Refractory Materials and the Glass Industry

JSGT 1918 V02 T262-T270 (9 pages)

There is quite a wide range of temperature to be covered by furnaces, and a corresponding range of material to be used in their construction. One class of furnace, not very widely used but of very great importance, must withstand temperatures above the melting point of silica. Another class is exemplified in the steel industry, where the temperatures used are such that silica bricks are most suitable, whilst in a further class a very wide range of furnaces and processes are in operation which do not require, excepting in certain positions, even such a temperature as can be withstood by the silica brick, and here we are introduced to a large class of refractory material of which the basis is fire-clay. The requirements of the glass industry are not, so far as temperature goes, very drastic. The maximum temperat.ure is something like 1400° excepting in certain tank furnaces, which may be worked hotter in order to secure a greater output. The temperature requirements are therefore modest but the chemical requirements are very stringent, and that is primarily because in the glass industry one silicate mass is required to remain solid and to hold another as a liquid, while both are in a form which facilitates interaction, inasmuch as they consist of oxides. In the bath of a steel furnace, the principal attack on refractory materials is not due to the molten steel, but to that oxidised portion of the charge, the slag, which floats on the metal. In the glass furnace, however, nearly the whole pot interior in the pot furnace or the whole surface of the tank blocks in the tank furnace has to withstand the continued action of a chemically active molten charge.

J. W. Cobb