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为了掌握自燃性低的Fe S的氧化自燃过程,为预防Fe S自燃事故的发生提供理论基础,对不同纯度化学试剂Fe S,利用定温、程序升温试验方法,结合XRD、TG-DTA、TG-DSC及化学分析的结果,研究其氧化反应历程。结果表明,不同纯度Fe S氧化时,试样都经历了先失重后增重再失重的变化过程。首先失重的是试样中易挥发的杂质,250~300℃时试样质量开始增加,意味着Fe S氧化反应的开始。在325~400℃范围内Fe S氧化反应复杂,涉及化学反应多,试样质量随试验时间延长而增加,直至恒重,增重的主要物质经XRD表征和化学分析为Fe SO4。试验温度达到480℃时,试样质量先增加后减小,增重的主要物质为Fe2(SO4)3,该温度下Fe2(SO4)3分解速率慢。在550~650℃内,Fe2(SO4)3热分解或Fe S的完全氧化反应引起试样质量迅速减小。试验温度高于660℃时Fe S发生完全氧化反应,最终产物为Fe2O3。具有不同氧化反应活性的Fe S,其氧化反应历程也不同。
In order to grasp the process of oxidative spontaneous combustion of Fe S with low self-ignitability, this paper provides a theoretical basis for the prevention of spontaneous combustion of Fe S. Using different methods, such as fixed temperature and programmed temperature test, combined with XRD, TG-DTA and TG- DSC and chemical analysis of the results to study the oxidation reaction process. The results show that the samples have experienced the process of weight gain and weight loss after losing weight. First of all weight loss is the sample volatile impurities, 250 ~ 300 ℃ sample mass began to increase, which means that the start of Fe S oxidation reaction. In the temperature range of 325-400 ℃, the oxidation reaction of Fe S is complex and involves many chemical reactions. The quality of the sample increases with the increase of the test time till constant weight. The main material of weight gain is characterized by XRD and chemical analysis is Fe SO4. When the test temperature reaches 480 ℃, the mass of the sample first increases and then decreases, and the main material of the weight gain is Fe2 (SO4) 3, and the decomposition rate of Fe2 (SO4) 3 is slow at this temperature. At 550 ~ 650 ℃, the thermal degradation of Fe2 (SO4) 3 or the complete oxidation of Fe S caused the sample mass to decrease rapidly. When the test temperature is higher than 660 ℃, the complete oxidation of Fe S takes place and the final product is Fe2O3. Fe S with different oxidation reactivity, the oxidation reaction process is also different.