Research On The Influence Of Mineralizers On Coal Graphitization And Its Control Mechanism

Graphite has excellent properties such as high temperature resistance,special earthquake resistance,lubrication,conductivity and corrosion resistance.It provides a good medium for modern industries such as metallurgical industry,electrical industry and mechanical industry,and graphite may occupy a place in new energy,microelectronics and aerospace in the future.Most graphite deposits exist in the form of coal measure cryptocrystalline graphite deposits,and coal measure cryptocrystalline graphite is generally formed by coal and carbonaceous shale under the action of magmatic heat and formation pressure.However,because the metallogenic mechanism of coal measure cryptocrystalline graphite is not clear,the influence of inorganic minerals on the mineralization of coal measure cryptocrystalline graphite is not clear,The exploration and development of cryptocrystalline graphite in coal measures are greatly affected.In this thesis,Rujigou anthracite and Fengfeng lean coal are selected as the research objects,and Fe S,Fe Cl₃ and Ca CO₃ are used as mineralizers.The graphitization of coal is analyzed and characterized by Raman spectroscopy(Raman),X-ray diffraction spectroscopy(XRD),Fourier infrared spectroscopy(FTIR)and scanning electron microscopy(SEM).The effect of mineralizers on the early stage of coal graphitization at natural metallogenic temperature is studied.Under high temperature and high pressure,The mineralization mechanism of cryptocrystalline graphite in coal measures was explored.Through the study of anthracite,it is found that pickling demineralization has no significant effect on anthracite.Taking the demineralized anthracite as the research object,the anthracite added with ferrous sulfide(Fe S)and ferric chloride(Fe Cl₃)is compared at the natural graphite mineralization temperature.It is found that iron and sulfur in Fe S can promote the graphitization of anthracite,but the"catalytic"effect of sulfur in coal graphitization is far less than that of iron.Calcium carbonate(Ca CO₃)added to anthracite gradually decomposes into calcium oxide(Ca O)and carbon dioxide(CO₂)with the increase of temperature,and the decomposed calcium oxide will also produce"catalytic"effect,but weaker than calcium carbonate.Under high temperature and high pressure,the Raman spectra of anthracite with ferrous sulfide,ferric chloride and calcium carbonate show sharp G'peaks,indicating that the mineralizer promotes the reorganization and crystallization of the internal structure of coal under high temperature and high pressure,which is close to the graphite structure.By exploring the influence of Mineralizer on the graphitization of lean coal,it can be seen that the internal structure and chemical bond of lean coal are not damaged during acid pickling and demineralization of lean coal,and the influence of minerals in coal on the graphitization of lean coal is eliminated.At the natural ore-forming temperature of graphite,the promoting effect of ferrous sulfide on the disorder of lean coal in the early stage of graphitization is stronger than that of calcium carbonate,mainly in deepening the disorder of lean coal,removing hydrogen and oxygen bonds and promoting the stratification of coal internal structure.The lean coal added with mineralizer under high temperature and high pressure will have the phenomenon of reconstituted crystallization in the later stage of graphitization.The promotion effect of ferrous sulfide on the reconstituted crystallization of lean coal is much greater than that of calcium carbonate,and the stratification effect of lean coal added with ferrous sulfide is obvious.Therefore,ferrous sulfide has a good effect on the graphitization of coal,but the effect of calcium carbonate is poor,which may be caused by the high-temperature decomposition of calcium carbonate.By studying the influence mechanism of inorganic minerals on coal graphitization,it is found that the recombination crystallization phenomenon of lean coal added with pyrite is poor in the later stage of graphitization,and the graphitization degree is less than that of anthracite under the same conditions.In the graphitization recombination stage of anthracite,the influence of pyrite on the recombination crystallization and graphitization degree of anthracite is greater than that of calcite,but anthracite still has obvious stratification and fragmentation under the action of calcite.