An expanded mineral material suitable for use as a filler, e.g. instead of or in addition to sand or gravel in concrete mixes, is produced by dropping a stream of solid pellets into a rising stream of heated gas contained in a substantially vertical reactor space; the pellets consist essentially of a...http://www.google.es/patents/US4602962?utm_source=gb-gplus-sharePatente US4602962 - Process for producing an expanded mineral material
Process for producing an expanded mineral material
