JPS5973763A - Rapid measurement of silicon content in molten metal - Google Patents

Abstract

PURPOSE:To eliminate the sampling and conveyance of a specimen at all and to simply and rapidly measure the silicon content of molten iron or the like, by measuring electromotive force generated between reference substance known in the silicon content and a molten metal being a specimen to be measured. CONSTITUTION:A silicate electrolyte 6 is held inside a holding pipe 5 and reference substance 7 is charged into said pipe so as to be positioned on said electrolyte 6. As the silicate electrolyte 6, a silicate having ion conductivity is used and, as the reference substance 7, a pure metal Si, Fe-Si or a silicon compound known in the Si-concn. thereof is used. When the lower end of a measuring probe 1 is immersed in molten iron, the silicate electrolyte 6 and the reference substance 7 are directly melted to form a silicon concn. cell between the reference substance 7 and molten iron and electromotive force is generated between contacts A, B of lead wires 3a, 3b. If the calibration curve of the electromotive force value corresponding to the silicon concn. of molten iron is preliminarily calculated, the silicon concn. of molten iron can be directly known.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for easily and quickly measuring the amount of silicon in molten metal of a hot metal sieve.

For example, the amount of silicon in bath pig iron is closely related to the heat balance during converter operation, the amount of stubs produced, the basicity of slag, etc., and accurately understanding the amount of silicon is important for converter steelmaking. This is extremely important in order to proceed efficiently. Recently, as one of the pretreatment methods for bath pig iron, so-called preliminary desiliconization has been carried out, in which scale is added to hot metal in a blast furnace casthouse, etc., and then oxygen is blown into the hot metal to remove desiliconization. Since the amount of silicon in pig iron changes considerably, it is necessary to measure the amount of silicon before the desiliconization treatment and accurately control the amount of desiliconizing agent added.

In particular, in the above-mentioned blast furnace casthouse desiliconization, a desiliconizing agent is added to the hot metal flowing on the tap trough and desiliconization is carried out while it is flowing down, so the amount of silicon in the hot metal can be quickly measured and It is necessary to add the appropriate amount of desiliconizing agent, and if the measurement takes a long time, the bath pig iron will flow downstream during that time, so the meaning of measuring one silicon amount will be halved or become meaningless. Put it away.

By the way, as methods for analyzing silicon in molten metal, in addition to the gravimetric method and the molybdenum blue class photometric method, instrumental analysis methods such as the fluorescent X-ray method and the optical emission spectrometry are known. In the case of the analytical method, the time required for the analysis itself is about 1 to 2 minutes, which seems to satisfy the speed.

However, even with these 41M instrument analysis methods, the time required for segregation, including the preparation time for collecting, transporting, and loading the analysis sample into the equipment, takes at least about 10 minutes, and the speed is not satisfactory. It's hard to say.

The inventors of the present invention have focused on these circumstances and have been conducting intensive research in an attempt to establish a technique that can accurately measure the amount of silicon in an extremely short period of time. The present invention was completed as a result of such research, and its structure is a method of measuring the silicon-containing layer in metal by immersing a silicon measuring probe under the liquid surface of molten metal such as hot metal. A silicate electrolyte is held at the lower end of a longitudinal heat-resistant holding tube, and a silicon standard material is charged above the held electrolyte and brought into contact with the electrolyte. It is fixed to the tip of the probe, and when measuring the silicon chamber, the measuring element is kept in a substantially vertical position and its lower end is immersed in the molten metal, and a molten silicate electrolyte is placed between the molten metal and the reference material. The gist lies in that the silicon-containing layer of the molten metal No. 611 is detected by the electromotive force generated between the molten metal and the standard substance.

In the present invention, as described in detail below, a standard substance with a known silicon content and a bath #i which is a measurement sample! The amount of silicon in the molten metal is determined by the electromotive force generated between the molten metal and the molten metal. All you need to do is measure the power. That is, measurement 2: There is no need to collect or transport strips, and the amount of silicon can be accurately measured in a very short time, for example within 1 to 2 minutes, by simply immersing the probe directly into the hot metal of a blast furnace cast bed. be able to.

By the way, the basic principle of electrochemically controlling the amount of silicon in hot metal by measuring the electromotive force generated by placing molten iron and a reference material adjacent to each other by sandwiching the molten surface of silicate electrolyte is based on, for example, the invention of the present application. This was reported by one of the researchers, Otani et al. (K, Sanbongian and M, ohtani
H5oi, Sci, Rep, Res, Ins t,
Tohoku' (Jn 1, A5 (1958) e
d50, M, 0htani: Sci, Rep, ne
s.

In5t, Tohohu Uni, A5 (1955)
, 487. ) However, this principle has only been confirmed on an experimental scale;
? At present, no research has been reported to try to use it as a regular probe stop for IlII, and of course it has not been put to practical use.

The biggest reason for this is: ■ The melting point of the silicates used as electrolytes for determining electromotive force is lower than that of the bath metal (the melting point of the silicates used as electrolytes for determining the electromotive force is lower than that of hot metal). The separation is to maintain the stability within the probe while making contact with the
The specific gravity of a molten silica substance is lower than that of pure Si or PE-8T, which are used as standard materials, so an electrolyte must be charged under the standard material before measurement. Even if the electrolyte and the standard substance are placed in contact with each other, if they melt at 61 degrees at +1+lJ and obtain fluidity, the vertical relationship between the electrolyte and the standard substance will be reversed due to the difference in specific gravity, and the standard substance and the hot iron will not come into contact with each other. This makes it impossible to measure the amount of silicon using electromotive force. The present invention solves this problem and makes it possible to measure the amount of silicon using a blow-buoy measuring element, the specific configuration of which will be described in detail below.

FIG. 1 is a schematic longitudinal cross-sectional view In1 illustrating the tip structure of the silicon content measuring probe used in the present invention, in which 1 is the measuring probe body, 2 is the measuring element, 8 is the thermocouple, 8a
, 8b19c are lead wires, and 4'' is a heat insulating material. At the inner lower end of the elongated holding tube 5 having heat resistance and insulation,
While holding the silicate electrolyte 6, a reference material 7 is charged above the electrolyte 6 in contact with the F[electrolyte 6, and the 4
The lower end of the lead 113a is buried in the J skewer substance 7 charge, and the upper end of the lead wire 8a is connected to an electromotive force measuring device (not shown). The silicate electrolyte 6 is a silicate having ionic conductivity (e.g. CaO5j02-A1203,
CaO-S i 02- M g 01CaO-S
i O2-A / 203- Silicates such as M g O)
, the standard material 7 is pure gold known to 5iaJX.
Si, Fe-8i or other silicon compounds are used, all of which melt at the measured temperature (e.g. hot metal temperature). Moreover, in the melted state, the silicate electrolyte 6 has a lower specific gravity than the standard substance 7, so there is a risk that the silicate electrolyte 6 will float above the standard substance 7 during melting due to the difference in specific gravity. Therefore, when manufacturing the measuring element 2, the material, shape, inner diameter, etc. of the holding tube 5 are determined by considering the surface tension of the silicate electrolyte 6 and the standard substance 7 during melting and the wettability with the holding tube 5. By adjusting the electrolyte 6
and standard substance 7 from reversing. If a holding tube 5 with a small inner diameter or a large inner surface area (with a rough inner surface) is used, the melt of the silicate electrolyte 6 will be affected by its own surface tension and flow. It is held at the lower part of the holder 95 by frictional resistance. Further, a heat-resistant insulating material such as quartz, magnesia, boron nitride, etc. is used for the holding tube 5, but if a material with high wettability with the melted electrolyte 6 is used,
The retention effect of the B melt is further improved. and probe 1
A lead wire 8 is connected to the protruding side of the measuring element 2 at a position close to the protruding side of the measuring element 2.
b is provided in a protruding manner so that its tip is immersed in hot metal during measurement, and the other end is connected to the electromotive force measuring device. In addition, a thermocouple 8 for detecting the measured temperature is protruded from the tip of the probe 1, and the other end is connected to the electromotive force measuring device +yl.
K connection so that temperature correction of electromotive force i+n+fixed value is automatically performed.

Therefore, when the constant probe 1 is made approximately vertical to 1.11 and its lower end is immersed in hot metal, the silicate electrolysis w6 and the standard? The material 7 melts immediately at hot metal temperature. The silicate 1 sandwiches the solute 6, and a silicon DA cell is formed between the standard material 7 and the hot metal, and an electromotive force is generated between the contacts A and H of the lead wires 8a and 8b. By detecting the electromotive force with the electromotive force measuring device +1 and correcting it with the temperature measured by the thermocouple 8, it is possible to measure the electromotive force value corresponding to the difference in m degrees of silicon between the standard material 7 and the bath iron. Therefore, silicon 4 of hot metal
If a calibration curve of electromotive force values corresponding to one time is determined in advance and the actual measured values are compared with the standard curve, the silicon concentration of the hot metal can be immediately known.

By the way, @2 diagram shows 624S 1 as silicate electrolyte 6.
02-go Cao-81MgO silicate slag, pure metal silicon as the standard substance 7, and a transparent quartz tube as the holding tube 5 (dimensions and shapes are shown in Figure WS8: Units). The amount of silicon inside and the electromotive force (measured temperature is 150
0 'C). As is clear from this figure, there is a linear relationship between the amount of silicon and the electromotive force, so by setting this as a calibration curve and comparing it with the actually measured electromotive force value, we can calculate the silicon concentration of the hot metal. can be determined accurately. Moreover, if it is a measurement method of Mumu, simply 1 measurement probe 1
Since the electromotive force is simply measured by immersing the metal in hot metal, the time required for measurement is extremely short, and the amount of silicon can be quickly determined within 1 to 2 minutes.

In Fig. 1.8, the lower end of the holding tube 5 is formed into a serpentine shape, and the mK configuration is used to prevent the electrolyte 6 from diffusing in the direction of the hot metal as much as possible during measurement. 7@ Since the specific gravity of molten metal is lower than that of hot metal, and its compatibility with hot metal is also poor, if the material and inner diameter of the holding tube 5 are carefully selected, a swath-trade shape may be used. The holding tube 5 is most commonly cylindrical, but it may of course be rectangular or irregularly shaped. As the material for this holding tube 5, it was explained earlier that quartz, magnesia, and boron nitride are preferable.
ζ In short, it has electrical insulating properties and heat resistance to withstand the measurement temperature, and does not react with the silicate electrolyte 6, standard material 7, and molten metal to be measured, or even if it does, it has a rich electromotive force measurement value. Any material may be used as long as it does not affect the image. The same goes for the lead wires 88 to 8C, as long as they have appropriate heat resistance, do not react with contact objects (hot metal or silicate electrolyte), and have good 4 properties, typical examples include Examples include carbon and high melting point metals.

FIG. 4 is a schematic longitudinal sectional view illustrating another measuring element 2 used in the present invention, in which a porous heat-resistant tube with a sealed lower end is used as the holding tube 5. In use, the pores of the porous heat-resistant tube are impregnated with a molten silicate electrolyte, and if necessary, it is chemically bonded to a heat-resistant material by heat treatment, etc., and the electrolyte is applied to the tube wall. The standard substance 7 is held in this.
Charge. With this measuring element 2, the silicate electrolyte held in the wall of the holding tube 5 is melted as it is during measurement, so the electromotive force generated between the standard material 7 and the hot metal is generated as in the example shown in Fig. 1. can be measured. In this example, the silicate electrolyte is encapsulated in the fine pores of the wall of the holding tube 5, and combined with the action of its own surface tension, it is stably held in the wall of the tube. Therefore, a situation where the 7 phases of the standard substance and the 6 phases of the electrolyte are reversed due to a difference in specific gravity does not occur at all.

The present invention is roughly constructed as described above, and the silicon content can be detected extremely quickly and accurately by simply dipping a measurement probe into molten metal and measuring the electromotive force. Moreover, in the present invention, there is no need to separately sample the molten metal, and the measurement can be carried out at any time, such as on the bath pig shaft, in the ladle, or while being transported by the pig iron mixer car. In addition, although this specification mainly describes the determination of silicon in hot bath iron, the present invention is not limited to this, and can be similarly applied to the determination of silicon in molten steel and various steel alloys. The value is often great.

[Brief explanation of drawings]

Figure 1 shows an example of a measurement probe used in the present invention. Fig. 2 is a graph showing the relationship between Si content and electromotive force, No. 8 (2) is an explanatory diagram of the measuring element used in the trial, and Fig. 4 is a diagram showing the measurement element used in the present invention. FIG. 1... Measuring probe body 2... Measuring element 8... Thermocouple ga--9o
... Lead wire 4 ... Insulation material 5 ... Holding tube
6...Silicate electrolyte 7...Reference material procedural amendment October 31, 1982 1. Indication of the case 1984 Patent Application No. 184365 2. Name of the invention Method for rapidly measuring the amount of silicon in molten metal 3. Relationship with the case of the person making the amendment Patent applicant: 3-18 (119) Wakihama-cho, Chuo-ku, Kobe City, Kobe Steel, Ltd. Representative: Fuyuhiko Maki 4, Agent: 2 Dojima, Kita-ku, Osaka City, 530 The "Scope of Claims" and "Detailed Description of the Invention" columns (1) "Scope of Claims" in Book 3-7 Shinko Building Mei 1i111 will be corrected as shown in the attached sheet. (2) The specified parts of the detailed document will be corrected according to the attached errata. Claims: A method for measuring the silicon content in a molten metal by immersing a silicon content measuring probe having a silicon standard electrode material under the liquid surface of the molten metal, the method comprising: bringing a silicate electrolyte into contact with the molten metal; silicon in the molten metal, which is present between the standard electrode material and the molten metal, and the silicon content of the molten metal is detected by superpower generated between the molten metal and the standard electrode material. Quantity rapid measurement method.

Claims (1)

[Claims] 11) A method of measuring the silicon content in the metal by immersing a silica basin measuring probe under the liquid level of the eluted metal, in which a silicate electrolyte is held at the lower end of a longitudinal heat-resistant holding tube, and A measuring element, which is made by charging a silicon standard substance above the retained electrolyte and bringing it into contact with the electrolyte, is fixed to the tip of the measuring probe, and when measuring the amount of silicon, the measuring element is held approximately vertically. The lower end of the silicate electrolyte is immersed in the molten metal, and a molten silicate electrolyte is interposed between the molten metal and the standard substance, and the electromotive force generated between the molten metal and the standard substance causes the molten metal to immerse in the molten metal. A method for rapidly measuring the amount of silicon in f4 molten metal, which comprises detecting the silicon content of the molten metal.