Production of activated-belite-CSA clinkers at extremely low firing temperature
A raw meal for a cement clinker, a cement clinker made from that raw meal and a process for producing a cement clinker are provided. The clinker contains mainly the hydraulically activate alpha′H-belite polymorph and calcium sulfoaluminate (ye'elimite or C 4 A 3 Ś), at the low firing temperature of 1050° C., using a combination of fluoride and boron oxide.
1 . A raw meal of a cement clinker, comprising:
about 45-57 weight percent calcium oxide;
about 15-25 weight percent silicon dioxide;
about 9-18 weight percent aluminum oxide;
about 0.5-5 weight percent iron oxide;
about 2-8 weight percent sulfur trioxide;
about 0.2-3 weight percent calcium fluoride;
about 0.2-4 weight percent sodium oxide; and
about 0.5-5 weight percent boron oxide wherein the raw meal is adapted to produce a cement clinker with no more than 2.4 weight percent tetracalcium aluminoferrite.
2 . The raw meal of claim 1 , further including at least one of limestone, hydrated lime, river sand, calcium sulfate, flue gas desulfurization gypsum, fly ash, bauxite, red mud, calcium fluoride, borax, boric acid, and sodium oxide.
3 . The raw meal of claim 1 incorporating fluoride and boron oxide.
4 . The raw meal of claim 3 wherein the fluoride is calcium fluoride and the boron oxide is borax.
5 . The raw meal of claim 4 , including about 48-54 weight percent calcium oxide.
6 . The raw meal of claim 5 , including about 18-22 weight percent silicon oxide.
7 . The raw meal of claim 6 , including about 12-15 weight percent aluminum oxide.
8 . The raw meal of claim 7 , including about 1.5-4 weight percent iron oxide.
9 . The raw meal of claim 8 , including about 4.5-5 weight percent sulfur trioxide.
10 . The raw meal of claim 9 , including about 1-1.5 weight percent calcium fluoride.
11 . The raw meal of claim 10 , including about 1-2 weight percent sodium oxide.
12 . The raw meal of claim 11 , including about 2-4 weight percent boron oxide.
13 . The raw meal of claim 1 including:
about 51-52 weight percent calcium oxide;
about 19.5-21 weight percent silicon dioxide;
about 13-14.5 weight percent aluminum oxide;
about 2-3 weight percent iron oxide;
about 4.5-5 weight percent sulfur trioxide;
about 1.1-1.4 weight percent calcium fluoride;
about 1.2-1.6 weight percent sodium oxide; and
about 2.5-3.5 weight percent boron oxide.
14 . A cement clinker made from the raw meal of claim 1 .