Study On The Migration Of Sulfur During The Pyrolysis Of High-sulfur Coal

With the rapid development of economy,energy consumption has gradually increased,and the consumption of coal resources has been increasing.At the same time,due to the continuous development and utilization of high-quality coking coal resources,the reserves are seriously insufficient,the shortage of high-quality coking coal resources and the decrease of coal quality.Therefore,in order to alleviate the shortage of coal,resources reasonable use of high sulfur coal for coal blending coking coal is an effective solution.In this paper,the coking coal from Maanshan Iron and Steel Co.LTD is selected as the test object to investigate the effects of coal pyrolysis conditions such as coal rank,pyrolysis atmosphere,minerals and additives on sulfur migration during coal pyrolysis.The influence of volatiles in coal on sulfur migration during pyrolysis was investigated,and the pyrolysis behavior,chemical structure,sulfur form and sulfur-containing gas were characterized and analyzed by TG,FT-IR,XPS and MS.The results show that the proportion of thiophene and sulfoxide sulfur in high sulfur coal with high coal rank is higher than that in low sulfur coal with high coal rank.The main sulfur-containing gases produced by pyrolysis are H₂S,SO₂,COS and CS₂,of which H₂S and SO₂are the main ones.The sulfur gas produced by coal pyrolysis mainly comes from the decomposition of pyrite sulfur and unstable organic sulfur in coal.The temperature range of the decomposition of unstable organic sulfur is 300～500 ^oC,and the temperature range of the decomposition of pyrite sulfur is500～700 ^oC.After 2% and 5%H₂were added in N₂atmosphere,the desulfurization rate of coal pyrolysis increase significantly,from 31.91%in N₂atmosphere to 45.43%and49.49%.The sulfur content in gas products accounted for 30～40%of the sulfur content in raw coal,and the main component is H₂S.After acid washing and deashing,ash content in high sulfur coal decreases,the sulfur fixation effect of alkaline minerals weakens,and the pyrolysis desulfurization rate increases.The pyrolysis of ZL coal and XW coal with the addition of Ca O,γ-Al₂O₃and Fe₂O₃in the same proportion shows thatγ-Al₂O₃can promote the removal of sulfur in the coal,and the pyrolysis desulfurization rate of ZL coal reaches 39.49%.Ca O and Fe₂O₃play a role of sulfur fixation in the pyrolysis process,reducing the pyrolysis desulfurization rate.With the increasing CY coal ratio,the amount of active hydrogen produced by volatile coal can combine with more sulfur-containing free radicals in coal to generate sulfur-containing gas,making the desulfurization rate gradually increase.ZL coal is pyrolyzed with three different volatile coals,desulfurization of volatile matter during pyrolysis is affected by the nature of coal itself.CY coal ash contain more Ca O,causing sulfur to stay in the coke.The pyrolysis desulfurization rate under the addition of high-volatile CY and XW coal are close to that of low-volatile LL coal.