METHOD FOR PRODUCING CEMENT Russian patent published in 1998 - IPC

FIELD: production of building materials, more specifically, production of oil-well cement. SUBSTANCE: traditionally, proposed method resides in mixing and grinding mixture of Portland cement clinker, gypsum and mineral additive, namely, siliceous sedimentary rock, such as Tripoli earth and crushed scrap of moulding boxes. Inventive novelty of proposed method resides in fact that, before step of mixing components, 75-85% siliceous sedimentary rock is heated up to temperature 200-300 C, heating being conducted, in particular, in rotary kiln. Besides, optionally, mixing step can be preceded by admixing to mixture carbonaceous component, weight ratio of components in mixture being as follows, wt.%: Portland cement clinker 43-52, gypsum 5-7, siliceous sedimentary rock 45-50, carbonaceous component 1-2. EFFECT: 1) reduced density of grouting cement mortar; 2) increased water-to-cement ratio; 3) higher strength. 2 cl, 1 tbl