| The separation of low-rank coal differential components and studying the difference of different coal differential properties on thermal gasification reaction activity contribute to the efficient utilization of low-order coal.In this paper,low-rank coal separates the coal differential components and obtains the optimal flotation separation process conditions to study the variability of coal differential components from the perspective of molecular micro and chemical bonding.TG-MS-IR was used to study the macerals pyrolysis process and the CO2 reactivity of the isothermal gasification experiment,revealing the reaction mechanism and providing the basis for the identification of efficient utilization of low-order coal.The main research contents are as follows:The macerals of coal were separated by flotation,and the optimum technological conditions of macerals separation were studied by single factor method and orthogonal experiment.The optimum technological conditions are as follows:pulp concentration 55 g/L,collector 0.4 g/L,foaming agent 0.16 g/L and rotating speed 1800 r/min.The collector has the greatest influence on the separation of macerals from coal.Finally,the effects of different types of collectors on the macerals separation of coal were investigated.It was found that cationic collectors could regulate the electrical properties,so that the cationic collectors could selectively collect vitrinite,while inertinite remained in the pulp.However,The anions in the anion trap will bind to the hydrogen ions and the metal cations in the sample,causing a decrease in the flotation effect.To explore the differences in physical and chemical properties of macerals in coal.Modern analysis and testing techniques were used to test the differences in the physical and chemical properties of coal macerals,and to explore whether the demineralization had an impact on the properties of samples,paving the way for the subsequent study of pyrolysis and gasification process.The results show that the surface of vitrinite is smooth and flat,while that of inertinite is rough and porous,and the surface of sample particles is damaged to a certain extent by pickling.The aromatic monolayer distance of vitrinite is higher than inertinite,the microcrystalline accumulation height and the aromatic degree of vitrinite are lower than inertinite,indicating that the graphitization degree of inertinite is higher than inertinite,and the process of mineral removal by pickling damages the microcrystalline structure of coal samples to a certain extent.There were many hydroxyl groups in vitrinite,and the peak intensity of vitrinite decreased significantly after pickling,which may be due to the reaction between organic matter containing hydroxyl and acid in pickling process,leading to the weakening of absorption intensity.After pickling,the absorption strength of C-O bond stretching vibration region of the sample was significantly enhanced,indicating that metal ions were removed from the carbon chain during pickling,and oxygen atoms formed new bonds with unsaturated carbon atoms,leading to the generation of more C-O groups.There are many defects and low order of carbon structure in vitrinite.Due to the destruction of the surface structure,the content of the carbon skeleton small molecule alkyl and aromatic ring increases,thus reducing the ordering degree of the carbon skeleton.The reactivity of coal macerals after demineralization was measured by thermogravimetric detection.Due to the rough surface and well-developed pores of inertinite and the coal samples with weak reducibility,inertinite has high pyrolysis reaction activity and low degree of gasification.There are significant differences between vitrinite and inertinite in thermal gas evolution,which are embodied in escape intensity and escape temperature.The evolution of maceral pyrolysis gas is closely related to the rupture of chemical bonds and the release of volatile matter at different temperatures.In the process of gasification,inertinite tends to graphitization and has less disordered carbon microcrystalline structure,resulting in poor gasification reactivity.In the early stage of the gasification reaction,the transformation rate of the sample shows a rapid increase.This is because with the increase of temperature,the micropores of the coke sample increase,resulting in the increase of specific surface area of the sample,so the transformation rate increases.As the reaction progresses,the micropores in the particles are gradually reduced,and the adjacent micropores are connected,resulting in the reduction of the specific surface area of the sample and the reduction of the conversion rate.Figure[36]Table[30]Reference[93]... |
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