Thermochemistry of Clinkering Process

Wachtler and Jannsen [90] studied the material phase composition in the kiln with partial precalcinahon, and without its shut down. In the material from cyclone preheater spurrite, C2F and aluminates CA and and free CaO were found. In the samples also these phases and additionally C AF were present Then the gehlenite appears, C2S and C3A. Appearing of CjA is accompanied with the disappearing of C2F and CA. When C3S appears the samples have already the composition of clinker. 

In the second part of seventieth Humboldt introduced to the industry a very short kiln Pyrorapid , with the extremely rapid temperature increase of burned material, which provides a very favourable qtrick reaction of CaO after decarbonisation with silica [91]. The clinker phases formatiort, particularly of alite, became accelerated. The phase composition of rrraterial in the kiln are shown in Fig. 2.40 [91]. 

In the rotary kiln the process of rrraterial nodulising, parallel to clinker formation is occiuing. The studies have shown thatfor nodulising the siuface tension of clinker melt is very importarrt and its rise has advarrtageous effect [38]. It is shown on Fig. 2.41. 

The experimental difficulties of direct clinkering heat measurements caused that they are seldom. Much frequently the indirect measurements were used, for example Eitel and Richter [95] the heat of oxides and clinker dissolution have measured, for the exothermic clinkering effect calculation. Many calculations have also been done on the basis of known specific heats and some heats of reactions. 

The formulae for these calculations can be found in Babnshkin et al. book [13]. The heats of several reactions, which constitute the overall clinkering process, are given in the Table 2.1, and specific heats of components participating in this process in Table 2.2. On the basis of these data the theoretical thermal balance of clinkering can be obtained and heat of this process can be calculated (Table 2.3). 

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