What are described is a process for producing casting molds, cores and mold base materials regenerated therefrom, a mixture for combination with a solution or dispersion comprising waterglass for production of casting molds and/or cores, a molding material mixture, a mold base material mixture, and a casting mold or a core. What is also described is the corresponding use of an amount of particulate sheet silicates having a d.sub.90 of less than 45 μm or a corresponding mixture as additive for production of a molding material mixture comprising waterglass and particulate amorphous silicon dioxide, which is cured by chemical reaction of constituents of the molding material mixture with one another, in the production of a casting mold or a core, to facilitate the breakdown and/or to increase the regeneratability of the casting mold or core.

What are described is a process for producing casting molds, cores and mold base materials regenerated therefrom, a mixture for combination with a solution or dispersion comprising waterglass for production of casting molds and/or cores, a molding material mixture, a mold base material mixture, and a casting mold or a core. What is also described is the corresponding use of an amount of particulate sheet silicates having a d.sub.90 of less than 45 μm or a corresponding mixture as additive for production of a molding material mixture comprising waterglass and particulate amorphous silicon dioxide, which is cured by chemical reaction of constituents of the molding material mixture with one another, in the production of a casting mold or a core, to facilitate the breakdown and/or to increase the regeneratability of the casting mold or core.

A method of reusing core sand includes crushing a core used for casting into granules, the core includes water glass as a binder, and the water glass includes water-soluble water glass and water-insoluble water glass; heating the core; detaching the water glass from the core sand; and separating and collecting the core sand from a mixture of the water glass and the core sand.

A method of reusing core sand includes crushing a core used for casting into granules, the core includes water glass as a binder, and the water glass includes water-soluble water glass and water-insoluble water glass; heating the core; detaching the water glass from the core sand; and separating and collecting the core sand from a mixture of the water glass and the core sand.

A kneaded sand property adjusting system including: a kneading device; a kneaded sand storage hopper that stores kneaded sand; a molding device that molds the sand conveyed from the sand storage hopper; a control device that controls water injection until a property of the sand meets a kneaded sand target property; and kneaded sand amount measuring instruments that measure the amount of sand stored in storage hopper, wherein the control device stores the batch number of each kneaded batch and the kneaded sand property measured at the time of kneading, calculates the batch number of the kneaded batch that corresponds to the molding sand being loaded into the molding device by the kneaded sand amount measuring instruments, associates the property of the molding sand with the property stored on by the batch number that was calculated, and corrects the target property on the basis of the values of the properties.

Provided is a decompression kneader capable of stabilizing a moisture content of resultant kneaded sand. The decompression kneader includes a kneader main body configured to knead casting sand and water, a decompression pump configured to reduce a pressure inside the kneader main body, a condenser configured to condense water vapor sucked by the decompression pump, a tank configured to store water condensed by the condenser, and a supply amount calculation apparatus configured to calculate an amount of water supplied from the tank to the kneader main body. The tank comprises a water gauge and a weighing scale, and the supply amount calculation apparatus estimates an amount of the casting sand contained in the tank based on measured values of the water gauge and the weighing scale and corrects the amount of the water supplied from the tank with reference to the amount of the casting sand.

In the disclosed solution, a method is described for producing sand used in industry, in which method dis-carded power plant and/or foundry sand is processed into sand for use in products of the construction industry and/or into foundry sand by means of pre-treatment, drying, and after-treatment. In addition, an apparatus is described for producing sand used in industry, and use of discarded power plant and/or foundry sand in products of the construction materials industry or in foundry industry.

In the disclosed solution, a method is described for producing sand used in industry, in which method dis-carded power plant and/or foundry sand is processed into sand for use in products of the construction industry and/or into foundry sand by means of pre-treatment, drying, and after-treatment. In addition, an apparatus is described for producing sand used in industry, and use of discarded power plant and/or foundry sand in products of the construction materials industry or in foundry industry.

In a casting sand reclamation system and a casting sand reclamation method, an appropriate reclamation process is performed according to the properties of casting sand to improve the reclamation accuracy and the reclamation yield. Capacitance measuring devices 70 and 71 that measure the capacitance of casting sand 1 (recovered sand 1a or reclamation sand 1b) are arranged on an upstream side and a downstream side of a batch-type polishing device 7, and feedback control is performed based on the measurement results of the capacitances by these capacitance measuring devices 70 and 71. A sorting device 10 sorts the recovered sand 1a polished by the polishing device 7 into a sand grain component (reclamation sand) and a fine grain component (containing a binder), and has a capacity N times that of the polishing device 7. A control device 80 performs feedback control based on capacitance RU of the recovered sand 1a measured for each polishing process on an upstream side of the polishing device 7, and an average value of N capacitances RD of the reclamation sand 1b measured for each polishing process on a downstream side of the sorting device 10.

In a casting sand reclamation system and a casting sand reclamation method, an appropriate reclamation process is performed according to the properties of casting sand to improve the reclamation accuracy and the reclamation yield. Capacitance measuring devices 70 and 71 that measure the capacitance of casting sand 1 (recovered sand 1a or reclamation sand 1b) are arranged on an upstream side and a downstream side of a batch-type polishing device 7, and feedback control is performed based on the measurement results of the capacitances by these capacitance measuring devices 70 and 71. A sorting device 10 sorts the recovered sand 1a polished by the polishing device 7 into a sand grain component (reclamation sand) and a fine grain component (containing a binder), and has a capacity N times that of the polishing device 7. A control device 80 performs feedback control based on capacitance RU of the recovered sand 1a measured for each polishing process on an upstream side of the polishing device 7, and an average value of N capacitances RD of the reclamation sand 1b measured for each polishing process on a downstream side of the sorting device 10.