Study On Oxidation Properties And Micro Structure Of Modified Shengli Lignite

Thirty years of reform and opening up,The wide use of large amountsof high quality coal resources has acceleratedeconomic development.However, the total reserve of high-quality coal resources is limited on earth, and it is nonrenewable.With the increasing of the demand of human for energy, the application of the abundant low rank coal has become a hot topic.Exploring clean and efficient approach to utilize the low rank coal, for example, lignite, has been drawn much attention. Lignite is not suitable for direct use because it has high water and volatiles content but low energy density. It is commonly necessary to conduct the drying process before applying lignite. One of the problems in the drying process is the oxidation and spontaneous combustion, which also occur during thetransportation and storage process.This thesistookShengli lignite as the research object and studied the oxidation behavior of lignite. The oxidation tests were carried out by treating the lignite samples under oxygen atmosphere for aspecific time in the fixed bed reactor.The coal sampleswerecharacterized by industrial analysis, FT-IR, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy.The oxidation behavior of two lignite samples, the acid treatment lignite and the Fe3+-added lignite, were studied in detail and the results were compared with the raw samples. The experimental resultsshowed that the organic conversion rate of acid treated coal was slowerthan that of the raw coal and the Fe3+-added coal. The organic conversion rate of raw coal was close to that of the Fe3+-added coal. It was provedthat the oxidation property of lignite was promoted by the presence of the minerals by the result that the oxidation property of the Fe3+-added coal was greater than the acid treatment coal.By the means of industrial analysis, FT-IR, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and other methods to characterize the coal sample, it was found that the micro structures of the samplechanged with the prolonging of oxidation time.Lignite contains amounts ofreactive groups like phenolic hydroxyl, hydroxyl, aliphatic hydrocarbons and so on. During the oxidation process, aliphatic C-H group reduced and the long chains fractured to be small structure fragments leading to the increasing of the defects, while thegroups containing oxygen increased, such as the C=O group. Hydroxyl and phenolic hydroxyl were oxidized to be carboxylic acid which makes the COOH group increased. The aromatic ring and ether bond were more stable so that they were not easy to be oxidized.Theresults in this thesis is helpful for theoretical understanding the oxidation behavior of lignite and promoting the clean and efficient utilization of the low rank coal resources.