The kinetics of carbon reduction of ZnFe2O4 in the temperature range of 550-950 °C was investigated in a microwave tank-type reactor. The mechanism of formation of ZnO and Fe3O4/FeO by the decomposition of ZnFe2O...The kinetics of carbon reduction of ZnFe2O4 in the temperature range of 550-950 °C was investigated in a microwave tank-type reactor. The mechanism of formation of ZnO and Fe3O4/FeO by the decomposition of ZnFe2O4 was detailed using the equilibrium calculations and thermodynamics analysis by HSC chemistry software 6.0. In addition, the effects of decomposition temperature, the C/ZnFe2O4 ratio, the particle size and the microwave power were assessed on the kinetics of decomposition. Zn recovery as high as 97.93%could be achieved at a decomposition temperature of 750 °C with C/ZnFe2O4 ratio of 1：3, particle size of 61-74 μm and microwave power of 1200 W. The kinetics of decomposition was tested with different kinetic models and carbon gasification control mechanism was identified to be the appropriate mechanism. The activation energy for the carbon gasification reaction was estimated to be 38.21 kJ/mol.展开更多
The central composite process optimization was performed by response surface methodology technique using a design for the treatment of methyltin mercaptide with modified semi-coke. The semi-coke from the coal industry...The central composite process optimization was performed by response surface methodology technique using a design for the treatment of methyltin mercaptide with modified semi-coke. The semi-coke from the coal industry was suitably modified by treating it with phosphoric acid, with a thermal activation process. The objective of the process optimization is to reduce the chemical oxygen demand （COD） and NH4＋-N in the methyltin mercaptide industrial effluent. The process variables considered for process optimization are the semi-coke dosage, adsorption time and effluent pH. The optimized process conditions are identified to be a semi-coke dosage of 80 g/L, adsorption time of 90 min and a pH value of 8.34. The ANOVA results indicate that the adsorbent dosage and pH are the significant parameters, while the adsorption time is insignificant, possibly owing to the large range of adsorption time chosen. The textural characteristics of modified semi-coke were analyzed using scanning electron microscopy and nitrogen adsorption isotherm. The average BET surface area of modified semi-coke is estimated to be 915 mE/g, with the average pore volume of 0.71 cm3/g and a average pore diameter of 3.09 nm, with micropore volume contributing to 52.36%.展开更多
Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmen...Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry （XRD）. Effects of particle size of high titanium slag anal mixtures of high titanium slag with different mass fractions of V2o5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and irgn titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.展开更多
基金Projects (51004059,E041601) supported by the National Natural Science Foundation of ChinaProject (14051157) supported by Natural Science Foundation of Yunnan Province
文摘The kinetics of carbon reduction of ZnFe2O4 in the temperature range of 550-950 °C was investigated in a microwave tank-type reactor. The mechanism of formation of ZnO and Fe3O4/FeO by the decomposition of ZnFe2O4 was detailed using the equilibrium calculations and thermodynamics analysis by HSC chemistry software 6.0. In addition, the effects of decomposition temperature, the C/ZnFe2O4 ratio, the particle size and the microwave power were assessed on the kinetics of decomposition. Zn recovery as high as 97.93%could be achieved at a decomposition temperature of 750 °C with C/ZnFe2O4 ratio of 1：3, particle size of 61-74 μm and microwave power of 1200 W. The kinetics of decomposition was tested with different kinetic models and carbon gasification control mechanism was identified to be the appropriate mechanism. The activation energy for the carbon gasification reaction was estimated to be 38.21 kJ/mol.
基金Projects(5114703,51004059/E041601)supported by the National Natural Science Foundation of China
文摘The central composite process optimization was performed by response surface methodology technique using a design for the treatment of methyltin mercaptide with modified semi-coke. The semi-coke from the coal industry was suitably modified by treating it with phosphoric acid, with a thermal activation process. The objective of the process optimization is to reduce the chemical oxygen demand （COD） and NH4＋-N in the methyltin mercaptide industrial effluent. The process variables considered for process optimization are the semi-coke dosage, adsorption time and effluent pH. The optimized process conditions are identified to be a semi-coke dosage of 80 g/L, adsorption time of 90 min and a pH value of 8.34. The ANOVA results indicate that the adsorbent dosage and pH are the significant parameters, while the adsorption time is insignificant, possibly owing to the large range of adsorption time chosen. The textural characteristics of modified semi-coke were analyzed using scanning electron microscopy and nitrogen adsorption isotherm. The average BET surface area of modified semi-coke is estimated to be 915 mE/g, with the average pore volume of 0.71 cm3/g and a average pore diameter of 3.09 nm, with micropore volume contributing to 52.36%.
基金Project(2007CB613606) supported by the Major State Basic Research and Development Program of ChinaProject(50734007) supported by the National Natural Science Foundation of China
文摘Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry （XRD）. Effects of particle size of high titanium slag anal mixtures of high titanium slag with different mass fractions of V2o5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and irgn titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.
