaction and an activation energy value of 193.0 k J/mol was obtained in this temperature range. Based on the volatilization kinetics at the melting temperatures, for linear behaviour in nitrogen gas, kinetic constants were determined, and an activation energy of 73.9 k J/mol was calculated for the volatilization reaction with a surface area of 8.171×10^（-5）m^2.展开更多
Sub-molten salt was applied to the decomposition of zircon sand(ZrSiO4).The kinetics of the decomposition of zircon sand and the effects of reaction temperature,reaction time,NaOH content,agitation speed,and the NaOH/...Sub-molten salt was applied to the decomposition of zircon sand(ZrSiO4).The kinetics of the decomposition of zircon sand and the effects of reaction temperature,reaction time,NaOH content,agitation speed,and the NaOH/ore mass ratio on the decomposition rate of zircon sand in NaOH sub-molten salt were investigated.The results indicate that the decomposition rate of zircon sand increases with the increase in the reaction temperature,reaction time,and NaOH content.The shrinking-core model with surface chemical reaction-controlled process is the most applicable for the decomposition of zircon sand,with the apparent activation energy of 77.98 kJ/mol.The decomposition product is sodium zirconium silicate(Na2ZrSiO5),and the decomposition rate is higher than 99%under the optimal conditions.展开更多
基金Project(2013CB632605)supported by the National Basic Research Development Program of ChinaProjects(51274178,51274179)supported by the National Natural Science Foundation of China
文摘A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring speed on vanadium and chromium extraction were studied. The results suggest that the reaction temperature and KOH-to-ore mass ratio are more influential factors for the extraction of vanadium and chromium. Under the optimal reaction conditions （temperature 180 °C, initial KOH-to-ore mass ratio 4：1, stirring speed 700 r/min, gas flow 1 L/min, and reaction time 300 min）, vanadium and chromium extraction rates can reach up to 95% and 90%, respectively. Kinetics analysis results show that the decomposing process of vanadium slag in KOH sub-molten salt can be well interpreted by the shrinking core model under internal diffusion control. The apparent activation energies for vanadium and chromium are 40.54 and 50.27 kJ/mol, respectively.
文摘The volatilization kinetics of senarmontite（Sb_2O_3） was analyzed in a neutral atmosphere in two temperature ranges： 550-615 °C（roasting temperature） and 660-1100 °C（melting temperature） by using a thermogravimetric analysis method under various gas flow rates and using a 1.3 m L ceramic crucible（11 mm in internal diameter and 14 mm in height）. The effect of particle size was also analyzed. The experimental results of mass loss data, X-ray diffraction（XRD） analysis of partially reacted samples and thermodynamic studies indicate that the senarmontite becomes volatile in the form of Sb_4O_6（g） without the formation of any intermediary compound in the entire temperature range. At roasting temperatures, the volatilization kinetics of Sb_2O_3 was analyzed using the model X=kappt. The volatilization reaction was controlled by the surface chemical reaction and an activation energy value of 193.0 k J/mol was obtained in this temperature range. Based on the volatilization kinetics at the melting temperatures, for linear behaviour in nitrogen gas, kinetic constants were determined, and an activation energy of 73.9 k J/mol was calculated for the volatilization reaction with a surface area of 8.171×10^（-5）m^2.
基金Project(51704270)supported by the National Natural Science Foundation of ChinaProject(ZDRW-ZS-2018-1)supported by the Key Research Program of Chinese Academy of SciencesProject(KFJ-STS-ZDTP-040)supported by the Science and Technology Service Network Plan of Chinese Academy of Sciences
文摘Sub-molten salt was applied to the decomposition of zircon sand(ZrSiO4).The kinetics of the decomposition of zircon sand and the effects of reaction temperature,reaction time,NaOH content,agitation speed,and the NaOH/ore mass ratio on the decomposition rate of zircon sand in NaOH sub-molten salt were investigated.The results indicate that the decomposition rate of zircon sand increases with the increase in the reaction temperature,reaction time,and NaOH content.The shrinking-core model with surface chemical reaction-controlled process is the most applicable for the decomposition of zircon sand,with the apparent activation energy of 77.98 kJ/mol.The decomposition product is sodium zirconium silicate(Na2ZrSiO5),and the decomposition rate is higher than 99%under the optimal conditions.
