2020-2-28 · Silica bricks are extremely suitable for those parts of a furnace which are subjected to uniformly high temperature, e.g., fire bridges, roofs of Acid and Basic Open and Hearth, Electric furnaces, copper smelting and refining furnaces etc. Fire Clay: The main constituent of fire-clay is kaolinite, Al 2 O 3. 2SiO 2. 2H 2 O. The fire clays