BLAST FURNACE OPERATING METHOD

摘要

Provided is a blast furnace operating method that enables further improvement of combustion temperature and reduction of reductant prime cost. When two or more lances for blowing a reductant from tuyeres, with an LNG serving as a flammable reductant and pulverized coal in the form of a solid reductant, are used, the front end of a lance for blowing the LNG is positioned away from the front end of a lance for blowing the pulverized coal by l0-50mm in the blowing direction. Consequently, the temperature of the pulverized coal is effectively increased by the LNG, the LNG burns first and explosively expands upon coming into contact with oxygen, and the temperature of the pulverized coal is drastically increased. Because the combustion temperature is drastically improved as a result, the reductant prime cost can be reduced. When a double-pipe lance is utilized as the lance for blowing the pulverized coal, the pulverized coal is blown in through the inner pipe, and oxygen is blown in through the outer pipe so as to ensure enough oxygen for burning the pulverized coal, so the combustibility can be further improved. Also, the flow velocity at the outlet of the lance is set to 20-120m/sec in order to prevent deformation of the lance.