Research On Zhundong Coal’s Slagging Characteristic And Its Ash Fusibility Of Blending Coal

Zhundong region is the most enriched areas of coal resources in Xinjiang, predicted reserves of390billion tons, which is of great significance to relieve the strain on the national supplies of coal. Limited by geographical location and transportation conditions, Zhundong coal was greatly applied in local power plant. However, Zhundong coal’s strong slagging tendency greatly limited its burning in the boiler plant. In this paper, tentative research was conducted to explore Zhundong coal’s slagging characteristics and the ash fusibility of its blends.To explore Zhundong coal’s slagging mechanism, mineral transmutation in the melting process was studied by the thermal analysis and X-ray diffraction phase analysis. There are anhydrite, calcite, quartz, hematite, albite, nepheline and hauyne in the coal ash, which are all melting-easy minerals. High alkali ends with many alkali-contained minerals:albite (NaAlSi3O8), nepheline (Na7(Al7Si9O32)) and hauyne (Na6Ca (AI6Si6O24)(8O4)2). Those minerals react with CaO and SiO2to form gehlenite, akermanite and augite etc., which will further react with each other in eutectic reaction to produce low melting eutectic of melting point at1170℃. During the eutectic reaction of hauyne, the jadeite(NaAlSi2O6) with low melting point at900～1000℃forms. There are melting-easy minerals but not refractory minerals in high alkali Zhundong coal’s ash and in the ash melting process which leads to low temperature eutectic reaction which forms the melt with low melting point, reduce the ash melting temperature, increase the viscosity of ash and slag, and this is the root cause of Zhundong coal’s strong slagging tendency.The minerals with low melting point in coal sah lead the escape in the ash melting process, which was testified by the Microwave digestion test on the coal and ash. The escapes of minerals increase the ash melting temperature measureed in the national standard. When Preparing the ash at lower temperature of500℃,the ash melting temperature of ST reduced to1230℃. This is the reason why Zhundong coal’s ash melting temperature was tested high but showed strong slagging tendency. Experiment ZhunDong coal Ning coal and lignite were burned on sedimentation furnace. ZhunDong coal’s slagging situation accords with lignite which is known for its low melting pointand easy slagging. Three coals’ slagging situation coincides with the situation in power plant. Test on sedimentation furnace is an effective method to predict Zhundong coal’s slagging tendency.Blending is one of the important methods to slove slagging of coal burnng in power plant. Restricted by itself coal quality and coal blending conditions, the key to slove Zhundong coal’s slagging in power plant through coal blending is to find a suitable blending coal. Blend Zhundong coal with Balikun coal neighboring Zhundong coalfield. The ash melting temperature of the blends shows the "V" glyph distribution which is rare in blend’s ash. The ash melting temperatures of the blends reach the lowest, when the proportion of tow coals at5:5, at which proportion the mineral species is in the most which is the result of low temperature eutectic reaction in the blends’ash.