| 摘要 |
PURPOSE:To obtain a light weight spherical gypsum having a homogeneous and fracture-free crystal by the procedure in which gypsum is heated with stirring in an aqueous solvent in the presence of the bubbles of air or N2 introduced. CONSTITUTION:A spherical gypsum consisting of fibrous hemihydrate gypsum is manufactured by heating with stirring an aqueous solution of dihydrate (or hemihydrate) gypsum or soluble anhydrous gypsum, containing an acid, e.g., acetic acid, hydrochloric acid, etc., and a water-soluble organic substance, e.g., ethylene glycol, glycerine, etc., under the conditions: the inclusion of air or N2 together with an air entrainer or a foaming agent, e.g., saponin, soap, etc., and hydrothermal reaction at 100-180 deg.C for 1-90min, preferably 105-140 deg.C for 3- 60min. Thus, a light weight, homogeneous, and spherical gypsum having a diameter of 0.01-10mm, usually 0.05-1mm, and a bulk density of 0.01-0.1g/cm<2> can be obtained. And, the gypsum can be used in the manufacture of a light weight gypsum hardened material which is excellent in heat insulation property and so forth. |
