硫化亚铁氧化反应的研究

Research on the oxidation reactions of ferrous sulfide

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。

The paper intends to make an investigation of the spontaneous oxidation reaction process and the inherent mechanism of ferrous sulfide in hoping to set up preventive measures to get rid of such accidents likely to be caused by such events. To achieve our purpose,we have laid out some experiments concerning the testing of the different degrees of the purity of the chemical reagent ferrous sulfide,the volatile impurities involved in the said experiment,and the chief materials that would lead to the massgain process of the samples. Our experiments have shown that,as to the temperature-programming experimental results,the mass of the participant samples may have experienced a process of massloss,mass-gain,and a secondary mass-loss process. The whole process can be depicted in the following manner： the volatile impurities tend to get lost at first,when the mass of samples begins to increase in a temperature range between 250 ℃ to 300 ℃,and then the oxidation reactions of ferrous sulfide are likely to start.Actually,there exist many pathways via which the ferrous sulfide tends to get oxidized,depending on the different temperatures and the reactivity of the samples of the ferrous sulfide. For example,at the temperature of 480 ℃,the reaction between the ferrous sulfide with a purity at 98% and the oxygen in the air would begin to combine and result in a ferric sulfate that would lead to increase the mass of the sample. Though the ferric sulfate is not the final product,it tends to decompose bit by bit in a slow-going manner to ferric oxide. And,eventually,the mass of the sample chosen would gradually shrink. On the other hand,in the temperature range from 550 ℃ to 650 ℃,the process of decomposition of the ferric sulfide at a purity of 98% tends to speed up. And,in case of the entire process of the oxidation reaction between the ferrous sulfide at a purity of 80% and the oxygen,the sample mass of the ferrous sulfide tends to lose more quickly. If treated at the temperature of 660 ℃ or more for a sufficiently long period,the sulfide would eventually oxidize to ferric oxide, with the sulfur coming off totally in a gaseous form. Therefore,it can be said that the ferrous sulfide may experience a different oxidation reaction process at a different oxidation reaction rate. The higher the reactivity of the ferrous sulfide with oxygen,the lower the reactivity of the ferrous sulfide may experience with oxygen in a temperature range of 250 ℃ to 480 ℃.