METHOD OF PREPARING QUARTZ SAND FOR GLASS PRODUCTION Russian patent published in 1998 - IPC

FIELD: glass-making. SUBSTANCE: method is distinguished by replacing corrosive and expensive sodium hydroxide component by sodium chloride and conducting heat treatment in two steps: first, at 30-90 C, pressure 0.25-5 MPa for 1-1.5 h in presence of saturated ammonia solution and then, at 500-800 at atmosphere pressure for 1-1.5 h. EFFECT: reduced cost and improved environmental safety.