Porous clay moldings are fired in a fluorine-containing tunnel kiln atmosphere

摘要

Porous clay moldings (2) are tunnel kiln fired using a kiln atmosphere of fluorine content controlled according to the kiln operation and raw material composition. Preferred Process: The fluorine content is controlled by feeding a volatile fluorine-containing material into the kiln atmosphere or adding a non-volatile fluorine-containing material (preferably calcium fluoride, especially fluorspar) to the raw material mixture before molding.