JPH0810792Y2 - Consumable crucible used for oxygen activity measuring device in slag - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable crucible suitable for highly accurately measuring oxygen activity in slag produced in refining processes other than iron making processes, that is, non-ferrous refining processes.

[0002]

2. Description of the Related Art Slag is produced in both metal and nonmetal refining processes. Since this slag indirectly controls the progress of refining of metals and nonmetals, slag components are analyzed. This is an extremely important matter, and it is extremely meaningful to know the oxygen activity in the slag.

For example, in the steelmaking process, not only is slag indispensable as an element for shutting off molten steel from the atmosphere, but steelmaking slag is in a floating state on molten steel so that it comes into contact with molten steel. It causes a chemical reaction and indirectly controls the chemical reaction of the molten steel itself. Therefore, in order to adjust the composition of the molten steel as a product, it is inevitably important to control the slag composition. However, it is not enough to know the chemical composition of slag to estimate the degree of chemical reaction between molten steel and slag, and it is very important to directly know the oxygen activity in the slag. The fact that the slag analysis is important for knowing the state of the substance to be refined, and particularly the measurement of the oxygen activity in the slag is extremely important, is applicable not only to the steelmaking process but also to the refining process in general.

By the way, as an apparatus for measuring the oxygen activity in slag in the steelmaking process, the same applicant has filed Japanese Patent Application No. 1-271033.
(Japanese Patent Application Laid-Open No. 3-131748), Japanese Patent Application No. 3-5141 (Japanese Utility Model Publication 4-9)
7837), Japanese Patent Application No. 3-181948 (Japanese Patent Application Laid-Open No. 5-146625) and Japanese Patent Application No. 4-269350 (Japanese Patent Application Laid-Open No. 6-94673). For example, in Japanese Patent Application No. 1-271033, a principle device diagram of an oxygen activity measuring device is shown. In this apparatus, as shown in FIG. 6, a reaction tube b filled with an inert gas is vertically provided in a condensing type heating furnace a, and an iron crucible c and a support base are installed in a heating section in the reaction tube b. The thermocouple e for temperature measurement is placed in the outer tube d, which is also made of metal, so as to be detachable, and the temperature-sensing part thereof is placed close to the lower surface of the iron crucible c. In the iron crucible c, the specific metal M that does not form an alloy with iron in the iron crucible c, does not easily form an oxide, and has a specific gravity larger than that of the slag S is measured in the iron crucible c. They were housed together in a molten state. Then, in this application, pure silver is exemplified as a specific example of the specific metal M.

In the measuring method using this apparatus, the solid electrolyte f containing the standard electrode is immersed in the specific metal M and the slag S which are brought into a molten state by the heating of the condensing type heating furnace a, and the reference electrode is set. Measure the electromotive force between the iron crucible c and the standard electrode
The oxygen activity of the slag S was actually measured by measuring the thermoelectromotive force of the thermocouple e with the instrument h. The reason why the oxygen activity of the steelmaking slag can be measured by this apparatus, that is, the equilibrium oxygen partial pressure of the iron-slag reaction can be measured, is described in detail in Japanese Patent Application No. 4-269350. In this device, the equilibrium oxygen partial pressure of solid iron and pure iron oxide is measured in advance by an oxygen concentration battery (solid electrolyte). If you measure the equilibrium oxygen partial pressure of the slag whose iron oxide activity you want to know, The iron oxide activity of the can be obtained. In this way, by knowing the iron oxide activity in the slag, it became possible to estimate the reaction of phosphorus or sulfur, which is not so preferable for the product.

In the same application, the present applicant proposes a so-called consumable iron crucible, which is discarded as an iron crucible c at the end of each measurement in order to avoid inclusion of impurities other than the sample to be measured. As a specific configuration, by melting and solidifying the specific metal in advance inside the consumable crucible, it is not necessary to store the specific metal in each measurement work, and this makes it possible to avoid forgetting to insert the specific metal. It was also proposed to promote the efficiency of measurement work.

Further, in order to maintain the accuracy of measuring the oxygen activity by the apparatus, a substance having a known oxygen activity is used as a calibration substance, and the calibration substance is periodically put in the iron crucible instead of the slag. I also proposed to calibrate the instruments.

[0008] In addition, Japanese Patent Application No. 3-5141 and Japanese Patent Application No. 3-1819
No. 48 also proposes a concrete device with various ideas for applying the above-mentioned measurement method.

[0009]

In the apparatus for measuring oxygen activity in slag, which has been proposed by the present applicant, an iron crucible is used as the crucible. this is,
This is because the iron crucible can have a function as an electrode because it has conductivity, and the iron crucible can be provided industrially at low cost.

As is clear from the principle, the above-mentioned measuring device is not limited to steelmaking slag, but can be used for measuring oxygen activity in slag produced in the refining process of non-ferrous metals and non-metals such as glass. Should also be applicable. However, when the above device is applied to such slag measurement,
It was found that an error occurred in the measurement result, making it impossible to perform highly accurate measurement.

The present inventor has made the following conclusion as a result of examining the cause. That is, although the amount of the crucible is very small, the crucible constituent material is eluted in the slag as the measurement target, or the crucible constituent material reacts with the slag. If the eluted component or the component generated after the reaction is a component that does not originally exist in the slag that is the measurement target, or is a component that is essentially present in a very small amount, it is ignored in the component composition of the slag. Not expected to have an impact. Further, when the oxygen in the slag is consumed during the reaction, it affects the oxygen activity in the slag. When the crucible is an iron crucible and the slag to be measured is steelmaking slag, since a large amount of iron is originally present in the steelmaking slag, the effects of the iron eluted from the iron crucible and the reaction between the iron and the slag However, when the measured slag is produced slag in the non-ferrous refining process, iron and iron oxide are essentially present in the slag in a very small amount, and therefore, the iron content is eluted in such slag and the iron oxide is not present. If oxygen is generated, the oxygen activity in the slag will fluctuate greatly. As described above, when the slag generated in the non-ferrous refining process is to be measured, the conventional iron crucible is not suitable for use, and it is necessary to develop an alternative crucible.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a consumable crucible suitable for highly accurately measuring the oxygen activity in slag produced in the non-ferrous refining process. is there.

[0013]

[Means for Solving the Problems] The inventors of the present invention have earnestly studied to solve the above problems, and have obtained the following ideas. That is, while utilizing the advantages of the iron crucible that it has sufficient electrical conductivity capable of carrying out the electrode function, is also excellent in heat conduction and workability, and can be provided industrially at low cost, it is possible to obtain the iron content from the iron crucible. In order to prevent the elution of iron, the inner surface of the iron crucible located in the range of the slag, that is, the inner surface of the iron crucible in contact with the slag, may be provided with a barrier layer for preventing the elution of iron and the reaction between the iron crucible and the slag. I noticed. As a material for the barrier layer, they have found that the object can be achieved by selecting a substance that does not react with slag, that is, a substance that does not react with slag. Further, since the iron crucible also has a function as an electrode, it must be at least electrically connected to the specific metal in the crucible. Therefore, a contact portion between the iron crucible and the specific metal is also provided. And
If this idea is further developed, it is possible to use other metal crucibles in place of the iron crucible. Especially, if the material of the metal crucible is of the same kind as the refining target metal, the oxygen activity in the slag is reduced. It can also be expected to improve the accuracy of quantity measurement.

The consumable crucible of the present invention completed based on such an idea has the following contents. That is, the consumable crucible is composed of a metal outer container and a blocking layer formed of an anti-slag non-reactive substance disposed on the inner surface thereof, and the blocking layer is located under the slag. It is characterized in that it is arranged in at least the entire contact area of the inner surface of the metallic outer container with at least the slag while leaving a partial contact portion between the specific metal and the metallic outer container.

Although there are various concrete modes of the consumable crucible, for example, a bottomless cylinder whose outer diameter substantially matches the inner diameter of the metal outer container, or an outer diameter substantially matches the inner diameter of the metal outer container. A bottomed cylindrical body with a through hole formed at the bottom is formed using a substance that does not react with slag, and these cylindrical bodies are fitted inside a metal outer container, or a part of the inner bottom part of the metal outer container is formed. It is possible to employ a form in which the inner surface of the metal outer container is coated, coated or sprayed with a non-slag non-reactive substance.

As the material of the barrier layer, it is preferable to use a material that does not significantly change the oxygen activity of the slag to be measured, that is, a material close to the constituent components of the slag, such as aluminum oxide and calcium oxide. It is possible to use a substance containing one or more selected from magnesium oxide, silicon dioxide, stabilized zirconia, partially stabilized zirconia or mullite as a main material.

Further, instead of the iron crucible, the crucible body may be made of the same metal as the refining target metal.

[0018]

The oxygen activity in the slag using the consumable crucible having such a structure is measured as follows. First, a specific metal such as pure silver is pushed and installed in an inactive atmosphere in the crucible in which a blocking layer is arranged in a predetermined range on the inner surface of a metallic outer container, and then a slag to be measured is put on the specific metal.
Next, this crucible is housed in a melting furnace filled with an inert gas, and the crucible is heated to melt the slag and the specific metal. Then, the closed-ended tube type solid electrolyte containing the standard electrode is passed through the molten slag layer and immersed in a specific metal, and the electromotive force between the outer metal container also serving as the reference electrode and the standard electrode is set. By measuring the oxygen activity in the specific metal, the oxygen activity in the slag is obtained from this value.

Since the barrier layer exists in the slag existing range on the inner surface of the metal outer container, the constituent materials of the metal outer container are not eluted into the slag or reacted with the slag. Moreover, since the barrier layer itself is formed of a material that does not affect the oxygen activity of the slag even when it is eluted, the oxygen activity in the slag can be maintained in a stable state without changing during the measurement time. Further, since the specific metal and the metal outer container are partially in contact with each other, an electric closed circuit is formed between the solid electrolyte and the metal outer container, and an electromotive force corresponding to the oxygen activity in the slag is generated. Occurs.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, details of the present invention will be described based on embodiments. The basic embodiment of the oxygen activity measuring apparatus in which the consumable crucible of the present invention is set is shown in FIG. The apparatus is the same as the conventional apparatus shown in FIG. 6 except for the consumable crucible 1. That is, a reaction tube b filled with an inert gas is vertically installed in a condensing type heating furnace a, and a consumable crucible 1 is attached to a heating part in the reaction tube b, and a metallic jacket that also serves as a support base. It is detachably mounted on the tube d, and a thermocouple e for temperature measurement is arranged in the outer tube d in a state where the temperature-sensing part thereof is brought close to the lower surface of the consumable crucible 1. is there.

The consumable crucible 1 contains a specific metal M in a molten state together with the slag S to be measured.
The specific metal M is a material that does not form an alloy with the material of the metal outer container 2 in an inert atmosphere, is hard to generate an oxide, and has a heavier specific gravity than the slag S.
For example, pure silver or the like is used. The specific metal M may be accommodated in a molten state, or a plate-shaped or linear material may be pushed and installed in the crucible and melted by heating.

At the time of measurement, the solid electrolyte f containing the standard electrode is immersed in the specific metal M and the slag S which have been melted by the heating of the converging type heating furnace a, and the consumable type which also serves as the control electrode is formed. The electromotive force between the crucible 1 and the standard electrode is measured with a meter g.
The oxygen activity in the slag S is measured by measuring the thermoelectromotive force of the thermocouple e with the meter h as well as by measuring the oxygen activity.

The feature of the present invention resides in the construction of the consumable crucible 1. The consumable crucible 1 comprises a metallic outer container 2 and a barrier layer 3 formed on the inner surface of the metallic crucible 1 and made of a substance that does not react with the slag S. It is characterized by being configured. The criteria for selecting the material of the metal outer container 2 are that it has conductivity that can be used as an electrode, has a higher melting point than the slag S or the specific metal M, and is easy to process. To be selected. In addition to satisfying all of these conditions, iron is also a material that can be supplied industrially at low cost, so an existing iron crucible is generally used as the metallic outer container 2. From the viewpoint of completely eliminating the elution of the iron component from the metallic outer container 2 and the reaction between the iron content and the slag, it is considered to use a non-ferrous metal as the metallic outer container 2, but the metallic outer container 2 Is set in a non-contact state with the slag S by the blocking layer 3 and only the specific metal M is in contact with the metal outer container 2, so even if iron is used as the material of the metal outer container 2, It does not cause a large error in measurement accuracy. However, for the material of the metal outer container 2,
Needless to say, if a metal component present in a large amount in the slag to be measured, that is, a metal of the same type as the refining target metal is used, the measurement error will be smaller, for example, if the refining target metal is nickel. Is made of nickel as the material of the metal outer container 2, and chromium is also used as the material of the metal to be refined. Further, if the metal to be refined is copper or bronze, it is made of metal. If the material of the outer container 2 is also copper or bronze, the measurement accuracy can be further improved.

As the material of the barrier layer 3, a substance which hardly affects the oxygen activity in the slag is used. The substance that hardly affects the oxygen activity in the slag is a substance that does not react with the slag or form an alloy, and mainly ceramics represented by metal oxides, nitrides, and carbides can be adopted, More specifically, a substance containing one or more selected from aluminum oxide, calcium oxide, magnesium oxide, silicon dioxide, stabilized zirconia, partially stabilized zirconia or mullite as a main material can be employed. Since these substances are generally present in a large amount in the slag S, even if the substances are eluted in the slag S or the specific metal M, they do not significantly change the oxygen activity of the slag S. In addition, since these substances are extremely stable and do not bind with oxygen or react with slag, they do not affect the oxygen activity in the slag. In addition, it is a more preferable example that the material of the blocking layer 3 is specified more specifically in accordance with the component composition of the slag.

Various forms can be adopted as the concrete shape of the barrier layer 3, and for example, as shown in FIGS. 2 (a) and 2 (b), the barrier layer 3 substantially matches the inner diameter r1 of the metal outer container 2, or It is possible to adopt a configuration in which a tubular blocking member 3a having a slightly smaller outer diameter r2 is formed and is fitted into the metallic outer container 2 or the like. Here, the outer diameter r2 of the tubular blocking member 3a is set to be smaller than the inner diameter r1 of the outer metal container 2 in consideration of the coefficient of thermal expansion of metal being larger than that of ceramics. This is because consideration has been given to prevent the breaker 3a from breaking.

Since the cylindrical blocking member 3a is intended to block the contact between the slag S and the metallic outer container 2, the arrangement range in the depth direction of the metallic outer container 2 is such that at least the slag S exists. It suffices to cover the range, and therefore, as shown in FIG. 3, it is possible to use a short tubular blocking member 3b halfway in the depth direction of the metallic outer container 2. In this case, the specific metal M comes into contact with the inner surface of the outer metal container 2 over a wide range, but the specific metal M does not form an alloy with the metal material of the crucible in an inert atmosphere and hardly forms an oxide. Since the metal is used, the specific metal M hardly reacts with the metallic outer container 2, and therefore the wide range contact between the specific metal M and the metallic outer container 2 affects the oxygen activity in the slag. Little to give. However, in order to completely eliminate the influence of the metal outer container 2 on the oxygen activity in the slag, it is more preferable to narrow the contact range between the specific metal M and the metal outer container 2. There is no end.

An embodiment based on this idea is shown in FIG. 4, in which a bottomed container 3c having a through hole 4 in the center of the bottom is formed by using a non-slag non-reactive substance. This is the case where 3c is fitted inside the metallic outer container 2. The through hole 4 provided at the center of the bottom is provided with the metal outer container 2 and the specific metal M.
Although it is essential for making electrical contact with each other, the formation position thereof is not limited to the center of the bottom portion, and an appropriate position may be adopted as long as it is within the existence range of the specific metal M on the inner surface of the crucible.

The above-mentioned is the case where a cylindrical material or a container with a bottom is molded from a ceramic material or the like and is fitted into the metallic outer container 2 to form the blocking layer 3. Other methods may be employed as the method for forming the metal outer container, for example, as shown in FIG. 2 Coating on the inner surface, coating or thermal spraying to form the film layer 3
It is also considered to form d and use this film layer 3d as the blocking layer 3.

Consumable crucible 1 thus created
Like the conventional iron crucible, is used by being set at a predetermined position in the reaction tube b vertically installed in the concentrating heating furnace a as shown in FIG. Further, a thermocouple e is arranged on the lower surface of the consumable crucible 1 to monitor the crucible temperature, and a standard electrode is provided inside the specific metal M and the slag S which are melted by the heating of the concentrating type heating furnace a. The solid electrolyte f
The oxygen activity of the slag S can be actually measured by measuring the electromotive force between the metal outer container 2 also serving as the control electrode and the standard electrode with the meter g, as in the conventional case.

As described above, in the present invention, the consumable crucible 1 is composed of the metallic outer container 2 and the barrier layer 3 disposed on the inner surface thereof, and a material that does not react with slag is used as a material for forming the barrier layer 3. Therefore, it becomes possible to measure the oxygen activity in the slag produced in the refining process of non-metals such as non-ferrous metals and glass with high accuracy. Needless to say, the present consumable crucible 1 can also be used for measuring oxygen activity in steelmaking slag.

[0031]

According to the present invention, the consumable crucible is provided with at least the slag on the inner surface of the metal outer container while leaving the metal outer container and the specific metal located in the lower layer of the slag partially contacting with the metal outer container. The barrier layer is formed over the entire contact area of the crucible, and a material that does not react with the slag is used as the barrier layer material.Therefore, the crucible material does not lose its electrode function and the crucible material elutes into the slag. It is possible to prevent the reaction between the material and the slag. Therefore, it becomes possible to measure the oxygen activity in the slag with high accuracy, and in particular, it is generated in the refining process of non-metals such as non-ferrous metals and glass, which could not be measured with high accuracy in the conventional iron crucible. It becomes possible to measure the oxygen activity in the slag with high accuracy.

When an iron crucible is used as the metal outer container, the consumable crucible of the present invention can be provided only by disposing the blocking layer on the inner surface of the existing inexpensive iron crucible. In addition, when a metal of the same type as the refining target metal is used as the material of the metal outer container, the elution of the constituent material of the metal outer container into the specific metal and the reaction between the constituent material of the metal outer container and the specific metal Since it can be completely eliminated, the measurement accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a simplified explanatory view showing a state in which the consumable crucible of the present invention is set in an oxygen activity measuring device.

FIG. 2 is an embodiment of the consumable crucible of the present invention,
(A) is a perspective view showing a state before assembly, and (B) is a sectional view after assembly.

FIG. 3 shows another embodiment of the consumable crucible of the present invention,
Sectional view when using a tubular barrier material as the barrier layer

FIG. 4 shows another embodiment of the consumable crucible of the present invention,
Sectional view when using a bottomed container as a barrier layer

FIG. 5 shows another embodiment of the consumable crucible of the present invention,
Sectional view when a film layer formed by coating, coating or thermal spraying is used as a blocking layer

FIG. 6 is a simplified explanatory diagram showing a basic configuration of an oxygen activity measuring apparatus and a conventional iron crucible set in the apparatus.

[Explanation of symbols]

 S Slag M Specified metal 1 Consumable crucible 2 Metal outer container 3 Barrier layer 3a Cylindrical barrier material 3b Cylindrical barrier material 3c Bottomed container 3d Membrane layer 4 Through hole a Focusing heating furnace b Reaction tube c Iron crucible d Overcoat tube e Thermocouple f Solid electrolyte g Meter h Meter

Claims (5)

[Scope of utility model registration request] 1. A crucible made of metal is housed in a melting furnace filled with an inert gas, and an alloy is not formed with a metal material of the crucible in an inert atmosphere in the crucible and an oxide is produced. It is a difficult metal and a specific metal having a higher specific gravity than the slag is accommodated in a molten state together with the slag to be measured, and the specific metal is immersed in a solid electrolyte of a one-end closed tube type having a standard electrode inside, which is a control. A consumable crucible used for an oxygen activity measuring device in a slag, which measures an electromotive force between a crucible that also serves as a pole and the standard electrode, and the consumable crucible includes a metal outer container and an inner surface thereof. It is composed of a slag arranged and a barrier layer formed of a substance that does not react, and the barrier layer is a metal while leaving a partial contact point between the specific metal located below the slag and the metal outer container. Consumable crucible used for oxygen activity measuring device in the slag, wherein at least slag is located throughout the range which contacts the outer container inner surface. 2. A bottomless cylinder whose outer diameter is substantially the same as the inner diameter of the metal outer container, or a bottomed cylinder whose outer diameter is substantially the same as the inner diameter of the metal outer container and in which a through hole is formed at the bottom. The consumable crucible used in the apparatus for measuring oxygen activity in slag according to claim 2, which is formed by using a substance that does not react with slag and uses the cylindrical body as a blocking layer. 3. A film layer is formed on the inner surface of the metal outer container by applying, coating or spraying a substance which does not react with slag on the inner surface of the metal outer container, leaving a part of the inner bottom of the metal outer container,
The consumable crucible for use in the apparatus for measuring oxygen activity in slag according to claim 1, wherein the film layer is used as a barrier layer. 4. The barrier layer is formed using a substance whose main material is one or more selected from aluminum oxide, calcium oxide, magnesium oxide, silicon dioxide, stabilized zirconia, partially stabilized zirconia or mullite. A consumable crucible used for the apparatus for measuring oxygen activity in slag according to claim 1, 2, or 3. 5. A consumable crucible for use in the apparatus for measuring oxygen activity in slag according to claim 1, 2, 3 or 4, wherein the same kind of metal as the refining target metal is used as the material of the metal outer container.