Exothermic And Insulating Feeder Sleeves Having A High Gas Permeability

The invention relates to a molding composition for producing insulating or exothermic feeders and other filling funnels and feeding elements for casting molds, which comprises at least: at least 10% by weight of a porous refractory material which has a continuous open pore structure; a binder for curing the molding mixture; if appropriate, a refractory filler; a proportion of a reactive aluminum oxide having a specific surface area of at least about 0.5 m2/g and an average particle diameter (D50) of from about 0.5 to 8 mum. The invention further relates to a process for producing a feeder and other filling funnel or feeding elements for casting molds; feeders, filling funnels or feeding elements for casting molds which are obtained by the process and also their use for producing metal castings. The feeders and further shaped bodies for the foundry industry obtained from the molding composition of the invention have a particularly high gas permeability and a low density.