The iron is melted in the hot air blast cupola furnace and is then poured into the casting moulds. The hot air cupola has a melting capacity of 18 to 27 tons per hour and can melt basic iron for both nodular and grey cast iron. The charging system is fully automatic and the cupola consists of a long, vertical cylinder into which the charge is loaded from above. Hot air is blown in near to the bottom around the melting zone where the temperature is approximately 2000°C, enabling the iron and steel in the charge to melt. The coke causes carburetion of the metal and removes any rust by deoxidization. The entire process is controlled from the control room. The molten iron flows out at the bottom through a tap hole, while on the other side of the furnace the liquid slag is drawn off through the slag hole. The slag is used for road building and the construction industry. Before the molten iron is used for casting, thermal and spectrographic analyses are carried out in the lab to determine the carbon and silicon content as well as other elements.