Sintering Zone

In this zone liquidus phase reactions are formed. The main component, C3S (AH = +448kJ/kg C3S), is formed by a reaction between QS formed earlier and any available free lime as. 

The kinetic rate constants for fhe dissociation, Equation (10.10), and Equations (10.15) through (10.18) assembled by Gumz and Bac (1981) are presented in Table 10.2. Similar rates were obtained by Mastorakos et al. (1999) by trial and error to give the expected (measured) composition of charge at the exit of cement kilns. 

Obviously these equations are by no means the only reactions involved, since there are traces of other metal oxides that evolve or 

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Klischat, H.J. and Bartha, P., Further development of magnesia spinel bricks with their own specific properties for lining the transition and sintering zones of rotary cement kilns , World Cement, 1992 52-8. 

The powder is preformed to a void-free condition during the preforming stage and, as such, is moved through the die tube. The process maintains pressure on the molten PTFE in the sintering zone to coalesce the resin particles. The rate of compaction has to be slow enough to allow the air mixed with the resin to escape. 

During the sintering, the powder is heated by conduction. Thus, the time needed to heat it to the sintering temperature depends on the size and shape of the extrudate as well as on its heat transfer properties. Temperature settings in the sintering zone are from 380°C to 400°C (716°E to 752°E), although for large-diameter rods, where... 

Equipment used for that purpose is a vertical coating tower consisting of three heated zones, namely, drying zone, baking zone, and sintering zone (Figure 6.1). 

Fig. 9.13 Cross section through the sintering zone of a tunnei kiin [B.12C].

The burner must produce a short, narrow, strongly radiant flame, as this is a condition for good heat transfer from the flame to the material in the sintering zone of the kiln. 

As it is known, that the heat consiunption of the clinkering process is mainly due to the calcium carbonate decomposition and the long period (about 20 min) of clinker heating in sintering zone at maximirm temperamre, to assirre full alite formation. Therefore the energy consirmption increases with lime saturation factor (see Chap. 2). 

Belite laminae on rhombic alite planes, usually three groups intersecting Reducing conditions in sinter zone (Gille and others, 1965)... 

Scheubel (1989) characterized the sintering processes of two raw materials, one with silica distributed as clay minerals and the other with coarse quartz. With the former material, the reaction that forms the silicates in the short sintering zone with a steep temperature profile was said to be dependent primarily on the physical parameters of the melt (diffusion constant) and the mean path length for elemental migration. With the raw material containing coarse quartz and burned with a shallow temperature profile, coarsely crystalline belite which had formed... 

Decrease in volume of the sintered zone observed with increase in pressure is caused by a diminishing role of the surface combustion mode. To obtain easily... 

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