JPH05180580A - Measuring method for thickness of slag - Google Patents

Abstract

PURPOSE:To accurately measure a thickness of a slag by sensing a variation in pressure of flow rate of blow-off gas, sensing a level of molten slag and molten metal, and measuring a thickness of a slag layer at an upper surface of the molten metal. CONSTITUTION:When a gas blow-off tube 3 is dipped from above in slag 1 existing on molten metal 2 and the molten metal 2 at a predetermined speed, a variation in pressure or fluidization of the blow-off gas generated when a gas discharge port 4 is brought into contact with the surface 5 of the slag and the surface 6 of the molten metal is sensed to detect a level of the slag 1 and the metal 2. A thickness 11 of the slag existing on the metal 2 can be detected based on the detected result. When inert gas is injected from the port 4 horizontally or upward in a range of 0 to 30 deg. to the horizontal surface of the slag 1 and the metal 2, fluctuations of the surfaces 5, 6 of the slag 1 and the metal 2 are reduced, and an accurate molten metal surface can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag thickness measuring method used in the field of manufacturing process control of ferrous or non-ferrous metals.

[0002]

2. Description of the Related Art Conventionally, in the metal manufacturing industry, slag (slag) mainly composed of metal oxides has been used for removal of impurity elements in molten metal and prevention of reoxidation of molten metal, and deoxidation and unavoidable Slag is generated by the oxidation of various metals. As described above, the slag is inevitably present in the metal refining process, and it is important to control the composition of the slag.Of course, if the amount is not grasped, the yield control of alloy elements and the concentration of solute elements in the metal control,
Advanced quality control for the manufacture of metal products such as non-metallic inclusion control is not possible. Therefore, conventionally, in the metal manufacturing industry, in order to grasp the amount of slag existing on the molten metal, the thickness of the slag has been measured. This is because if the shape of the container holding the molten metal is constant, the volume of the slag can be calculated by measuring the thickness of the slag. For example, in the conventional steel manufacturing industry, in order to measure the thickness of slag, the steel wire is immersed in molten steel from above the ladle that holds the molten steel, held and then pulled up, at which time the part immersed in the molten steel melts and disappears. Therefore, the slag thickness is measured by measuring the length of the red-hot portion in contact with the slag.

[0003]

However, in the above method, the measured values vary due to the melting time of the steel wire depending on the molten steel temperature, the molten steel composition, and the holding time. Since the steel wire melts and disappears for each measurement and becomes shorter, it becomes necessary to replace the steel wire at regular intervals. Further, manpower is required to measure the length of the red-hot portion of the steel wire, which is an obstacle to automation of the process and labor saving.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a slag thickness measuring method capable of automatically and accurately detecting the slag thickness of molten metal.

[0005]

In order to achieve the above object, the gist of the present invention is to provide a blow-in pipe having a gas discharge port at its tip end, and inject an inert gas from the blow-in pipe. While performing the operation of immersing in the molten metal and the slag existing on the molten metal upper surface, the pressure fluctuation or flow rate fluctuation of the blown gas generated when the gas discharge port comes into contact with the molten slag surface or the molten metal molten metal surface is detected. By measuring the molten metal level of the molten slag and the molten metal, the thickness of the slag layer existing on the upper surface of the molten metal is measured.

In carrying out the present invention, the inert gas is 0 including 0 ° with respect to the horizontal surfaces of the slag and the molten metal.
It is desirable that the gas is jetted horizontally or upward from the gas discharge port at an angle within the range of 30 ° to 30 °.

[0007]

According to the present invention, when the blow pipe is immersed in the slag existing on the molten metal and the molten metal from above at a constant speed, when the gas discharge port comes into contact with the slag surface and the molten metal surface. It is possible to detect the pressure fluctuation or flow rate fluctuation of the blown gas that is generated to detect the molten metal level of the slag and the molten metal, and to accurately detect the slag thickness existing on the molten metal based on the detection result.
In addition, when the inert gas is jetted horizontally or upward from the gas discharge port at an angle within a range of 0 ° to 30 ° including 0 ° with respect to the horizontal plane of the slag and the molten metal, the molten metal surface of the slag and the molten metal is discharged. Oscillation can be reduced and the slag and molten steel surface position can be accurately detected.

Further, in the apparatus for carrying out the present invention, the gas pressure or the gas flow rate of the inert gas supplied when the blowing pipe is immersed in the slag existing on the molten metal and the molten metal becomes a predetermined constant value. Detection means that emits a signal when it reaches,
An accurate slag thickness can be measured by providing a means for receiving the signal from the detection means and calculating the slag thickness from the immersion speed of the blowing pipe.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic view showing a slag thickness measuring device which is an example of a device for carrying out the present invention. In FIG. 1, 1 is slag existing on the molten metal 2, 3 is an inert gas blowing pipe, 4 is a gas discharge port formed at the tip of the gas blowing pipe 3, 5 is a slag surface, and 6 is a molten metal 2 Of the molten metal, 7 is an elevating device for elevating the gas blowing pipe 3, 8 is a surface detecting device, 9 is a gas supply device, and 10 is a control unit.

In order to accurately measure the slag thickness 11, which is the distance between the slag surface 5 and the molten metal 2 molten metal surface 6 with the above-described structure, first, the inert gas blowing pipe 3 is connected to the slag surface 5 of the slag 1. Rest above. At this time, the gas discharge port 4 of the gas blowing pipe 3 is located above the slag surface 5. In this state, the gas blowing pipe 3 is lowered by the elevating device 7 while blowing gas from the gas discharge port 4 through the molten metal surface detection device 8 by the inert gas supply device 9 such as Ar. The lifting device has a motor-driven structure that can set the lifting speed and distance. Gas outlet 4 is slag 1
When it is on the slag surface 5, the gas blown out from the gas discharge port 4 is diffused into the atmosphere as it is, so that the pressure of the blown gas does not change, and the flow rate of the blown gas is constant. However, when the gas outlet 4 contacts the slag surface 5 of the slag 1, the outlet load of the gas outlet 4 changes,
The flow rate of the injected gas changes. The change in the flow rate is detected, and first, the slag surface 5 of the slag 1 is detected. afterwards,
When the gas blowing pipe 3 further descends and the gas discharge port 4 comes into contact with the molten metal surface 6 of the molten metal 2, the outlet load of the gas discharge port 4 further changes, and the flow rate of the gas to be blown further changes. By detecting this change in flow rate, the molten metal 2 level 6 is detected. The change in the flow rate of the blown gas is detected by the molten metal level detector 8.

FIG. 2 is a schematic block diagram of the molten metal surface detecting device 8. In FIG. 2, 12 is a three-way valve that branches the gas path,
15 is a pressure regulating valve, 16 is a pressure gauge, 17 is a micro valve,
18 is an internal heat type mass flow meter, 19 is a digital meter, 2
Reference numerals 0 and 21 are check valves, 22 is a pressure reducing valve, 23 is a float type volume flow meter, and 10 is a control unit. Other reference numerals are the same as those in FIG.

The inert gas such as Ar gas supplied from the gas supply device 9 is a pressure fluctuation detecting gas path for detecting pressure fluctuations of the main gas path 13 and the gas ejected from this gas path 13 by the three-way valve 12. (Auxiliary gas path) 14 is branched. A pressure reducing valve 22 and a float type volume flow meter 23 are arranged in the main gas passage 13, and an inert gas set to a gas flow rate of 5 to 20 l / min is introduced into the gas blowing pipe 3 via the check valve 21. Supply.

A pressure regulating valve 15, a pressure gauge 16, a micro valve 17 and an internal heat type mass flowmeter 18 are arranged in the pressure fluctuation detecting gas passage 14, and join the main gas passage 13 via a check valve 20. Then, the inert gas is supplied to the gas blowing pipe 3. The internal heat type mass flowmeter 18 has a digital meter 19
Are connected and the gas flow rate is set to 50 to 500 ml / min. This digital meter 19 is a gas blowing tube 3
In order to detect the pressure fluctuation of the blown gas that occurs when the gas discharge port 4 of the above comes into contact with the slag surface 5 existing on the molten metal, the control unit when the flow rate of 1 to 3 ml / min decreases with respect to the set flow rate. An electric signal is sent to 10 and the arithmetic unit 24.

The pressure fluctuation generated in the jetted gas is caused by the contact of the slag surface 5 with the gas discharge port 4,
It depends on the flow rate of the ejected gas. That is, the pressure fluctuation received at the gas discharge port 4 gives the same pressure fluctuation to the gas flowing through the main gas passage 13 and the pressure fluctuation detecting gas. Therefore, even if the pressure fluctuation detecting gas passage 14 is provided separately from the main gas passage 13, the slag surface 5 can be accurately detected.

When the control unit 10 receives this signal, the elevator device 7 is continuously lowered. On the other hand, when the arithmetic unit 24 receives this signal, it records the time and holds the data. When the gas discharge port 4 comes into contact with the molten metal surface 6 of the molten metal 2 due to further lowering of the gas blowing pipe 3, in order to detect the pressure fluctuation of the blown gas that occurs when the molten metal 2 comes into contact with the molten metal surface 6, it is necessary to set the flow rate from 30 to 30 When the flow rate of 40 ml / min decreases, an electric signal is sent to the control unit 10 and the arithmetic unit 24. When the arithmetic unit 24 receives this signal, it records the time, calculates the difference from the previously received detection time of the slag surface 5, and calculates the slag thickness by multiplying the set descending speed of the gas blowing pipe 3. And display it.

Here, the gas discharge port 4 is the molten metal 2 level 6
Unlike the case of the slag surface 5, it is set to send an electric signal to the control unit 10 and the arithmetic unit 24 when the flow rate of 30 to 40 ml / min decreases with respect to the set flow rate. This is because, generally, the density of the molten metal 2 is higher than that of the slag 1, and the pressure fluctuation when the gas discharge port 4 contacts the molten metal 2 molten metal surface 6 is larger than the pressure fluctuation when the molten metal 2 contacts the slag surface 5.

When the control unit 10 receives the detection signal of the molten metal 2 molten metal level 6, it controls the elevating device 7 to further lower the blowing pipe 3 for a certain period of time, and then stops the lowering. This time is determined in relation to the descending speed, and the gas blowing pipe 3
The gas discharge port 4 is 15 to 30 mm below the molten metal 2 molten metal surface 6.
Set to stop at position. By the way, the discharge angle of the inert gas ejected from the gas discharge port 4 of the gas blowing pipe 3 is 0 ° with respect to the horizontal plane (slag surface 5).
It is desirable to be in the range of -30 °. That is, when the jet angle of the inert gas is larger than 30 °, the slag 1 and the molten metal 2 are blown up by the jet of the inert gas,
The amounts of the slag 1 and the molten metal 2 that are scattered become large, and there is a high possibility of becoming a factor that hinders operations, such as adhesion of the slag and the metal to the molten metal holding container. On the other hand, when the ejection angle of the inert gas is below the horizontal plane (slag surface 5), pressure fluctuations may be detected before the gas discharge port 4 contacts the slag surface 5, and the slag thickness 11 may be overestimated. It becomes large and the measurement accuracy deteriorates.

If there is a mass flowmeter capable of accurately setting a gas flow rate of 5 to 20 l / min, the main gas passage 13 and the pressure fluctuation detecting gas passage 14 are separately provided as shown in FIG. It is not necessary, and it is possible to use both the main gas passage 13 and the pressure detection gas passage 14 only with the gas passage provided with the mass flowmeter for setting 5 to 20 l / min. However, the current technology is 5 to 20 l / min.
Since it is difficult to manufacture a mass flow meter capable of accurately setting a large flow rate gas, a small flow rate gas path is provided separately from the large flow rate blowing gas path in this embodiment.

In the above embodiment, the case where the flow rate fluctuation of the supply gas is detected to detect the slag surface 5 and the molten metal 2 molten metal surface 6 has been described, but the present invention is not limited to this. The slag thickness 11 may be measured by detecting the pressure fluctuation of the supplied inert gas, detecting the slag surface 5 and the molten metal 2 molten metal surface 6.

[0020]

As described above, according to the present invention, the slag thickness 11 is determined by automatically detecting the slag surface 5 of the slag 1 and the molten metal surface 6 of the slag 1 which are present on the molten metal 2. It is possible to measure with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic view showing a slag thickness measuring device which is an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a molten metal surface detection device.

[Explanation of symbols]

 1 slag 2 molten metal 3 gas blowing pipe 4 gas discharge port 5 slag surface 6 molten metal 2 molten metal surface 7 lifting device 8 molten metal level detection device 9 gas supply device 10 control unit 11 slag thickness 12 three-way valve 13 main gas path 14 pressure Fluctuation detection gas path 15 Pressure regulating valve 16 Pressure gauge 17 Micro valve 18 Internal heat type mass flow meter 19 Digital meter 20 Check valve 21 Check valve 22 Pressure reducing valve 23 Float type volume flow meter 24 Computing device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Ono 1618 Ida, Nakahara-ku, Kawasaki, Kanagawa Kanagawa Prefecture Advanced Technology Research Laboratory (72) Inventor Yasuhiro Hayakawa 1618 Ida, Nakahara-ku, Kawasaki, Kanagawa Nippon Steel Corporation Advanced Technology Research Center

Claims (1)

[Claims] 1. When performing an operation of immersing a blow-in pipe having a gas discharge port at a tip end thereof into a molten metal and a slag existing on the upper surface of the molten metal while ejecting an inert gas from the blow-in pipe, Exists on the upper surface of molten metal by detecting the pressure level or flow rate fluctuation of the blown gas that occurs when the gas outlet contacts the molten slag surface or molten metal level. A method for measuring slag thickness, which comprises measuring the thickness of a slag layer.