JP2003226908A - Process of suppressing elution of fluorine in steel-making slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel-making process using no fluorite, to inexpensively and effectively suppress the elution of a trace amount of fluorine from other substances than the fluorite, and further to reduce the final total contents of steel-making slag generating from the steel-making process. <P>SOLUTION: The fluorine-containing steel-making slag is mixed with slag in the reduction period of AOD (Argon Oxygen Degassing) essentially consisting of calcium silicate. Preferably, by subjecting the mixture of both slag in the presence of moisture, the elution of fluorine is suppressed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to stainless steel and Fe-
Eliminating the inconvenience that occurs when using steelmaking slag generated when manufacturing Ni alloy steel or Ni-based alloys as a material for civil engineering and construction, that is, suppressing the elution of fluorine from the slag It proposes an advantageous method for doing so.

[0002]

2. Description of the Related Art Stainless steel, Fe-Ni alloy steel or Ni
As slag generated during refining of base alloys, etc., steelmaking slag (primary smelting slag) generated when melting raw materials such as scrap in an electric furnace or converter, molten steel is deoxidized in an AOD furnace (argon oxygen decarburization furnace). There are AOD reduction stage slag (secondary slag) generated when carbon and deoxygenation, or finish slag generated when desulfurizing molten steel or adjusting components.

An example of an electric furnace slag will be described below as the steelmaking slag. When melting raw materials such as stainless steel, Fe-Ni alloy steel or Ni-based alloys in an electric furnace, it is common to add Si into the furnace and use the heat of oxidation to supplement the melting power energy. Is. As a result, a large amount of SiO ₂ is generated in the furnace, but since this SiO ₂ also causes melting damage of the furnace wall, a method of diluting by adding CaO or the like is adopted. The calcium silicate-based compound produced by SiO ₂ and CaO is called an electric furnace slag, and the electric furnace slag also contains a small amount of MgO due to melting of the furnace wall.

[0004] Generally, in the operation of an electric furnace, since it is processed at a relatively low temperature, fluorite (main component is Ca
The addition of F ₂ ) is unavoidable, and it is necessary to adjust the melting point and viscosity of the slag to activate the refining reaction and to easily discharge the slag that is no longer needed. For this reason, the electric furnace slag usually contains about 1 to 3 wt% of fluorine.

By the way, regarding fluorine, in March 2001, a notification was issued regarding the addition of soil environmental standard items, and the environmental standard was clarified. Up to now, since there is no emission control for fluorine, almost no study has been made on a method for reducing the elution of fluorine contained in slag. Therefore, when using this slag as a substitute for sand or crushed stone for materials for civil engineering and construction, when the slag comes into contact with rainwater or groundwater, the fluorine contained in the material elutes and the soil environment The possibility has arisen that the criteria cannot be met.

Conventionally, as a technique for reducing the elution of fluorine from such a steelmaking slag, JP2000-225383A, JP2000-247694A, JP2000-335946A, or JP2000-336421A. There is a method disclosed in a bulletin or the like. For example, in Japanese Unexamined Patent Publication No. 2000-335946, a fluorine-containing steelmaking slag contains a fluorine-fixing agent (a synthesized calcium aluminate compound, a naturally-occurring calcium aluminate mineral, and / or a calcium aluminate compound. Next refining slag) and a volume increasing material (decooling blast furnace slag, granulated blast furnace slag, concrete scraps and / or limestone) are mixed, and the calcium ion, aluminate ion or hydroxyl ion, etc. eluted from the fluorine fixing agent Captures the fluorine ions eluting in
A method for coprecipitation to remove fluorine is proposed.

Further, in Japanese Patent Laid-Open No. 2000-248307, fluorite which is a main source of fluorine is not used as a slag material,
Instead, a steelmaking method using an aluminum-containing substance is proposed. However, each of these methods has the following problems.

In the former method, a calcium aluminate compound or a substance containing a large amount of a calcium aluminate compound is used as a fluorine removing material, and therefore it is necessary to separately procure them. Synthetic products are extremely expensive and are not suitable for using by-products such as steelmaking slag. Also,
The slag generated in the ordinary stainless steel refining process is mainly composed of calcium silicate compounds, and the refining slag containing a large amount of calcium aluminate compound is
Virtually difficult. Even if a calcium aluminate compound can be procured from the outside, the method according to the above-mentioned conventional technique requires a maximum of 80 parts by weight with respect to 100 parts by weight of the steel slag to be treated. , It is almost double that before processing. Therefore, the above conventional technique cannot be said to be desirable as a method for utilizing slag, which is a by-product of stainless steel, Fe-Ni alloy steel, Ni-based alloy, or the like, as a material.

The latter is a method of using an aluminum-containing substance in place of fluorite, and in this method as well, the main raw material, slag material, recycled raw material, or refractory scraps, etc. are charged into the furnace. Since fluorine is contained as an impurity, a maximum of about several thousand ppm inevitably migrates into the slag. In other words, this method is also able to reduce the elution amount of fluorine as compared with the conventional slag containing about 1 to 3 wt% fluorine, but satisfies the environmental standard value of fluorine elution amount of 0.8 mg / l or less. It was insufficient as a measure to make it happen.

Incidentally, these prior arts have the basicity (CaOw
t% / SiO ₂ wt%) is effective for ordinary steelmaking steel slag containing high concentration of CaO such as 4, but it is special for stainless steel, Fe-Ni alloy steel or Ni-based alloy. It was not a proposal for a steel slag having a relatively low CaO concentration of CaO wt% / SiO ₂ wt% ≈1.

[0011]

DISCLOSURE OF THE INVENTION In view of the problems of the prior art, the present invention has investigated the solution to the problems, and as a result, it has been found that stainless steel, Fe-Ni alloy steel, Ni-based alloys, etc. For refining slag (steel making slag), we provide a steelmaking method that does not use fluorite, which is the main source of fluorine, and at a relatively low cost and effectively suppress the elution of a small amount of fluorine mixed in from other than fluorite. Moreover, it is an object of the present invention to propose a method for suppressing the elution of fluorine in steelmaking slag, which can reduce the final total amount of steelmaking slag generated from the steelmaking process.

[0012]

[Means for Solving the Problems] In order to solve the above problems, the present inventors have investigated in detail the elution behavior of fluorine from steelmaking slag such as stainless steel, Fe-Ni alloy steel or Ni-based alloy. . As a result, if the composition of the steelmaking slag is properly adjusted, the use of fluorite can be eliminated and the amount of slag produced can be reduced.Especially, the steelmaking slag is mixed with the reducing stage slag of the AOD furnace, which is the secondary refining equipment. Or further after that, when the slag mixture is subjected to a stabilization treatment in the presence of water, it is unavoidable from a raw material containing fluorine as an impurity, a slag material or refractory waste, and a furnace charge containing fluorine as another impurity. It was found that the elution of a small amount of fluorine that is mixed in effectively can be suppressed effectively and at low cost.

The gist of the present invention based on the above findings is as follows. That is, the method of the present invention is basically to mix fluorine-containing steelmaking slag with an AOD reduction phase slag mainly composed of a calcium silicate system, and preferably further, a mixture of both slags in the presence of water. The method for suppressing elution of fluorine in the steelmaking slag is characterized in that the elution of fluorine is suppressed by the stabilization treatment.

In the present invention, the above-mentioned addition and mixing are performed.
AOD reduction period slag should be mixed with steelmaking slag at 10-80wt%, and stabilization treatment in the presence of water should be the same as steelmaking slag.
A method of spraying hot water of 50 ° C or higher, or immersing the mixture in hot water, a method of spraying hot water of 80 ° C or higher, or immersing the mixture in hot water to a mixture with AOD reducing slag Or aging treatment with steam, the steelmaking slag should be CaO: 20-40
wt%, SiO ₂ : 25-45 wt%, A1 ₂ O ₃ : 10-20 wt% and F: 0.5 wt
% Or less and CaO / SiO ₂ is mainly 0.6 to 1.1 of calcium alumina silicate compound,
As the slag for the AOD reduction period, CaO: 40 to 55 wt%, SiO ₂ :
Using 30 to 45 wt%, MgO: 5 to 15 wt%, and F: 0.5 wt% or less, CaO / SiO ₂ being mainly composed of a calcium silicate compound of 1.1 to 1.8, and the steel making Slag is 0.5w of fluorine, which is generated when melting stainless steel, Fe-Ni alloy steel or Ni-based alloy in a steelmaking furnace.
It is preferable that the primary refining slag contains t% or less.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In developing the present invention, first of all, the inventors of the present invention, in a normal electric furnace operation of stainless steel, Fe-Ni alloy steel or Ni-based alloy The method of eliminating the use was examined. Especially, the fluidity of the steelmaking slag (primary refining slag) generated during the operation of the electric furnace was focused and examined. As a result, the steelmaking slag composition was 20-40 wt% CaO and 25-4 SiO ₂ .
By adjusting 5 wt%, Al ₂ O ₃ to 10 to 20 wt%, and CaO / SiO ₂ to 0.6 to 1.1, the fluidity of the slag can be secured to some extent, and fluorite, which is the elution source of fluorine, can be secured. It was found that stable operation of the electric furnace can be realized without using it.

The composition of the steelmaking slag produced during melting in the electric furnace is CaO: 20-40 wt% and SiO ₂ :
The reason why the above-mentioned effect occurs when the content is 25 to 45 wt% is that, in the case of CaO, if the content is 20 wt% or less, a high-melting point substance such as SiO ₂ will be generated, and the fluidity of the slag will be extremely deteriorated. In that case, high-melting-point substances such as 2CaO / SiO ₂ and CaO are generated, and the fluidity of the slag is extremely deteriorated, which makes it difficult to operate the slag and requires the use of fluorite. Regarding SiO _{2, if} it is 25 wt% or less, a high melting point substance such as 2CaO ・ SiO ₂ or CaO will be generated, and the flow of the slag will be extremely deteriorated.If it is 45 wt% or more, a high melting point substance such as SiO ₂ will be generated. This is because the slag is generated, the fluidity of the slag is extremely deteriorated, the operation at the time of slag is made difficult, and the use of fluorite is required. These are more preferably in the ranges of 30 to 40 wt% and 25 to 35 wt%, respectively, and the basicity CaO / SiO ₂ should be in the range of 0.6 to 1.1.

The basicity CaO / SiO ₂ of this steelmaking slag is 0.6
The reason for prescribing to the range of 1.1 to 1.1 is that in the case of calcium silicate slag such as steelmaking slag such as stainless steel, Fe-Ni alloy steel or Ni-based alloy, if the CaO content is too high relative to SiO ₂ , the molten slag Refractory substances such as 2CaO / SiO ₂ and CaO are generated in the inside, which significantly deteriorates the fluidity of the slag.
On the other hand, if the amount of CaO is too small, high melting point substances such as SiO ₂ will be generated, which will extremely deteriorate the fluidity of the slag, making it difficult to operate at the time of slag and using fluorite. This is because it ends up. The basicity of the steelmaking slag is preferably 0.7 to 1.0
It is a degree.

Further, the amount of Al ₂ O ₃ is preferably in the range of 10 to 20 wt%. The reason for this is that the appropriate amount of Al ₂ O ₃ is
For the calcium silicate-based slag, CaO ・ SiO ₂ and C
A eutectic of aO · Al ₂ O ₃ · 2SiO ₂ (or 2CaO · Al ₂ O ₃ · SiO ₂ etc.) is formed to lower the melting point of the slag and improve the fluidity of the slag. However, when Al ₂ O ₃ is 20 wt% or more, the high melting point substance A
MgO existing as l ₂ O ₃ or as an impurity in the slag
And Al ₂ O ₃ react with each other to form a high melting point substance such as MgO / Al ₂ O ₃ , which extremely deteriorates the fluidity of the slag and makes it difficult to operate the slag. On the other hand, when the amount of Al ₂ O ₃ is less than 10 wt%, the effect of lowering the melting point of the slag is small and the fluidity of the slag is extremely deteriorated, which is not preferable. Within this range, it is more preferably 12 to 18 wt%.

The steelmaking slag contains Cr ₂ O ₃ , FeO, MnO and P in addition to MgO as impurities in addition to the above components.
And unavoidable impurities such as S may be contained. This is because it has no particular adverse effect on the fluorine elution inhibiting effect.

In the present invention, the steelmaking slag preferably has a slag composition rich in calcium aluminate silicate-based compound, as described later. Therefore, during melting and refining in an electric furnace, Al ₂ O ₃ is added as a solvent to control the slag composition. As the Al source, in addition to metallic aluminum, aluminum dross, aluminum ash, aluminum can empty can waste, aluminum facets, and other aluminum-containing waste such as aluminum-containing iron scrap are used. Since each of these contains metallic Al, the heat of oxidation of the Al can be used to supplement the melting power. Also,
Since Al generates a larger amount of heat than Si, the amount of Si added can be significantly reduced. As a result, the amount of SiO ₂ generated can be reduced and the amount of slag generated in the electric furnace can be significantly reduced.

According to such a method, it is possible to eliminate the use of fluorite during refining in an electric furnace, so that the fluorine content in the slag can be finally reduced to 0.5 wt% or less. Become. Even without the use of fluorspar, 0.5w
The reason why fluorine (F) of t% or less is mixed is that, for example, the scrap which is the main raw material is subjected to fluorine coating treatment,
It is conceivable that a small amount of fluorine is contained as an impurity in recycled raw materials such as aluminum dross, refractory scraps, and ingots with slag used for slag material, and these may be mixed into slag. As a result, a maximum of several thousand ppm
A certain amount of fluorine will be mixed as an impurity in the slag. Compared with the conventional slag that contains 1 to 3 wt% of fluorine, the amount of fluorine that elutes can be reduced, but it is 0.8 mg which is the environmental standard value of the amount of fluorine elution.
It is still insufficient as a measure to satisfy / l or less.

Therefore, in the present invention, in order to suppress the elution of fluorine that has been mixed in a small amount in the slag, the above-mentioned steelmaking slag is subjected to secondary refining of stainless steel, that is, AOD.
We decided to mix the reducing slag that is generated during the reducing period during refining. This is because the operation during the reduction period during refining of the AOD furnace has a higher operating temperature compared to that during melting and refining in the electric furnace, which is advantageous for securing the fluidity of slag and CaO /
Despite the relatively high SiO ₂ of 1.1 to 1.8, fluorite is not required as a slag material. However, for this AOD reduction period slag, due to the same reason as steelmaking slag, a maximum of several thousand
Fluorine of about ppm is inevitably mixed in the slag as an impurity.

Therefore, the inventors conducted a fluorine elution test for the steelmaking slag and the slag for the AOD reduction period, and examined the behavior thereof. According to the result, as shown in Table 1, although the steelmaking slag and the AOD reduction stage slag contain almost the same amount of fluorine, the amount of fluorine eluted from the slag is higher in the AOD reduction furnace slag. However, it was about 1/10. The fluorine elution test was carried out in accordance with the Environmental Agency Notification No. 46, which is a soil environmental standard verification method.

[0024]

[Table 1]

The reason why the elution of fluorine from the AOD reducing period slag is suppressed is not necessarily clear, but when a sample after the elution test of the AOD reducing period slag was investigated, Ca ₂ Al (OH , F) from ₇ · 3H ₂ O and the CaF ₂ is detected number is assumed as follows.

That is, although the AOD reducing phase slag is mainly composed of calcium silicate compounds, it is made of stainless steel or Fe-Ni.
Compared with the electric furnace primary refining slag made of alloy steel or Ni-based alloy, CaO / SiO ₂ is large, so that many calcium ions can be released. As a result, the eluate is mutated to be alkaline, and the hydroxyl ion becomes rich, and at the same time, a little aluminate ion is released in addition to silicate ion. As a result, in aqueous _{solution, Ca 2 Al (OH) 7} · 3H
_{It is considered that 2} O captures fluorine and coprecipitates, or is fixed as CaF ₂ in the precipitate, and exhibits an action of suppressing the elution of fluorine.

Therefore, the inventors of the present invention, if it is true that Ca ₂ Al (OH) ₇ .3H ₂ O contributes to the fixation of fluorine, the steelmaking slag having a higher Al ₂ O ₃ content than the AOD reduction stage slag. In addition, it was thought that the elution of a small amount of fluorine contained in the steelmaking slag could be suppressed more effectively by mixing the AOD reduction stage slag containing a large amount of CaO. That is, as a result of calcium ions being released from the AOD reduction phase slag, the eluate is mutated to be alkaline and becomes rich in hydroxyl ion, and by the alkaline stimulation from this eluate, aluminate ions are released from the steelmaking slag, and in the aqueous solution. It was thought that the formation of Ca ₂ Al (OH) ₇ · 3H ₂ O in the catalyst was promoted and the elution of fluorine was suppressed.

FIG. 1 shows the results of investigating the effect of reducing the amount of fluorine elution by mixing the slag in the AOD reduction period with the stainless steel electric furnace refining slag produced by the above method. The fluorine elution test was carried out in accordance with the Environmental Agency Notification No. 46, which is a verification method for soil environmental standards. The fluorine elution index on the vertical axis was based on the elution amount in the untreated state. The dotted line in the figure simply shows the effect of dilution, but the reduction of the amount of fluorine elution by mixing AOD reduction phase slag exceeds the simple mixing effect (dilution effect) of both. I understand. The effect of reducing the amount of fluorine elution is exhibited from the case where the mixing ratio of the AOD reducing phase slag is several%, the maximum value is exhibited at about 10 to 30%, and the mixing ratio is maintained up to about 50%. Then, when it is added more than that, the effect of reducing the amount of fluorine elution becomes small, and when it exceeds 80%, only a simple mixing effect is obtained. Therefore, the mixing ratio of AOD reduction period slag is 10-80.
wt% is preferable, and more preferably 10 to 50 wt%.

The composition of the AOD reducing period slag which is preferably used for carrying out the method of the present invention is as follows: CaO: 40-55 wt%, SiO2: 3
0-45wt%, MgO: 5-15wt%, F: 0.5wt% or less, and CaO / S
Those mainly containing a calcium silicate compound having iO ₂ of 1.1 to 1.8 are preferable. Here, the reason for defining CaO to 40 to 55 wt% is that CaO is 40 wt% or less, the release of calcium ions as described above is insufficient, effective fluorine elution prevention cannot be realized, and conversely, CaO is At 55 wt% or more, 2CaO / SiO ₂ is generated in the slag during the AOD reduction period, and the volume expansion due to the phase transformation during cooling causes the AOD reduction period slag itself to be pulverized into fine powder, which can be used as an alternative to sand and crushed stone for civil engineering and construction. This is because it becomes unsuitable for the use of materials. Within this range, it is more preferably 45 to 50 wt%.

Further, the reason for defining the SiO ₂ to 30～45Wt%, in the SiO ₂ is less 30 wt%, 2CaO · SiO ₂ in the slag is produced in large quantities by volume expansion due to phase transformation during cooling, AOD
This is because the reducing-phase slag itself is pulverized into fine powder, or a large amount of unmelted CaO remains in the slag, which adversely affects the water immersion expansion of the slag, making it unsuitable for civil engineering and building materials. Further, if SiO ₂ is 45 wt% or more, stable CaO · SiO ₂ is generated, the above-mentioned release of calcium ions is insufficient, and effective prevention of fluorine elution cannot be realized. Within this range, more preferably
It should be 35-40 wt% and the basicity CaO / SiO2 should be in the range of 1.1-1.8.

The reason for defining CaO / SiO ₂ as 1.1 to 1.8 is as follows.
If it is 1.1 or less, the release of calcium ions will be insufficient and effective prevention of fluorine elution will not be realized, and if 1.8 or more,
A large amount of 2CaO ・ SiO ₂ is generated in the slag, and the volume expansion due to the phase transformation during cooling causes the AOD reduction slag itself to be pulverized into fine powder, or CaO unmelted in the slag.
This is because a large amount of slag remains, which adversely affects the water immersion expansion of the slag, making it unsuitable for civil engineering and building materials. Within this range, it is more preferably 1.2 to 1.7 wt%.

MgO is added to protect the refractory material of the AOD furnace, but if the addition amount is too large, the fluidity of the slag is extremely deteriorated, the activity of the refining reaction is impaired, and It becomes difficult to operate. Therefore, the suitable amount of MgO added is 5 to 15 wt.
%, More preferably 7 to 13 wt%.

The AOD reducing phase slag may contain, as impurities, inevitable impurities represented by Al ₂ O ₃ , Cr ₂ O ₃ , FeO, MnO, P and S. . This is because there is no particular adverse effect on the fluorine elution inhibiting effect.

Further, as described above, hydration products such as Ca ₂ Al (OH) ₇ / 3H ₂ O contribute to suppression of fluorine elution,
The inventors have performed a stabilization treatment on the mixed slag produced by the above method in the presence of water in order to promote the hydration reaction, and the mixed slag is used as a substitute for sand or crushed stone for civil engineering and building materials. We have found that it is desirable to stabilize the system before it is used. This stabilizing treatment may be a natural aging treatment in the atmosphere, a water spray at room temperature or a dipping treatment, but in order to perform this stabilizing treatment in a shorter period of time, spray warm water at 50 ° C or higher, or Curing is preferably performed by a method of immersing in hot water, a method of spraying hot water of 80 ° C. or higher, or a method of immersing in hot water, or an aging treatment using steam.

As described above, by the stabilization treatment by the coexistence of water, the mixed slag produces a hydrate such as Ca ₂ Al (OH) ₇ / 3H ₂ O, which promotes the coprecipitation reaction of fluorine, and Further, since fluorine is fixed before being used as a building material, it becomes possible to more effectively suppress the elution of fluorine.

As described above, the present invention is superior to the prior art method of adding a calcium aluminate compound in that the same effect can be obtained without using an expensive calcium aluminate compound. And CaO / SiO ₂
It has become possible to treat stainless steel, Fe-Ni alloy steel or Ni-based alloy steelmaking slag with a low CaO concentration of around 1 using the AOD reduction slag, which is a by-product from the plant. In addition, the total amount of steelmaking slag generated as a by-product from the steelmaking process of stainless steel, Fe-Ni alloy steel or Ni-based alloy can be reduced rather than increased.

[0037]

EXAMPLE The composition of each slag used in this example is shown in Table 2.
Table 3 shows the results of the fluorine elution test of the steelmaking slag performed using each of the slags in Table 2. As the stabilization treatment of the mixed slag in the coexistence with water according to the method of the present invention, steam curing was performed for 720 minutes. In addition, the fluorine elution test complied with the Environmental Agency Notification No. 46, which is a verification method of soil environmental standards.

[0038]

[Table 2]

[0039]

[Table 3]

As shown in Table 3, even in the conventional steelmaking slag, the amount of fluorine leached can be reduced by mixing with the AOD reduction stage slag and hot water treatment, but all of them are in the environmental standard value of fluorine leaching. It was not possible to clear a certain 0.8mg / l or less. Further, in the steel slag of the present invention, since fluorine was inevitably mixed in 0.3 wt%,
It was not possible to completely prevent the elution of fluorine. However, by mixing 10-80 wt% of AOD reducing phase slag,
It is possible to significantly reduce the amount of fluorine elution, and in the case where steam curing was performed, the amount of fluorine elution was reduced to a value that could clear the soil environmental standard of 0.8 mg / l or less, and to prevent the elution of fluorine. On the other hand, it was found to be more effective.

[0041]

As described above, according to the method of the present invention, the elution of fluorine from the steelmaking slag can be effectively suppressed by a relatively inexpensive method. As a result, it became possible to use steelmaking slag, which is a by-product of the production of stainless steel, Fe-Ni alloy steel, Ni-based alloy, etc., for civil engineering materials.

[Brief description of drawings]

FIG. 1 is a graph showing the effect of suppressing the elution of fluorine from slag when AOD reduction stage slag is added to steel-making slag of stainless steel, Fe-Ni alloy steel or Ni-based alloy.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Nagashima             4-2 Kojima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa             Main metallurgical industry Kawasaki factory F-term (reference) 4D004 AA43 AB08 BA02 CA34 CC03                       DA03 DA06                 4K013 CF01 CF12 CF13 FA01 FA05                       FA06                 4K070 AB11 BC14 EA02 EA03 EA07                       EA10

Claims (6)

[Claims] 1. Fluorine in a steelmaking slag, characterized in that elution of the fluorine is suppressed by mixing a fluorine-containing steelmaking slag with an AOD reduction stage slag mainly composed of calcium silicate. Elution suppression method. 2. The elution of fluorine is suppressed by mixing a fluorine-containing steelmaking slag with an AOD reduction stage slag mainly composed of calcium silicate and stabilizing the mixture in the presence of water. A method for suppressing elution of fluorine in steelmaking slag, which is characterized in that 3. The elution suppressing method according to claim 1, wherein the AOD reduction stage slag is mixed with steelmaking slag in an amount corresponding to 10 to 80 wt%. 4. The stabilization treatment in the presence of water is carried out by spraying hot water of 50 ° C. or higher onto a mixture of steelmaking slag and AOD reduction slag, or immersing the mixture in hot water at 80 ° C.
4. The elution suppressing method according to claim 2 or 3, which is carried out by either spraying hot water, immersing the mixture in the hot water, or aging treatment with steam. . 5. The steelmaking slag includes CaO: 20-40 wt%, Si
O₂: 25-45wt%, A1₂O ₃: 10 to 20 wt% and F: 0.5 wt% or less
Contains, CaO / SiO₂Is 0.6 to 1.1
Using those mainly composed of minasilicate compounds,
As AOD reduction period slag, CaO: 40-55wt%, SiO₂: 30 ~
Contains 45 wt%, MgO: 5-15 wt%, and F: 0.5 wt% or less, C
aO / SiO₂Is a 1.1-1.8 calcium silicate compound
Claims 1 to 4, characterized by using a main body
The method for suppressing elution according to any one of 1. 6. The steelmaking slag is a primary refining slag containing 0.5 wt% or less of fluorine, which is generated when stainless steel, Fe-Ni alloy steel or Ni-based alloy is melted in a steelmaking furnace. The method for suppressing elution according to any one of claims 1 to 5, wherein