Adjustable tuyere for oxygen converters

Abstract

In ferrous metallurgy, there is a pressing need to increase the proportion of scrap in the metal batch for steel smelting—primarily in oxygen converters. This is of particular concern at OAO Nizhnetagil'skii Metal� lugicheskii Kombinat (NTMK), on account of the shutdown of openhearth shop 1. In the oxygencon� verter shop, hot metal that is naturally alloyed with vanadium undergoes a twostage process. In the first stage, oxygen injection of the vanadium hot metal in the converter generates slag containing 17-21% V2O5, which is used in ferrovanadium production, and a molten metal product, which is converted to steel in the second stage. Thus, in the oxygenconverter shop at OAO NTMK, metal scrap may only be used in the second stage of the process. The complications in the second stage are mainly due to the chemical composition of the molten metal, which is in fact ferrocarbon melt. As a result, slag pro� duction is very slow. This leads, first, to unstable injec� tion, accompanied by splashing and entrainment of metal from the converter; second, to ineffective desphosphorization; third, to unstable oxidation of car� bon; and, fourth, to intense loss of iron, with the forma� tion of a large quantity of brown smoke at the end of smelting. In addition, in the second stage of the process, there is a problematic thermal balance, on account of the insufficient heat liberation in oxidation. This heat will be sufficient if the batch in the converter consists solely of the molten metal product but is far from suffi� cient with even 20% scrap in the batch. Thus, effective processing of metal scrap in 160�t oxygen converters entails the following improvements: