JPS60255911A - Method for controlling supply of refining agent in continuous refining - Google Patents

Abstract

PURPOSE:To supply automatically an appropriate amt. of a refining agent and to reduce the consumption of the agent by measuring continuously the inflow rate of an inflowing molten metal and the objective components to be smelted, and controlling the necessary supply rate of the refining agent on the basis of said measured results. CONSTITUTION:In the outlet of a launder 6 of molten iron 4, laser light is emitted from an emitter 28, and irradiated on the surface of molten iron through a pipe 30. The excited and emitted light is again detected by a photodetecting part provided in parallel with the emitter 28, and inputted to a microcomputer 26. The means value of Si concns. is thus obtained. Meanwhile, the weight of a torpedo ladle car 12 is measured by a load cell 36, and inputted to the microcomputer 26 to obtain the means value. Then the amt. of a desiliconizing agent is obtained by a specified equation, and transduced into the current value of a supply feeder 18. The supply feeder 18 is operated with said transduced value, and the appropriate amt. of the desiliconizing agent corresponding to the amt. of molten iron and the silicon concn. both of which change mementarily is supplied.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the amount of refining agent supplied in continuous refining, and in particular, to a method for controlling the amount of refining agent supplied in continuous refining, and in particular to a method for controlling the amount of refining agent supplied in continuous refining of molten metal such as hot metal tapped from a blast furnace. This invention relates to a control method that can automatically supply an appropriate amount.

Hot metal tapped from a blast furnace does not necessarily have the optimum composition for steelmaking, and there are variations in each component of the hot metal depending on the influence of the ironmaking raw materials and the operating conditions of the blast furnace. For this reason, after blast furnace tapping, out-of-furnace refining such as desiliconization, desulfurization, and dephosphorization is performed. Conventionally, batch-type devices such as torpedoes and ladles have been mainly used as these outside-furnace refining devices, but continuous refining has recently been adopted from the viewpoint of improving reaction efficiency and preventing temperature drop. The present invention is utilized for controlling the amount of refining agent supplied in such continuous refining of molten metal.

[Conventional technology]

An example of a cast bed desiliconization apparatus for blast furnace tapping will be explained with reference to FIG.

This was recently developed in response to the need to reduce the concentration in pig iron [S1] in the steelmaking process.In other words, a desiliconizing agent such as iron ore is introduced into the trough in the casthouse, and 3 C8i ] + 2Fe! Oa −+ 384Ch
The [81] concentration in the hot metal is continuously refined to below a predetermined value by the reaction of +4Fe.The hot metal 4 tapped from the taphole 2 is passed through the tap trough 6, the desiliconization trough 8, the inclined trough 10, etc. The iron is then transferred to the torpedo car 12. The desiliconizing agent 14 passes through the desiliconizing agent hopper 16, the supply feeder 18, and the desiliconizing agent chute 20, and then is sprayed onto the hot metal 4 in the tapping trough 6 and the downstream inclined trough 10, and is then sprayed on the hot metal 4 in the desiliconizing machine 8 by the falling energy). Mixing and desiliconization reactions are carried out. In addition, the tap duct 6 and the desiliconization machine 8
A skinmer 22 is installed at each.

The conventional technology for the above-mentioned desiliconization equipment is, for example, disclosed in Japanese Patent Application Laid-open No. 56
-217, the tapped (81) concentration is determined based on the average silicon content in the hot metal in the furnace estimated from the furnace heat control model. The basic unit of desiliconization agent is determined from the difference between this (sB concentration and the target [ai] concentration, and the addition rate of desiliconization agent is calculated via the tapping rate. However, the addition rate of desiliconization agent is determined by The biggest factor is the (:Si) concentration during tapping.

It is also a well-known fact that the concentration in the hot metal in the furnace estimated from the furnace thermal control model is not very accurate.

Even at the average (84) concentration for each tap, the accuracy is around ±0.1 s at most. Furthermore, although the average time for one tap is around two hours, changes in (87) concentration during this time cannot be known by predictions from conventional furnace heat control models.

Therefore, in the conventional method, the target (81) after desiliconization is 0.
20-, a maximum error of o, o s s occurs, and even the fluctuation value is about σ0.05-. Target (Si) 0.
For 20 pieces, the fluctuations in σo and o s s are values that cannot be ignored in order to desiliconize the iron and send it to the next process as low [Si] pig iron.

We have described a specific example of desiliconization by continuous refining of hot metal, but since the amount of molten metal that flows in conventional continuous refining and the components of the molten metal to be refined change from moment to moment, the desiliconization agent added during refining, etc. It is difficult to control the supply amount of the refining agent, and as a result, the accuracy of the target components of refining is low.
This also led to a loss of refining agent.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems of the conventional technology, and provides a method for controlling the amount of refining agent supplied by continuously measuring the amount of inflowing molten metal and the components to be refined, and injecting an appropriate amount of refining agent based on the measurement results. is intended to provide.

[Structure of the invention]

The gist of the present invention is as follows.

That is, in a method for controlling the amount of refining agent supplied in continuous refining performed by injecting a refining agent into continuously flowing molten metal, there are a step of measuring the amount of molten metal flowing into the molten metal, and a step of measuring the amount of refining agent in the molten metal that is to be refined. The method comprises the steps of measuring with an emission spectrometer, and calculating the supply amount of the refining agent based on the measured values of the inflow amount and the components, and adding the refining agent to the molten metal. This is a method for controlling the amount of refining agent supplied in continuous refining.

Let me explain with an example. First, the apparatus used in this example will be explained. A laser emission spectrometer 24 and a microcomputer 26 as shown in FIG. 2 are installed at the outlet of the tap trough 6 shown in FIG. 1. death.

- The laser emission spectrometer 24 includes a transmitter 28, a pipe 30,
It is composed of Nt gas piping 32.

Further, a load cell 36 is installed at the bottom of the rail 34 of the torpedo car 12 receiving pig iron, and the load cell 36 is communicated with a microcomputer. Note that the measurement of the amount of molten metal flowing in is not limited to the load cell 36, and conventional electromagnetic flowmeters, weir flowmeters, tracer one-type flowmeters, etc. can also be used.

Next, a method of controlling the amount of desiliconizing agent supplied using the above-mentioned apparatus will be explained. The laser is emitted from the transmitter 28, passes through the pipe 30, and is irradiated onto the bath iron surface.The light excited by the laser and emitted light passes through the pipe 30 again and reaches the transmitter
The light is received by a light receiving section installed in parallel with the 100% Si concentration, is converted into a current signal through a spectrometer, and is input to the microcomputer 26.The laser emission spectrometer 24 analyzes the signal every 30 seconds [Si3 concentration is 10 Calculate the average value every minute. That is, the average concentration (S i )a is calculated using 18 pieces of data excluding the maximum and minimum values of each analysis value [S i ).

On the other hand, the load cell 36 measures the weight W of the torpedo car 12.
i is measured every 30 seconds and input into the microcomputer 26. The microcomputer 26 calculates a 10-minute moving average Wl based on the value excluding the maximum and minimum values of the measured values for the past 10 minutes. W'l is calculated every 30 seconds, but the values are averaged every 10 minutes to calculate the average weight WaL.・Required amount of desiliconization agent Dsio! is [Si:la, Wai
It can be determined by the following formula using .

Di io, −((Si)a −(st JT)X
(Wal-Wai-1) F((S')T) is a coefficient depending on the desiliconization efficiency of the desiliconization device, and is determined experimentally for each ore.

FIG. 3 shows the relationship between the desiliconization efficiency of two types of iron ores A and B and the target S1 concentration (81)T after desiliconization.

The required amount of desiliconization agent Dslo2 requested by calculation is converted into the current value of the supply feeder 18 of the desiliconization agent supply device, and the supply feeder 18 is operated according to this converted value to remove the desiliconization agent. was put into hot metal 4.

That is, it was possible to supply an appropriate amount of desiliconizing agent according to the ever-changing amount of hot metal and [S1] concentration.

The results of continuous desiliconization refining examples are shown in FIGS. 4 to 7. Figure 4 shows the concentration of S in the tapping, Figure 5 shows the tapping speed, and Figure 6 shows the tapping speed.
The figure shows the amount of desiliconizing agent supplied, but since there is no accurate value for the amount of iron tapped for 10 minutes immediately after tapping, a constant value of 100 Kf/m is used.
The supply amount of in is set.

Figure 7 shows the change in the concentration of hot metal (81) after desiliconization sampled at the outlet of desiliconization sluice 8, and shows the change in the concentration of hot metal (81) after desiliconization.
) It increases somewhat during periods when the concentration changes rapidly, but
It can be seen that the other concentrations are almost controlled to the target concentration (8j, ]T O, 15%.

The [S1] concentration in hot metal after desiliconization is the target concentration (S l )
When T is 0.20 inches and 0.15%, the frequencies are shown in FIGS. 8(A) and 8(B) for this embodiment and the conventional example using the furnace heat control model. 0 indicates an example, and 0 indicates a conventional example. The statistical values are summarized in Table 1K.

As is clear from FIG. 8(e), @, and Table 1, Y is 0.021 lower in the embodiment than in the conventional example, and σ is also significantly smaller. In Italy, the target (
si)t The lower the 6 degrees, the higher it is.

In the method of the present invention, the (81) concentration during tapping can be accurately measured, so the only factor that affects the fluctuation of the (81) concentration after desiliconization is the error in the desiliconization efficiency F((Si)t). However, since this desiliconization efficiency was measured in the same device, there is little difference between them, and the accuracy of the [S1] concentration after desiliconization is extremely good, the average value is the same as the target value, and σ Also 0
．． The range of 0.01 to 0.02 was sufficient for practical use, and the amount of desiliconizing agent supplied could be controlled with high accuracy.

Although the present invention has been mainly explained with respect to desiliconization in a blast furnace cast bed, the method of the present invention also includes a continuous refining reaction of molten metal, such as a desulfurization reaction,
It can be widely applied to supplying refining agents for dephosphorization reactions or alloy component addition operations.

〔Effect of the invention〕

In continuous refining, the present invention continuously measures the inflow amount of molten metal and the components to be refined in the molten metal using a laser emission spectrometer, and controls the required amount of refining agent to be supplied based on these measured values. This enables continuous refining of target ingredients and rice, and further reduces the amount of refining agents used.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a blast furnace casthouse desiliconization device showing an embodiment of the present invention;
Fig. 2 is a front view showing the installation status of the laser emission spectrometer according to the embodiment of the present invention, and Fig. 3 shows the desiliconization efficiency and after desiliconization (8i).
Diagrams 4 to 7 show the relationship between the tapping (Si) concentration, tapping speed, desiliconization agent supply amount, and (Si) concentration of the hot metal after desiliconization in the examples of the present invention, respectively. Diagrams showing changes over time, FIG. indicates a conventional example. 4...Hot metal 6...Tapping trough 18...Supply feeder 24/Laser emission spectrometer 26...Microcomputer- 36...Load cell agent Patent attorney Medium To Takeshi Φ rorQ Figure 2 Figure 3 00, + 0.20, 30.4 Q50, 60.70.
8Silicon (Si) manufacturing method (%) Fig. 8 (A) 0, +0 0.20 0.30 Theory of silicon barley (S i ) μ (%) Sl) concentration (%)

Claims (1)

[Claims] U) A method for controlling the supply amount of a refining agent in continuous refining performed by injecting a refining agent into continuously flowing molten metal, which includes a step of measuring the amount of inflow of the molten metal, and a step of measuring the scouring target component of the molten metal with a laser. The method comprises the steps of measuring with an emission spectrometer, and calculating the supply amount of the refining agent based on the measured values of the inflow amount and the components, and adding the refining agent to the molten metal. A method for controlling the amount of refining agent supplied in continuous refining, characterized by: