The spontaneous combustion of the sulfur concentrate is the main hazard faced in ore storage bins. To understand the thermodynamic characteristics of spontaneous combustion of the sulfur concentrate and test whether the kinetic compensation effects are present in the spontaneous combustion process of the sulfur concentrate, typical sulfur concentrate samples were selected as the research object, and thermogravimetric experiments were carried out under an air atmosphere at heating rates of 5, 10, and 15 K/min. On this basis, the contributions of different reaction models to the mass change during the spontaneous combustion of the sulfur concentrate, as well as the thermodynamic model and kinetic compensation effect, are analyzed. The results show that solid-phase combustion contributes the most to mass loss among different mechanisms of the reaction between the sulfur concentrate and oxygen. The contributions of reaction models to mass loss are affected by the different heating rates, and the contribution of solid-phase combustion to mass loss increases with increasing heating rates. The Malek method is used to obtain the kinetic model of the spontaneous combustion of the sulfur concentrate, and its mechanism function changes from a chemical reaction model to a three-dimensional diffusion model. There is a kinetic compensation effect in the spontaneous combustion process of the sulfur concentrate, and the level of the kinetic compensation line may be one of the bases for distinguishing the spontaneous combustion tendency of the sulfur concentrate.

Oil sludge (OS) is an organic solid waste in the petrochemical industry and improper treatment of OS will cause environmental pollution. Pyrolysis is an effective way to realize its resource reuse. In order to understand the pyrolysis behavior and thermodynamic characteristics of OS, four OS samples from storage tanks were used as the research object, and pyrolysis experiments were carried out at heating rates of 5, 10, and 15?/min under a nitrogen atmosphere. The kinetic parameters of pyrolysis of OS are calculated by three equal conversion methods (Friedman method (FR), Flynn-Wall-Ozawa method (FWO) and Distributed activation energy model (DAEM)), and the most possible thermodynamic models for the main pyrolysis phase were analyzed and discussed by introducing the Malek method. The results show: High heating rate can promote the pyrolysis of OS; In the pyrolysis stage, the apparent activation energy increases with the increase of the conversion rate. The apparent activation energy calculated by the FR method is more reliable. The average apparent activation energies of the four OS are 221.23, 84.71, 94.67 and 116.56 kJ/mol, respectively. The apparent activation energy and the pre-exponential factor are positively correlated, indicating that there is a kinetic compensation effect in the pyrolysis process. The thermodynamic models of the four OS samples are all three-dimensional diffusion models, but their integral functions are different. The research results can provide theoretical support for the industrialization, harmlessness and resource utilization of OS pyrolysis.

No abstract

No abstract

No abstract