| 1. |
- Dubina, Elina, et al.
(author)
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Impact of environmental moisture on C(3)A polymorphs in the absence and presence of CaSO4 center dot 0.5 H2O
- 2014
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In: Advances in Cement Research. - : Thomas Telford Ltd.. - 0951-7197 .- 1751-7605. ; 26:1, s. 29-40
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Journal article (peer-reviewed)abstract
- The phenomenon of water vapour sorption by anhydrous C(3)A polymorphs both in the absence and in the presence of CaSO4 center dot 0.5 H2O was studied utilising dynamic and static sorption methods. It was found that orthorhombic C(3)A starts to sorb water at 55% relative humidity (RH) and cubic C(3)A at 80% RH. Also, C(3)Ao sorbs a higher amount of water which is predominantly physically bound, whereas C3Ac preferentially interacts with water by chemical reaction. In the presence of calcium sulfate hemihydrate, ettringite was observed as the predominant pre-hydration product for both C(3)A modifications: that is, ion transport had occurred between C(3)A and sulfate. Environmental scanning electron microscopic imaging revealed that in a moist atmosphere, a liquid water film condenses on the surface of the phases as a consequence of capillary condensation between the particles. C(3)A and sulfate can then dissolve and react with each other. Seemingly, pre-hydration is mainly facilitated through capillary condensation and less through surface interaction with gaseous water molecules.
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| 2. |
- Hökfors, Bodil, 1971-, et al.
(author)
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Modelling the cement process and cement clinker quality
- 2014
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In: Advances in Cement Research. - : ICE Publishing. - 0951-7197 .- 1751-7605. ; 26:6, s. 311-318
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Journal article (peer-reviewed)abstract
- This paper presents a recently developed simulation model that can be used as a tool for evaluating sustainable development measures for cement and lime production processes. Examples of such measures are introducing new combustion technologies such as oxy-fuel combustion, using biomass fuel and using alternative materials in the raw material feed. One major issue when introducing process changes is the need to maintain product quality. In some ways, oxygen-enriched air combustion resembles oxy-fuel combustion. The model results were validated and found to be consistent with full-scale operational data for normal running conditions and for a full-scale test with oxygenenriched air. The model shows, for example, that with an additional 1500 m3/h of oxygen, fuel addition at the calciners can increase up to 108% and the raw material feed rate can increase up to 116% for a process with a raw meal feed of 335.5 t/h.
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