| In the thesis,the thermal dissolutions(TDs)of Xilinguole lignite(XLGL)and coking coal were stuidied respectively,the optional condition and the effects of temperature and solvent to the TD performance of XLGL lignite and coking coals were compared.Fourier transform infrared spectroscopy,elemental analyzer TG-DTG,Rheometers and cohesion index analyzers respectively were used to characterize the composition and structure of the TD soluble fractions(TDSFs).Added the TDSFs in coal blend for coke-making,the effect of the quality of coke was further investigated to discuss the coking coal blending mechanism.The purpose of this study laid the foundation for the exploration of the TDs for low rank coal in coal blending coking technology.The experimental results showed that the temperature of TD play an important role to the TDSF performance of XLGL lignite.1-MN as a solvent,the TD yield of XLGL promotes with the increase of temperature,and it gets the highest value of 29.4% at 360°C.As the temperature continues to rise,the TD yields dropped instead.It was found that different solvents had different degrees of influence on the XLGL lignite thermal properties.The TD yield in polar solvent CMNO was about 45.4%,and in 1-MN was 29.4%.But the mixed solvent that added 10% methanol in 1-methylnaphthalene(1-MN+10% MT)had the highest TD yield of 62.5%.The result indicated that the polar solvent had better effect on XLGL lignite than non-polar solvent at 360°C.The polar solvent can destroy the macromolecular network structure of coal,thus extract more aromatic compounds.Coking coal also has similar TD rules in the non-polar solvent 1-MN and the polar solvent CMNO.Elemental analysis and FTIR showed that the C% content of TDSFs of coking coal was higher and the H/C was relatively lower than those of TDSFs from XLGL,indicating that the TDSFs of coking coal contains more the aromatic substances than XLGL lignite.The caking index of TDSFs of XLGL is related to TD temperature and the polarity of the solvent.The light product with 360°C has the highest caking index for the same solvent.TDSFs of CMNO have the highest caking property at the same TD temperature.The dynamic viscoelastic measurement of TDSFs of XLGL showed that the TDSFs at 360°C have the lowest softening temperature when the solvent remained unchanged.While the temperarure keeps constant,softening temperature of the TDSFs of CMNO was the lowest so the thermoplastic range gets longer,because the TDSFs of CMNO contain more moderate molecular compounds.Compared with XLGL lignite,the TDSFs of coking coal in 1-MN at360°C get the lowest softening temperature.The longer the TDSFs keep in the thermo plasticity,the better improvement it to the coke-making quality.The TDSFs of XLGL lignite and coking coal under differern conditions were used in coking coal blend to investigate the coking properties.The results showed that the quality of coke was obviously improved after adding TDSFs in the coal blends compared to the coke from the standard coal blends.The TD temperature plays an important role to themodification of coke quality.Adding the TDSFs of XLGL in 1-MN at 360°C in coal blends,the coke quality gave the most obvious promotion on account of its best caking property.Meanwhile,adding the TDSFs of XLGL from different solvent in coal blends showed that the TDSFs from CMNO had the best coke quality improvement indicatied that the particle reaction index is reduced and the particle strength after reaction and the microstrength index are obviously improved.The effect of the TDSFs from 1-MN+10%MT to the coke quality was worse than that of the TDSFs from CMNO.Comparing with XLGL raw coal,the quality of coke after adding TD heavy products and residues also can be improved to some extent.The TDSFs of coking coal in 1-MN had the best coking effect than the TDSFs of coking coal in CMNO at the same TD temperature.The improvement effect of coke quality adding TDSFs of coking coal was generally higher than that of the TDSFs of XLGL lignite. |
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