Research On Spontaneous Combustion Tendency Of Sulfur Concentrate And Prediction Of Self-ignition Duration For Ore Stockpiles

The society and economy in China have been developing rapidly,and the demand for sulfur concentrates is getting larger ever since.However,spontaneous combustion can occur easily because of the nature of sulfur concentrates.As sulfur concentrates can release a large amount of heat in natural oxidation process,the temperature of the ore heap raises.In order to prevent spontaneous combustion,it is urgent to do research on mechanism of spontaneous combustion of sulfer concentrates.The dissertation analysed the spontaneous combustion tendency of sulfer concentrates and then simulated and predicted the spontaneous combustion period of mine heap.To identify combustion tendency,the dissertation used thermogravimetry test method and thermal analysis kinetic method.With these methods,linear fitting could help get the thermal analysis kinetic parameters of ore samples by using data obtained through experiments including X-ray diffraction analysis(XRD)and thermogravimetric analysis(TG).These parameters were Factor A,activation energy E and the corresponding reaction order n.The sulfur spontaneous combustion tendency was determined with comprehensive consideration of the low-temperature oxidation capacity,auto-ignition point,and activation energy of sulfur concentrates,obtain the self-ignition tendency of the four ore samples.Based on burning characteristics of sulfer concentrates,ANSYS FLUENT simulation software simulated natural oxidation process of sulfur concentrate heap at different temperatures.In these simulations,factors influencing on spontaneous combustion of sulfer concentranes such as mineral composition and content,ignition point,wind speed,temperature,and oxygen content of the accumulation site were considered.According to the simulation results,it was concluded that spontaneous natural oxidation occurred 10 days before the accumulation of sulphur concentrates until the point of autogenous ignition at about 25 days,and the temperature-increasing curve of the ore heap under different ambient temperatures was given.The dissertation made a conclusion about the period of spontaneous combustion of sulphur concentrate heap and proposed suggestions about preventing sulfer concentrate heap spontaneous combustion.The research on the spontaneous combustion tendency of sulfur concentrates and prediction of spontaneous combustion period of mine heap showed the combustion characteristics parameters,thermal analysis kinetics parameters and other important factors.ANSYS FLUENT simulation software was applied to simulate the spontaneous combustion process of sulfer concentrates and determine the natural firing period of the ore heap under corresponding conditions based on those parameters and factors.Finally,the dissertation constructed fitting formula of spontaneous combustion period of mine heap,calculated safe accumulation period of sulfer ore concentrates,and suggested some effective implements to achieve the purpose of early prediction and early prevention.