Research On The Influence Rules Of High-ash Coal On Sintering Of Portland Cement Clinker

Coal is the main fuel used in the cement industries. With the reduction of highquality coal, the inferior coal is used more and more now. High-ash coal as therepresentative of inferior coal, it will be used frequently in the cement production.However, the change of the coal quality will be certain influence the clinker burning,quality and the stable of the kiln's condition. Therefore, Systematic research thecombustion characteristics of high-ash coal and the mechanism of sintering ofportland cement clinker, which have great significance for the effective use of inferiorcoal resources and the stable of clinker quality. In this thesis, considering somedifferent high-ash coal quality, the combustion characteristics of different quality ofhigh-ash coal and influence rules of coal ash and combustible components onsintering of portland cement clinker were studied, aiming to provide theoreticalguidance for the rational use of high ash coal resources.The studying results that thermo-gravimetric analysis of different high ash coalshow that the kindling point and the combustion ending-tilne were increased, and theindex D_i and D_f lower. Volatile content similar to the different coal, ignition andcombustion characteristics, not with the ash content of the changes there are clearrules. When ash content of coal similar, SiO₂/(Al₂O₃+Fe₂O₃) of ash increase, itsignition and combustion characteristics lower, especially when content of Fe₂O₃ in theash particularly high, combustion characteristics there are a significant decrease.The studying results that effects of coal ash on the Sintering of Portland CementClinker show that with increaseing ash content of coal, primary the temperature ofliquid phase of cement raw meal lower. When modulus value of clinker is stabilitated,the temperature of liquid phase reduces 36℃, and when the same raw mealingredients, the temperature of liquid phase reduces 64℃, especially when thesintering temperature above 1250℃, the raw meal ingredients are the main factorswhich influence the temperature of liquid phase. Experiments show that withincreaseing ash content of coal, content of C₃S declined while the content of C₂Sincreased. When the raw meal ingredients unchanged, the introduction of high ashcontent, C₂S become a major mineral. Meanwhile, with increaseing ash content of coal, resulting in more uneven distribution of minerals and more corrosionphenomenon in cement clinker.In this thesis, the experimental study on adding different burnout degree of charand pulverized coal show: with increaseing fixed carbon content, reducing burnoutdegree of char, primary the temperature of liquid phase of cement raw meal lower.But when extent of burning char R>80%, carbon to the liquid phase has little effect,meanwhile volatile matter content has little effect on the temperature of liquid phase.With increaseing fixed carbon content, burnability of raw mixes have greatly improvein the 1250℃, especially when content of Fe₂O₃ in the ash particularly high, contraryto the introduction of the volatile matter content makes burnability lower. When thetemperature rise to 1450℃, along with increaseing fixed carbon content, themorphology and distribution of clinker mineral becomes more uneven and grain sizeincrease, A mine etch phenomenon more serious, aspect ratio decrease. But whenR>80%, fixed carbon has little effect on petrographic structure of Portland cementclinker.