JP3299174B2 - Method for treating chromium oxide-containing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stainless steel slag generated during the refining of stainless steel, a chromium slag generated during the production of a chromium compound such as sodium dichromate, waste slag, sewage sludge, and the like. those related to the processing method of the chromium oxide can be prevented the dissolution of Cr ⁶⁺ from to that object substance containing chromium oxide-containing substances, such as sewage sludge slag.

[0002]

2. Description of the Related Art Stainless steel slag generated during stainless steel refining and chromium slag generated during the production of chromium compounds such as sodium dichromate contain several percent of chromium oxide, depending on operating conditions. Is part of
It was oxidized to the Cr ^6+, which may cr ⁶⁺ elutes.

When stainless steel slag, chromium slag, or the like is used as a roadbed material, a temporary material, a civil engineering landfill material, or the like, it is an absolute condition that Cr ⁶⁺ does not elute from the slag. In recent years, it has been considered that slag is formed by melting garbage incineration ash, sludge, etc., and the generated slag is effectively used as roadbed material, tile, etc., but depending on the type of garbage incineration ash, sludge, etc. From the generated slag
Cr ⁶⁺ may be eluted, making effective use difficult.

[0004] Therefore, when slag is reused as a roadbed material, a civil engineering landfill material, or the like, a new technique for preventing the elution of Cr ⁶⁺ has been proposed. As a method for preventing the elution of Cr ⁶⁺ from stainless steel slag, a method has been disclosed in which aluminum ash and magnesia-based industrial waste are added to stainless steel slag (see JP-A-6-171993).

However, if the above-mentioned method is to be carried out industrially, the aluminum ash and the magnesia-based industrial waste are spread over a slag pan, and the molten stainless steel slag is discharged there and the slag is dropped. In this case, a method of stirring and mixing with energy is used. In this case, unlike molten steel, slag has a high viscosity, so it is difficult to form a homogeneous mixed state by such a stirring and mixing means using only the falling energy, and the chromium oxide in the slag is completely stabilized. Elution of Cr ⁶⁺ cannot be prevented.

[0006] After decarburization and refining of stainless steel, a divalent S compound such as FeS is added to the molten slag that has undergone a reduction treatment for recovering Cr in the slag into molten steel. S concentration in slag is 0.20wt
%, And a method for preventing the elution of Cr ⁶⁺ is disclosed (see JP-A-8-104553). This method is intended to stabilize the chromium oxide by blowing an inert gas to homogeneously mix the additive into the molten slag, and is an effective method to prevent the elution of Cr ^{6+ in} the slag. There is
After completion of the reduction treatment, it is necessary to perform an operation such as blowing in an inert gas or using an additive for reducing the viscosity of the slag, which is problematic in terms of economy.

In addition, in the case of the above method, in order to sufficiently mix with the slag in a molten state, if added in a smelting furnace,
There is a problem that the additive contaminates the molten steel. On the other hand, the chromium slag generated during the production of the chromium compound, as an elution prevention method of Cr ^6+, generally by reduction roast slag Cr ⁶⁺ Cr
^Although a method of detoxifying by reducing to ³⁺ is employed, there is a problem in terms of economic efficiency due to the roasting method.

In the case of sewage sludge, incineration is performed to reduce the volume before landfill disposal. As a method of preventing the generation of Cr ⁶⁺ from this incineration ash, the air ratio at the time of incineration is set at 1 ^%. Control method has been adopted (JSSE, vo
l.38 No.378, pp29-32 (1994)]. However, as shown in the literature, it is a very difficult task to perform optimal operation in response to sludge having various properties such as the source, and the same is true for incineration of industrial waste. it is conceivable that.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and comprises stainless steel slag, chromium slag, waste molten slag, sewage sludge, sewage sludge molten slag, and soil containing chromium oxide. chromium oxide inclusions <br/> substance such as that commercially treated excellent way economical in simple, to prevent the elution of Cr ⁶⁺ from those chromium oxide-containing substances completely and to provide a processing method capable chromium oxide-containing substances.

[0010] Further, the present invention provides the above chromium oxide .
The contents of quality, was treated without significantly increasing the volume of the short time and the material to be treated, and aims to provide a processing method of the above-mentioned excellent effect capable of obtaining chromium oxide-containing substances I do.

[0011]

Means for Solving the Problems The present inventors have considered the above-mentioned problems of the prior art, and as a result, in the case of the prior art, it is necessary to set chromium reduction conditions in a high temperature state such as melting, roasting, and incineration. In addition, it was thought that there were difficulties in setting conditions and problems in economics. We investigated a method for the reduction of Cr ⁶⁺ in a state close to normal temperature or room temperature.

[0012]

[0013]ThatResults, belowofFindings [1]-[3]Obtained. [1]: below ~ Use of sulfur-containing substances
Chrome oxidationMaterial contentCr from quality⁶⁺Extremely effective
That can be effectively prevented.  Blast furnace slag with natural aging less than 3 months (hereinafter
Unaged blast furnace annealing slag), hot metal pretreatment
Sulfur such as slag and / or oxidation number is +5 or less
Slag containing sulfur  Such as elemental sulfur, yunohana purified from sulfur-containing hot springs
Substances containing elemental sulfur (hereinafter also referred to as elemental sulfur-containing substances)
You  Oxidation of sodium thiosulfate, iron sulfide, hydrogen sulfide, etc.
Compounds of sulfur with a number of +5 or less (hereinafter sulfur with a value of +5 or less)
(Hereinafter also referred to as compound) Are also collectively referred to as sulfur-containing substances. [2]: above Using the sulfur-containing substance
Process (a) ~(b)By chromium oxidationMaterial contentFrom quality
Cr⁶⁺Can be prevented very effectively.
That.

(A): A method of standing in an air atmosphere(b) ; Steam blowing method [3]: Sulfur content ofQualityCombine
And byOfTo be effective.

[0015]

[0016] In the dissolution test according to Environment Agency Notification No. 46 Method
Even Cr elution amount is large slug of ⁶⁺ or slag porosity is low, and mixed with elemental sulfur-containing substances the chromium oxide-containing substances, by blowing steam into the mixture and the it slag is treated without causing a volume increase for a short time and the material to be treated, it is possible to completely prevent the dissolution of Cr ⁶⁺ from chromium oxide-containing substances.

[0017]

[0018] The first aspect of the present invention, chromium oxide-containing Substance,
Mixing the slag sulfur and / or oxidation number contains pentavalent less sulfur, a processing method of a chromium oxide-containing substances, characterized in that the stand in the atmosphere.

[0019] The second aspect of the present invention, chromium oxide-containing Substance,
Chromium, characterized by mixing with slag containing sulfur and / or sulfur having an oxidation number of +5 or less, and sprinkling the mixture with water and / or blast furnace slag eluate generated during sprinkling cooling of blast furnace slag. it is a method of treating the oxide-containing substances.

A third aspect of the present invention, chromium oxide-containing Substance,
Mixing the substances sulfur and / or oxidation number contains pentavalent less sulfur, a processing method of a chromium oxide-containing substances, characterized in that blowing steam into the mixture.

[0021] A fourth invention, chromium oxide-containing Substance,
Mixing the slag sulfur and / or oxidation number contains pentavalent less sulfur, a processing method of a chromium oxide-containing substances, characterized in that blowing steam into the mixture.
A fifth invention is a chromium oxide containing material quality, sulfur and /
Or a slag containing sulfur having an oxidation number of +5 or less,
Mixing the substances sulfur and / or oxidation number contains pentavalent less sulfur, a processing method of a chromium oxide-containing substances, characterized in that blowing steam into the mixture.

The first invention described above, the second invention, the fourth invention, in the fifth invention, the slag sulfur and / or oxidation number contains pentavalent less sulfur, non-aging slowly cooled blast furnace It is preferable to use slag and / or hot metal pre-treated slag, and it is more preferable to use unaged blast furnace slow cooling slag. The third invention described above, as the material for sulfur and / or oxidation number of definitive to inventions of the fifth contains a +5 valence less sulfur,
It is preferable to use a sulfur-containing substance having a total content of sulfur and / or sulfur having an oxidation number of +5 or less of 10% by weight or more.

The above sulfur and / or oxidation number is +5
Sulfur-containing substances having a total content of sulfur of less than 10% by weight or more include simple sulfur, simple sulfur-containing substances such as Yunohana purified from sulfur-containing hot springs, and sodium thiosulfate, iron sulfide, and hydrogen sulfide. The following sulfur compounds are preferably exemplified, and these can be used in combination. The second invention described above, in the third inventions to fifth invention, chromium oxide-containing material quality and the mixture of the slag (the
2 of the invention, the fourth invention) or chromium oxide inclusions quality and sulfur and / or a mixture of substances which oxidation number contains pentavalent following sulfur (third invention) or chromium oxide Mono含
Yubutsu protein and slag and sulfur and / or a mixture of substances which oxidation number contains pentavalent following sulfur (fifth invention),
It is preferable that the above-described treatment is performed by allowing the substrate to stand in an air atmosphere.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to the first invention to the first invention.
The invention will be described in more detail in the order of the fifth invention .

The present inventors dissolve the reagent, CrO ₃ , in pure water and ^add it to an aqueous solution having a Cr ⁶⁺ concentration of 100 mg / l. 100 g of cold slag or blast furnace slowly cooled slag after natural aging treatment for 6 months was added, and after shaking for 6 hours, the Cr ⁶⁺ concentration in the aqueous solution was measured to investigate the amount of Cr ⁶⁺ reduction.

Table 1 shows the measurement results. In Table 1,
The amount of reduction of Cr ⁶⁺ per kg of blast furnace slowly cooled slag was shown as the reduction capacity. It can be seen that the ^unaged blast furnace slow-cooled slag has about 10 to 100 times the reduction ability of Cr ⁶⁺ than the blast furnace slow-cooled slag after the natural aging treatment for 6 months, depending on the particle size.

The reducing ability of the fine powder is higher. The reason why Cr ⁶⁺ can be reduced by the blast furnace slowly cooled slag is considered to be that the sulfur component present in the blast furnace slowly cooled slag elutes into water to reduce Cr ⁶⁺ . Similarly, a blast furnace slag eluate containing 0.05% by weight of reducing sulfur having an oxidation number of +5 or less in 10 liters of an aqueous solution having the reagent CrO ₃ dissolved in pure water and having a Cr ⁶⁺ concentration of 100 mg / l. After adding 100 g and shaking for 6 hours, the concentration of Cr ^{6+ in} the aqueous solution was measured, and the amount of decrease in Cr ⁶⁺ was investigated.

Table 2 shows the measurement results. In Table 2,
The amount of reduction of Cr ⁶⁺ with respect to 1 kg of blast furnace slag leaching water was shown as the reducing ability. As shown in Table 2, it can be seen that the blast furnace slag elution water also has approximately the same Cr ⁶⁺ reduction capacity as the ^unaged blast furnace slowly cooled slag per unit weight.

[0029] Table 3 shows the mode-dependent concentration of sulfur before and after reduction treatment of Cr ⁶⁺ in the slowly cooled blast furnace slag used in the reduction treatment of Cr ^6+. Comparing the concentrations before and after the reduction treatment, after reduction S ^2-
Is lower except. Further, as a result of measuring the concentration of sulfur in the aqueous solution after the reduction treatment, most of the sulfur was SO ₄ ^2- .

Therefore, S ⁰ , S ₂ O ₃ in the blast furnace slag
^2- , SO ₄ ^2- are dissolved in water, and S ⁰ , S ₂ O ₃ ^2-
₄ when oxidized to ^2, it is believed to reduce the Cr ^6+. The reason that the ^finer the slag is, the higher the reducing ability of Cr ⁶⁺ is, because the ^finer the powder, the larger the specific surface area is, so that S ⁰ and S ₂ O ₃
^It is considered that ^2- is easily dissolved in water. The present invention has been completed based on the above findings.

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]BookThe inventors,underObtained the knowledge,1Invention of
~ No.5Invention. [1]: below ~ Use of sulfur-containing substances
From the chromium oxide containing material⁶⁺Extremely effective
That can be effectively prevented.

[0040]  Blast furnace slag with natural aging less than 3 months (: not yet
Aging blast furnace slow cooling slag), hot metal pretreatment slag, etc.
Contains sulfur and / or sulfur with an oxidation number of +5 or less
Slag  ; Elemental sulfur, yunohana purified from sulfur-containing hot springs (: simple
Body sulfur-containing substance)  Oxidation of sodium thiosulfate, iron sulfide, hydrogen sulfide, etc.
Sulfur compounds having a number of +5 or less (: sulfuration of +5 or less)
Compound) [2]: above Using the sulfur-containing substance
Method (1) ~(3)From chromium oxide-containing substances
Cr⁶⁺Can be prevented very effectively.
That.

(1): Stilling method in air atmosphere: A chromium oxide-containing substance and a slag containing sulfur and / or sulfur having an oxidation number of +5 or less are mixed and left to stand in air atmosphere. to (first invention). (2): watering method ;

[0042] and chromium oxide-containing material and a slag sulfur and / or oxidation number contains pentavalent following sulfur were mixed, to the mixture, sprinkling water and / or blast furnace slag leachate (second Invention) .

(3) : Water vapor blowing method; (a) A chromium oxide-containing substance and a substance containing sulfur and / or sulfur having an oxidation number of +5 or less are mixed, and steam is blown into the mixture (No. 3 invention).

(B) A chromium oxide-containing substance is mixed with slag containing sulfur and / or sulfur having an oxidation number of +5 or less, and steam is blown into the mixture (a fourth invention). (c) mixing a chromium oxide-containing substance, a slag containing sulfur and / or sulfur having an oxidation number of +5 or less, and a substance containing sulfur and / or sulfur having an oxidation number of +5 or less; Water vapor is blown into the mixture ( fifth invention).

[3]: As described above Sulfur content ofQualityset
By combiningOfTo be effective.

[0046] In the dissolution test according to Environment Agency Notification No. 46 Method
Even if the slag has a large amount of Cr ⁶⁺ eluted or has a low porosity, the slag containing a chromium oxide-containing substance or a chromium oxide-containing substance and sulfur and / or sulfur having an oxidation number of +5 or less is used. Mixing both with sulfur and / or a substance containing sulfur having an oxidation number of +5 or less,
By blowing steam into the mixture, the above-mentioned slag can be treated in a short time without increasing the volume of the material to be treated, and the elution of Cr ⁶⁺ from the chromium oxide-containing substance can be completely prevented. ( Third invention, fourth invention).

That is, the first to fifth inventions have the following technical contents. [First invention:] first invention, chromium oxide-containing substances, sulfur and /
Alternatively, it is a method for treating a chromium oxide-containing substance which is mixed with a slag containing sulfur having an oxidation number of +5 or less and allowed to stand in an air atmosphere.

In the first aspect of the present invention, as the slag containing sulfur and / or sulfur having an oxidation number of +5 or less, the unaged blast furnace slow-cooled slag and / or
Alternatively, it is preferable to use hot metal pretreatment slag, and it is more preferable to use unaged blast furnace slow cooling slag . [ Second invention:] A second invention relates to a chromium oxide-containing substance, sulfur and / or
Alternatively, a method for treating a chromium oxide-containing substance by mixing water and / or blast furnace slag elution water generated during water spray cooling of blast furnace slag with the mixture by mixing slag containing sulfur having an oxidation number of +5 or less. is there.

In the second aspect of the present invention, the slag containing sulfur and / or sulfur having an oxidation number of +5 or less may be an unaged blast furnace slowly cooled slag and / or
Alternatively, it is preferable to use hot metal pretreatment slag, and it is more preferable to use unaged blast furnace slow cooling slag .

The sulfur and / or oxidation number is +5
As the substance containing sulfur having a valence of less than 0, it is preferable to use a sulfur-containing substance having a total content of sulfur and / or sulfur having an oxidation number of +5 or less of 10 wt% or more. Also,
The above-mentioned sulfur and / or the sulfur-containing substance having a total content of sulfur having an oxidation number of +5 or less of 10 wt% or more is not particularly limited. For example, it is purified from elemental sulfur or sulfur-containing hot spring. It is preferable to use sulfur compounds having an oxidation number of +5 or less (: sulfur compounds having a valence of +5 or less) such as Yunohana (: a simple substance containing sulfur), sodium thiosulfate, iron sulfide, and hydrogen sulfide. These can be used together.

As the above-mentioned substance containing sulfur having an oxidation number of +5 or less, a substance which does not easily react with oxygen dissolved in water is suitable. This means that if a sulfur-containing substance that easily reacts with oxygen dissolved in water is used, it will react with oxygen in water before completely reducing Cr ⁶⁺ in the chromium oxide-containing substance, and the reducing ability will be lost That's why.

[0052]

[0053]

[0054]

[0055]

In the present invention, it is also preferable to add a substance containing divalent iron (ferrous iron-containing substance) such as ferrous sulfate and ferrous chloride to the blast furnace slag elution water.
This is because Cr ⁶⁺ in the chromium oxide-containing substance can be completely reduced in a short time by adding divalent iron ions to the blast furnace slag elution water. [ Third invention:] A third invention relates to a chromium oxide-containing substance, sulfur and / or
Alternatively, it is a method for treating a chromium oxide-containing substance by mixing a sulfur-containing substance having an oxidation number of +5 or less and blowing steam into the mixture.

In the dissolution test according to the Environment Agency Notification No. 46 method, the present inventors ^prepared a slag in which 10 mg / l or more of Cr ⁶⁺ was eluted or a slag having a porosity of about 5% or less in a short period of time. It is processed by a method that is industrially simple and economical without causing an increase in volume.
^Intensive studies and experiments were conducted on a treatment method capable of completely preventing the elution of Cr ⁶⁺ .

As a result, the chromium oxide-containing substance is mixed with a sulfur-containing substance and / or a sulfur-containing substance having an oxidation number of +5 or less, and steam is blown into the mixture so that the slag is reduced in a short time. The present invention has been newly found that it is possible to completely prevent the elution of Cr ⁶⁺ from these chromium oxide-containing substances by treating the material without increasing the volume of the material to be treated.

In the third aspect of the present invention, sulfur and / or
Alternatively, as the substance containing sulfur having an oxidation number of +5 or less, it is preferable to use a sulfur-containing substance having a total content of sulfur and / or sulfur having an oxidation number of +5 or less of 10 wt% or more. This means that the sulfur and / or oxidation number is +5
The larger the total content of sulfur below the valence, the lower the addition rate to the chromium oxide-containing substance, the more the volume of the material to be treated can be minimized, and the less the amount of steam used. This is because the material to be treated can be easily transported after the treatment, while reducing the amount.

The above sulfur and / or oxidation number is +5
The sulfur-containing substance having a total content of sulfur of not more than 10% by weight or more is not particularly limited. For example, elemental sulfur, yunohana purified from sulfur-containing hot springs (: elemental sulfur-containing substance), thiol It is preferable to use a sulfur compound having an oxidation number of +5 or less (such as a sulfur compound having +5 or less) such as sodium sulfate and iron sulfide, and it is also possible to use two or more of them. [ Fourth invention:] A fourth invention relates to a chromium oxide-containing substance, sulfur and / or
Alternatively, it is a method of treating a chromium oxide-containing substance by mixing a slag containing sulfur having an oxidation number of +5 or less and blowing steam into the mixture.

In the fourth aspect of the present invention, as the slag containing sulfur and / or sulfur having an oxidation number of +5 or less, an unaged blast furnace slow-cooled slag and / or
Alternatively, it is preferable to use hot metal pretreatment slag, and it is more preferable to use unaged blast furnace slow cooling slag. [ Fifth invention:] A fifth invention relates to a chromium oxide-containing material, sulfur and / or
Or a slag containing sulfur having an oxidation number of +5 or less,
This is a method for treating a chromium oxide-containing substance by mixing a substance containing sulfur and / or sulfur having an oxidation number of +5 or less and blowing steam into the mixture.

In the fifth aspect of the present invention, the slag containing sulfur and / or sulfur having an oxidation number of +5 or less may be an unaged blast furnace slowly cooled slag and / or
Alternatively, it is preferable to use hot metal pretreatment slag, and it is more preferable to use unaged blast furnace slow cooling slag. In the fifth aspect of the present invention, the substance containing sulfur and / or sulfur having an oxidation number of +5 or less has a total content of sulfur and / or sulfur having an oxidation number of +5 or less of 10 wt% or more. It is preferred to use a sulfur-containing substance.

This means that the sulfur and / or oxidation number is +5
The larger the total content of sulfur below the valence, the lower the addition rate to the chromium oxide-containing substance, the more the volume of the material to be treated can be minimized, and the less the amount of steam used. This is because the material to be treated can be easily transported after the treatment, while reducing the amount. The above-mentioned sulfur and / or the sulfur-containing substance having a total content of sulfur having an oxidation number of +5 or less of 10 wt% or more is not particularly limited. For example, it is purified from elemental sulfur or sulfur-containing hot spring. Sulfur compounds having an oxidation number of +5 or less, such as Yunohana (: a simple substance containing sulfur), sodium thiosulfate, and iron sulfide (: +5
It is preferable to use a sulfur compound having a valency of less than or equal to 2, and it is also possible to use two or more of them.

According to the fifth aspect of the present invention, by blowing steam, Cr ⁶⁺ in the chromium oxide-containing substance is easily released, that is, reduced, and furthermore, sulfur and / or sulfur such as blast furnace slow-cooled slag can be obtained. Alternatively, slag containing sulfur having an oxidation number of +5 or less and sulfur and / or sulfur having a valence of +5 or less are dissolved from a substance containing sulfur and / or sulfur having an oxidation number of +5 or less, and sulfur and sulfur having a valence of +5 or less are dissolved. Oxidation reduces Cr ⁶⁺ in the chromium oxide-containing material to Cr ³⁺ .

That is, according to the present invention, sulfur and / or
Or a slag containing sulfur having an oxidation number of +5 or less,
By combining a substance containing sulfur and / or sulfur having an oxidation number of +5 or less, a shorter time than before can be achieved.
Moreover, the treatment can be performed by adding a small amount of slag. The reduction mechanism in the fifth invention is as follows.

It takes about one day to blow water vapor into a chromium oxide-containing substance having a porosity of 5% or less and a particle size of 40 mm or less so that 50% of Cr ^{6+ in} the chromium oxide-containing substance can be easily eluted. About 2 days to make 80% easy to elute
It takes about 3 days to make 0% easy to elute.
On the other hand, when steam is blown into the unaged blast furnace slow-cooled slag, the amount of +5 or less sulfur dissolved in the unaged blast furnace slow-cooled slag is proportional to time, and it takes approximately 10 days for the entire amount to be dissolved.

On the other hand, elemental sulfur dissolves in about three days.
Therefore, when only the unaged blast furnace slow-cooled slag was added, 100% of Cr ⁶⁺ in the chromium oxide-containing material was obtained in about 3 days.
% Of the blast furnace slag, the rate at which +5 or less sulfur is dissolved out becomes rate-determining, and the treatment required 3 days or more.

Of course, if an unaged blast furnace slow cooling slag is excessively added, the treatment can be performed in three days. However, the volume of the material to be treated increases, the required amount of steam increases, and the amount of the material to be treated after the treatment increases. Transport problems arise. On the other hand, for example, when only elemental sulfur is added as a substance containing sulfur and / or sulfur having an oxidation number of +5 or less, the elemental sulfur dissolves in about 3 days, and the elementary sulfur reduces Cr ⁶⁺ continuously. The effect is also about 3 days.

On the other hand, chromium oxide containing porosity of 5% or less
By injecting water vapor into a substance,
Cr in oxide-containing materials⁶⁺Easily elute 100% of
That is, it takes about 3 days to make it easy to reduce
From Cr in chromium oxide containing material⁶⁺Completely reduce
Before, elemental sulfur Cr⁶⁺No reduction effect, completely Cr ⁶⁺
Could not be reduced.

For this reason, the unaged blast furnace slow-cooled slag is combined with sulfur and / or a sulfur-containing substance having an oxidation number of +5 or less, and steam is blown. As a result, Cr ⁶⁺ in the chromium oxide-containing substance is It has become possible to complete reduction in a short time without greatly increasing the volume of the material to be treated. That is, in the first one or two days of the steam injection, a substance mainly containing elemental sulfur and sulfur such as hot water and / or a sulfur having an oxidation number of +5 or less is used. Cr ⁶⁺ in the chromium oxide-containing substance is reduced by slag containing sulfur and / or sulfur having an oxidation number of +5 or less such as slowly cooled slag.

Hereinafter, the I.I. in the first to fifth aspects of the present invention will be described. Slag containing sulfur and / or sulfur having an oxidation number of +5 or less, preferable conditions for blast furnace slag elution water, II. Addition amount of slag containing sulfur and / or sulfur having an oxidation number of +5 or less, blast furnace slag elution The water sprinkling amount, the reducing sulfur concentration of the blast furnace slag effluent, and III. [I. Slag containing sulfur and / or sulfur having an oxidation number of +5 or less, preferable conditions of blast furnace slag effluent:] In the present invention, as the slag containing sulfur and / or sulfur having an oxidation number of +5 or less, It is preferable to use an unaged blast furnace slow cooling slag and / or a hot metal pre-treatment slag, and more preferably to use an unaged blast furnace slow cooling slag. (Unaged Blast Furnace Slowly Cooled Slag;) The unaged blast furnace slow cooled slag used in the present invention is a slag that generates turbid water, that is, a slag having a color according to the color determination test method in Annex 1 of JIS A 5015. It is a blast furnace slag that has been naturally aged for less than 3 months.

Further, it is more preferable to use an unaged blast furnace slow cooling slag which is a blast furnace slow cooling slag immediately after cooling and crushing, that is, within one week after the crushing. The particle size of the unaged blast furnace slowly cooled slag is not particularly limited, but the finer the powder, the more preferable. This is because, as described above, the finer the powder, the higher the chromium oxide reducing ability.

Further, it is preferable to use an unaged blast furnace slowly cooled slag having a particle size suitable for the purpose of effective use after the reduction treatment. For example, if stainless steel slag is effectively used as a roadbed material after reduction treatment, if too little unaged blast furnace grading blast furnace slag is used as a reducing agent, the particle size distribution standard specified in JISA 5015 will be used as the roadbed material. No longer satisfied.

That is, in this case, it is preferable to use an unaged blast furnace slowly cooled slag having a particle size suitable for the particle size distribution standard of the roadbed material. (Hot Metal Pretreatment Slag) The hot metal pretreatment slag used in the present invention is slag obtained when desulfurizing and dephosphorizing hot metal in a blast furnace. (Blast furnace slag elution water) The blast furnace slag elution water used in the present invention includes, for example, elution water generated by spraying water on an unaged blast furnace slowly cooled slag, for example, water into a high temperature blast furnace slag discharged from a blast furnace. Is preferably eluted water.

Further, as the blast furnace slag leaching water in the present invention, it is preferable to use leaching water generated by sprinkling water on a blast furnace slowly cooled slag having less than about three months of natural aging. Eluted water generated by sprinkling water is suitable. When blast furnace slag eluate is used, the concentration of sulfur and / or sulfur compounds having an oxidation number of +5 or less in the blast furnace slag eluate is preferably 0.05% by weight or more in total.

When blast-furnace slag elution water is used, the content of sulfur and / or sulfur having an oxidation number of +5 or less in the blast-furnace slag elution water is preferably more than 0.03% by weight in total. This is due to the sulfur and / or
In the case of elution water containing less than 0.05% by weight of a sulfur compound having an oxidation number of +5 or less, or elution water containing 0.03% by weight or less of sulfur and / or sulfur having an oxidation number of +5 or less, chromium This is because the reduction treatment of the oxide-containing substance requires several months or more, and is industrially difficult to use. [II. The amount of slag containing sulfur and / or sulfur having an oxidation number of +5 or less, the amount of water discharged from blast furnace slag,
Reducing sulfur concentration of blast furnace slag effluent:] Addition amount of slag containing sulfur and / or sulfur whose oxidation number is +5 or less, amount of blast furnace slag effluent water, blast furnace slag elution when immersed in blast furnace slag eluate The reducible sulfur concentration of water is not particularly limited, but is preferably the amount and concentration shown below.

[0077] before Symbol first aspect of the present invention (standing method of in the atmosphere), the second of the calling
Akira ( water sprinkling method), in the case of the third to fifth inventions (steam blowing method); In all of these cases, the sulfur and / or oxidation number of the unaged blast furnace slow-cooled slag is +5 or less. Sulfur-containing slag addition amount (hereinafter also referred to as slag addition amount), blast furnace slag elution water sprinkling amount, elemental sulfur-containing substances,
The addition amount of a substance containing sulfur such as a sulfur compound having a valence of +5 or less and / or a sulfur having an oxidation number of +5 or less preferably satisfies the following formula (1).
Is more preferably satisfied.

10 ≧ A ≧ 0.1 ………………… (1) 10 ≧ A ≧ 0.2 …………………………………… (2) A in (2) indicates the following. A = [addition amount of slag to be mixed (parts by weight)] x 10 + [amount of blast furnace slag elution water to be sprinkled (parts by weight)] + [sulfur and / or a substance containing sulfur with an oxidation number of +5 or less] Addition amount (parts by weight)] × 500 (3) Note that all parts by weight in the above formula (3) are based on 1 part by weight of the chromium oxide-containing substance and in the chromium oxide-containing substance.
Cr ⁶⁺ are parts by weight per elution amount 1 mg / l, the amount of chromium oxide-containing substances may be used in an amount proportional to the respective Cr ⁶⁺ elution of chromium oxide-containing material.

In the above formula (1), when A is less than 0.1, the effect of preventing the elution of Cr ⁶⁺ from the chromium oxide-containing substance is low. Not a target. The amount of water sprayed when a mixture of a chromium oxide-containing material and an unaged blast furnace slow-cooled slag is sprayed is not particularly limited, but it is preferable to water the chromium oxide-containing material so that the chromium oxide-containing material becomes saturated. .

This is because the reduction of chromium oxide by the unaged blast furnace slowly cooled slag and the like is based on the fact that sulfur eluted from the unaged blast furnace slowly cooled slag and the sulfur having an oxidation number of +5 or less are contained in the chromium oxide-containing material. Alternatively, it is caused by reducing Cr ⁶⁺ eluted in water from the chromium oxide-containing substance .

[ III. Treatment Method:] In the above-mentioned first invention, the chromium oxide-containing material and the slag containing sulfur and / or sulfur having an oxidation number of +5 or less such as an unaged blast furnace slowly cooled slag are used. Mix and let stand in air atmosphere.

This is because when the mixture is allowed to stand in an air atmosphere, the water content in the mixture becomes 5 wt% or more, and the reduction reaction of Cr ⁶⁺ proceeds. Also, in the invention of the second inventions to fifth mentioned above, slag chromium oxide-containing substances or chromium oxide-containing substances and sulfur and / or oxidation number, contains pentavalent following sulfur or further added, It is preferable to carry out the above-mentioned treatment by leaving a mixture with a substance containing sulfur and / or a sulfur having an oxidation number of +5 or less in an air atmosphere.

This is because the method of standing in the air atmosphere is the cheapest. As a method of standing still in an air atmosphere, a method of stacking in a yard having a wastewater treatment facility is preferably used. The size of the mountain may be any size from several m ³ to several tens of thousands m ³ . When piled up, it is preferable not to pile up high. This is because when piled high, the surface area of the mountain becomes small, and it becomes difficult for water due to watering, rainfall, etc. to spread over the entire mountain, and as a result, it takes time for the reduction treatment.

In the above third to fifth aspects, the chromium oxide-containing substance, the substance containing sulfur and / or sulfur having an oxidation number of +5 or less, and the sulfur and / or oxidation number of +5 or less can be used. When steam is blown into the mixture with the sulfur-containing slag, steam is blown to the surface of the deposited mixture, steam is blown into the deposited mixture, and steam is blown from the bottom of the deposited mixture. Any of these may be used.

The temperature of the steam blown into the mixture is not particularly limited. This is because when steam is blown in the atmosphere, the temperature of the steam is usually 100 ° C, but when steam with high pressure is blown into the pile of slag, the inside of the slag has a high pressure.
This is because the temperature is higher than ° C, and the temperature of the water vapor also increases according to the pressure.

The method of blowing steam in the present invention is not limited to the method of blowing steam alone, and steam containing another gas such as air or N ₂ may be blown. In the first to fifth inventions described above, slag containing sulfur and / or sulfur having an oxidation number of +5 or less, such as blast-furnace slag elution water, unaged blast-furnace slow-cooled slag, and the like, contain elemental sulfur. In addition to the substance and the sulfur compound having a valence of +5 or less, it is also possible to use another reducing agent such as the above-mentioned iron (II) -containing substance having an action of reducing chromium oxide or activated carbon in combination.

The present invention is applicable not only to slag such as stainless steel slag, chromium slag, industrial waste molten slag, sewage sludge and sewage sludge molten slag, but also to other substances that may elute Cr ^6+. By applying, it is possible to prevent the elution of Cr ⁶⁺ from these substances.

[0088]

The present invention will be described more specifically below with reference to examples. The amount of Cr ⁶⁺ eluted in this example was measured based on an elution test method according to the Environment Agency Notification No. 46 method. (Example 1) [First invention to second invention, fourth invention] As a chromium oxide-containing substance, stainless steel slag, chromium slag generated during the production of sodium dichromate, and sewage sludge were used. .

The stainless steel slag is a sample extracted during the reduction process during refining. Also,
Unaged blast furnace slowly cooled slag, 6
The blast furnace slow cooling slag and the blast furnace slag elution water after the natural aging treatment were used. As the unaged blast furnace slow-cooled slag, a sample within one week after cooling and crushing was used.

Further, as the effluent of blast furnace slag, eluted water generated by spraying water on blast furnace slag in a high temperature state was used.
The concentration of reducing sulfur having a valence of +5 or less in the elution water was 0.05% by weight. Table 4 shows the chemical composition and Cr ⁶⁺ elution amount of the ^unaged blast furnace slowly cooled slag, stainless steel slag, chromium slag, and sewage sludge used in the experiment.

As shown in Table 4, the elution amount of Cr ⁶⁺ was 1.0 mg / l for stainless steel slag, 9.7 mg / l for chromium slag, and 0.80 mg / l for sewage sludge. The above-mentioned chromium oxide-containing substance (: material to be subjected to reduction treatment) was treated under the conditions shown in Table 5. The addition rate (wt%) of the unaged blast furnace slow-cooled slag in Table 5 is a percentage by weight based on 100% by weight of the target substance.

Table 5 shows the obtained results together with the experimental conditions. The material to be reduced and the unaged blast furnace slowly cooled slag were mixed uniformly. The size of the mountain when left standing in the air atmosphere was about 100 t, and the height was set to 2 m.

As shown in Comparative Examples 1 to 4, even when the unaged blast furnace slow cooling slag was added and the air was allowed to stand still in an air atmosphere or a steam treatment at 100 ° C.
The elution amount of ⁶⁺ does not fall below the environmental standard value of 0.05 mg / l, because there is no reducing agent. Further, as shown in Comparative Example 5, even if the blast furnace slow cooling slag after the natural aging treatment for 6 months was added and the mixture was allowed to ^stand still in the air atmosphere, the elution amount of Cr ⁶⁺ was 0.05 mg / l or less. did not become.

In Comparative Example 6, the stainless steel slag was allowed to stand in an air atmosphere and sprinkled with the same amount of tap water as the stainless steel slag, but almost no change was observed in the Cr ⁶⁺ elution amount before and after the treatment. I couldn't. On the other hand, as shown in Examples 1 to 13 of the present invention , [1] an unaged blast furnace slowly cooled slag was mixed and allowed to stand in an air atmosphere (Examples of the present invention 1 to 4, 9 , 12 ),
[2] While the unaged blast furnace slow-cooled slag is mixed and left standing in an air atmosphere, one or both of the blast furnace slag elution water and water is sprinkled (Examples 6 , 7 , 8 , 9 of the present invention) . 1
0 , 13 ) and [3 ] by mixing the unaged blast furnace slow-cooled slag and blowing high-temperature steam (Examples 5 and 11 of the present invention ), the elution amount of Cr ⁶⁺ becomes less than 0.05 mg / l. Meets environmental standards.

[0095] The Contact, stainless steel slag of the embodiment described above, chromium slag, sewage sludge, after the reduction treatment according to the present invention described above, the elution of hexavalent chromium even when left for one year in the atmosphere is not observed Was.

[0096]

[Table 4]

[0097]

[Table 5]

[0098]

[Table 6]

(Example 2) [ Third invention and fifth invention] As chromium oxide-containing substances, stainless steel slag, chromium slag generated during production of sodium dichromate, sewage sludge molten slag, stainless steel Slag attached refractory waste was used. Table 6 shows the chemical composition, porosity, and Cr ⁶⁺ elution amount of the chromium oxide-containing substance used in the experiment.

As shown in Table 6, the elution amount of Cr ⁶⁺ was as follows: stainless steel slag-A: 6.50 mg / l;
B is 32.7 mg / l, stainless steel slag-C is 13.2 mg / l, chromium slag is 25.3 mg / l, sewage sludge molten slag is 0.8 mg / l,
The amount of refractory waste adhering to stainless steel slag was 0.12 mg / l.
The porosity is 18% for stainless steel slag-A, 25% for stainless steel slag-B, 4% for stainless steel slag-C,
Chromium slag was 10% and sewage sludge molten slag was 8%.

Incidentally, the stainless steel slag is normally discharged after reduction treatment in a converter, but was discharged without reduction for the experiment of the present invention. As the sulfur-containing substance, unaged blast furnace slow-cooled slag, sulfur (: single element sulfur), and Yunohana were used. As the unaged blast furnace slow-cooled slag, a sample within one week after cooling and crushing was used.

The slag to be subjected to the reduction treatment was subjected to a treatment by a steam blowing method under the experimental conditions shown in Table 7. Table 7 shows the obtained experimental results together with the experimental conditions. As shown in Comparative Example 8 in Table 7, stainless steel slag-A can prevent Cr ⁶⁺ elution when 10% of unaged blast furnace slow cooling slag is added and steam is blown for 2 days. However, the elution amount was 0.05
It cannot be less than mg / l.

Further, as shown in Comparative Example 9, stainless steel slag-B was added with 10% of unaged blast furnace slow cooling slag to prevent elution of Cr ⁶⁺ when steam was blown for 3 days. However, the elution amount cannot be reduced to 0.05 mg / l or less in 3 days after the injection of steam. However, as shown in Examples 14 to 22 of the present invention, by using a high concentration of a sulfur-containing substance, it is possible to reduce the elution amount to 0.05 mg / l or less by adding a small amount and blowing water vapor within 3 days. did it.

Further, as shown in Comparative Example 10, stainless steel slag-C was prepared by adding 20% of unaged blast furnace slow cooling slag and preventing elution of Cr ⁶⁺ when steam was blown in for 3 days. Although the elution amount could not be reduced to 0.05 mg / l or less in 3 days after steam injection, the present invention Example 21
As shown in Fig. 5, the elution amount could be reduced to 0.05 mg / l or less by blowing steam for 3 days by adding 5% of unaged blast furnace slowly cooled slag and 1% of sulfur.

[0105]

[Table 7]

[0106]

[Table 8]

[0107]

[Table 9]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

According to the present invention, stainless steel slag,
Chromium oxide-containing substances, such as chromium slag, industrial waste molten slag, sewage sludge, and sewage sludge molten slag, are industrially treated in a simple and economical manner, and Cr ⁶ from these chromium oxide-containing substances is treated. ⁺ Elution can be completely prevented.

Further, according to the present invention, the above-described excellent effects can be obtained by treating the chromium oxide-containing substance in a short time and by a treatment method which does not increase the volume of the material to be treated as much as possible. As a result, it has become possible to easily reuse the chromium oxide-containing substance for roadbed materials, temporary materials, civil engineering landfill materials, and the like.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Kishimoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Works Co., Ltd. Chiba Works (72) Inventor Toshikazu Sakuraya 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Inside Steel Works Co., Ltd. (72) Inventor Yukio Sato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Kawatetsu Mining Co., Ltd. Chiba Works (56) References JP-A-6-279817 (JP, A) JP-A-54-33294 (JP, a) JP Akira 53-102273 (JP, a) JP Akira 54-118304 (JP, a) JP Akira 58-36690 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) C04B 5/00-5/06 B09B 3/00 C02F 11/00 C21B 3/04 F27D 15/00

Claims (6)

(57) [Claims] 1. A chromium oxide containing material quality, sulfur and /
Or a slag containing sulfur whose oxidation number is +5 or less
Mixing, processing method chromium oxide-containing substances, characterized in that the stand in the atmosphere. 2. A chromium oxide-containing Substance, sulfur and /
Or a slag containing sulfur whose oxidation number is +5 or less
Mix and sprinkle the mixture with water and / or blast furnace slag.
Processing method chromium oxide-containing substances, characterized in that sprinkling blast furnace slag eluent water generated during water cooling. 3. A chromium oxide-containing Substance, sulfur and /
Or oxidation number by mixing a substance containing pentavalent less sulfur, processing method chromium oxide-containing substances, characterized in that blowing steam into the mixture. 4. A chromium oxide-containing Substance, sulfur and /
Or a slag containing sulfur whose oxidation number is +5 or less
Mixing, processing method chromium oxide-containing substances, characterized in that blowing steam into the mixture. 5. A chromium oxide-containing Substance, sulfur and /
Or a slag containing sulfur having an oxidation number of +5 or less ,
Contains sulfur and / or sulfur with an oxidation number of +5 or less
That the materials are mixed, processing method chromium oxide-containing substances, characterized in that blowing steam into the mixture. 6. The method according to claim 1, wherein said sulfur and / or oxidation number is +
Pentavalent following slag containing sulfur, non-aging
A blast furnace slow cooling slag is used .
2,4,5 processing method chromium oxide-containing substances according to any one.