The present invention pertains to a process for producing captured carbon dioxide. Calcium carbonate may be reacted with sulfur dioxide to produce calcium sulfite and gaseous carbon dioxide. Calcium sulfite may be thermally decomposed to produce gaseous sulfur dioxide. The processes may be used in conjunction with combusting various fuels such as a carbonaceous fuel, or a sulfurous fuel, or a nitrogenous fuel, or a hydrogen fuel, or a combination thereof.

The present invention pertains to a process for producing captured carbon dioxide. Calcium carbonate may be reacted with sulfur dioxide to produce calcium sulfite and gaseous carbon dioxide. Calcium sulfite may be thermally decomposed to produce gaseous sulfur dioxide. The processes may be used in conjunction with combusting various fuels such as a carbonaceous fuel, or a sulfurous fuel, or a nitrogenous fuel, or a hydrogen fuel, or a combination thereof.

The present invention pertains to processes of, for example, preparing zinc oxide and other substances. In one embodiment an exemplary process pertains to reacting ammonium chloride with zinc oxide to form a zinc chloride, gaseous ammonia, and gaseous water vapor. The zinc chloride may be reacted with sulfuric acid to form a zinc sulfate and hydrochloric acid. The zinc sulfate may be decomposed to produce zinc oxide among other substances.

The invention provides a novel, steam-assisted production methodology and associated compositions and methods of use in the manufacture of carbonatable or non-carbonatable metal silicate or metal silicate hydrate (e.g., calcium silicate or calcium silicate hydrate) compositions. These metal silicate compositions and related phases are suitable for use hydraulic, partially hydraulic or non-hydraulic cement that sets and hardens by a hydration process, a carbonation process or a combination thereof, and may be applied in a variety of concrete components in the infrastructure, construction, pavement and landscaping industries.

Processes and plants for producing cement clinker, in which an oxygen-containing gas having a proportion of 15% by volume or less of nitrogen and a proportion of 50% by volume or more of oxygen is conveyed from a first section of the cooler directly adjoining the top of the furnace into the rotary furnace and is optionally additionally conveyed to the calciner, and where the total gas streams fed in to the combustion processes consist to an extent of more than 50% by volume (preferably more than 85% by volume) of oxygen.

Disclosed is a method for manufacturing calcium aluminates in an industrial furnace, according to which, continuously, into a tank made of refractory material containing a molten pool that is constantly heated, fine particles are introduced of a raw material source of alumina and/or of aluminium and of a raw material source of calcium oxide and/or of calcium having a median diameter d50 less than or equal to 6,000 m in order to melt the fine particles of raw material, and, continuously, at the outlet of the tank a mass of liquid calcium aluminates is recovered.

The present invention relates to apparatus for thermal treatment of a mineral starting material, wherein the apparatus comprises a calciner, wherein the calciner comprises at least a first calciner section and a second calciner section, wherein the first calciner section is arranged vertically, wherein the second calciner section is arranged at an incline, wherein the second calciner section has an angle ? between the horizontal and the flow direction of the second calciner section, wherein the angle ? is between 20? and 80?, wherein the first calciner section has a first hydraulic diameter d.sub.h,1, wherein the second calciner section has a second hydraulic diameter d.sub.h,2, wherein the second hydraulic diameter d.sub.h,2 is less than or equal to the first hydraulic diameter d.sub.h,1 multiplied by the sine of the angle ?.

Disclosed is a method for manufacturing calcium aluminates in an industrial furnace, according to which, continuously, into a tank made of refractory material containing a molten pool that is constantly heated, fine particles are introduced of a raw material source of alumina and/or of aluminium and of a raw material source of calcium oxide and/or of calcium having a median diameter d50 less than or equal to 6,000 m in order to melt the fine particles of raw material, and, continuously, at the outlet of the tank a mass of liquid calcium aluminates is recovered.

A process for preparing dicalcium silicate includes providing a starting material comprising calcium carbonate (CaCO.sub.3) and silicon dioxide (SiO.sub.2), wherein a molar ratio of calcium:silicon (C:S) is from 1.5:1 to 2.5:1. At least one of an inorganic alkali metal salt and an alkaline earth metal salt is added as a mineralizing agent to the starting material in an amount of from 0.5 wt.-% to 20 wt.-%, based on a total weight of the starting material. The starting material is reacted with the mineralizing agent in a gas atmosphere having a CO.sub.2 partial pressure of from 0.05 MPa to 0.2 MPa at a temperature of from 900 C. to 1100 C. so as to obtain a dicalcium silicate product. The dicalcium silicate product comprises a content of an unreacted starting material of <5 wt.-% and a total carbon content of <1.5 wt.-%, each based on a weight of the dicalcium silicate product.

A process for preparing dicalcium silicate includes providing a starting material comprising calcium carbonate (CaCO.sub.3) and silicon dioxide (SiO.sub.2), wherein a molar ratio of calcium:silicon (C:S) is from 1.5:1 to 2.5:1. At least one of an inorganic alkali metal salt and an alkaline earth metal salt is added as a mineralizing agent to the starting material in an amount of from 0.5 wt.-% to 20 wt.-%, based on a total weight of the starting material. The starting material is reacted with the mineralizing agent in a gas atmosphere having a CO.sub.2 partial pressure of from 0.05 MPa to 0.2 MPa at a temperature of from 900 C. to 1100 C. so as to obtain a dicalcium silicate product. The dicalcium silicate product comprises a content of an unreacted starting material of <5 wt.-% and a total carbon content of <1.5 wt.-%, each based on a weight of the dicalcium silicate product.