| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a production process of low-heat cement having a high phosphorus content, which involves using cement clinker having a high phosphorus content, so as to solve problems in a conventional production process of low-heat cement, such that firing of its raw material in a rotary kiln is difficult as compared with that in the production process of normal portland cement and since when the kiln operation is switched from or to normal portland cement production to or from low-heat cement production, large amounts of a cement raw material and cement clinker, each having a chemical composition intermediate between those of the normal portland cement and low-heat cement, are produced, the treatment of each of the cement raw material and cement clinker is required. SOLUTION: This production process comprises preparing a blended raw material from a limestone raw material, a clay raw material, a silica stone raw material, an iron oxide raw material and a raw material having a high phosphorus content, so as to have a (CaO)/(SiO2+Al2O3+Fe2O3) ratio of 1.8-2.3, a (SiO2)/(Al2O3+Fe2O3) ratio of 2.3-2.7, a (Al2 O3)/(Fe2O3) ratio of 1.4-1.8 and a 2-5 wt.% phosphorus content expressed in terms of P2O5, on the fired material basis, subjecting the prepared blended raw material to grinding and firing to obtain clinker, mixing the clinker with gypsum so that resulting mixture has a 1-4 wt.% SO3 content, and grinding the mixture, wherein optionally, the clinker and gypsum are ground separately from each other and thereafter, the ground materials are mixed together; and substituting 10-50 wt.% of the resulting cement material by fine-powdery blast-furnace slag having a 6,000-12,000 m2/g Blaine specific surface area.</p> |
