Research On The Preparation Of High Cementitious Clinker With Industrial Solid Waste

The preparation of high cementitious clinker with industrial solid wast could save energy, resource and depress the environmental load of cement industry.To improve the burnability of cement raw material, this paper investigated the feasibility of praparaing high cementitious clinker with the industrial solid wasts. On the basis of four technique routes of high active calcium, low caloricity, crystal seed mineralizer and minor element, with the aids of metallographic microscope, XRD and SEM, the influence of the slags such as phosphorous slag (PS), magnesium slag (MS), high-calcium fly ash, coal gangue, fluorgypsum, ardealite and minor earth elements on the burnability of cement raw material, the composition and the performance of clinker was investigated. The effect of sintering system and cooling method on the formation of high cementitious clinker, and the kinetic parameter of sintering process were analyzed.The results indicated that all kinds of slag used in this investigation could facilitate the absorption of f-CaO, improve the burnability of raw meal, and accelerate solid phase reaction. The active CaO in the calcic wastes such as PS, MS and high-calcium fly ash could decrease the energy cost of CaCO₃ calcination, reduce the heat comsumption of clinker production, lessen the coal demanded and save energy. The later-age compressive strength of clinker with 7% PS is over 70 MPa, which indicated that PS enhanced the binding performance of clinker. The minor earth elements and the high activity clinker formation additive that mainly comprising PS could remarkably increase the content and activity of C₃S, and improve the quality and yield of clinker.It was found that the f-CaO content of the sample without thermal retardation was higher, whereas after kept at 1450℃ for 30min, a number of high-grade cement clinker generated. Heating-up rate had less affects on the mineral composition. The higher heating-up rate was, the finer crystals were obtained. While high-binding clinker formed through rapid sintering, compact crystals formed. Longer sintering time caused less C₃S content in clinker. Quench cooling could prevent the decomposation of C₃S from high-class clinker. High content of C3S in clinker, fine and well grown crystal were helpful to increase hydration activity of cement clinker.In order to study the dynamics of sintering, the burning process of partially substituted MS for CaCO₃ to prepare clinker was analyzed. The results showed that the kinetics of clinker formation accorded well with Gentling equation, and the reaction rate was controlled by the diffusion velocity of ion. Although MS hadn't changed the kinetic controlling system, it had evidently reduced the apparent activation energy, reaction temperature and accelerated the reaction.