METHOD FOR THE PRODUCTION OF CORE SAND AND/OR MOLDING SAND FOR CASTING PURPOSES

1 . In a method of making a core sand and/or mold sand for foundry use, according to which a granular, mineral mold base material is mixed with at least one inorganic binder and also an inorganic expanding additive, the improvement comprising the step of:

using water glass as the binder and expanded graphite as the expanding additive.

2 . The method according to claim 1 , wherein the expanded graphite has an expansion of max. 350 cm 3 /g.

3 . The method according to claim 1 , wherein the starting temperature for expansion of the expanded graphite is higher than 180° C.

4 . The method according to any claim 1 , wherein the expanded graphite is added in a particle size of more than 20 μm.

5 . The method according to claim 1 , wherein SO x or NO x expanded graphite is used as the expanded graphite.

6 . The method according to claim 1 , wherein the expanded graphite has a carbon content of 85% by weight to 99.5% by weight.

7 . The method according to claim 1 , wherein the expanded graphite is added to the mixture of mold base material and water glass in an amount of up to approximately 1% by weight.

8 . The method according to claim 1 , further comprising the steps of:

adding the expanded graphite to the water glass to form a mixture and then

mixing the mixture with the mold base material or the mixture as a separate additive to the mold base material, including the water glass.

9 . Use of a core sand and/or mold sand produced according to claim 1 for making casting molds for cast aluminum alloys, iron-carbon alloys, copper alloys and/or magnesium alloys.

10 . The use according to claim 9 , wherein the casting mold is used in the automobile industry.