A Study On The Reaction Kinetics Of Metal Sulfide In Water Vapor

On the basis of previous work, the reaction kinetics of antimony trisulfide ?lead trisulfide s zinc trisulfide and ferric trisulfide in argons water vapor and gas was studied with thermogravimetry at temperature range from 973K to 1173K. The gas flow-rate adopted was 1500ml/min.The investigation of antimony trisulfide was made in argon and water vapor. A theoretical model was developed to calculate the overall rate constant and the mass transfer coefficient in gas phase. The experimental results show that the vaporization rate is enhanced with increasing temperature and gas flow-rate. The apparent activation energy for the process is found to be 55.54 kJ/mol. It is demonstrated that the mass transfer coefficient in gas phase is decreased with increasing temperature.The evaporation mechanism of antimony trisulfide in water vapor is different from that in argon. Some antimony trisulfide vaporize solely and theother antimony trisulfide is oxidized to antimony oxide by water vapor. The reaction between antimony trisulfide and antimony oxide produce antimony in the gas phase. The advantages of water vapor will be discussed. The partial pressure of gaseous antimony trisulfide in bulk gas is fall while it is oxidized by vapor. The diffusion coefficient of antimony trisulfide in water vapor is bigger than that in argon. The melt surface temperature in water vapor is higher than that of argon because the values of heat transfer coefficient and thermal capacity of water vapor is bigger. Data from experimental prove that the evaporation rate is mainly controlled by mass transport in the gas phase whether in argon or in water vapor.The weight loss of lead sulfide in water vapor is exceptional. It is shown that the weight-time curves display an ascending result at temperature of 973K and 1023K. XRD analysis shows that nPbO .PbSO4 is produced. The chemical reaction leads to the weight increase. But the chief reason of weight loss is the evaporation of lead trisulfide at the top of 1073K.zinc sulfide is oxidized by water vapor that causes weight loss. The apparent reaction activation energy for the process has a value of 49.5 kJ/mol in the temperature range investigated.The roasting reaction of ferric sulfide in water vapor is very complex. XRD analysis indicates that the products contain Fe1-xS FeS FeS2 Fe2O3 and Fe3O4. The analysis indicates that the chemical kinetic aspects appear to affect the weight loss.