Process for producing tobermorite and ettringite

Claim 2

A process for producing ettringite by adding an alkali solution to siliceous material and gypsum material and reacting the mixture at room temperature or hydrothermally, characterized by the steps of: admixing an alumina-containing siliceous material and a lime material with an alkali solution, subjecting the resulting mixture to hydrothermal reaction with water vapor at a pressure of 4 to 40 kg/cm 2 to form tobermorite, filtering off the tobermorite from the reaction mixture, and admixing a lime material and a gypsum material with the resulting alkali reaction product in the filtrate and reacting the mixture at room temperature to a temperature of up to 90° C. to form ettringite.

Claim 3

A process as defined in claim 4 wherein the siliceous material is selected from the group consisting of kaolin, fly ash, terra alba, mica, volcanic ash and granulated blast furnace slag, or a mixture of at least two of said materials.

Claim 4

A process as defined in claim 1 wherein the alkali solution has the concentration of 10 to 200 g of sodium hydroxide in 1 liter of water.

Claim 5

A process as defined in claim 1 wherein the lime material is selected from the group consisting of quick lime, slaked lime and carbide residuum, or a mixture of at least two of said materials.

Claim 6

A process as defined in claim 1 wherein the gypsum material is selected from the group consisting of calcined gypsum, hemihydrate gypsum, gypsum dihydrate and gypsum produced by the desulfurization of exhaust gases, or a mixture of at least two of said gypsum materials.

Claim 7

A process for producing ettringite by adding an alkali solution to siliceous material and gypsum material and reacting the mixture at room temperature or hydrothermally, characterized by the sequential steps of: admixing an alumina-containing siliceous material and a lime material with an alkali solution, subjecting the resulting mixture to hydrothermal reaction with water vapor at a pressure of 4 to 40 kg/cm 2 to form tobermorite, filtering off the tobermorite from the reaction mixture, and admixing a lime material and a gypsum material with the resulting alkali reaction product in the filtrate and reacting the mixture at room temperature to a temperature of up to 90° C. to form ettringite, the process further being characterized by thereafter repeating said sequential steps with addition of the alumina-containing siliceous material and the lime material to a filtrate resulting from said fourth-mentioned step and separated from the ettringite.

Claim 8

A process for producing ettringite by adding an alkali solution to siliceous material and gypsum material and reacting the mixture at room temperature or hydrothermally, characterized by the sequential steps of: admixing an alumina-containing siliceous material and a lime material with an alkali solution, subjecting the resulting mixture to hydrothermal reaction with water vapor at a pressure of 4 to 40 kg/cm 2 to form tobermorite, filtering off the tobermorite from the reaction mixture, and admixing a lime material and a gypsum material with the resulting alkali reaction product in the filtrate and reacting the mixture at room temperature to a temperature of up to 90° C. to form ettringite, the process further being characterized by thereafter repeating said sequential steps with addition of the alumina-containing siliceous material and the lime material to a filtrate resulting from said fourth-mentioned step and separated from the ettringite.

Claim 9

A process for producing ettringite by adding an alkali solution to siliceous material and gypsum material and reacting the mixture at room temperature or hydrothermally, characterized by the steps of: admixing an alumina-containing siliceous material and a lime material with an alkali solution, subjecting the resulting mixture to hydrothermal reaction with water vapor at a pressure of 4 to 40 kg/cm 2 to form tobermorite, and admixing a lime material and a gypsum material with the resulting alkali reaction product in the reaction mixture containing the tobermorite and reacting the mixture at room temperature to a temperature of up to 90° C. to form ettringite.

Claim 10

A process for producing ettringite by adding an alkali solution to siliceous material and gypsum material and reacting the mixture at room temperature or hydrothermally, characterized by the steps of: admixing an alumina-containing siliceous material and a lime material with an alkali solution, subjecting the resulting mixture to hydrothermal reaction with water vapor at a pressure of 4 to 40 kg/cm 2 to form tobermorite, and admixing a lime material and a gypsum material with the resulting alkali reaction product in the reaction mixture containing the tobermorite and reacting the mixture at room temperature to a temperature of up to 90° C. to form ettringite.