By improving the ignition oven efficiency, significant reductions in fuel demand can be achieved. In a Japanese application, the heat-retention oven is removed from the conventional ignition oven with a large oven capacity and an ignition oven with lower capacity is introduced, in which the inner pressure of the ignition oven is regulated by controlling each window box located immediately under the ignition oven. Moreover, a multi-slit burner which can achieve uniform ignition in the pallet width direction and rapid heating has been developed and introduced to realize a large fuel reduction. This burner consists of fuel exhaust nozzles located in the sintering floor width direction and a slit-like burner tile containing these fuel exhaust nozzles. The fuel supplied from the fuel exhaust nozzles reacts with the primary air inside the burner tile, then with the secondary air supplied to flame outer periphery area. By using the slit-like buruner tile, non-flamed places can be eliminated. By controlling the ratio between the primary air and the secondary air the length of the flame can be controlled to minimize the ignition energy (NEDO, 2008. p. 66).