Effect of additive iron ore on pyrolysis characteristics of a low rank coal from Hami

The effect of iron ore on pyrolysis characteristics of a low rank coal from Hami was explored.By means of thermogravimetric analyzer (TGA), fixed bed reactor, fourier transform infrared spectroscopy (FT-IR), gas chromatograph (GC) and gas chromatography-mass spectrometer (GC-MS), the changes of pyrolysis reactivity, products distribution, the functional groups in the tar and the composition of tar of three coal samples were investigated and analyzed.The results show that when the pyrolysis temperature increases from room temperature to 150℃, the peak of weight loss rate of HM-CT and HM-JT gradually moves to high temperature.When the pyrolysis temperature is more than 450℃, the catalytic effect of different iron ores on coal pyrolysis is more obvious and in the order of specularite> the inherent minerals in HM> hematite.When the two kinds of iron ores added are up to 20%, there is a higher pyrolysis tar and gas yield.The tar yield is 7.88% for HM-JT coal sample and the yield of H₂, CH₄, CO₂ and CO increases by 4.27%, 3.76%, 4.39% and 3.61%, respectively, compared with HM coal.For HM-CT coal sample, the tar catalytic cracking is influenced by the additive amount of iron ore.As the additive amount of specularite and hematite is increasing to 20%, the yield of tar decreases gradually, while the light tar yield rises to 6.37% and 5.34%, respectively for two iron ores, and the light tar fraction increases to 58.48% and 56.22%, respectively.Besides, the removal of oxygen in tar reaches to 43.16% and 36.89%, respectively.With the addition of iron ore, the relative content of m/p-xylene in tar decreases from 4.32% to 3.78% and 3.93%, respectively for two iron ores, and the relative content of toluene increases from 1.11% to 1.32% and 1.45%, respectively.The methyl substituents of o-cresol and m/p-xylenol molecules in tar are removed to produce phenol or cresol, and the demethylation for benzene series and phenolic compounds in tar on the specularite is stronger than that on the hematite.