The present disclosure relates to a method of generating high-purity hydrogen from waste plastic without producing carbon dioxide. In the method of generating hydrogen according to the embodiments of the present disclosure, reactants include hydroxide, and thus, the amount and purity of the generated hydrogen increases, a reaction temperature suitable for reaching an appropriate hydrogen production rate is lowered, and the amount of generated carbon dioxide is significantly decreased.

The present application pertains to processes producing oxides using a weak acid intermediate. In one embodiment a material comprising calcium carbonate is reacted with a solution comprising aqueous carboxylic acid to form a gas comprising carbon dioxide and a solution comprising aqueous calcium carboxylate. The solution comprising aqueous calcium carboxylate is reacted with sodium sulfate to form a solution comprising aqueous sodium carboxylate and a solid comprising calcium sulfate. The solution comprising aqueous sodium carboxylate is reacted with sulfur dioxide to form sodium sulfite and an aqueous carboxylic acid. The sodium sulfite is separated from said aqueous carboxylic acid and reacted to form a solid comprising calcium sulfite which is decomposed to form calcium oxide and sulfur dioxide.

Techniques are described for chemical sequestration of carbon dioxide and production of precipitated magnesium carbonate. The process can include contacting carbon dioxide from industrial emissions with water and magnesium-containing particulate material, such as serpentinite, which is thermally pre-treated and has a particle size of at most 75 microns. The process can also include separation of the loaded aqueous stream from the solids, followed by precipitation of magnesium carbonate material that includes carbon and oxygen from industrial emissions and magnesium from serpentinite or chrysotile mining residue, for example.

The invention provides a method for the production of a composite comprising microfibrillated cellulose (MFC) and precipitated calcium carbonate. The method is characterized in that MFC is added to a suspension of calcium hydroxide during carbonation, whereby calcium carbonate is precipitated onto fibers or fibrils of the MFC in a controlled manner. By adding microfibrillated cellulose to the calcium suspension during the carbonation, the brightness and the strength of the MFC/PCC-composite is enhanced. Moreover, the inventive method facilitates the distribution of calcium dioxide and MFC in the suspension and thus gives rise to a more homogenous product.

The present invention provides a method for integrated utilization of a calcium chloride solution and CO.sub.2. In this method, with the calcium chloride solution and the CO.sub.2 being taken as raw materials, a water-soluble amine is added as an auxiliary agent to promote the occurrence of a mineralization reaction. As a result of crystallization following the reaction, calcium carbonate and a solution of a hydrochloride of the water-soluble amine are obtained. After the reaction is completed, the water-soluble amine is regenerated by subjecting a liquid phase resulting from separation to bipolar membrane electrodialysis, and dilute hydrochloric acid is obtained as a by-product at the same time. The method provides a novel perspective and approach to integrated utilization of calcium chloride-containing liquid waste and flue gas CO.sub.2. The water-soluble amine allows excellent mineralization, and the bipolar membrane electrodialysis enables excellent regeneration of the amine. By means of process regulation, a calcium carbonate product of high value with controlled morphology and particle size can be obtained. For applications equipped with a lime kiln and allowing recycling of calcium carbonate, such as the ammonia-soda industry, the present invention also provides a combined cycle process for carbon and calcium resources, in which calcium carbonate produced by a mineralization reaction is calcined in lieu of limestone used in the soda production process to provide the soda production process with CO.sub.2 and milk of lime, enabling recycling of carbon and calcium resources in an ammonia soda plant. The entire process is free of waste discharge, showing a promising prospect of application. It is of great significance to the fields of calcium chloride-containing liquid waste disposal and carbon emission reduction.

The present disclosure relates to a method for producing calcium carbonate solids from alkaline minerals including the following method steps: Supplying alkaline minerals and an extraction agent into a reactor tank. Stirring the alkaline minerals and the extraction agent in the reactor tank such that a first suspension is formed. Draining of the first suspension from the reactor tank and separating a liquid phase comprising calcium from the first suspension and transferring the liquid phase into a carbonation tank. Supplying a gas comprising CO2 into the carbonation tank, wherein the consumption of CO2 results in the precipitation of calcium carbonate solids thereby generating a second suspension and nucleating and growing of the calcium carbonate solids. Furthermore, a measure of the consumed CO2 is determined by at least one sensor.

The present application pertains to processes producing oxides using a weak acid intermediate. In one embodiment a material comprising calcium carbonate is reacted with a solution comprising aqueous carboxylic acid to form a gas comprising carbon dioxide and a solution comprising aqueous calcium carboxylate. The solution comprising aqueous calcium carboxylate is reacted with sodium sulfate to form a solution comprising aqueous sodium carboxylate and a solid comprising calcium sulfate. The solution comprising aqueous sodium carboxylate is reacted with sulfur dioxide to form sodium sulfite and an aqueous carboxylic acid. The sodium sulfite is separated from said aqueous carboxylic acid and reacted to form a solid comprising calcium sulfite which is decomposed to form calcium oxide and sulfur dioxide.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

Techniques are described for chemical sequestration of carbon dioxide and production of precipitated magnesium carbonate. The process can include contacting carbon dioxide from industrial emissions with water and magnesium-containing particulate material, such as serpentinite, which is thermally pre-treated and has a particle size of at most 75 microns. The process can also include separation of the loaded aqueous stream from the solids, followed by precipitation of magnesium carbonate material that includes carbon and oxygen from industrial emissions and magnesium from serpentinite or chrysotile mining residue, for example.

The present invention aims to provide techniques for preparing complexes of calcium phosphate particles and a fiber. According to the present invention, complexes of calcium phosphate particles and a fiber are provided. According to the present invention, calcium phosphate-fiber complexes in which titanium is retained can be further obtained.