Migration characteristics and morphological changes of sodium during ashing process of Zhundong coal

ZHANG Xiaoyu; ZHANG Haixia; NA Yongjie

doi:10.13226/j.issn.1006-6772.2015.02.010

Abstract：In order to study the Migration characteristics and morphological changes of sodium during ashing process of Zhundong coal, Zhundong coal samples from five coal mines were ashed at 575 ℃ and 815 ℃,meanwhile,the ignition temperature and burnout tempera-ture of the samples were analyzed through thermogravimetric experiment. The influence of ashing temperature on ash characteristics of Zhundong coal was investigated. The ash was characterized with X-ray fluorescence( XRF),X-ray diffraction( XRD)and scanning elec-tron microscope and energy dispersive spectrometry( SEM-EDS). FactSage was used to explain and forecast sodium migration characteris-tics during ashing process. The results showed that,the ignition temperature of five Zhundong coals was below 400℃,the burnout tempera-ture was below 500 ℃. The form and physicochemical properties of ash which were obtained at 575 ℃and 815 ℃ respectively had large differences. Compared with the sodium in ash gotten at 575 ℃,the sodium content decreased by 47. 67%,88. 89%,62. 45%,52. 48%, 85. 78% at 815 ℃. The sodium on the surface of ash decreased by 67. 52%,75. 70%,44. 87%,63. 71% and 90. 08%. The ashing tem-perature influenced not only the sodium content,but the form of sodium. When the ashing temperature was higher than 800 ℃,the ash showed adhesive phenomenon. At last,575℃ was determined finally as ashing temperature which ensured complete combustion of Zhundo-ng coal and reduced volatilization of sodium content.