Experimental Study Onthe Structural Transformation During Pyrolysis Process Of Xinjiang Coal And Modification Mechanism

With the strengthening and popularization of the technology in injecting pulverized coal into the blast furnace,the function of heating,reduction and carburization can be replaced to some degree.But the function as the skeleton of the blast furnace appears to be more and more important.Therefore,how to improve the coke strength becomes a very important task.In Xinjiang,China,the resource of coking coal is abundant.But the forming period in Early and Middle Jurassicis later compared with mainland coal,and the geological conditions are special.For those reasons,Xinjiang coking coal performs some characteristics like the high CRI(coke reaction index)and low CSR(coke strength after reaction).In this paper,the Xinjiang single coking coal and coke were analyzed.According to the Xinjiang coking coal properties,we used the additive invented by our research group to do basic modification experiment and successfully improved the coke thermal strength.To probe into the transformation mechanism of Xinjiang coal during the pyrolysis process with and without additive,we did a series of experiment such as Elemental Analysis(EA)and fourier transform infrared spectrum(FTIR).In addition,the coke cold strength prediction model was been built.The main conclusions were as follows:? The results of Xinjiang coals analysed by coal quality analysis,EA,vitrinite reflectance and FTIR spectrograms showed that the coalification degree of Xinjiang coking coal was lower than inland coking coal.The oxygen-containing functional groups occurred more in the coal but contained little carboxyl,which indicated that the coal molecular structure had lower condensation degree and longer alkyl side chains relatively.? The best modification effect to the Xinjiang coking coal by additive was gas coal,which was low metamorphic degree coal.By thermogravimetric analysis(TG)we found that the additive can slow-down the pyrolysis rate of gas coal in low temperature(about 450?),but it accelerated the polycondensation degree in high temperate(about 750?).Elemental analysis showed that Xinjiang gas coal contained little sulfur content.FTIR demonstrated that the gas coal contained little carboxyl,the HRTEM analysis conclusion was consistent with TG.According to the data of the analysis,the average molecular formula and molecular weights of the gas coal and chars were determined.The average molecular formula of gas coal.450 °C and 750 °C blank samples was C31.99H24.05N0.48SO.08O5.12,C48.72H29.17N0.70 S0.12O6.22 and C47.95H11.67N0.73S0.10O4.06 respectively.The average molecular weight of gas coal,450? and 750? blank samples was 499.13,726.97 and 665.45 respectively.? During the experiment of HRTEM,we found that the gas coal contained special ball-like structure,which probably was fullerene.The special structure may be one reason for the special characteristic of Xinjiang coal.? According to the influencing factors of coke code strength,we built the coke code strength prediction model,the final prediction models were as follows:M25 = 94.936-0.381Vdaf+0.176G-0.367Y M10 = 18.817-0.285Vdaf-0.110G + 0.368Y...