GB1272921A - Improvements in the control of the refining of pig iron by means of commercially pure oxygen - Google Patents

Abstract

1,272,921. Automatic control of oxygen in steelmaking. FREID KRUPP G.m.b.H. Jan. 9, 1970 [Jan. 9, 1969], No. 1202/70. Heading G3R. [Also in Division C7] In a process for the refining of pig iron by means of commercially pure oxygen the slag layer height in the refining vessel or converter is physically measured by a suitable method. A mathematical expression for the slag height HSC as a function of the oxygen combined with the slag is then established, which expression allows for the fact that the slag height is determined both by physical factors and factors associated with the mean chemical composition of the slag. The expression is then equated with the measured slag height and other quantities in the expression being known the total oxygen combined with the slag is calculated. This calculated quantity is compared with a predetermined set value and a control arrangement (not described) automatically causes the calculated value to approach the set value i.e. by automatic control of the oxygen flow to a lance or of the lance height above the melt or by automatic modification of addition agents. Alternatively the oxygen flow and addition agents may be manually controlled. The slag height may be measured by means of thermocouples mounted along the lance, by radiation responsive cells sensing the radiation from the slag surface, or by sensing the acoustic level of the oxygen jet from the lance the jet noise being attenuated in varying degrees depending upon the height of the slag. The slag height is then obtained by comparing the acoustic noise level with pre-drawn graphs giving the slag height as a function of acoustic level for any lance height.