Abstract: The present invention relates to the use of closed-pore microspheres of expanded perlite as a filler for producing moldings for the foundry industry, to a composition for producing moldings for the foundry industry, comprising closed-pore microspheres of expanded perlite as a filler, and a binder, the binder being selected from the group consisting of water glass, phenol-formaldehyde resins, two-component systems comprising as reactants a polyisocyanate and a polyol component containing free hydroxyl groups (OH groups), and starch, and also to moldings for the foundry industry and to a process for producing a molding for the foundry industry.

Abstract: In a vibratory mill, a plurality of parallel, horizontal grinding tubes are mounted in groups on an upper and a lower part of a carrier. The two carrier parts are linked together by two pairs of links which form a parallel crank linkage and stationary bearings mount each of the links intermediate their ends for pivoting about an axis parallel to the grinding tube axes. An eccentric drive mechanism is arranged to vibrate the carrier in a direction transverse to the grinding tube axes. The drive mechanism includes an eccentric mounted on one of the carrier parts for imparting to the carrier an amplitude of vibration of at least 15 mm about a central position of the links which is inclined from the horizontal at an angle of 30.degree.-60.degree., preferably 45.degree., a connecting rod connected to the eccentric and extending at a right angle to the central position of the links, and a rubber or helical spring connecting the connecting rod to the other carrier part.