Refining of molten metal, esp. steel, in oxygen converter - using top blowing through lance, and bottom blowing through tuyeres with small outlet dia.

摘要

In the converter, 75-97% of the total O2 required is blown downwards through an injection lance; whereas the rest (R) of the O2, viz. 3-25%, is blown upwards through vertical or oblique tuyeres located below the surface of the bath. Oxygen (R) is fed as jets with max. dia. 18 mm, esp. max. 12 mm, at the tuyere outlets; and is used at a non-increasing rate of flow. A neutral or oxidising stirring gas may be added to oxygen (R). Oxygen (R) is pref. supplied at a constant or decreasing rate during the entire blowing period; and the stirring gas is pref. added to oxygen (R) at the critical stage of decarburisation of the melt, and then at the end of refining. Oxygen (R) pref. forms 3-10% of the total O2 required. The benefits of top blowing are combined with the advantages of bottom blowing in a flexible process; and the life of the tuyeres is increased.