The present invention pertains to a method for manufacturing cement, wherein the gypsum is first calcined separately before being inter-grinded with the clinker so as to minimize the release of water of crystallization of during the inter-grinding stage. The method produces cement of high strength at all ages, better rheology, enables higher use of fly ash, and reduces CO.sub.2 emission during manufacturing.

There is provided a method for reforming unburned carbon-containing coal ash of the present invention, including: a receiving process of measuring L value and b value of unburned carbon-containing coal ash in a Lab color order system and sorting unburned carbon-containing coal ash of which the L value is 54 or more and the b value is 2 or more and 10 or less; and a classifying process of classifying the unburned carbon-containing coal ash sorted in the receiving process under a condition that a residue on a 45 m sieve of reformed coal ash which has been reformed by classification is 8% by mass or less.

The present invention provides a method and system for manufacturing cement wherein ground particles of cement and calcium sulfate are subjected to infrared sensors, laser sensors, or both, so that emanated, irradiated, transmitted, and/or absorbed energy having wavelengths principally within the range of 700 nanometers to 1 millimeter can be monitored and compared to stored data previously obtained from ground cement and sulfate particles and preferably correlated with stored strength, calorimetric, or other data values, such that adjustments can be made to the mill processing conditions, such as the form or amounts of calcium sulfate (e.g., gypsum, plaster, anhydride), or cement additive levels. The strength and other properties of cement can be thus adjusted, and its quality can be more uniform.

The present invention provides a method and system for manufacturing cement wherein ground particles of cement and calcium sulfate are subjected to infrared sensors, laser sensors, or both, so that emanated, irradiated, transmitted, and/or absorbed energy having wavelengths principally within the range of 700 nanometers to 1 millimeter can be monitored and compared to stored data previously obtained from ground cement and sulfate particles and preferably correlated with stored strength, calorimetric, or other data values, such that adjustments can be made to the mill processing conditions, such as the form or amounts of calcium sulfate (e.g., gypsum, plaster, anhydride), or cement additive levels. The strength and other properties of cement can be thus adjusted, and its quality can be more uniform.

A low-calcium silicate cement consists of calcium oxide, silica, alumina, and iron oxide. A preparation method of the low-calcium silicate cement consists of: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300? C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m.sup.2/Kg, thereby obtaining a low-calcium silicate cement.

An apparatus for producing pozzolanic material from waste includes a glass separator unit to remove glass material from the waste and a size reduction unit downstream the glass separator unit. The glass separator unit includes an outer member and a wound member positioned within the outer member and defining an open central bore. The outer member and the open central bore define respective longitudinal axes extending on a common plane that are disposed at an angle relative to a horizontal reference plane, with the inlet higher than the outlet. Non-glass/non-ceramic material is output through the open outlet end of outer member utilizing a flow of separation fluid. The glass/ceramic material is output to the size reduction unit through the open inlet end of the outer member utilizing the rotating wound member of the glass separator unit.

A low-calcium silicate cement, comprising: based on the total mass of oxides as 1, 50-60% of calcium oxide, 30-45% of silica, 2-6% of alumina, and 1-4% of iron oxide. A preparation method of the low-calcium silicate cement comprises: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300? C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m.sup.2/Kg, thereby obtaining a low-calcium silicate cement.

A conveying device for conveying bulk material for a plant for producing cement clinker, wherein the plant operates in the recirculation process and/or in the oxy-fuel process, and wherein the conveying device has a connection to the plant, in which the bulk material to be transported passes into the plant. A connection between the conveying device and the plant for producing cement clinker has a gas supply for pressurizing the connection with recirculation gas.

A conveying device for conveying bulk material for a plant for producing cement clinker, wherein the plant for producing cement clinker operates in the recirculation process and/or in the oxy-fuel process, and wherein the conveying device has a connection to the plant, in which the bulk material to be transported passes into the plant. The connection between the conveying device and the plant for producing cement clinker has a gas supply for pressurizing the connection with recirculation gas. Also a method.

The present invention provides a method and system for manufacturing cement wherein ground particles of cement and calcium sulfate are subjected to infrared sensors, laser sensors, or both, so that emanated, irradiated, transmitted, and/or absorbed energy having wavelengths principally within the range of 700 nanometers to 1 millimeter can be monitored and compared to stored data previously obtained from ground cement and sulfate particles and preferably correlated with stored strength, calorimetric, or other data values, such that adjustments can be made to the mill processing conditions, such as the form or amounts of calcium sulfate (e.g., gypsum, plaster, anhydride), or cement additive levels. The strength and other properties of cement can be thus adjusted, and its quality can be more uniform.