The Influence Of Mineralizer On Coal Graphitization And Its Mechanism

Graphite is a kind of high-quality carbon material.Its excellent electrical conductivity,high temperature resistance and corrosion resistance make it widely used in aerospace,machinery manufacturing and many other fields.Many countries have listed graphite as a national strategic resource.Coal measures graphite is an important part of cryptocrystalline graphite and its main type.It is generally believed that coal measures graphite is formed by metamorphism of coal and carbonaceous shale under high temperature and high pressure.However,the development and utilization of coal measures graphite resources are greatly restricted due to the unclear metallogenic mechanism and occurrence law.It is of great significance to explore the metallogenic mechanism and occurrence law of coal measures graphite for the development and utilization of coal measures graphite and the industrial utilization of coal resources.Previous studies have found that under natural ore-forming conditions,the ore-forming temperature of coal measures graphite is about 600℃～900℃.The experimental temperature of coal graphitization in the laboratory is higher than 2000℃.Under this temperature,the properties of some mineral components in coal are changed,and the action and reaction mechanism of mineralizer are not consistent with the reaction under the condition of mineralization temperature.Taking Taixi anthracite as raw material,FeS,Fe Cl₃,Ca CO₃and kaolinite（purity more than 95%）as mineralizer,the effects of different mineralizers on the graphitization process of anthracite were studied by high temperature heating in nitrogen atmosphere,and the graphitization phenomenon of anthracite under the coupling effect of high temperature and high pressure mineralizer was explored XRD,Raman spectrum,scanning electron microscope,infrared spectrum and other technical means were used to characterize and analyze the products after graphitization.The effect of Mineralizer in the process of coal graphitization evolution was explored.The mineralization mechanism of coal measure graphite was improved.The difference of effect of Mineralizer in the early and late stage of graphitization was analyzed and explained.In addition,the results of this thesis have a certain reference value for the utilization of coal graphitization.The main research results are as follows（1）The influence of temperature on the graphitization process of coal under natural mineralization temperature was studied.XRD,Raman spectrum,infrared spectrum and scanning electron microscope were used to characterize the reaction products at different temperatures.The microstructure and crystal morphology of the products were observed.The results show that the higher the experimental temperature is,the higher the degree of graphitization of the products is.However,at the natural ore-forming temperature,the higher the temperature is,the higher the degree of graphitization of the products is,Anthracite does not form graphite crystal structure.（2）The graphitization process with the participation of different mineralizers was studied,and the catalytic mechanism of different mineralizers was explored.The experimental results show that the selected mineralizer can effectively promote the graphitization process,and the iron mineralizer has the best catalytic effect,which plays a catalytic role in the early and late stages of graphitization,and the catalytic effect is better than other mineralizers.Clay minerals in coal promote coal graphitization in the early stage of graphitization,and inhibit coal graphitization in the late stage of graphitization.（3）Under the condition of high temperature and high pressure reaction,the graphitization degree of anthracite is close to that of natural coal measures,and the promotion effect of Mineralizer on the graphitization process is more obvious.Without mineralizer,the graphitization degree of the sample is 0.75,the graphitization degree of the sample with FeS is 0.54,and the graphitization degree of the sample with Ca CO₃is0.59,The graphitization degree of the product is 1.35 when kaolinite is added.（4）The mineral transformation of anthracite in the early stage of graphitization is studied.The experimental results show that the mineral decomposition or oxidation reaction occurs near the geological mineralization temperature,which has the effect of strengthening temperature and promoting the process of graphitization.