Abstract: A continuous hydrothermal synthesis method which comprises pressurizing and heating a material slurry below a saturated vapor temperature or pressurizing a material slurry at normal temperature, pressurizing and heating an aqueous liquid above the saturated vapor temperature, atomizing and mixing the slurry and the aqueous liquid, effecting hydrothermal synthesis in a reaction section above the saturated vapor temperature, cooling the reaction product and taking out the product while retaining the pressurized state in the system by alternately opening and closing shut-off valves provided above and below a product discharging section or through a thin pipe provided in the product discharging section. The method is performed using an apparatus comprising heating-pressurizing sections respectively connected to a material slurry feeding section and an aqueous liquid feeding section, an atomizing-mixing section and a reaction section provided after these feeding sections, and a product discharging section.

Abstract: A method for spraying starting material particles in a continuous hydrothermal reaction, comprising spraying an aqueous fluid pressurized and heated in excess of the saturated vapor temperature and a starting material slurry pressurized at ordinary temperature. A starting material slurry feed orifice is provided in a central portion of an aqueous fluid spray orifice to spray and mix the aqueous fluid and the staring material slurry. In order to avoid entry of heat into the starting material fluid from the aqueous fluid, a heat-insulating layer is provided between feed paths for the respective two fluids. According to the above method, the starting material slurry is sprayed particularly under subcritical to supercritical conditions beyond the saturated vapor temperature to form fine particles without agglomeration thereof, whereby a hydrothermal reaction can be continuously and efficiently effected.

Abstract: A continuous hydrothermal synthesis method which comprises pressurizing and heating a material slurry below a saturated vapor temperature or pressurizing a material slurry at normal temperature, pressurizing and heating an aqueous liquid above the saturated vapor temperature, atomizing and mixing the slurry and the aqueous liquid, effecting hydrothermal synthesis in a reaction section above the saturated vapor temperature, cooling the reaction product and taking out the product while retaining the pressurized state in the system by alternately opening and closing shut-off valves provided above and below a product discharging section or through a thin pipe provided in the product discharging section. The method is performed using an apparatus comprising heating-pressurizing sections respectively connected to a material slurry feeding section and an aqueous liquid feeding section, an atomizing-mixing section and a reaction section provided after these feeding sections, and a product discharging section.

Abstract: Underground rock cracks are blocked by using a slurry of blocking agent containing hectorite raw materials in an amount of 1 to 10 wt %, which comprises an acidic precipitate of water glass and magnesium chloride, sodium hydroxide, and lithium hydroxide and water, through the steps of injecting the slurry, allowing the slurry to flow into the cracks produced in rocks, and allowing hectorite synthesized from the raw materials contained in the slurry to gel under high temperature conditions of underground.

Abstract: A process for the desulfurization of a sulfur-containing composition is described. The process comprises providing a sulfur-containing composition, adding an aqueous medium and a sulfur absorbent to the composition, and subjecting the resultant mixture to hydrothermal reaction under specific conditions to obtain a desulfurized product. When the sulfur-containing composition is made of vulcanized rubbers, the rubber can be converted into oily substances by treating the rubber product under supercritical conditions using an aqueous medium. The conversion reaction is facilitated by addition of metal oxides or salts.

Abstract: A process for the desulfurization of a sulfur-containing composition is described. The process comprises providing a sulfur-containing composition, adding an aqueous medium and a sulfur absorbent to the composition, and subjecting the resultant mixture to hydrothermal reaction under specific conditions to obtain a desulfurized product. When the sulfur-containing composition is made of vulcanized rubbers, the rubber can be converted into oily substances by treating the rubber product under supercritical conditions using an aqueous medium. The conversion reaction is facilitated by addition of metal oxides or salts.

Abstract: According to the method of this invention for fixation of incinerator ash, incinerator ash containing SiO.sub.2 and Al.sub.2 O.sub.3 is incorporated with NaOH or NaOH and an SiO.sub.2 -containing substance in such an amount that the resulting mixture contains 25 to 90 wt % of SiO.sub.2, 2 to 10 wt % of Na.sub.2 O, and more than 3 wt % of Al.sub.2 O.sub.3 which is less than the content of SiO.sub.2 in terms of mol %; 100 parts by weight of the mixture is mixed with more than 5 parts by weight of water; and the resulting mixture is subjected to hydrothermal reaction under a pressure of 70 kg/cm.sup.2 or above and at a temperature of 150.degree. C. and above, whereby the fixation is accomplished.