METHOD FOR MELTING GLASS

PROBLEM TO BE SOLVED: To prevent the generation of waste gas contg. much NOx and melting segregation in a melting process and to suppress the generation of bubbles in glass by adding antimony pentoxide as a clarifier to nitrate-free starting materials for glass. SOLUTION: Antimony pentoxide is added as a clarifier by 0.1-3 wt.%, preferably 0.3-3 wt.% to nitrate-free starting materials for glass consisting of, by weight, 45-70% SiO2 , 7.5-25% Al2 O3 , 4-17.5% B2 O3 , 0-10% MgO, 0-10% CaO, 0-10% SrO, 0-30% BaO, 0-5% ZnO, 0-5% TiO2 and 0-5% ZrO2 , contg. no alkali metal oxide and having >=620 deg.C strain point and they are melted. This method is effective to alkali-free glass having a high melting temp. and difficult to clarify.