The conditions of crystallization of micaceous iron oxide （MIO） were studied through the synthesis of MIO from precursor Fe（OH）3 formed during oxidization of FeSO4·7H2O with H2O2. The experimental results sho...The conditions of crystallization of micaceous iron oxide （MIO） were studied through the synthesis of MIO from precursor Fe（OH）3 formed during oxidization of FeSO4·7H2O with H2O2. The experimental results showed that the concentration of NaOH as a hydrothermal medium had a strong effect on the formation,morphology,color and luster of crystal. The red iron oxide,yellow iron oxide and MIO with various types of crystal could be produced in the range of 0.019-14 mol·L -1 of NaOH concentration with the reaction temperature equating to 433 K or above. The color of MIO crystal produced varied from reddish brown,brown to steel grey with increasing NaOH concentration.The reaction temperature also affected the formation,morphology,color and luster of crystal. There was a great difference in conversion time from precursor Fe（OH）3 to MIO because of the changes of both NaOH concentration and reaction temperature. It was an effective method to age the crystal for a certain length of time to get more thinner MIO. The preferred technology parameters for the crystallization of MIO were as follows:a reaction temperature of 443-453 K,a NaOH concentration 12-14 mol·L -1 and a reaction time of 250 min.展开更多
The three-demensional turbulent flow in a stirred vessel driven by a Rushton turbine was simulated by using the anisotropic differential Reynolds stress model (RSM).The effect of the turbulent model, modeling approach...The three-demensional turbulent flow in a stirred vessel driven by a Rushton turbine was simulated by using the anisotropic differential Reynolds stress model (RSM).The effect of the turbulent model, modeling approach and discretization scheme on mean velocities and turbulent kinetic energy was investigated.The RSM was found to give vortex structure and positions near the blade reasonably.The two peak distribution of turbulent intensity near the blade tip could be effectively reflected by both the RSM and the anisotropic k-ε model;however the predicted results of velocity fluctuations by the RSM and the sliding mesh approach showed better agreement with the reported experimental data than by the anisotropic k-ε model and the multiple reference frames(MRF)approach, and the simulated turbulent kinetic energy was still under-predicted by the RSM.The simulated results validated by reported experimental data showed that the prediction ability for turbulent flow by the QUICK scheme approached second-order upwind scheme’s ability and both of them were better than first-order precision schemes.展开更多
文摘The conditions of crystallization of micaceous iron oxide （MIO） were studied through the synthesis of MIO from precursor Fe（OH）3 formed during oxidization of FeSO4·7H2O with H2O2. The experimental results showed that the concentration of NaOH as a hydrothermal medium had a strong effect on the formation,morphology,color and luster of crystal. The red iron oxide,yellow iron oxide and MIO with various types of crystal could be produced in the range of 0.019-14 mol·L -1 of NaOH concentration with the reaction temperature equating to 433 K or above. The color of MIO crystal produced varied from reddish brown,brown to steel grey with increasing NaOH concentration.The reaction temperature also affected the formation,morphology,color and luster of crystal. There was a great difference in conversion time from precursor Fe（OH）3 to MIO because of the changes of both NaOH concentration and reaction temperature. It was an effective method to age the crystal for a certain length of time to get more thinner MIO. The preferred technology parameters for the crystallization of MIO were as follows:a reaction temperature of 443-453 K,a NaOH concentration 12-14 mol·L -1 and a reaction time of 250 min.
文摘The three-demensional turbulent flow in a stirred vessel driven by a Rushton turbine was simulated by using the anisotropic differential Reynolds stress model (RSM).The effect of the turbulent model, modeling approach and discretization scheme on mean velocities and turbulent kinetic energy was investigated.The RSM was found to give vortex structure and positions near the blade reasonably.The two peak distribution of turbulent intensity near the blade tip could be effectively reflected by both the RSM and the anisotropic k-ε model;however the predicted results of velocity fluctuations by the RSM and the sliding mesh approach showed better agreement with the reported experimental data than by the anisotropic k-ε model and the multiple reference frames(MRF)approach, and the simulated turbulent kinetic energy was still under-predicted by the RSM.The simulated results validated by reported experimental data showed that the prediction ability for turbulent flow by the QUICK scheme approached second-order upwind scheme’s ability and both of them were better than first-order precision schemes.
