Provided herein are compositions, methods, and systems comprising vaterite and magnesium oxide.

Provided herein are compositions, methods, and systems comprising vaterite and magnesium oxide.

An apparatus for thermally treating mineral solids includes a preheater, a separating apparatus arranged at an outlet of an entrained flow reactor, and a thermal treatment zone at an outlet of a gas stream of the separating apparatus, with an outlet of the treatment zone being connected to an inlet of the preheater for the gas stream. A process may involve preheating a mineral material, thermally treating the mineral material in an entrained flow reactor in a reducing atmosphere for reducing coloring metal compounds, separating a solid/gas mixture from the entrained flow reactor in a separating apparatus, oxidizing reducing constituents of a gas from the separating apparatus in a thermal treatment zone between the separating apparatus and the preheater via supplied oxygen, and supplying gas emerging from the thermal treatment zone to the preheater and thereby utilizing thermal energy recovered in the thermal treatment zone by transfer to mineral material

An apparatus for thermally treating mineral solids includes a preheater, a separating apparatus arranged at an outlet of an entrained flow reactor, and a thermal treatment zone at an outlet of a gas stream of the separating apparatus, with an outlet of the treatment zone being connected to an inlet of the preheater for the gas stream. A process may involve preheating a mineral material, thermally treating the mineral material in an entrained flow reactor in a reducing atmosphere for reducing coloring metal compounds, separating a solid/gas mixture from the entrained flow reactor in a separating apparatus, oxidizing reducing constituents of a gas from the separating apparatus in a thermal treatment zone between the separating apparatus and the preheater via supplied oxygen, and supplying gas emerging from the thermal treatment zone to the preheater and thereby utilizing thermal energy recovered in the thermal treatment zone by transfer to mineral material

Methods of preparing engineered cementitious composite precursors include carbonating a fly ash comprising >about 25% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the fly ash to a first gas stream comprising carbon dioxide to form a carbonated fly ash. A steel slag is also carbonated that comprises>about 40% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the steel slag to a second gas stream comprising carbon dioxide to form a carbonated steel slag. The carbonated fly ash and the carbonated steel slag are suitable for use as engineered cementitious composite precursors in a bendable engineered cementitious composite composition that further comprises Portland cement, a polymeric fiber, and a superplasticizer.

Described are cementitious reagent materials produced from globally abundant inorganic feedstocks. Also described are methods for the manufacture of such cementitious reagent materials and forming the reagent materials as microspheroidal glassy particles. Also described are apparatuses, systems and methods for the thermochemical production of glassy cementitious reagents with spheroidal morphology. The apparatuses, systems and methods make use of an in-flight melting/quenching technology such that solid particles are flown in suspension, melted in suspension, and then quenched in suspension. The cementitious reagents can be used in concrete to substantially reduce the CO.sub.2 emission associated with cement production.

Embodiments described herein relate to capturing and sequestering CO.sub.2 emissions from the cement production process with the potential to produce carbon-negative cement. Methods described herein can include contacting calcium oxide (CaO) with ambient air at a carbonation station to form a first stream of calcium carbonate, combining the first stream of calcium carbonate with a second stream of calcium carbonate in a calciner to form a combined stream of calcium carbonate, and applying heat to the calciner to decompose the combined stream of calcium carbonate into a stream of calcium oxide and a CO.sub.2 stream. The method further includes sequestering the CO.sub.2 stream, dividing the stream of calcium oxide into a first calcium oxide stream and a second calcium oxide stream, feeding the first stream of calcium oxide to the carbonation station, and feeding the second stream of calcium oxide to a kiln to produce a clinker.

A rotary kiln includes a stationary fuel nozzle and a perforated flame holder positioned within an inclined rotating shell. The flame holder includes a plurality of perforations that collectively confine a combustion reaction of the burner to the flame holder to shift most heat transfer from the combustion reaction from radiation heat transfer to convective heat transfer.

The present invention relates to the use of particulate mineral material comprising barite for scavenging heavy metal anions from a liquid medium, wherein the heavy metal anions form water-insoluble barium salts with barium cations of the barite, and wherein the particulate mineral material has a specific surface area of from 0.1 m.sup.2/g to 100 m.sup.2/g, measured using nitrogen sorption and the BET method.

A method for sequestating carbon dioxide from flue gas by using a cement clinker. The products of this method can also be used to prepare microfiber-reinforced cement. The method of the present disclosure is capable of capturing and storing carbon dioxide in flue gas, such as cement kiln flue gas.