A method and system for producing nano-active powder materials. The method can be used with a reactor system comprising stages in which input particles flow under gravity progressively through stages of the reactor. A powder injector first stage in which ground input precursor powder is injected into the reactor. An externally heated preheater stage may be in the reactor, in which the precursor powder is heated to a temperature of calcination reaction. An externally heated calciner stage in the reactor, in which primary precursor volatile constituents can be rapidly removed calcination reactions as a high purity gas stream to produce the desired nano-active product. A post-processing reactor stage in which there is a change of the gas stream composition to produce the desired hot powder product by virtue of the nano-activity of the first powder material. A powder ejector stage in which the hot powder product is ejected from the reactor.

Cement and concrete compositions are produced via metal hydroxides and metal oxides isolated from aqueous sources such as seawater or wastewater. Aqueous solutions are electrolyzed to produce an alkaline component stream having an elevated pH, which when mixed with mineralized seawater causes metal ions dissolved therein to precipitate out in the form of metal hydroxides such as Mg(OH).sub.2 and Ca(OH).sub.2. These metal hydroxide products are then utilized as feedstocks for production of cement and concrete structural elements, or are converted to metal oxides suitable for the same purpose. The hydroxide products are then subjected to pressure and prolonged exposure to carbon dioxide to accelerate carbonation of the hydrated product. The resulting carbonates exhibit sufficient compressive strength for use in making structural components for construction, while reducing or eliminating the carbon footprint associated with traditional methods of cement and concrete manufacturing. Excess demineralized alkaline component can be recycled for additional electrolysis, or returned to a neutral pH for use in water desalination processes or even returned to the environment.

Disclosed are a method for separately preparing light magnesium oxide and calcium oxide by using dolomite and an application thereof in preparation of a calcium-magnesium composite expanding agent. In the method for preparing light magnesium oxide and calcium oxide, based on the difference in decomposition temperature between magnesium carbonate and calcium carbonate during the calcination and decomposition of dolomite and the difference in the weight of the materials after decomposition, the effective separation of magnesium oxide and calcium oxide is realized by a one-step method, thus separately preparing light magnesium oxide and light calcium oxide. The calcium-magnesium composite expanding agent is prepared by using the foregoing light magnesium oxide and calcium oxide. On the one hand, the present invention solves the problem of the limited origin of the light magnesium oxide raw material of the magnesium expanding component in the calcium-magnesium composite expanding agent.

A process for producing a highly calcined and uniformly calcined product from a feedstock. The process comprising the steps of grinding the feedstock to powder, preheating the powder, and calcining the powder in a reactor plant that comprises a number of reactor segments in which a flash calciner is used in each progressive reactor segment to incrementally react the powder by raising the temperature in each segment. The last segment may be a high-temperature reactor that has a controlled residence time and temperature that may allow controlled finishing of the calcination process to achieve a desired degree of calcination and sintering of the product; and cooling of the product.

The present disclosure relates to a process for the decarbonation of limestone, dolomite or other carbonated materials. The process may include heating particles of carbonated materials in a reactor of a first circuit to obtain decarbonated particles. Particles of carbonated materials are conveyed by a first entraining gas in the first circuit for preheating. The gas includes the carbon dioxide, the gas composition being substantially free of nitrogen. The carbonated particles are separated from a first entraining gas flow. The decarbonated particles are transferred to a cooling section of a second circuit having a second entraining gas in which the conveyed decarbonated particles release a portion of their thermal energy. The decarbonated particles are separated from a second entraining gas flow. The second entraining gas is substantially free of carbon dioxide.

An apparatus for production of burnt lime or dolomite has: a shaft furnace having a preheating zone, a reaction zone, a separation zone and a cooling zone; a first feed apparatus for CO.sub.2 at the boundary of the separation zone to the reaction zone; a first removal apparatus at the boundary of the cooling zone to the separation zone; a second removal apparatus for CO.sub.2 at the start of the preheating zone; and at least one heating apparatus, wherein the heating apparatus has a regenerator system.

The regenerator system has at least two regenerators, a preheater, a feed for fuel and a feed for fresh air; the second removal apparatus opens into the at least one heating apparatus; and the first feed apparatus is formed by the at least one heating apparatus for the shaft furnace.

A method and system for producing nano-active powder materials. The method can be used with a reactor system comprising stages in which input particles flow under gravity progressively through stages of the reactor. A powder injector first stage in which ground input precursor powder is injected into the reactor. An externally heated preheater stage may be in the reactor, in which the precursor powder is heated to a temperature of calcination reaction. An externally heated calciner stage in the reactor, in which primary precursor volatile constituents can be rapidly removed calcination reactions as a high purity gas stream to produce the desired nano-active product. A post-processing reactor stage in which there is a change of the gas stream composition to produce the desired hot powder product by virtue of the nano-activity of the first powder material. A powder ejector stage in which the hot powder product is ejected from the reactor.

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 mineral composition made from a mixed solid phase of calcium and magnesium carbonates, method of preparing same and use thereof. A mineral composition made from a mixed solid phase of calcium and magnesium carbonates, formed from a crystallized calcium portion and a crystallized magnesium portion in the form of platelets, the crystals of the calcium portion and those of the magnesium portion being aggregated in the form of composite aggregates, said aggregates themselves being at least partially agglomerated, said calcium portion comprising at least one carbonate chosen from the group consisting of calcite, aragonite and the mixtures thereof, said magnesium portion comprising hydromagnesite in platelet form, said mixed solid phase having a bulk density less than or equal to 250 kg/m.sup.3, and greater than or equal to 80 kg/m3, measured according to standard EN 459.2.