| 摘要 |
<p>A method of operating a rotary hearth type reducing furnace, characterized in that a combustion gas generated in the furnace is held in a state, wherein the temperature of the gas is 800 ° C or higher, the concentration of carbon monoxide is 2000 ppm by volume or less and turbulent flow is satisfactorily developed, for a period of a predetermined time or more, in at least one of the inside of an exhaust gas exit duct and the vicinity of the exhaust gas exit duct, and then is cooled rapidly; and rotary hearth type reducing furnace facilities required for the practice of the method of operation. The operating method allows the suppression of generation of dioxins in a combustion exhaust gas and also the efficient recovery of heat from the combustion exhaust gas having an elevated temperature, in a process of firing and reducing pellets or the like formed from a ore powder such as a chromium ore or iron ore powder, or a dust, a sludge or the like containing an oxidized metal such as iron oxide generated in the metal industry in a rotary hearth type reducing furnace, and also allows the total mole number of zinc and lead, the total mole number of alkali metals, and the total mole number of halogen elements contained in a dust in the combustion exhaust gas to be controlled so that the three numbers satisfy a specific relationship.</p> |
