Applications of By-product Gypsum in the Plaster Industry

This paper describes experiments at the pilot-plant scale on the conversion of by-product gypsums from Brisbane, Kwinana, Melbourne and Newcastle, to calcined gypsum (plaster of Paris) and the subsequent manufacture of cast gypsum boards reinforced with glass fibre. The slightly acidic by-product gypsums were co-calcined with small quantities of CaO and then ground. The properties of calcined and cast materials were compared with one sample of commercial calcined gypsum and with two samples of natural gypsum calcined in the laboratory under conditions similar to those used for the by-product gypsums. It was found that most of the by-product gypsums could be converted to calcined and cast gypsums with properties similar to those made from natural gypsum. The glass-reinforced cast gypsum boards made from the by-product gypsums were of inferior quality.