The precalciner outlet material (hot meal) of Ordinary Portland (OP) cement production is an intermediate product mainly resulting from decarbonation and dehydration of the raw material at temperatures up to 900°C. Since the decarbonation reaction is highly endothermic, about 60% of the total required process energy is consumed. For preheater optimization a process dependent decarbonation degree has been established, which can be controlled. Up to now this degree of decarbonation is determined off-line by CO_2-content or by loss of ignition. In order to ensure effective process control an on-line determination method is required. And additionally it was proofed by our investigations, that there exists no clear correlation between loss of ignition and the degree of decarbonation. For these reasons an alternative direct method using X-ray diffraction supported by Rietveld analysis for quantification of Calcite content in hot meal was worked out.
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