Study On Slagging Behaviour Of Huainan Coal Ash In High Temperature And Reductive Atmosphere

This paper selects three high ash fusion temperature coal samples in Huainan mining area,Anhui.The mineral composition of Huainan coal are analyzed by CCSEM,the characteristics of the Huainan coal slagging are discussed by using the experiment and the prediction index of slagging characteristics,by means of XRD,FactSage thermodynamic software and SEM-EDS,the crystal mineral composition of coal ash slag,the transformation behavior of coal ash mineral,the apparent morphology and the microregion chemical composition of coal ash slag in Huainan coal under high temperature and reductive atmosphere were studied.The following four conclusions are obtained:(1)The mainly minerals in ZJX coal,ZJD coal and XQ coal are refractory minerals such as kaolinite and quartz.The refractory mineral content of three kinds of coal(including kaolinite,quartz,rutile and alumina)is 91.02%,68.81%and 79.04%,respectively.This is the main reason why Huainan coal is not easy to slagging.Although the content of refractory minerals in Huainan coal is higher,a small amount of fusible minerals still exist in coal(including iron oxide,calcite,pyrite),the content is about 2%?5%.So there is still the possibility of Slagging in Huainan coal at high temperature.(2)From the analysis of the experiment of slagging characteristics,we can see that Huainan coal is a weak slagging coal,among them,the slag rate of ZJD coal is the highest,followed by XQ coal,and the slag rate of ZJX coal is the lowest.The reason is that the content of refractory mineral in Huainan coal is caused by more,The atmosphere conditions also affect the coal slagging characteristics to a certain extent,for example,the slagging rate of coal samples increases with the increase of the intensity of the blast.From the prediction analysis of slagging characteristics,we can see that the prediction results of each discriminant index of ZJX coal and XQ coal are weak slagging,the prediction of ZJD coal to silica alumina ratio(SiO2/Al2O3)is medium slagging,and the prediction results of the other discriminant index are also weak slagging.From the comprehensive analysis of the experiment and prediction of slagging characteristics,ZJX coal,ZJD coal and XQ coal are basically weak slagging coal.lt is preliminarily judged that Huainan coal is more suitable for direct application of dry slag disposal technology in entrained flow bed.(3)The results of XRD and FactSage analysis show that:Huainan coal has appeared in liquid phase at 1100? and a large amount of liquid phase formation will increase with the increase of temperature,at the same time,the mineral content of quartz,feldspar,leucite,cordierite decreased,even disappeared,and the content of mullite decreased a little.The atmosphere also has a certain effect on the transformation of minerals,with the increase of the CO ratio in the atmosphere,the transformation of quartz to high temperature liquid phase material is promoted,and the production of mullite is promoted.(4)The results of SEM-EDS analysis show that:The situation of Huainan coal ash slagging is similar,coal ash at low temperature is made up of a large number of isolated fine particles,as the temperature rises,the slag gradually changed from isolated granular to dense bond.The content of Fe,Ca,Na,Mg and K also has a certain upward trend.The atmosphere has a certain effect on the apparent morphology and the microregion chemical composition of coal ash slag.For example,the enrichment of Fe elements in some regions at high temperature,the phenomenon of enrichment regions melting is obvious.The reason is that CO has reducibility at high temperature.