Research On Preparing Cement Clinker By Utilizing Silicate-calcium Slag

With the application of high alumina fly ash replacement bauxite alumina extraction technology in industrial practice,a large number of high alumina fly ash extraction by-product of aluminum calcium silicate slag were produced,If the calcium silicate slag can not be treated in time,it would pollute the environment and cause waste of resources.Silicon calcium slag contains about 40% calcium oxide and 12% silica,which can replace some of the cement raw materials to fire cement clinker.In this study,the appropriate ratio values,calcination temperature and the different mixing amount of calcium silicate slag in cement raw materials were used to illustrate the influence of the amount of calcium silicate slag on the firing results;the influence of the mixing amount of calcium silicate slag and the calcination temperature on the easy burning of cement raw meal was studied by testing the value of free calcium oxide;the mineral composition of the calcined clinker was quantified by XRD analysis and Rietveld full-spectrum fitting,the influence of the mixing amount of calcium silicate slag and calcination temperature on the mineral content of clinker was studied;the effects of the mixing amount of calcium silicate slag on the size and distribution of the mineral phase and the growth and development of the mineral phase were investigated by the petrographic analysis and SEM-EDS analysis.The results showed that the effect of de-alkali slag on the flammability is better than that of the original slag when the silicate slag(de-alkali residue and the raw slag)are mixed into the cement raw material.It can reduce the sintering temperature of clinker by using calcium silicate slag(de-alkali residue and the raw slag)as raw material,to control the clinker calcination temperature,to prevent the cement clinker melting.The mineral phase of clinker produced by the addition of calcium silicate slag was mainly composed of tricalcium silicate(C3S),dicalcium silicate(C2S),tricalcium aluminate(C3A)and calcium aluminate(C4AF).With the increase of calcination temperature,the content of tricalcium silicate gradually increased.When the mixing amount of calcium silicate slag(de-alkali residue)was more than 10%,with the increase of the mixing amount of calcium silicate slag,the content of tricalcium silicate gradually decreased and the content of dicalcium silicate and tricalcium aluminate gradually increased;When the mixing amount of calcium silicate slag is less than 10%,with the increase of the content of calcium silicate slag,the content of tricalcium silicate increased gradually.The calcination temperature was 1350℃,and the amount of calcium silicate slag in raw material was 0%,30% and 60% respectively,the C3 S mineral phase in the clinker was in the form of plate,columnar and scattered,and the C2 S mineral phase was elliptical and correlated with crossed double crystal and concentrated in the nest.With the increase of the mixing amount of calcium silicate slag,the Ca/Si molar ratio of C3 S mineral phase increased first and then decreased,which is not conducive to the formation of C3 S and the growth of crystal.