This furnace is a large structure, mostly built underground, on a floating foundation. It consists of several pits or cells. Several type of fireclay and insulation Refractories are used in these furnaces. High grog super duty bricks are mostly used in the flue duct. In back up walls and head walls, high duty and medium duty bricks depending on service conditions are being used. The furnace temperature varies from 13000C to 15000C.