The additive composition of the present invention is one blended in a sand composition which is subjected to foaming to mold a sand mold, and includes (A) an alkylsulfonate metal salt having an alkyl group with 9 to 22 carbon atoms. The additive composition may further include at least one component selected from a group consisting of (B) an alkylsulfate metal salt, (C) a polyoxyalkylene alkyl ether sulfate metal salt, and (D) an alkylbenzene sulfonate metal salt.

There is provided a binder for molding a casting mold, which contains water glass and aluminum silicate obtained by carrying out dissolution in the water glass, where the binder for molding a casting mold contains 2 to 15 parts by mass of the aluminum silicate with respect to 100 parts by mass of a solid content of the water glass.

[Task] There is provided a mold release agent for forming a water glass-containing sand mold with high release properties which can prevent attachment of a water glass to a flask and the accumulation of the water glass on the flask in the formation of the sand mold when using the water glass as a binder. [Solution] The mold release agent for forming the water glass-containing sand mold is structured to contain an organic compound, the organic compound having a proton-donating functional group that reacts with the water glass to produce silicon dioxide. The water glass contained in a raw material for the sand mold reacts with the proton-donating functional group contained in the mold release agent so as to produce silicon dioxide. Since silicon dioxide has no adhesion, it can prevent that the attachment (fixing) of the water glass contained in a formed sand mold to the flask and the accumulation of the water glass on the flask.

A method of reusing core sand includes: crushing a core used for casting into granules; heating the granules at a temperature of 300 C. to 550 C.; causing the heated granules to collide against each other such that water glass used as a binder detaches from the core sand; and blowing air into a mixture of the water glass and the core sand, which are detached from each other, such that the core sand is separated and collected from the mixture due to a difference in specific gravity between the water glass and the core sand.

Purposes of the present invention are to provide a dry coated sand having a high degree of fluidity at the room temperature, a method of advantageously producing the coated sand, and a method of producing a casting mold having excellent properties, by using the coated sand. The dry coated sand is obtained by mixing an aqueous solution of a water glass used as a binder, with a heated refractory aggregate, whereby water in the aqueous solution is evaporated, and a coating layer of the binder is formed on surfaces of the refractory aggregate. A moisture percentage in the thus obtained dry coated sand is controlled so as to be not more than 0.5% by mass. The intended casting mold is obtained by filling a molding cavity of a forming mold, with the dry coated sand, and passing a steam through the coated sand, to solidify or cure the coated sand.

The disclosure concerns printable refractory compositions, more particularly ceramic-based pastes for 3D printing of molds for additive metal casting. In particular, the present disclosure concerns composition for forming mold regions having controlled thermal conductivity and dissipation and controlled release of gaseous products therefrom during heating to mitigate mechanical failure risks in an additive casting process of metal objects.

A molding method of molding a mold for producing iron castings includes generating mixed sand using engineered sand as an aggregate and a binder, filling the mold with the mixed sand, and solidifying the mixed sand filled in the mold.