Abstract: The present invention relates to a novel cement which makes possible the preparation of concrete, grout or mortar which is resistant to internal sulfate reactions and to external sulfate attacks, and also the use of this cement for the preparation of concrete, grout or mortar.

Abstract: In the method according to the invention for operating a cement plant, the raw meal is preheated in a preheating zone, the preheated material is precalcined in a calcining zone and the precalcined material is finally sintered in a sintering zone. The cement plant is operated in such a manner that the precalcined material which is supplied to the sintering zone has an SO3 concentration of at least 5.5% by mass and a CaSO4 proportion of at least 75%, preferably 90%, of the total salt content.

Abstract: A method for producing a clinker for cement, comprising grinding a raw flour comprising, especially, Al2O3, Fe2O3 and SO3 in contents such that the formula for calculating SO3 content of=0.261×Al2O3?0.638×Fe2O3+k, where 2.5<k<3.5, then by sintering flour in an overn wherein the temperature is between 1250° C. and 1350° C. and oxygen content is between 2.5% and 10% by volume.

Abstract: The present invention relates to a novel iron-doped sulphoaluminate-belite clinker, a process for preparing this clinker, and also the use of the clinker for the preparation of hydraulic binder and, consequently, of grout, concrete or mortar.

Abstract: A cement composition is made from a heat activated chemical salt selected from the group consisting of magnesium oxide, potassium oxide, sodium oxide, and calcium oxide and mixtures thereof. This activated salt is the mixed with hydraulic cement in an amount of 2½ to 3½ parts activated salt to one part hydraulic cement and the resulting mixture of hydraulic cement and activated salt is mixed with water and aggregate.

Abstract: The invention provides a process for preparing a sulphur cement product comprising the following steps: (a) selectively oxidising hydrogen sulphide to elemental sulphur by contacting, in a reaction zone, a hydrogen sulphide containing feed gas and a molecular-oxygen containing gas with a particulate oxidation catalyst under selective oxidation conditions; (b) discharging a stream comprising liquid and/or solid elemental sulphur and particulate oxidation catalyst from the reaction zone; (c) admixing the stream comprising elemental sulphur and particulate oxidation catalyst with at least any one of elemental sulphur, a sulphur cement filler, a sulphur cement modifier, or aggregate at a temperature at which sulphur is molten; (d) solidifying the mixture obtained in step (c) by cooling it to a temperature below the melting temperature of sulphur to obtain the sulphur cement product.

Abstract: Processes for making cement which when used to make concrete can stabilize the concrete against alkali-silica reactivity (ASR) from alkali containing components. The process includes adding lithium containing materials in the front of a cement kiln along with the cement starting materials in an amount sufficient to minimize ASR.

Abstract: The present invention regards a particularly quick-setting Portland cement clinker containing calcium fluoro-aluminate (11CaO.7Al.sub.2 O.sub.3.CaF.sub.2) mixed with lime that has not undergone the burning process of the clinker.

Abstract: A Portland cement clinker free of C.sub.4 A.sub.3 S having the following proportions of clinker phases, in % by wt.:--C.sub.3 S: 40 to 80--C.sub.4 AF: <20--C.sub.2 S: <30--C.sub.3 A: <20and a SO.sub.3 content from 1.0 to 3.0% by wt., based on the clinker, obtained by burning a mixture of raw materials containing CaO, SiO.sub.2, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3 and an additive containing SO.sub.3 at temperatures from 1200.degree. to 1350.degree. C. centigrade, the use thereof and a Portland cement.

Abstract: Processes for making cement which when used to make concrete can stabilize the concrete against alkali-silica reactivity (ASR) from alkali containing components. The process includes adding lithium containing materials in the front of a cement kiln along with the cement starting materials in an amount sufficient to minimize ASR.

Abstract: The invention relates to a method and a plant for manufacturing mineralized portland cement clinker. The method and plant provides for preheating, calcining, burning and finally cooling the clinker. The mineralizer may e.g. be gypsum, fluorine, or a waste product containing these or other mineralizers. The mineralizer is added to the feedstock after the feedstock has been fed to the process, preferably after the cyclone which handles the feed to the calciner, i.e. the last cyclone in the preheater, or the lowermost preheater stage in a plant which does not incorporate a calciner.

Abstract: With the present invention, a feed preparation system for producing cement includes mixing raw materials with a source of potassium. The mixture is conveyed to feed preparation system where it is placed in condition for treatment in a fluidized bed reactor for thermal processing to produce cement clinker. The potassium combines with the SO.sub.2 generated in the process to form potassium sulfate solids that are filtered from the process gas stream before emission to the atmosphere to thereby reduce sulfur emissions from the fluid bed cement process. The starting material may include white cement raw meal, grey cement raw meal and cement kiln dusts.

Abstract: The present invention pertains to a portland cement clinker containing the following amounts of clinker phases, in wt. %:C.sub.3 S: 30 to 80,C.sub.4 A.sub.3 S: 5 to 30,C.sub.4 AF: <30,C.sub.2 S: <40,C.sub.3 A: <20,and an SO.sub.3 content between 2 and 8 wt. %, obtained by calcining a raw material mixture containing CaO, SIO.sub.2, AL.sub.2 O.sub.3, and Fe.sub.2 O.sub.3 in the presence of an additive containing SO.sub.3 and an additive containing fluorine at temperatures between 1,150.degree. C. and 1,350.degree. C.

Abstract: A flux composition for cement comprises mainly wollastonite. One of the compositions of the flux is wollastonite 99%, fluorite 5-15% and gypsum 30-35%. The flux is added during the preparation of the cement raw materials and comprises 1-10% of the admixture. Thus, the firing temperature firing time may be shortened, the consumption of coal may be decreased and manufacturing productivity of the cement may be improved. In addition, the compression strength and the binding strength of the cement are also improved.