Production of Fused Portland Cement and Sulphur Gas from Sulphatic Phosphorus-Containing Raw Materials with Added Fluorine,
BUILDING RESEARCH STATION WATFORD (ENGLAND)
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Previous work has established that when CaSO4 is heated to 1350C a eutectic is formed with the composition CaSO4 - 88, CaO - 12. When phosphoanhydrite obtained from phosphogypsum which in addition to an admixture of calcium phosphate also contains about 0.4 of fluorine is heated, the temperature of the eutectic is reduced to 1270C and the level of dissociation of CaSO4 at this temperature corresponds to a CaO content of 16.7. Research was conducted to use this system to produce Portland cement clinker without having to employ huge rotary kilns. Studies were made of the process of dissociation of CaSO4 in a molten Portland cement raw materials mix in oxidising and in slightly reducing media.
- Industrial Chemistry and Chemical Processing