The Study On The Characteristics Of Minerals In High Silicon Coal And The Ash Melting Characteristics

Coal resource is the basic energy for our country, Large scale consumption of coal notonly caused a serious environmental pollution but also damaged human health. Thecompositions of mineral in coal is very complex, and the mineral transformation in theprocess of coal combustion have a significant impact on the boiler slagging, and silicate isthe most common mineral in coal, Therefore, this paper made an investigation on seventypical high silica coal, analysis and summarize the chemical characteristics and mineralmicro-features of low temperature ash, high temperature ash, light ash and heavy ash ofhigh silica-coal by related instrument, and to explore the mineral transform law, meltingbehavior and the affect of ash composition to slag-bonding.XRD analysis showed that compositions of mineral matters in the seven high silicacoal are very complex, nearly20kinds of minerals are identified, The content of light ashis very high, which acount for about90%to98%(wt%) of low-temperature ash, andcompositions of light mineral are almost as same as the low-temperature ash. Although thecontent of heavy ash is small, mineral compositions are absolutely different from that in theLTA and LA, and those heavy minerals play a very important role in boiler slagging.FSEM-EDX analysis showed that in four types high-silicon coal heavy ash,distinguished many kinds of chlorite, based on their morphology, they canbe roughly divided into the following types: board page shape, strip four square shape,cylinder shape, cube shape, berry bulk shape, acicular shape, strip shape and ball shape.these types of high-silica coal heavy ash have basically the same chlorite composition,including O, Fe, Si, Al, Mg, and some also contain Ca, K, Ti and other impurities, thecontent of magnesium, aluminum, silicon is stable, and the atomic ratio n (Si): n (Al) is1:1,but the iron element content changed greatly, the average elemental content changed from5%to17%.All seven high-silica coal ash melting point are high (FT>1300℃), The diagrambetween slagging index and ash fusion point of high-silica coal showed that with theincrease of B/A, G, and SiO2/A12O3, the melting point of these types of coal ash are in general respectively declining, rising and declining. These types of trends accord with thecharacteristics of slagging index. ash melting temperature observably depends on thecontent of quartz and kaolinite.