A method of utilizing construction and demolition waste is disclosed. The method comprises pretreating the construction and demolition waste into particles with a predetermined range of size; and obtaining calcium carbonate from the particles. The method of the present invention enables to recycle a wide range of construction and demolition waste, furthermore it can convert these waste materials into the high purity calcium carbonate which can be widely used in many applications.

This invention is about calcium oxide. The invention relates more particularly to obtaining the calcium oxide with high purity and on the implementation.

This invention is about calcium oxide. The invention relates more particularly to obtaining the calcium oxide with high purity and on the implementation.

Provided herein are methods comprising a) calcining limestone in a cement plant to form carbon dioxide and calcium compound selected from calcium oxide, calcium hydroxide, or combination thereof; b) treating the calcium compound with N-containing salt in water to produce an aqueous solution comprising calcium salt and N-containing salt; and c) contacting the aqueous solution with the carbon dioxide under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant aqueous solution wherein the calcium carbonate comprises vaterite.

Provided herein are methods comprising a) calcining limestone in a cement plant to form carbon dioxide and calcium compound selected from calcium oxide, calcium hydroxide, or combination thereof; b) treating the calcium compound with N-containing salt in water to produce an aqueous solution comprising calcium salt and N-containing salt; and c) contacting the aqueous solution with the carbon dioxide under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant aqueous solution wherein the calcium carbonate comprises vaterite.

The disclosure discloses a method for preparing calcium oxide using multistage suspension preheater kiln. The steps of the method are: (1) the limestone powder is fed to the multistage suspension preheater kiln for preheating to 800 C. to 900 C.; (2) A preheated material is fed to a decomposition furnace, and calcined at 900 C. to 1100 C. for 25 s to 35 s; (3) A calcined material is fed to a rotary kiln, and calcined at 1100 C. to 1300 C. for 25 to 35 minutes, and finally cooled to obtain calcium oxide.

The disclosure discloses a method for preparing calcium oxide using multistage suspension preheater kiln. The steps of the method are: (1) the limestone powder is fed to the multistage suspension preheater kiln for preheating to 800 C. to 900 C.; (2) A preheated material is fed to a decomposition furnace, and calcined at 900 C. to 1100 C. for 25 s to 35 s; (3) A calcined material is fed to a rotary kiln, and calcined at 1100 C. to 1300 C. for 25 to 35 minutes, and finally cooled to obtain calcium oxide.

The present application pertains to methods for making metal oxides and/or citric acid. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.

The present application pertains to methods for making metal oxides and/or citric acid. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.

Provided is a method of preparing an activated mineral solution, which includes steps of pulverizing granite and/or vermiculite into a powder by grinding, subjecting the powder to an electrolysis treatment, dissolving the powder in an aqueous ammonia solution and an acidic solution to prepare a mixed solution, emitting ultrasonic waves on the mixed solution, introducing microorganisms onto the mixed solution, and neutralizing the mixed solution, in which the mineral is selected from the group consisting of Fe, Mg, Al, Ti, K, Ca, Mn, Nb, P, Na, Zn, V, Cr, Ni, Si, B, Cu, Li, Ga, Co, Sr, In, Rb, Sb, Ta, Y, and combinations thereof.