Study Of Coal Ash Fusion Characrteristics In Shanbei Region

In this paper, we choose four coals for the coal sample which in shanbei region. Weanalyzed the ash composition of coal ash, studied how coal ash composition affect ashmelting point, researched the process of mineral change in ash fusion through XRD andelectron microscope scanner, finally, studied the slag characteristic of the coal. Theresearch results are as follows:1. We add CaO, Fe₂O₃, MgO, Na₂O and K2O to ash, its fusion point showed a trendof decrease at first, and then rising. Due to the different content of each oxide in the ash,after joining the same oxide on the ash, the melting temperature change trends are not thesame, the influence of different oxides are also different in ash melting point. Jioning theSiO₂and Al₂O₃, coal ashes melting temperature can increase for low ash fusion. But formedium ash fusion, with the increase of SiO₂and Al₂O₃addition, ash meltingtemperature will decrease at first, and then rise.2. We analyze the morphology of coal ash by electron microscope scanning. At815℃, the ash particle is fine, mainly is the floc. At deformation temperature, they aremainly composed of much debris, and not of uniform size. After joining oxides, theyirregularly fused larger particles, it occurred congruent melting between the minerals incoal ash, appeared the melting phenomenon. XRD analyze mineral composition afterjoining oxides. After joining oxides, they have taken place great changes in thediffraction peak intensity of the minerals in coal ash, weaken or disappear. This showsadded oxidesinteraction with minerals in the ash; it generated other eutectic materialwhich make the coal ash melting changed and reduce the ash melting point.3. We measure the slag of coal samples through slag tester, and compared with theslag distinguish index of coal ash commonly used. For coal ash melting point when it ishigh or medium, the slag four conxergence indicators is consistent with the experimentalresults, thus, we can use the convergence indicators to distinguish these coal ash slag property in practice. For low ash melting point coal, some slag convergence indicatorsare not coincide with the experimental results, therefore, its slag index should beintegrated, comprehensive, not be single, so we can more accurately identify its slagtendency.4. The fusing characteristics of coal ash affect the degree of slag in coal gasification;ash is not easy to melt in the hearth and won’t bond together when ash fusion is high. Onthe other hand, some or all of ash melt together when ash melting point is low, andproduce slag. Therefore, ash fusion can distinguish the degree of slag coal.