FIELD: manufacture of building materials.
SUBSTANCE: process comprises (i) providing starting cement mix containing carbonate, aluminosilicate, and ferrous ingredients, (ii) firing thereof until caking in rotating furnace with flame combustion of process fuel, and (iii) cooling thus obtained clinker, which contains free CaO, β-C2S, C3S, C3A, and C4AF. According to invention, firing is conducted under neutral atmosphere with content of oxygen in gases leaving rotating furnace 0.2-0.7 wt % until first clinker melt is formed at 1050-1179оС from mixture of CaO-C, CF2, RF, RA contained in fired material, which is partially granulated and crystallized from free CaO melt with dendrite and dot microstructure, after which a second eutectic clinker melt is formed from the preceding melt at 1230-1270оС and second clinker is then granulated therefrom with following proportions of principal phases, wt %: free CaO 5-25, β-C2S 40-60, C3S 3-10, C3A 0.01-10, and C4AF 8-20. Carbonate and aluminosilicate ingredients of raw mix and fineness of their grinding are selected from the criterion of at least partial overlapping of firing temperature ranges for decarbonization of carbonate ingredient and dehydroxylation of aluminosilicate ingredient of raw mix at weight ratio of these ingredients within a range of 0.5 to 0.6 corresponding to lime saturation factor for raw mix. Caking is completed when porosity of belite clinker achieves 35-47 vol %. Silica modulus of raw mix varies from 0.05 to 0,8. Combustion flame of process fuel in rotating furnace during firing of clinker is approached to segment of the material being fired so adjusting central angle of segment to 115-125о, whereas fuel supply is controlled until full transparency of surface atmosphere is reached. Cement obtained upon joint grinding of indicated belite clinker with separately fired alite Portland cement clinker including at least 60% alite, and gypsum component further contains active mineral additive with 3-8% moisture and finally contains, wt %: belite clinker 15-30, alite clinker 45-50, mineral additive 10-35, and gypsum component 3-10. During the grinding, free CaO contained in belite clinker is simultaneously converted into calcium hydroxide with degree of conversion 70-98%. Gypsum component is selected from reagent-grade calcium sulfate, gypsum stone, gypsum-anhydrite stone, phosphogypsum, borogypsum, titanogypsum, and their mixture.
EFFECT: reduced dust formation during clinker firing operation, diminished furl consumption, increased strength and grinding ability of cement, productivity of furnaces and mills.
7 cl, 1 tbl, 2 ex
