Abstract: A furnace 10 for smelting iron ore and/or refining molten iron 20 is equipped with an overhead pneumatic lance 40, through which a center stream of particulate coal 53 is ejected at high velocity into a slag layer 30. An annular stream of nitrogen or argon 51 enshrouds the coal stream. Oxygen 52 is simultaneously ejected in an annular stream encircling the inert gas stream 51. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus 84 to react with carbon monoxide gas rising from slag layer 30, thereby adding still more heat to the furnace.

Abstract: A furnace 10 for smelting iron ore and/or refining molten iron 20 is equipped with an overhead pneumatic lance 40, through which a center stream of particulate coal 53 is ejected at high velocity into a slag layer 30. An annular stream of nitrogen or argon 51 enshrouds the coal stream. Oxygen 52 is simultaneously ejected in an annular stream encircling the inert gas stream 51. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus 84 to react with carbon monoxide gas rising from slag layer 30, thereby adding still more heat to the furnace.

Abstract: The carbon and dissolved oxygen contents of molten steel are reduced by a vacuum degassing treatment which may employ oxygen blowing. A determination is made of the idealized trajectory or path reflecting the change in carbon content and dissolved oxygen content, between atmospheric pressure and a preselected sub-atmospheric pressure at which the vacuum degassing treatment occurs. The idealized trajectory also reflects the effect of extraneous factors on the carbon content, dissolved oxygen content and temperature of the molten steel during the treatment. A selection is made of the boundaries of the idealized trajectory based upon the permissible limits of carbon content, dissolved oxygen content and temperature at the end of the vacuum degassing treatment. Adjustments are made at the beginning of the treatment and periodically throughout the treatment to maintain all three parameters, carbon content, dissolved oxygen content and temperature, within the boundaries of the idealized trajectory.