Experimental Study On Minimum Ignition Temperature Of Sulfide Dust

It will produce a large number of sulfide mineral dusts in the process of sulfide mine exploitation,which has a potential risk of inflaming or exploding when there is sufficient energy source.In order to explore the minimum ignition temperature and ignition pattern of sulfide dust,the paper firstly measures the minimum ignition temperature of sulfide dust utilizing standard test equipment and analyzes ignition phenomenon;then it works out the primary and secondary relations and optimal combination of the factors by utilizing orthogonal experimental design and by means of range analysis,it respectively experiment studies the effect patterns of sulfur content,particle size and dust concentration on dust minimum ignition temperature and investigates the experiment employing auto-ignition theory;Later,it carries out the ignition process test on three sulfide dusts with the thickness of 12.5mm and 5mm with the device for testing various dust layers ignition temperature,the dynamic temperature changes of the dust layers at different heights are recorded by a thermocouple beam and the SO₂ produced in the process are dynamically monitored by gas transmitter.Based on the theory of chemical reaction dynamics,law of heat conduction and the theory of self-ignition,a theoretical model for solving the critical ignition temperatures of dust layers is discussed in the paper,the research shows:⑴ The minimum ignition temperatures of A、B、C three kinds of sulfide dust are 386℃,454℃,512℃ respectively.⑵ When burning,the sulfide dust can only spark without smoke or fire,which is a form of solid surface burning.⑶ The primary and secondary orders of the factors that affect the minimum ignition temperature of sulfide dust are: Dusting pressure> sulfur content> particle size> dust concentration,the optimal combination of the factors is: A1B1C1D1.⑷ The minimum ignition temperature of sulfide dust decreases with the increase of sulphur content,decreases with the decrease of particle size,and firstly increase and then decrease with the increase of dust concentration,that is to say there exists a critical ignition concentration,which is tested to be 1327.43 g/m3 in the experiment.⑸ The higher the amount of sulfur in dust particles,the smaller particle size,and larger ignition propensity of mineralized dust layer.⑹ There is a certain temperature gradient in the dust layer,and there will be a large number of SO₂ gas produced in the process of oxidation,self-heating and igniting.⑺ The sulfide dust layer goes through mainly three stages as low temperature oxidation,chemical oxidation and self-heating,and igniting stage in the process from oxidation,self-heating to igniting.There are great differences in heat release rate,reaction rate and heating rate between each stage,and in addition,the corresponding SO₂ gas production rates vary from that of other stages.⑻ It can be concluded by combining the ignition temperature of sulfide dust layer in the process of comprehensive experiment that the igniting temperature of sulfide dust is≤386℃.