Research On Preparation Of Portland Cement From Desulphurization Gypsum

Desulfurization gypsum as a byproduct of coal-fired power plants caused the secondary pollution of environment. If desulphurization gypsum has not been effective used, A large amount of land will be wasted on storage and sulfur may be dissolved in water or soil. If desulphurization gypsum has not been effective handled, it will cause damage to the environment.This paper studied the preparation of portland cement from desulphurization gypsum. Firstly, the basic characteristics of desulphurization gypsum had been studied, determining the decomposition temperature and the amount of mixed anthracite when the desulphurization gypsum fully decomposed to CaO. Secondly, the cement clinker had been prepared from desulphurization gypsum, finding out the best C/S and best burning conditions. Finally, the desulphurization gypsum as a retarder had been used to prepare portland cement, determining the best amount of desulphurization gypsum and testing the performance of the prepared cement to decide its qualification.By XRD and XPS detection, particle size analysis and thermal difference analysis known that, the main mineral composition of desulphurization gypsum was CaSO4?2H2O,the major impurity was SiO2、Al2O3and Fe2O3,the mean grain size was39.34μm, the bound moisture and crystal water was removed at around200℃. The decomposition temperature of desulphurization gypsum was much high, which could been decomposed when burned at1600℃in30minutes. When the C/S was1.3, anthracite as reducing agent, desulphurization gypsum could be fully decomposed to CaO at1450℃The decomposition temperature of desulphurization gypsum declined and decomposition rate raised by adding reducing agent.Burning the desulphurization gypsum with Anthracite, SiO2、Al2O3and Fe2O3to prepare cement clinker. When the C/S was2, the desulphurization gypsum could be fully decomposed. Combining detecting the content of f-CaO and SO3in clinker and XRD detection concluded that clinker formed best when the C/S was2. By studying the effects of calcinations temperature and moisture retention time of clinker, concluded that the best preparation of cement clinker calcinations conditions:burning temperature was1450℃with thermal insulation60min. Testing the content of f-CaO and SO3in clinker met national standards and formation of minerals was the best when the burning was under the best calcinations conditions. The cement was prepared from type P?I portland cement in this experiment. The clinker prepared from the best calcinations conditions and desulphurization gypsum mix granulated to portland cement. By detecting the physical properties of cement prepared from admixture amount desulfurization gypsum, concluded that the best amount of desulphurization gypsum as a retarder was5%. The physical properties detection of cement prepared from5%desulfurization gypsum as a retarder shown that the cement prepared in this experiment qualified with stability, met the requirement of national standards and strength grade was42.5.