The present invention describes an integrated process for carbon dioxide capture, sequestration and utilisation, which comprises: a) providing an aqueous slurry comprising an aqueous solution and a particulate solid comprising an activated magnesium silicate mineral; b) in a dissolution stage, contacting a CO.sub.2-containing gas stream with the aqueous slurry to dissolve magnesium from the mineral to provide a magnesium ion enriched aqueous solution and a magnesium depleted solid residue; c) recovering at least a portion of the magnesium depleted solid residue; d) in a separate acid treatment stage, reacting the recovered portion of the magnesium depleted solid residue with a solution comprising a mineral acid or acid salt to further dissolve magnesium and other metals and to provide an acid-treated solid residue; e) recovering the acid-treated solid residue; and f) in a separate precipitation stage, precipitating magnesium carbonate from the magnesium ion enriched aqueous solution.

The present invention describes an integrated process for carbon dioxide capture, sequestration and utilisation, which comprises: a) providing an aqueous slurry comprising an aqueous solution and a particulate solid comprising an activated magnesium silicate mineral; b) in a dissolution stage, contacting a CO.sub.2-containing gas stream with the aqueous slurry to dissolve magnesium from the mineral to provide a magnesium ion enriched aqueous solution and a magnesium depleted solid residue; c) recovering at least a portion of the magnesium depleted solid residue; d) in a separate acid treatment stage, reacting the recovered portion of the magnesium depleted solid residue with a solution comprising a mineral acid or acid salt to further dissolve magnesium and other metals and to provide an acid-treated solid residue; e) recovering the acid-treated solid residue; and f) in a separate precipitation stage, precipitating magnesium carbonate from the magnesium ion enriched aqueous solution.

A method/system for sequestering carbon dioxide from cement and lime production facilities wherein carbon dioxide from flue gases originating from cement or lime production facilities is recovered and transported to a building materials production facility where it is sequestered.

A method/system for sequestering carbon dioxide from cement and lime production facilities wherein carbon dioxide from flue gases originating from cement or lime production facilities is recovered and transported to a building materials production facility where it is sequestered.

Embodiments of the present disclosure are directed to systems and methods of removing carbon dioxide from a gaseous stream using magnesium hydroxide and then regenerating the magnesium hydroxide. In some embodiments, the systems and methods can further comprise using the waste heat from one or more gas streams to provide some or all of the heat needed to drive the reactions. In some embodiments, magnesium chloride is primarily in the form of magnesium chloride dihydrate and is fed to a decomposition reactor to generate magnesium hydroxychloride, which is in turn fed to a second decomposition reactor to generate magnesium hydroxide.

Embodiments of the present disclosure are directed to systems and methods of removing carbon dioxide from a gaseous stream using magnesium hydroxide and then regenerating the magnesium hydroxide. In some embodiments, the systems and methods can further comprise using the waste heat from one or more gas streams to provide some or all of the heat needed to drive the reactions. In some embodiments, magnesium chloride is primarily in the form of magnesium chloride dihydrate and is fed to a decomposition reactor to generate magnesium hydroxychloride, which is in turn fed to a second decomposition reactor to generate magnesium hydroxide.

An efficient low-energy carbon dioxide removal system comprises an automated air mover equipped with sensing devices to measure flow rate, volume, level, pressure, temperature and concentration. Packing materials and air-liquid distributors are used in a multi-stage catalytic reactor. The multi-stage catalytic reactor processes ambient air and generates pure carbon dioxide gas and generates exhausted gas released to ambient air. In operation, air contacts the base solution in the presence of a catalyst via the air mover, distributor, and packing materials. The air reacts with the base solution thereby generating a base solution having carbon dioxide and generating exhaust (absorption reaction). Next, the exhaust is released from the reactor. Next, a catalyst is added, heat is applied to the base solution having carbon dioxide thereby generating carbon dioxide and generating a base solution without carbon dioxide (desorption reaction).

An efficient low-energy carbon dioxide removal system comprises an automated air mover equipped with sensing devices to measure flow rate, volume, level, pressure, temperature and concentration. Packing materials and air-liquid distributors are used in a multi-stage catalytic reactor. The multi-stage catalytic reactor processes ambient air and generates pure carbon dioxide gas and generates exhausted gas released to ambient air. In operation, air contacts the base solution in the presence of a catalyst via the air mover, distributor, and packing materials. The air reacts with the base solution thereby generating a base solution having carbon dioxide and generating exhaust (absorption reaction). Next, the exhaust is released from the reactor. Next, a catalyst is added, heat is applied to the base solution having carbon dioxide thereby generating carbon dioxide and generating a base solution without carbon dioxide (desorption reaction).

Apparatus and methods for treating acid gas, which utilizes multi-stage absorption cycle of ammonia desulfurization to treat acid tail gas after pre-treatment of the acid gas, thereby achieving the purpose of efficient and low-cost treatment of acid tail gas. The parameters of the acid tail gas may be adjusted by a regulatory system such that the enthalpy value of the acid tail gas is in the range of 60-850 kJ/kg dry gas, for example, 80-680 kJ/kg dry gas or 100-450 kJ/kg dry gas, to meet the requirements of ammonia desulfurization, and achieve the synergy between the acid gas pre-treatment and ammonia desulfurization. Furthermore, hydrogen sulfide may be converted into sulfur/sulfuric acid plus ammonium sulfate at an adjustable ratio.

Apparatus and methods for treating acid gas, which utilizes multi-stage absorption cycle of ammonia desulfurization to treat acid tail gas after pre-treatment of the acid gas, thereby achieving the purpose of efficient and low-cost treatment of acid tail gas. The parameters of the acid tail gas may be adjusted by a regulatory system such that the enthalpy value of the acid tail gas is in the range of 60-850 kJ/kg dry gas, for example, 80-680 kJ/kg dry gas or 100-450 kJ/kg dry gas, to meet the requirements of ammonia desulfurization, and achieve the synergy between the acid gas pre-treatment and ammonia desulfurization. Furthermore, hydrogen sulfide may be converted into sulfur/sulfuric acid plus ammonium sulfate at an adjustable ratio.