Abstract: The invention relates to gas-permeable parts comprised, by weight, of (A) 60 to 90% of granules of a grain size from 5 mm to 0.2 mm formed from a material selected among the group consisting of a chamotte containing at least 42% of Al.sub.2 O.sub.3, mullite, fired gibbsite containing more than 90% Al.sub.2 O hd 3, sintered or fused cast corundum containing more than 95% Al.sub.2 O.sub.3, natural chromite, sintered MgO, zircon sand and stabilized zirconia, and (B) 10 to 40% of a bonding cement comprised a calcium aluminate, a material selected among SiO.sub.2, Al.sub.2 O.sub.3 and Cr.sub.2 O.sub.3 having a particle size between 100 A and 0.1 micron, and alumina having a particle size between 1 and 100 microns. These parts retain a high mechanical strength when heated between hydraulic setting and ceramization, and are useful for blowing a gas therethrough in order to stir molten steel and cast iron.