Study Of Effect Of Mineral Forms On The Microstructure And Reactivity Of Coke

In this paper, iron series( iron, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate) and cerium series(cerium chloride, cerium nitrate, cerium acetate) was added or adsorbed to blended coal for coking study,different various, valence iron and cerium salts of coke microscopic strength(MSI), structural strength(SSI), particle coke reactivity(PRI),microscopic structure of coke and kinetic parameters were studied by using X-Ray Diffraction、Scanning Electron Microscope、specific surface area、Cahn Thermax700 Thermo Gravity Analysis(TGA)other instruments.The results showed that:(1)The MSI and SSI of coke reduced after adding iron and cerium series minerals to blended coal, and their reduction degree was proportional to the adding amount of minerals.At the same loading ratio of minerals, the order of MSI and SSI of coke produced by adding different minerals were as following: iron > ferric sulfate > ferrous sulfate > ferric chloride > ferrous chloride and cerium acetate > cerium chloride > cerium nitrate.The PRI of coke increased after adding or adsorbing different minerals to coke, and its increased degree was proportional to the adding amount of minerals. At the same loading ratio of minerals the influence order of adding or adsorbting different iron and cerium series minerals on the PRI of coke were as following: ferrous chloride > ferric chloride > ferrous sulfate > ferric sulfate > iron and cerium nitrate > cerium chloride > cerium acetate.(2) The results of the optical texture analysis of coke produced by adding minerals showed that the sum of isotropy organizations, fine particle inlay organizations, fusain and fragment(I+Mf+FF) increased, and the anisotropy index(OTI) decreased. With the increased adding amount of the same mineral series, I+Mf+FF tended to increase and the OTI tended to decrease; The adding minerals in cokes deteriorated the quality of coke,causing the larger and deeper of surface pores on coke which even penetrated through the coke and the ragged surface of coke. The comparison of the coke before and after gasification showed that the porosity on the surface of coke presents obvious “collapse”and “rough” phenomenon after gasification. The results from mercury porosimetry also showed that the adding of minerals increased the middle and large pores significantly,while the microporous were basically unchanged. The adding minerals also changed coke’s microcrystalline structure which shrinked the coke’s microcrystalline height(Lc) and increased the coke’s microcrystaline layer spacing(d002), causing the worse of orderly degree of coke. After gasification, the Lc, La of coke tended to be larger, and d002 appeared to be smaller, indicating the increased graphitization degree of coke.(3) TGA results showed that the coke activity factor(K), the maximum gasification rate(rm)and the average gasification rate(Rm) all presented enhanced trend with increased gasification temperature, and the coke’s catalytic strength(dm) exhibited a decreased trend.The increment of the rm presented an increasing trend, while the increment of the Rm had a reduction trend. At same gasification temperature, K, rm, Rm and dm are showing enhanced trend with the increased addition of minerals. The increment of the Rm has increasing trend,while the increment of the dm has a tendency to reduce.The coke dynamics after adding iron and cerium series minerals were more in line with the homogeneous model, the fitting correlation coefficient(R) was bigger than 0.98 and 0.93 respectively. The parameters of gasification kinetics had an obvious compensation effect, the correlation coefficient(R)were bigger than 0.99. Whether adding iron or cerium series minerals, the activation energy of the reaction reduced, and with the increase of the adding amount of minerals, the activation energy of the reaction continued to decrease.