| Huangling oil-rich coal is an important coal used in chemical industry.Maceral separation and solvent extraction of different components are the basis for green,efficient,qualitative processing and conversion and utilization of related resources.On the basis of studying the characteristics of Huangling coal,the dissociation characteristics and separation law of maceral are systematically analyzed.The characteristics of solvent extraction products of raw coal and different macerals under ultrasonic-assisted conditions were discussed.By scanning electron microscopy,fourier transform infrared spectrum,gas chromatography-mass spectrometry and N2 adsorption at low temperature and other modern analytical techniques,examines the different solvents and extraction methods on extraction rate and composition,extraction tailings were functional groups,extraction tailings morphology and pore structure characteristics,the influence of especially different macerals in the variation in the process of solvent extraction.Huangling oil-rich coal has the characteristics of low medium ash,high volatile content,low sulfur,high tar yield and high calorific value.The content of vitrinite and inertinite in coal is 57.05%and 36.62%,and the content of chitinite and minerals is small,and the minerals are mainly composed of kaolinite,quartz and pyrite.The maximum weight loss rate is 0.18%/℃at 450℃ and 26.22%at 800℃.In the process of crushing and dissociation of Huangling coal,vitrinite is easily enriched in fine-grained products,inertinite is easily enriched in coarse-grained products.The dissociation degree of vitrinite and inertinite increases gradually with the deepening of crushing degree,and the optimal dissociation particle size of huangling coal macerals is 0.125-0.074 mm.The floatation and sink tests showed that the enrichment densities of vitrinite and inertinite were in the range of 1.25-1.33 g/cm3 and 1.39-1.45 g/cm3,respectively,and the purity of vitrinite and inertinite were 86.61%and 80.94%,respectively.Compared with raw coal,vitrinite volatile matter,carbon content,hydrogen content and nitrogen content increase,while inertinite is opposite.The mass loss rates of raw coal,vitrinite and inertinite were the highest at 450℃,and the mass loss rates at 800℃ were 27.64%,33.33%and 19.21%,respectively,indicating that vitrinite had the best volatility.Vitrinite contains more fatty structures and oxygen-containing functional groups than inertinite,and vitrinite has shorter fatty chains and more branched chains.Inertinite has higher aromatic degree and condensation degree than vitrinite,and there are multiple benzene ring substitution ways in inertinite’s benzene ring structure,indicating that inertinite’s molecular structure is more stable and polymerization degree is higher.Using different solvents to extract raw coal,it was found that carbon disulfide/N-methyl pyrrolidone(CS2/NMP),tetrahydrofuran(THF)and dimethylformamide(DMF)had good extraction effects.The optimal extraction conditions of the former two were as follows:ultrasonic power 200 W,coal dissolution ratio 50:1 and extraction time 4 h.The optimal extraction conditions of the latter were as follows:Under the optimal extraction conditions of ultrasonic power 400 W,coal dissolution ratio 30:1 and extraction time 2 h,the extraction rates were 18.72%,7.57%and 10.43%,respectively.Raw coal was successively extracted by petroleum ether(PE),carbon disulfide(CS2),methanol(MeOH),acetone(DMK)and carbon disulfide/acetone(CS2/DMK),and the extraction rates of each level were 4.63%,1.72%,4.57%,3.62%and 2.37%,respectively.The total extraction rate was 16.91%.The surface morphology,pore structure and functional group characteristics of the residual coal(raffinate)extracted by the solvent changed significantly.With the deepening of the extraction,the surface of the residual coal was loose and porous and the coal particles gradually became smaller.The structural modification is greater than that of DMF and CS2/NMP,and the content of aliphatic structure,aromatic hydrocarbons and oxygen-containing functional groups of residual coal is generally lower than that of raw coal.The distribution of CS2/NMP,DMF and THF extracts showed that aliphatic compounds were the most abundant and were dominated by straight alkanes.The carbon number was almost continuous from C17-C24,and n-eicosane and n-hexadecane were the most abundant,especially in DMF extracts.The contents of phenols were the most in DMF and THF extracts(2,4-di-tert-butylphenol and 2,4-bis(1,1-diethyl)-5-methylphenol were the main phenols).Again,they were esters,which were more abundant in CS2/NMP extracts than DMF and THF extracts.The CS2/NMP ratio of Vitrinite was higher than that of vitrinite by step extraction.The extracts of PE and CS2/DMK were mainly aliphatic hydrocarbons,CS2 contained more aromatic compounds,and MeOH was mainly ester compounds.CS2/NMP extraction of vitrinite and inertinite showed that the extraction rate of vitrinite was much higher than inertinite.The vitrinite extracts were rich in aliphatic hydrocarbons and oxygen-containing functional groups,while the inertinite extracts were rich in aromatic hydrocarbons with higher aromatization degree. |
PDF Full Text Request