A method for producing lime or dolime, which includes a calcination step for the calcination of calcareous or dolomitic material which is brought into contact with the first fumes which are obtained by combustion of fuel with an oxidizing gas, a cooling of calcined lime or dolime with discharge and collection thereof and a release of a gaseous effluent containing CO.sub.2. Subsequent processing steps result in the formation of a CaO-based sorbent material with separation between the CaO-based sorbent material and a CO.sub.2-concentrated gas stream which is collected. The recycling of said separated CaO-based sorbent material is recycled into a CO.sub.2 depletion step resulting in the extraction of a valorizable fraction of the CaCO.sub.3CaO based charge with a compensatory introduction of fresh CaCO.sub.3 in the calcination step.

A process for producing caustic calcined magnesia (CCM) includes calcining a magnesium containing material, such as magnesite, in a primary calciner to produce a primary calcined material and a primary exhaust comprising dust; subjecting the primary exhaust to separation to recover a dust material includes incompletely calcined dust particles; calcining the dust material in the secondary calciner to produce calcined dust, wherein the dust material is not co-calcined with the magnesium containing material or the primary calcined material. The primary calcined material and the calcined dues thus form two CCM products, which can be kept separate or combined. The primary calciner can be a multiple hearth furnace (MHF) while the secondary calciner can be a gas suspension calciner (GSC). Using a secondary calciner in such a manner can increase throughput of the primary calciner and provide other advantages for the calcination process.

A process and apparatus for manufacture of oxide products for use as biocide, chemical detoxifying, and catalytic support products, from caustic calcined carbonate powder, preferably from magnesite, dolomite, or hydromagnesite, is described. These oxide particles are characterized by high surface area, high porosity and a high degree of calcination, and the method of manufacture utilizes an indirectly heated counterflow reactor. The oxides may be used as a powder, granules, or formulated into a slurry and used as a spray, emulsion, foam or fog, or the powder product may be directly applied. Also described is the formation of particles with microstructures defined by at least one nano-crystalline structure positioned on the outer surface of the particles.

The present invention provides a process for producing high purity hydromagnesite from a source of magnesium chloride. The process involves preparation of a magnesium chloride brine of a specific concentration and reacting with sodium carbonate, while maintaining the reaction at a specific temperature range to form a hydromagnesite precipitate. The product can be calcined to generate high purity magnesium oxide compounds.

The present invention provides a process for producing high purity hydromagnesite from a source of magnesium chloride. The process involves preparation of a magnesium chloride brine of a specific concentration, which is ammoniated at a specific temperature range, followed by carbonation, while maintaining the reaction at a specific temperature range to form a hydromagnesite precipitate. The product can be calcined to generate high purity magnesium oxide compounds.

A process and apparatus for manufacture of oxide products for use as biocide, chemical detoxifying, and catalytic support products, from caustic calcined carbonate powder, preferably from magnesite, dolomite, or hydromagnesite, is described. These oxide particles are characterized by high surface area, high porosity and a high degree of calcination, and the method of manufacture of utilizes an indirectly heated counterflow reactor. The oxides may be used as a powder, granules, or formulated into a slurry and used as a spray, emulsion, foam or fog, or the powder product may be directly applied. Also described is the formation of particles with microstructures defined by at least one nano-crystalline structure positioned on the outer surface of the particles.

Methods for forming concrete mixed having improved crack resistance are provided. According to one embodiment, the method may include providing a shrinkage reduction admixture. The method may also include providing a shrinkage compensating additive. The method may also include providing concrete solids. The method may further include mixing the shrinkage reduction admixture, the shrinkage compensating additive, and the concrete solids.

Methods for forming concrete mixed having improved crack resistance are provided. According to one embodiment, the method may include providing a shrinkage reduction admixture. The method may also include providing a shrinkage compensating additive. The method may also include providing concrete solids. The method may further include mixing the shrinkage reduction admixture, the shrinkage compensating additive, and the concrete solids.