Method for the production of core sand and/or molding sand for casting purposes

Abstract

The invention relates to a method for producing core sand and/or molding sand for casting purposes. A granular mineral mold base material is mixed with at least one inorganic binder and additionally an inorganic expanding additive. According to the invention, water glass is used as the binder and expanded graphite is used as the expanding additive.

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.