Inorganic coated sand

A method for manufacturing inorganic coated sand in a dry state, the inorganic coated sand having refractory aggregate and an inorganic binder layer formed on a surface of the refractory aggregate,

• wherein the inorganic binder layer comprises a metasilicate hydrate, and
• wherein amount of the inorganic binder layer to be applied is 0.05 parts by mass or greater and 10 parts by mass or less with respect to 100 parts by mass of the refractory aggregate,
• the method comprising:
• a step (1) of obtaining a mixture by mixing the refractory aggregate with the metasilicate hydrate at a temperature equal to or higher than a melting point of the metasilicate hydrate;
• and
• a step (2) of cooling the mixture to a temperature lower than the melting point of the metasilicate hydrate.

An inorganic coated sand in a dry state, comprising:

• refractory aggregate;
• and
• an inorganic binder layer formed on a surface of the refractory aggregate,
• wherein the inorganic binder layer comprises at least one selected from sodium metasilicate pentahydrate and sodium metasilicate nonahydrate,
• wherein a water content in the inorganic binder layer is 60 parts by mass or greater and 140 parts by mass or less with respect to 100 parts by mass of the metasilicate,
• wherein the refractory aggregate comprises at least one selected from the group consisting of SiO2 and Al2O3,
• wherein amorphous degree of the refractory aggregate is 30% or greater,
• wherein amount of the inorganic binder layer to be applied is 0.05 parts by mass or greater and 10 parts by mass or less with respect to 100 parts by mass of the refractory aggregate, and
• wherein the inorganic coated sand has an average particle diameter of 0.05 mm or greater and 2 mm or less, and a sphericity of 0.80 or greater.