English: Iron ore roasting kiln. Swedish model, designed by the engineer Westman. It is 20 feet high and uses blast furnace gas as fuel. The combustion is effected by means of a blast of air introduced through the twyer(a), which communicates with the annular space (b), from which the air penetrates into the furnace by a number of small openings. The gas is conveyed by the pipes (dd), and enters the furnace by the channels (e). Above these are other channels (ee) which are kept closed; these are used for introducing bars to break up any lumps that may have caked together, or to admit additional air if necessary. The calcined ore is discharged through five radial openings (f). The charging is performed at the top, which is surmounted by a chimney for regulating the draught.