Abstract: Ceramic, porous filter body in the designed to overcome the lack of high temperature resistant thermoshock resistant and mechanical stable bodies for the filtration of metals, preferentially of iron and ferrous alloys. This filter body has a temperature resistance of 1600.degree. C., a linear thermal coefficient of expansion of 3-7.times.10.sup.-6 /.degree.C. and consists of hollow spheres based on minimum one homogeneous distributed refractory material and another refractory material, which at high temperature by chemical reaction forms with the hollow spheres a solid refractory binding phase. A process for the production of such a filter body is described such, that the spheres of the refractory materials are mixed with a powderous binding phase, then formed to a porous body and then, by retention of the porous homogeneous structure under formation of new refractory compositions by heat treatment are chemically reacted, at least in the contact areas of the spheres.

Abstract: Filter medium in the form of a stable body made of ceramic material and employed for filtering molten metals. The filter medium is made up of at least two effective filter layers such that a relatively thick layer of large pore diameter lies on a relatively thin layer of small pore diameter. This arrangement aims at attaining the maximum possible wetting of the interior of the filter medium.