Sintering dolomite and limestone as a function of their industrial processing and calcium fluoride additions

Abstract

During the calcination of pure, difficult-to-sinter varieties of limestone and dolomite their preliminary industrial processing, consisting in a calcination firing, and subsequent slaking of the material, allows the production of sintered dolomite and limestone clinker with an apparent density respectively of 3.28–3.31 and 2.96 g/cm3 at 1400–1500° C. An addition of calcium fluoride increases the crystallization rate of the lime, and appreciably reduces the temperature of the initial mass selective recrystallization during firing of the dolomite and limestone, as a result of which the intensive sintering of the material occurs at lower temperatures. The dolomite clinker obtained by sintering with an addition of calcium fluoride has a much higher moisture resistance. The calcination firing with slaking and incorporation of the calcium fluoride additive affects the sintering of limestone, and also the sintering of dolomite in the same way, but the final consolidation of the limestone clinkers under these conditions is less, which apparently is a consequence of the formation during firing of limestone having a coarser structure. The fluoride additive contributes to growth of the crystals of CaO, and reinforces this effect.