RU1772168C - Method of steel melting in convertor - Google Patents

Abstract

Usage: in the steel industry and can be used to control the oxygen-converter process. The method allows to obtain information on the decarburization rate during the melt purge. SUMMARY OF THE INVENTION: determine the effect of the cyclic movement of the oxygen tuyere on the temperature (T) of the exhaust gases in the exhaust gas duct, measure T and determine the start times by the shape of the curve and the end of the steady-state maximum decarburization rate, as well as the magnitude of the maximum decarburization rate. The tuyeres are cycled for 4-5 minutes of purging, the exhaust gas T is measured in the exhaust duct of the converter, and the moment of maximum decarburization rate is determined from the beginning of the temperature fluctuation of the exhaust gases with a steady-state maximum amplitude of 20-40 ° C. After determining its decline, the lance cycling is stopped. 1 s.p. f-ly, 2 ill.

Description

The invention relates to ferrous metallurgy and can be used in controlling an oxygen-converter process.

The known method consists in periodically changing the amplitude of the tuyere movement within 20-100% of the average height of the tuyere above the level of a calm bath during a given melting period, the amplitude changing cycle being 1-5% of the purge duration.

A disadvantage of the known method is that there is no operational information on the decarburization rate in each lance movement cycle, which leads to the removal and discharge of the metal, i.e. to reduce yield.

The aim of the invention is to increase the yield

Due to the probing effect of the cyclic movement of the tuyere on the decarburization process during melt blowing, it is possible to obtain information on the magnitude of the decarburization rate.

This is achieved by the fact that the proposed method additionally uses the influence of the cyclic movement of the tuyere on the temperature of the exhaust gases in the exhaust gas duct and the start and end moments of the steady-state maximum decarburization rate are determined by the shape of the curve, and the maximum decarburization rate is also determined.

The essence of the invention lies in the fact that in the proposed method for cyclic movement of the tuyeres by isolating and analyzing the tangents of the tilt angle

"XJ

 Yu

cЈ

00

the decarburization temperature in each cycle of oscillations determines the decarburization rate, and the moment of a sharp increase or decrease in the amplitude of the fluctuations in the temperature of the exhaust gas, the moments of growth or decay of the maximum decarburization rate during purging are determined.

In the converter process during metal purging, it is important to determine the moments of the beginning of increase and decrease of fluctuations in the maximum decarburization rate, since, knowing the moments of the beginning of the increase in the decarburization rate, you can quickly take measures to reduce metal emissions and removals, correctly evaluate the melt purge process, а. knowing the decay time of the maximum decarburization rate, predict the end time of the purge.

On the other hand, having information on the rate of change of the temperature of the exhaust gases, determined by the slope of the signal, which is equivalent to the decarburization rate, it is possible to control the purge while dynamically controlling the metal refining process, i.e. to control the decarburization rate in the long-term time range for one lance oscillation cycle.

Therefore, the availability of information on the decarburization rate in synchronism with its change provides timely dynamic control of the heat, i.e. adoption of technological operations preventing metal emissions and outflows, which increases the yield and converter productivity.

The method is as follows

The oxygen lance is lowered and the purge of the converter bath, consisting of scrap metal and molten iron, is started. After 4-5 minutes after melting the scrap metal, the cyclic movement of the oxygen lance begins, the amplitude of the oscillations changes to 20-100% of the average value and with a time cycle of 1-5% of the purge duration. The temperature of the exhaust gases is measured, and when the amplitude of the temperature of the exhaust gases reaches 20-40 ° C, the moment of establishing the maximum decarburization rate is determined, and when the amplitude of oscillations decreases, the cyclic movement of the tuyeres is stopped. The decarburization rate in each lance movement cycle is determined by the tangent

the angle of inclination of each semi-mode of the temperature variation of the exhaust gases.

In FIG. Figure 1 shows the curves of the temperature of the exhaust gases and the position

tuyeres during melt blowing; in FIG. 2 - change in the temperature of the exhaust gases to r ° and its speed V0.r dt0 r / dt during the purge time.

The method was tested on a 160-ton converter of the Yenakiyevo Metallurgical Plant. The research results are given below.

The magnitude of the amplitude of the cyclic movement of the tuyere is chosen to be 60% of the average working position. The cyclic movement of the tuyere began after the scrap metal was melted in the converter (4-5 minutes) and ended after the maximum decarburization rate decreased.

The selected magnitude of the amplitude of the cyclic movement of the tuyere was determined by the maximum afterburning of CO to CO2 in the cavity of the converter, which was calculated by the thermal balance method in the previous heats.

Based on the experimental swimming trunks (Fig. 1}, it can be seen that during vertically cyclic movement of the tuyere, the temperature signal of the exhaust gases, that is, its oscillations with a maximum amplitude, clearly reflects the time interval of the beginning and end of the maximum decarburization rate. sludge-forming components of CaO. beginning and

end of maximum decarburization rate.

In FIG. 2 shows fragments of measuring the amplitude of fluctuations in the temperature of the exhaust gases to.r ° (curve 1) in the period

the maximum decarburization rate and the corresponding change in the tangents of the tilt angle a of the exhaust gas temperature signal (curve 2). Also in FIG. 2 shows three dependencies a. b, c dl three

experimental swimming trunks, which show that the time interval of the maximum decarburization rate during purging can have different durations and different maximum speeds

decarburization.

It was found that the tangents of the slope angles tg а, measured as the rate of change V0 g for 1 s of the exhaust gas temperature to g °, expressed as a percentage of the instrument scale (% s), can take on different values. So. from FIG. 2a it follows that in this case the decarburization rate, which is equivalent to the slope angle V0 r, is growing rapidly, then

In this case, emissions and outflows of metal from the converter are possible. In FIG. 26 shows the normal course of the decarburization process, and FIG. 2c, the decarburization process proceeds in vivo, not intensively.

Therefore, each specific melting has its own characteristic trajectory of the maximum decarburization rate, which must be taken into account when blowing the melt. Based on the information received, it is possible to take appropriate measures in a timely manner during the purge process to prevent emissions and outflows of metal from the converter, to conduct purge in a given mode.

Based on the experimental swimming trunks, it follows that the fluctuations in the rate of change of the temperature of the exhaust gases Vo.g. it is possible to determine the average decarburization rate Vc in the range of the maximum decarburization rate, and it can also be determined for each lance oscillation period.

It should be noted that practically from the decrease in the maximum decarburization rate Vc, during the purge it is possible to predict the carbon content in the steel being smelted.

Thus, the proposed method of steel smelting using technology with a vertically-cyclic movement of the lance, for example, when CO is reached to COa, allows to reduce emissions and outflows of metal from the converter by determining the times of growth and decay of the decarburization rate, which allows predicting the magnitude of the current and final decarburization rate. In addition, the proposed method makes it possible to control the beating of the decarburization rate in each half-cycle of the tuyere oscillation and quickly take the necessary measures to prevent metal emissions and outbursts.

By reducing the amount of emissions and emissions of metal with slag, the yield of metal is increased by 0.2-0.4%.

The method can be implemented both on the basis of equipment available in the steelmaking shop and on special oxygen lance control equipment using digital computer technology.

Claims (2)

1. A method of steel smelting in a converter, including blowing oxygen of cast iron through a tuyere, which makes reciprocal motion in the vertical direction, periodically changing the amplitude of tuyere motion within 20-100% of the average tuyere height above the level of a calm bath during a given melting period with an amplitude change cycle equal to 1-5% of the purge duration, characterized in that, in order to increase the yield of metal and converter performance, the cyclic movement of the oxygen lance begins for 4-5 minutes ki, measure the temperature of the exhaust gases in the duct of the exhaust duct of the converter, and from the beginning of the fluctuations in the temperature of the exhaust gases with a fixed maximum amplitude of 20-40 ° C, determine the moment of reaching the maximum decarburization rate, then determine the decrease in the amplitude of the fluctuations in the temperature of the exhaust gases the decay of the maximum decarburization rate and stop the cyclic movement of the oxygen lance. 2. The method according to claim 1, characterized in that the decarburization rate in the melt in the course of purging is determined by the slope of each half-period of the temperature fluctuation of the exhaust gases. Ik o (SS 0.35 L CoO, 3r CaO, 3r 4 ° OfУо.Г.о / С (-OG / eShKrSCH J / yuilpay npubopa Q  / Ar-Ts5 / - / Chi / LALLLLLL / y 0 v t / o 0 40 0 to ftMuH. IT is Mi min ig / min  , 2 (/ mg /