Methods for producing pozzolanic or latent hydraulic cement clinker substitutes may involve calcining clay with a fuel comprising a mineral substance at temperatures in the range from 500 to 1250 C., preferably from 550 to 1150 C., most preferably from 700 to 900 C. A resulting mixture of mineral substance from the fuel and the calcined clay forms a pozzolanic or latent hydraulic cement clinker substitute, in which a fraction of the mineral substance incorporated into the pozzolanic or latent hydraulic cement clinker substitute by the fuel is 1-60% by weight.

Process for operating a cement or lime plant comprising a cement or lime kiln and a calciner, wherein heat is generated by combustion of a fuel in the kiln and/or calciner, wherein a gas fed to the kiln and the calciner or to the calciner for combustion of the fuel contains an oxygen rich exhaust gas from a bioreactor containing photoautotrophic organisms and wherein the plant is preferably operated in the oxyfuel mode by using exhaust gas from the kiln and/or calciner together with the oxygen from the bioreactor as the gas fed to the kiln and/or calciner for combustion of the fuel.

There is provided a method for operating a cement plant capable of simultaneously optimizing both combustion in a calciner and a heat consumption rate. The method for operating a cement plant includes: feeding first fuel to a calciner; feeding second fuel for maintaining the inside at a burning temperature to a cement kiln along with combustion primary air, and introducing air for cooling cement clinker to a cooler; and feeding a part of the air as secondary air to the cement kiln, feeding as tertiary air to the calciner, and discharging the rest of the air from the cooler, wherein relation between a first oxygen concentration at an exhaust gas outlet of the calciner and a heat consumption rate determined by the first fuel and the second fuel, and relation between a second oxygen concentration at an exhaust gas outlet of the preheater and the heat consumption rate are beforehand obtained, and amounts of the secondary air and the tertiary air are adjusted such that both the first oxygen concentration and the second oxygen concentration fall within a range including values of the oxygen concentrations at which the heat consumption rate becomes at its minimum.

There is provided a method for operating a cement plant capable of simultaneously optimizing both combustion in a calciner and a heat consumption rate. The method for operating a cement plant includes: feeding first fuel to a calciner; feeding second fuel for maintaining the inside at a burning temperature to a cement kiln along with combustion primary air, and introducing air for cooling cement clinker to a cooler; and feeding a part of the air as secondary air to the cement kiln, feeding as tertiary air to the calciner, and discharging the rest of the air from the cooler, wherein relation between a first oxygen concentration at an exhaust gas outlet of the calciner and a heat consumption rate determined by the first fuel and the second fuel, and relation between a second oxygen concentration at an exhaust gas outlet of the preheater and the heat consumption rate are beforehand obtained, and amounts of the secondary air and the tertiary air are adjusted such that both the first oxygen concentration and the second oxygen concentration fall within a range including values of the oxygen concentrations at which the heat consumption rate becomes at its minimum.

The invention relates to a method for grinding a carbonaceous solid, wherein a grinding additive is added before or during grinding, and the grinding additive, based on the dry mass, comprises 6% to 80% by weight of caprolactam and 1.5% to 30% by weight of aminocaproic acid, where, based in each case on the dry mass, 0.002% to 2% by weight of the grinding additive is used, based on the total amount of carbonaceous solid. Further claimed are a grinding additive and the use of a grinding additive for reducing the energy employed for a given grinding outcome and also for reducing the agglomeration tendency of the resultant product.

In a method of enhancing the dry grinding efficiency of petcoke including adding additives to the petcoke and dry grinding the petcoke together with the additives. The additives may include a combination of at least one organic additive and at least one inorganic additive.

In a method of enhancing the dry grinding efficiency of petcoke including adding additives to the petcoke and dry grinding the petcoke together with the additives. The additives may include a combination of at least one organic additive and at least one inorganic additive.

A method for controlling an NOx concentration in an exhaust gas in a combustion facility by: measuring a reaction velocity k.sub.i of each of a plurality of chars, each corresponding to a plurality of types of pulverized coals; determining a relationship between the NOx concentration in the exhaust gas and the reaction velocity k.sub.i for each of the chars; (iii) blending the plurality of the types of the pulverized coal, wherein a blending ratio of the plurality of the types of the pulverized coal is determined by using, as an index, a reaction velocity k.sub.blend of the char of the blended pulverized coal, which corresponds to a target NOx concentration or below, on the basis of the relationship; and supplying the blended pulverized coal to the combustion facility as the fuel of the combustion facility.

A method in which a parent hydrocarbon-rich material is processed so as to produce both a carbon-rich solid material that has a higher carbon to hydrogen ratio than that of the parent material and a carbon-deficient combustible gas that has a lower carbon to hydrogen ratio than the parent material. In the process, the material is activated by exposing it to a hot gas stream having elevated levels of one or both of carbon dioxide and water vapor. The combustible gas is combusted to produce heat. At least about 80% of the heat is used in one ore more endothermic steps that include drying coal or biomass.

A method in which a parent hydrocarbon-rich material is processed so as to produce both a carbon-rich solid material that has a higher carbon to hydrogen ratio than that of the parent material and a carbon-deficient combustible gas that has a lower carbon to hydrogen ratio than the parent material. In the process, the material is activated by exposing it to a hot gas stream having elevated levels of one or both of carbon dioxide and water vapor. The combustible gas is combusted to produce heat. At least about 80% of the heat is used in one ore more endothermic steps that include drying coal or biomass.