A method of forming high strength glass fibers in a refractory-lined glass melter, products made there from and batch compositions suited for use in the method are disclosed. The glass composition for use in the method of the present invention is up to about 64-75 weight percent SiO.sub.2, 16-24 weight percent Al.sub.2O.sub.3, 8-12 weight percent MgO and 0.25-3 weight percent R.sub.2O, where R.sub.2O equals the sum of Li.sub.2O and Na.sub.2O, has a fiberizing temperature less than about 2650 F., and a T of at least 80 F. By using oxide-based refractory-lined furnaces the cost of production of glass fibers is substantially reduced in comparison with the cost of fibers produced using a platinum-lined melting furnace. High strength composite articles including the high strength glass fibers are also disclosed.

A method of forming high strength glass fibers in a glass melter substantially free of platinum or other noble metal materials, products made there from and batch compositions suited for use in the method are disclosed. One glass composition for use in the present invention includes 50-75 weight % SiO.sub.2, 13-30 weight % Al.sub.2O.sub.3, 5-20 weight % MgO, 0-10 weight % CaO, 0 to 5 weight % R.sub.2O where R.sub.2O is the sum of Li.sub.2O, Na.sub.2O and K.sub.2O, has a higher fiberizing temperature, e.g. 2400-2900 F. (1316-1593 C.) and/or a liquidus temperature that is below the fiberizing temperature by as little as 45 F. (25 C.). Another glass composition for use in the method of the present invention is up to about 64-75 weight percent SiO.sub.2, 16-24 weight percent Al.sub.2O.sub.3, 8-12 weight percent MgO and 0.25-3 weight percent R.sub.2O, where R.sub.2O equals the sum of Li.sub.2O, Na.sub.2O and K.sub.2O, has a fiberizing temperature less than about 2650 F. (1454 C.), and a T of at least 80 F. (45 C.). A forehearth for transporting molten glass from the glass melter to a forming position is disclosed. By using furnaces and/or forehearths substantially free of platinum or other noble metal materials, the cost of production of glass fibers is significantly reduced in comparison with the cost of fibers produced using a melting furnace lined with noble metal materials. High strength composite articles including the high strength glass fibers are also disclosed.

The invention relates to a method for heating flowable molten glass in a feed channel which is enclosed by lateral walls and a cover and into which a plurality of fuel lances and oxidizing agent lances that are mutually spaced in the flow direction of the molten glass open above the molten glass, fuel or an oxidizing agent being supplied through said lances and being brought into reaction with each other in the feed channel. The invention is characterized in that in order to combust the fuel with the oxidizing agent, a flame is produced in front of the opening of each fuel lance, said flame being designed such that adjacent or opposite flames do not contact one another.