ES308215A1 - Improvements in or relating to bonded refractory materials - Google Patents

Abstract

A bonded refractory comprises by weight 30-50% coarse grains of size range between 1/4 inch (6.35 mm.) and 1 1/4 inches (31.75 mm.) and, as matrix, medium and fine grains of which the maximum size is 5/32 inch (4.1 mm.) the coarse grains are preferably 3/8 inch (9.5 mm.) to 5/8 inch (15.9 mm.) while the matrix is preferably composed of 40-70% - 5/32 inch + 10 mesh B.S.S. (-4 + 1.7 mm.), 10-30% -10 mesh B.S.S. (-1.7 mm.) and 20-30% - 100 mesh B.S.S. (-0.15 mm.). The refractory may be chemically bonded with a non-aqueous, e.g. tar, or aqueous, e.g. sulphite lye, molasses, sodium or potassium silicate, sulphuric or phosphoric acid, aluminium sulphate or phosphate binder, or may be "self" or "fired" bonded when 3-10%. Clay is included in the finely ground mix. A viscosity increasing agent e.g. methyl cellulose acetate or tar oils, in the case of aqueous, non-aqueous bonded refractories respectively, may be mixed with the matrix before addition of the coarse grains. The mix is pressed and dried conventionally. Examples specify (i) 40% coarse sillimanite (53% Al2O3), 60% matrix sillimanite (61% Al2O3) with 3% clay and 1% sulphite lye containing 0.1% methyl cellulose acetate, (ii) 40% coarse and 60% matrix magnesite with 2.5% C.H2SO4 and water and sulphite lye as in (i), (iii) 35% sinter-dolomite 65% magnesite as in (ii) with 5% water-free tar oil. Other matrices disclosed are calcined clay, lead-burned magnesite or dolomite, sillimanite (kyanite, andalusite), bauxite, silica (quartzite) and mullite, with clay, magnesite, dolomite, chrome ore, bauxite, mullite, sillimanite, kyanite, andalusite or quartzite as skeleton.