Study on sulfur-fixation effects of cement raw meal during pulverized coal combustion under different atmospheres

For the sake of desulfurization in cement kiln industry, the research on sulfur-fixation efficiency of cement raw meal during pulverized coal combustion under different atmospheres was performed experimentally. In O-2/N-2 atmosphere, the highest sulfur-fixation efficiencies reach 66%, 83%, 89%, 95% and 97% at 800 degrees C at Ca/S molar ratios of 0.5, 1, 2, 3 and 4, respectively. At over 800-900 degrees C, the recrystallization of CaO, the decomposition of the sulfur fixation product, and the carbothermic reaction lead to lower sulfur-fixation efficiency. In the O-2/N-2/CO2 atmosphere, the maximum sulfur-fixation efficiency is 89% under 79% CO2 at 900 degrees C. The sulfur-fixation efficiency increases with the rising of CO2 concentration and it is higher than that in O-2/N-2 atmosphere at 1000-1200 degrees C, due to the porosity of CaSO4 and the inhibition of CO2. Besides, the sulfur-fixation efficiency of the cement raw meal shows superiority than that of CaCO3 at 600-1200 degrees C, with higher sulfur-fixation efficiency of 6-11%. Alkali metal minerals and oxides in the cement raw meal may improve the sulfur-fixation effect and stability at high temperature of desulfurization products.