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

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

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

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

The present disclosure discloses a novel magnesium phosphate-alkali activated composite cementitious material with rapid hardening, early strength, and high water resistance and a preparation method thereof. The composite cementitious material is a mixture system of a magnesium phosphate cementitious material interweaving and coexisting with an alkali-activated cementitious material, where the alkali-activated cementitious material is prepared by alkali activation of an activatable mineral using a hydration product of a high-alkalinity magnesium phosphate cementitious material prepared from an alkaline hydrophosphate. The composite cementitious material obtained ensures excellent mechanical properties while actively converting part of or all of air-hardening material components into a hydraulic material, so that the problem of poor water resistance of the magnesium phosphate cementitious material can be effectively solved.

The present disclosure discloses a novel magnesium phosphate-alkali activated composite cementitious material with rapid hardening, early strength, and high water resistance and a preparation method thereof. The composite cementitious material is a mixture system of a magnesium phosphate cementitious material interweaving and coexisting with an alkali-activated cementitious material, where the alkali-activated cementitious material is prepared by alkali activation of an activatable mineral using a hydration product of a high-alkalinity magnesium phosphate cementitious material prepared from an alkaline hydrophosphate. The composite cementitious material obtained ensures excellent mechanical properties while actively converting part of or all of air-hardening material components into a hydraulic material, so that the problem of poor water resistance of the magnesium phosphate cementitious material can be effectively solved.

Disclosed is a magnesium-based cementitious material, preparation method and application thereof. The magnesium-based cementitious material, comprising magnesite, sandstone, and water, wherein: the magnesite is provided with CaO, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, and MgO, a mass percentage of the CaO is less than 5%, a mass percentage of SiO.sub.2 is less than 5%, a mass percentage of Al.sub.2O.sub.3 is less than 5%, a mass percentage of Fe.sub.2O.sub.3 is less than 7%, a mass percentage of MgO is between 37% and 50%; the sandstone is provided with SiO.sub.2, CaO, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3, a mass percentage of SiO.sub.2 is greater than 70%. The beneficial effects of this disclosure are: the cementitious material does not contain MgCl.sub.2, which avoids the reduction of the strength of the cementitious material due to the dissolution of MgCl.sub.2 in water; the magnesium-based cementitious material of this disclosure is immiscible with water and has strong water resistance.

Disclosed is a magnesium-based cementitious material, preparation method and application thereof. The magnesium-based cementitious material, comprising magnesite, sandstone, and water, wherein: the magnesite is provided with CaO, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, and MgO, a mass percentage of the CaO is less than 5%, a mass percentage of SiO.sub.2 is less than 5%, a mass percentage of Al.sub.2O.sub.3 is less than 5%, a mass percentage of Fe.sub.2O.sub.3 is less than 7%, a mass percentage of MgO is between 37% and 50%; the sandstone is provided with SiO.sub.2, CaO, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3, a mass percentage of SiO.sub.2 is greater than 70%. The beneficial effects of this disclosure are: the cementitious material does not contain MgCl.sub.2, which avoids the reduction of the strength of the cementitious material due to the dissolution of MgCl.sub.2 in water; the magnesium-based cementitious material of this disclosure is immiscible with water and has strong water resistance.

Methods of processing magnesium silicate materials are described to produce a number of products including magnesium hydroxide. Related methods of use of processed magnesium silicate and other reaction products are described for energy production, cement manufacture and carbon sequestration. In one embodiment the method comprises subjecting a magnesium silicate source to an acid digestion; increasing the digested liquid pH to produce a magnesium salt solution; subjecting the magnesium salt solution to electrolysis; and recovering magnesium hydroxide produced from electrolysis. By-products such as silica, iron oxy(oxides) and others are also described along with further reaction products such as magnesium oxide and magnesium carbonate.

Methods of processing magnesium silicate materials are described to produce a number of products including magnesium hydroxide. Related methods of use of processed magnesium silicate and other reaction products are described for energy production, cement manufacture and carbon sequestration. In one embodiment the method comprises subjecting a magnesium silicate source to an acid digestion; increasing the digested liquid pH to produce a magnesium salt solution; subjecting the magnesium salt solution to electrolysis; and recovering magnesium hydroxide produced from electrolysis. By-products such as silica, iron oxy(oxides) and others are also described along with further reaction products such as magnesium oxide and magnesium carbonate.