The present invention describes a hydraulic cement composition, process and use thereof, wherein the composition comprises a hydraulic cement composition with increased resistance against carbon dioxide (CO.sub.2) for application in reservoirs such as oil and gas and carbon capture and storage (CCS) wells; with improved performance of cement paste formulations as a material for application in primary, secondary cementing, recovery and/or plugging operations, of reservoirs/wells that operate with high CO.sub.2 content; as a technological alternative to guarantee the integrity of wells in CO.sub.2-rich environments for long periods of time, without any additional intervention to the already current operational procedures for cementing wells, and with cost reduction in relation to class G cement (currently, the main raw material); and sufficient chemical resistance to carry out enhanced oil (EOR) and gas (EGR) recovery by injecting high levels of CO.sub.2, increasing reservoir pressure throughout the extraction period of hydrocarbon reservoirs.

The present invention describes a hydraulic cement composition, process and use thereof, wherein the composition comprises a hydraulic cement composition with increased resistance against carbon dioxide (CO.sub.2) for application in reservoirs such as oil and gas and carbon capture and storage (CCS) wells; with improved performance of cement paste formulations as a material for application in primary, secondary cementing, recovery and/or plugging operations, of reservoirs/wells that operate with high CO.sub.2 content; as a technological alternative to guarantee the integrity of wells in CO.sub.2-rich environments for long periods of time, without any additional intervention to the already current operational procedures for cementing wells, and with cost reduction in relation to class G cement (currently, the main raw material); and sufficient chemical resistance to carry out enhanced oil (EOR) and gas (EGR) recovery by injecting high levels of CO.sub.2, increasing reservoir pressure throughout the extraction period of hydrocarbon reservoirs.

A method for separating hydrated concrete paste from aggregate includes the steps of providing a feedstock comprising waste concrete with a D10?0.1 mm and a D90?100 mm, passing the feedstock, a water containing liquid and carbon dioxide into a fragmentation vessel, where the wet feedstock is subjected to electric-pulse fragmentation, withdrawing fragmented solid material from the fragmentation vessel, separating the fragmented solid material from admixed liquid phase, separating the fragmented solid material into a fine fraction with a maximum particle size of 250 ?m to provide the carbonated recycled concrete paste and a coarse fraction, recycling the coarse fraction into the fragmentation vessel and/or discharging the coarse fraction as clean aggregate, use of the recycled concrete paste obtained thereby as supplementary cementitious material or filler.

A method for separating hydrated concrete paste from aggregate includes the steps of providing a feedstock comprising waste concrete with a D10?0.1 mm and a D90?100 mm, passing the feedstock, a water containing liquid and carbon dioxide into a fragmentation vessel, where the wet feedstock is subjected to electric-pulse fragmentation, withdrawing fragmented solid material from the fragmentation vessel, separating the fragmented solid material from admixed liquid phase, separating the fragmented solid material into a fine fraction with a maximum particle size of 250 ?m to provide the carbonated recycled concrete paste and a coarse fraction, recycling the coarse fraction into the fragmentation vessel and/or discharging the coarse fraction as clean aggregate, use of the recycled concrete paste obtained thereby as supplementary cementitious material or filler.

The invention discloses an in-situ high-strength gradient carbonized material and the preparation method thereof. The in-situ high-strength gradient carbonized material includes a core structure composed of partially calcined calcium carbonate and a shell structure; the shell structure comprises calcium hydroxide and calcium carbonate and covers the outer layer of partially calcined limestone. The invention utilizes an in-situ carbonization reaction to recycle a large amount of low-grade limestone stored or discarded in industry, providing a new technological route for solid waste disposal and resource utilization; this method not only has a green and low-carbon process but also can be widely applied in carbon dioxide capture/collection technology, as well as the preparation of new low-carbon gel materials and concrete.

The invention discloses an in-situ high-strength gradient carbonized material and the preparation method thereof. The in-situ high-strength gradient carbonized material includes a core structure composed of partially calcined calcium carbonate and a shell structure; the shell structure comprises calcium hydroxide and calcium carbonate and covers the outer layer of partially calcined limestone. The invention utilizes an in-situ carbonization reaction to recycle a large amount of low-grade limestone stored or discarded in industry, providing a new technological route for solid waste disposal and resource utilization; this method not only has a green and low-carbon process but also can be widely applied in carbon dioxide capture/collection technology, as well as the preparation of new low-carbon gel materials and concrete.

A process for producing a pozzolan from a starting material. The starting material is size-reduced and incorporated into an aqueous slurry. The size-reduction can be carried out before or after incorporation into the aqueous slurry. Pressurized gas containing carbon dioxide is supplied to the aqueous slurry, and the aqueous slurry is mixed in the presence of the pressurized gas for a treatment period.

A process for producing a pozzolan from a starting material. The starting material is size-reduced and incorporated into an aqueous slurry. The size-reduction can be carried out before or after incorporation into the aqueous slurry. Pressurized gas containing carbon dioxide is supplied to the aqueous slurry, and the aqueous slurry is mixed in the presence of the pressurized gas for a treatment period.

The invention relates to a method of producing a binder comprising the steps of preparing (20) a residual material comprising amorphous alumina-rich and/or aluminium hydroxide-rich constituents, heating (30) the residual material to produce a fired material, the heating (30) of the residual material being at a temperature of >800 C.

The invention relates to a method of producing a binder comprising the steps of preparing (20) a residual material comprising amorphous alumina-rich and/or aluminium hydroxide-rich constituents, heating (30) the residual material to produce a fired material, the heating (30) of the residual material being at a temperature of >800 C.