JP2001198567A - Slurry containing fine iron particle, method of producing the same, soil-cleaning agent and method of cleaning soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for directly and efficiently removing organic halogenated compounds or the like from the soil polluted with the organic halogenated compounds or the like, a soil-cleaning agent used in this method with advantage and a slurry containing fine iron particles suitably used in the soil-cleaning agent. SOLUTION: In the slurry containing fine iron particles, spherical fine iron particles having an average diameter of <10 μm are dispersed in water. The soil-cleaning agent is an aqueous suspension containing the slurry. The method of cleaning the polluted soil comprises using this agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an iron fine particle slurry suitable for a soil cleaning agent used for removing contaminants from soil contaminated with an organic halide, hexavalent chromium, and the like, and an iron fine particle slurry. Soil purification agents, including
And a method for purifying contaminated soil.

[0002]

2. Description of the Related Art Organic halides such as trichloroethylene have been used in large quantities for industrial cleaning such as removing oils from machinery. From the viewpoint of environmental pollution, the use of such organic halides has recently been regulated. However, a large amount of organic halides has already been used, so that soil pollution or water pollution has been progressing. That is, organic halides such as trichloroethylene are stable and hard to be decomposed by microorganisms, and organic halides dumped in the natural environment not only pollute soil, but also eventually pollute rivers and groundwater, which is It can be a source of water, which is a problem. It is known that such pollution of the natural environment is also caused by hexavalent chromium left on the site of a factory such as a plating factory.

As a method for purifying soil contaminated with volatile organic compounds such as the above-mentioned organic halides, a soil gas suction method, a groundwater pumping method, a soil excavation method and the like are known. The soil gas suction method forcibly sucks the target substance present in the unsaturated zone.A suction well is installed in the ground by boring, the inside of the suction well is depressurized by a vacuum pump, and Compounds are collected in a suction well, guided underground, and treated by a method such as adsorption of organic compounds in soil gas to activated carbon. In the case where the contamination by the organic compound reaches the aquifer, a method of installing a submersible pump in the suction well and pumping the water together with the soil gas for treatment is adopted.

[0004] The underground pumping method is a method in which a pumping well is installed in soil, and contaminated groundwater is pumped and treated. Further, the soil excavation method is a method in which contaminated soil is excavated, and the excavated soil is subjected to wind drying and heat treatment to remove and recover organic compounds.

As a method of purifying contaminated water such as collected contaminated water or groundwater as described above, for example, Japanese Patent Publication No. 2636171 discloses a method of removing dissolved oxygen in contaminated water and then removing contaminated water such as iron. A method of contacting a metal surface to reduce and remove an organic halide contained in contaminated water is disclosed. Such a method of purifying contaminated water using the reducing action of iron is disclosed in JP-A-3-106496, JP-A-3-30895, JP-A-6-501521, JP-A-8-257570, JP-A-10-26
It is also described in Japanese Patent No. 3522 and the like. Each of these methods is a method of treating contaminated water by passing it through a fixed portion such as a layer containing iron or a filter.

However, these methods do not purify soil directly, but purify contaminated water collected by the above-mentioned soil gas suction method, groundwater pumping method, or contaminated water such as rivers and groundwater. The objects are extremely large, and the processing often takes a long time. Another drawback is that the processing steps are often complicated. For this reason,
There is a need for a method for directly and easily purifying soil, which is a source of pollution.

[0007] A method of purifying soil contaminated with hexavalent chromium with a reducing agent such as ferrous sulfate is known. However, such soil is contaminated with trivalent and hexavalent chromium like chromium slag. In the presence of ferrous sulfate, sufficient reduction cannot be performed because ferrous sulfate has a short reducing action time.
Therefore, the emergence of a purifying agent that exhibits a reducing action over a long period of time is desired.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to detoxify or detoxify a soil contaminated with contaminants such as organic halides and hexavalent chromium by directly and efficiently reducing the contaminants. An object of the present invention is to provide an iron fine particle slurry suitably used as a soil purification agent that can be removed after chemical conversion, a method for producing the same, a soil purification agent containing the slurry, and a purification method using the soil purification agent.

[0009]

A conventional method for purifying soil contaminated with organic halides involves collecting contaminated water from contaminated soil and purifying it, or collecting and purifying the soil itself. However, this is not a simple and easy way to directly purify the contaminated soil.

The present inventors have paid attention to iron that exhibits an action of reductively decomposing organic halides (so-called dehalogenation action), and have been conducting research to develop the above simple purification method using the iron. Was. However, iron fine particles that have been used in the conventional purification method have a relatively large average particle size of several tens of μm and have an irregular shape. For example, even when the aqueous dispersion is directly applied to soil. Found that there is a problem that it is difficult to penetrate sufficiently. Based on such findings, further studies were carried out, and it was found that iron fine particles having a large surface area and being fine in shape were effective in solving the above-mentioned problems, and the present invention was reached. Things. As described above, the iron particles are finely divided, thereby increasing the surface area of iron to increase the treatment capacity of contaminants. In addition to the atomization, the spherical shape of the particles allows rapid transfer of iron into the soil. Infiltration is possible. As described above, iron fine particles conventionally used for purification have an average particle size of several tens of μm, whereas iron fine particles of the present invention have a mean particle size of 10 μm.
μm, and has a purification ability of 2 times or more (in some cases, 10 times or more), and has a spherical shape, and is far less permeable to soil than conventional amorphous shapes. Crab is excellent.

It has also been found that such a reducing action of iron fine particles is effective for pollutants which can be reduced, particularly hexavalent chromium.

[0012] Accordingly, the above object is solved by a soil cleaning agent containing an iron fine particle slurry in which spherical iron fine particles having an average particle diameter of less than 10 µm (preferably 0.1 to 6 µm) are dispersed in water. Can be.

[0013] The above-mentioned object is to infiltrate the contaminated soil with the above-mentioned soil purifying agent, so that pollutants (eg, organic halides, hexavalent chromium, etc., especially organic halides) are not toxic from the contaminated soil. Or detoxification or removal. Preferably, a method of permeating the soil cleanser by spraying the soil cleanser over substantially the entire surface of the soil; inserting an injection pipe for supplying the soil cleanser into the contaminated soil; A method comprising injecting a soil purifying agent into the injection pipe can be mentioned.

Further, the present invention also resides in a slurry of iron fine particles comprising spherical iron fine particles having an average particle diameter of less than 10 μm and dispersed in water, which is preferably used as the soil purifying agent. The average particle size is 0.1 to 6 μm (particularly 0.1 to 3 μm).
m) is preferred. By setting such an extremely small particle size, the cleaning power can be significantly improved. Further, the slurry preferably contains an antioxidant. This can keep the iron from being oxidized. The solid content of the slurry is 20 to 70% by mass.
(Especially 30 to 50% by mass) is preferred.

Such a slurry of iron fine particles can be advantageously obtained by a production method characterized by collecting steelmaking dust in exhaust gas generated after refining from an oxygen blowing furnace for steelmaking.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The iron fine particle slurry of the present invention is characterized by containing iron fine particles having an average particle diameter of less than 10 μm and a spherical shape. The soil purifying agent comprising an aqueous suspension containing the slurry is useful for detoxifying contaminants from contaminated soil by reduction or the like, or for removing after detoxification.

As the pollution source to be purified according to the present invention,
Organic halides, hexavalent chromium and cyanide can be mentioned, and organic halides and hexavalent chromium are suitable, and organic halides are particularly suitable. Examples of organic halides include 1,1-dichloroethylene, 1,2-
Dichloroethylene, trichloroethylene, tetrachloroethylene, dichloromethane, carbon tetrachloride, 1,2-dichloromethane, 1,1,1-trichloroethane, 1,1,
Examples thereof include 2-trichloroethane, 1,1,2,2-tetrachloroethane, and dichlorodifluoroethane. It is considered that these organic halides lose halogens and become corresponding hydrocarbons due to the dehalogenating action (reducing action) of iron, and are removed from soil. As an organic halide, it is particularly effective for an organic chloride (organic chlorine-substituted compound). Hexavalent chromium can be efficiently reduced to trivalent chromium by an effective iron reducing action over a long period of time, and then can be removed from the soil if necessary. Furthermore, cyanide (cyan ion)
Is detoxified by forming a complex with iron ions.

[0018] The iron fine particles contained in the slurry used in the soil purifying agent of the present invention are extremely fine particles, and therefore, when applied directly to contaminated soil, quickly permeate into the soil. The average particle size of the iron fine particles is less than 10 μm,
To 6 μm, particularly preferably 0.1 to 3 μm.
By using such ultrafine iron powder, the cleaning power can be greatly improved. Further, since the iron fine particles are ultrafine particles and are spherical in shape, when applied to contaminated soil, they penetrate into the soil very quickly and exhibit a purifying action.

The slurry has a solid content of 20-70.
% By mass (particularly 30 to 50% by mass) is preferred. Further, the slurry preferably contains an antioxidant. This can keep the iron from being oxidized. 90% by mass or more of the solid content is metallic iron and iron-containing compounds.
Metallic iron accounts for 30% by mass or more of the solid content.

Such a slurry is generally used to collect (preferably wet-type) steelmaking dust in exhaust gas generated during refining from an oxygen blower for steelmaking to remove gases such as carbon dioxide gas. Can be advantageously used. Usually, after dust collection, the steelmaking dust is made into a slurry of iron powder sludge by a thickener. If desired, a high-grade iron powder for a specific use (eg, for toner) may be further added to the obtained steelmaking dust to form a slurry.

An example of the method for producing the iron fine particle slurry will be described with reference to FIG.

In a steelmaking oxygen-blowing furnace, C, S
Pig iron or the like containing impurities such as i and P is charged, and oxygen is rapidly blown from above while stirring. In this state, a reaction occurs between the pig iron containing impurities and oxygen, and C,
Si, P and the like become oxides, and pig iron becomes a rope. During this time, exhaust gas containing fine iron powder generated by blowing oxygen is collected by wet dust collection through a gas recovery hood. In wet dust collection, gases such as CO are sent to a gas recovery tank. The steelmaking dust obtained by collecting the exhaust gas is in the form of a slurry, and this slurry is separated into coarse particles (60%).
μm), the coarse one is recovered as coarse iron powder, and the fine one is concentrated in a thickener and finally sorted only by a filter press into fine particles to obtain fine iron powder (ie, iron fine particle slurry). ) Can be obtained.

The iron fine particles thus obtained also contain iron oxides in various oxidation stages. Since such iron oxides are in a reduced state in dust captured in a gaseous combustion state, the iron fine particles have a reducing action leading to a purifying action. It is thought to show. Therefore, even if metallic iron does not account for 30% by mass or more, the above-mentioned iron fine particles can often exhibit a high reducing action.

Examples of the particle size of 97 mass% Fe in the coarse iron powder are as follows.

Table 1 97 mass% Fe total amount / metal particle size distribution (unit: T / M (production per month)) ≦ 70 μm 50 60 to 70 μm: 5% ≦ 80 μm 100 60 to 90 μm: 10% The composition example of the fine iron powder is as follows.

Table 2 Slurry Moisture powder Moisture SS Metal iron Wet powder Metal iron (Unit: T / D (amount generated per day)) (Unit: T / M (amount generated per month) Filter 35% after pressing 150 53 98 20 4200 546 Slurry 70 70% 325 228 98 25 9100 683 (Product) Meaning of the above-mentioned abbreviations; SS: suspended substance, wet powder: iron powder containing water.

The ranges of the components of the fine iron powder are as follows.

Table 3 Slurry Metal iron FeO Fe ₂ O Total iron CaO SiO ₂ After filter press 11-18 − − 67-71 3-5 0.4-1.0 Slurry 70 29-44 32-38-67-75-- (Product) All units of numerical values in Table 3 above are% by mass.

As described above, the iron fine particles of the present invention can be obtained by using a by-product at the time of iron smelting without using a special method and apparatus for producing the iron fine particles,
Simple and economical. Further, since it is obtained in the form of a slurry, oxidation of the surface of the iron particles can be prevented, and thus oxidation during transportation can also be prevented. During the transportation, it is preferable to stir so that the iron particles do not precipitate and solidify. It is preferable to add an antioxidant to the slurry in order to prevent oxidation of the iron particle surface. Examples of the antioxidant include organic acids (eg, ascorbic acid (vitamin C), citric acid, malic acid, particularly ascorbic acid) and salts thereof. The content is generally from 0.01 to 10% by mass, and preferably from 0.1 to 3% by mass. Furthermore,
Since the slurry is in the form of a slurry, there is an advantage that it can be easily mixed with other materials when producing the soil purification agent.

In the soil purification agent of the present invention containing the above-mentioned iron fine particle slurry, metals other than iron, such as Mn, Mg, Zn, Al and Ti, which have a reducing action, can be used in combination. These metals too. The average particle size is preferably as small as possible.

Since the fine iron powder has a large surface area and is easily oxidized (passivated) on the surface, it is preferable in the present invention to use a hydrophilic binder and / or a metal halide in combination to prevent this.

Metal halides include NaCl, KCl,
MgCl ₂ , CaCl _2, etc.
Cl is preferred. Metal halides are hydroxides of iron,
It works to reduce oxides to metallic iron. Its usage is
The content is generally 0.5 to 200% by mass based on the iron fine particles,
0.5 to 50% by mass is preferred.

The hydrophilic binder has a function of covering the surface of the iron fine particles and protecting the organic halide from being oxidized before exhibiting a reducing action. Examples of the hydrophilic binder include disaccharides such as sucrose, sucrose derivatives (eg, higher fatty acid esters of sucrose), monosaccharides such as glucose, alginic acid; pullulan, PVA (polyvinyl alcohol), CMC (carboxymethylcellulose), polyacrylamide, Water-soluble resins such as guar gum, methyl cellulose, hydroxyethyl cellulose and the like can be mentioned. Pullulan (having a particularly low viscosity in aqueous solution), hydroxyethylcellulose, sucrose, glucose and PVA are preferred. The use of a biodegradable polymer as a hydrophilic binder is particularly effective against secondary environmental pollution. The use amount is generally 0.01 to 200% by mass based on the iron fine particles, and 0.01 to 200% by mass.
100% by mass is preferred.

The soil purifying agent of the present invention is prepared by adding an antioxidant, a metal halide or a water-soluble polymer, or a metal halide and a hydrophilic binder to the above-mentioned iron fine particle slurry and suspending or dispersing the slurry. It can be obtained by Further, water can be appropriately added to obtain a desired concentration. If necessary, a surfactant can be used at the time of dispersion. Use of a biodegradable polymer (eg, biodegradable polycaprolactone) instead of the hydrophilic binder is particularly effective against secondary environmental pollution.

It is preferable that the soil purifying agent of the aqueous suspension further contains a metal sulfate (particularly, ferrous sulfate) as a reducing agent. Since this reacts with oxygen in the air, oxidation of the surface of the metal iron fine particles can be prevented.

The aqueous suspension preferably further contains an inorganic carbonate or a carbonate mineral. Examples of these are calcium carbonate, precipitated calcium carbonate,
Examples thereof include magnesium carbonate, coral fossil limestone, limestone, and dolomite, and sedimentable calcium carbonate is particularly preferable. Since the soil purifying agent of the present invention uses fine-particle iron, it can be injected into the gap between the soil particles in the soil. However, since the possibility of elution into groundwater or the like is increased by making the particles fine, in the present invention, it is preferable to fix the eluted iron ions by using the above-mentioned carbonate and prevent this.

As described above, the soil purifying agent of the aqueous suspension of the present invention is prepared by adding the iron fine particle slurry and, if desired, a water-soluble polymer, a metal halide or a metal halide and a hydrophilic binder. It is turbid or obtained by dispersion. At that time, it is preferable to use reducing electrolyzed water (preferably having a pH of 7 to 12) as water used for dispersion, from the viewpoint of minimizing iron oxidation. As a dispersant, a surfactant such as naphthalenesulfonic acid may be used. The amount of the dispersant used is generally 0.01 to 10% by mass, preferably 0.1 to 5% by mass, based on the iron fine particles. Further, the aforementioned antioxidant may be further used within the above range.

The method for purifying contaminated soil according to the present invention using a soil purifying agent comprises the steps of: contaminating an organic halide (soil)
The above-mentioned soil purification agent is applied so as to penetrate the soil. Preferably, the method of permeating the soil purifying agent by spraying the soil purifying agent (1); or inserting an injection pipe for supplying the above soil purifying agent into the soil contaminated with the organic halide. And (2) injecting the soil purifying agent into the injection pipe.

The above method (2) can be performed, for example, as follows.

An injection pipe for supplying a soil purifying agent by boring is provided on the surface contaminated with the organic halide. A plurality of injection tubes can be provided at intervals as needed. Inject the soil cleanser into the supply inlet. As a result, iron fine particles and the like penetrate into the contaminated soil, gradually come into contact with the organic halide, and decompose and remove the organic halide. Before injecting with an injection pipe, groundwater may be drained from an injection pipe and then a soil purifying agent may be injected. The soil surface may be covered with a water-impermeable sheet (eg, bentonite sheet) so that the injection liquid does not overflow from the soil surface. Alternatively, a sheet may be embedded in the soil.

The above purification method may be performed, for example, as follows. That is, as shown in FIG.
Blocked by an impermeable layer 12 leading to the impermeable underground ground 11,
An injection pipe 9 and, if necessary, a gas-permeable columnar portion 2 and a horizontal gas-permeable layer 4 are installed in the soil inside, covered with an air-impermeable sheet 6 and the peripheral edge is glued outside the air-impermeable layer. It can be blocked by the impermeable layer 7 made of backfilled earth and sand mixed with the material. In the horizontal ventilation layer 4, an intake pipe 5, which is a perforated pipe composed of many holes having a size that does not allow the gas-permeable material 3 to pass through, is embedded.

In the purification treatment, for example, water is drained through a water injection pipe, the cleaning agent of the present invention is injected from an injection pipe, and the pressure is reduced if necessary, so that substances generated by the diffusion of the cleaning agent and the reduction action by iron are removed. Can be removed.

Covering the surface of soil contaminated with organic halides with an impermeable sheet, as in the method described above (generally, the sheet covering is installed after injecting the purifying agent)
Preferably, a gas-permeable columnar portion (useful for removing the generated substance) can be provided as necessary.

Soil contaminated with contaminants other than organic halides can be carried out in the same manner as described above. In addition, contaminated soil (especially soil contaminated with hexavalent chromium)
Excavated soil can be introduced into a reaction tank or the like by the soil excavation method and treated with the soil purification agent of the present invention, and it may be advantageous to remove the treated chromium compound or the like.

The concentration of iron fine particles in the soil purifying agent injected into the soil is generally 0.1 to 50% by mass, preferably 1 to 30% by mass. The injection amount is generally 1 to 400 kg of iron fine particles per 1 m ³ of soil, preferably 10 to 200 kg.

The injection of the soil purifying agent may be performed separately by injecting an aqueous suspension of iron fine particles and an aqueous suspension containing a hydrophilic binder and the like used as desired.

[0047]

EXAMPLES Example 1 (a) Aqueous Suspension Containing Iron Fine Particle Slurry (Soil Purifying Agent) Using the method shown in FIG. 1, an iron fine particle slurry was obtained under the following production conditions.

Manufacturing conditions: Manufactured with an upper-bottom blow converter equipped with an OG (oxygen gas) gas treatment system. Capacity of converter: 350 T / time (T: equivalent to the mass of steel in the converter, indicated by capacity) Pig iron: Hot metal ratio 70-96% Oxygen blowing amount: Blowing time about 20 minutes Slurry production rate: 250 t / D (day) The following fine iron powder slurry was obtained by the above method. Its composition is as follows.

Table 4 Slurry Moisture powder Moisture SS Metal iron Wet powder Metal iron (Unit: T / D (amount generated per day)) (Unit: T / M (amount generated per month) Filter 35% after pressing 150 53 98 20 4200 546 Slurry 70 70% 325 228 98 25 9100 683 (Product) The components of the fine iron powder are as follows.

Table 5 Slurry Metal iron FeO Fe ₂ O Total iron CaO SiO ₂ After filter press 18 − − 71 4.8 0.4 Slurry 70 29 38-67-- (Product) (Unit: mass%)

The fine iron particles contained in the slurry after the above-mentioned filter pressing were confirmed to be spherical by observation with an electron microscope (20,000 ×). The particle size distribution was as shown in FIG. The average particle size was 1.3 μm.

The particle size distribution of the iron fine particles was measured under the following conditions.

Measuring device: SK laser micron sizer 7000S Dispersion medium: 0.2% NaHMP Dispersion condition: Ultrasonic wave (US WAVE) 5 minutes The volume fraction of each particle size and its composition in FIG. 1 and Table 2.

Table 6 Fractions Particle Size (μm) Volume (%) 1 0.1 11.2 0.2 0.2 16.9 3 0.4 25.3 4 0.6 31.4 5 0.8 36. 2 6 1.0 40.27 1.5 59.5 8 2.0 2.0 81.1 9 3.0 91.1 10 4.0 97.3 11 6.0 100.0 12 8.0 100.0 13 12.0 100.0 14 16.0 100.0 15 24.0 100.0 16 32.0 100.0 17 48.0 100.0 18 64.0 100.0 19 96.0 100.0 20 128.0 100.0 21 192.0 100.0

The slurry after filter pressing (solid content: 65% by mass) was reduced to 30% by mass by adding reducing electrolytic water in a stirring tank, and 0.1% by mass of ascorbic acid was further added thereto. A slurry soil cleanser was obtained.

Next, the above soil-purifying agent (a) is continuously introduced into a bead mill (dispersion device), and after dispersion, HCl is added to a pH of 4 with a pH meter described later, and mixed with a line mixer. After that, the pH was measured with a pH meter (this adjusts the amount of HCl added), and then N 2 was added.
aOH is added so as to have a pH of 7 with a pH meter to be described later, and an aqueous dispersion containing 20% by mass of ferrous nitrate and 0.1% by mass of ascorbic acid (in the same amount as the soil purification agent (a)) Was added and mixed with a line mixer. After mixing, the pH was measured with a pH meter to obtain a dispersion. This dispersion was manufactured continuously and the resulting dispersion was continuously injected into soil contaminated with trichlorethylene.

The contaminated soil is a layer of crushed stone having a depth of 30 cm from the ground, a silt layer up to a depth of 2 m, and a clay layer up to a depth of 30 m. I put a floor slab on top. The floor slab has 5 holes on the left and right every 3m, for a total of 25 holes (diameter 10cm)
, And the dispersion was injected from there. The injection amount is 4m
48 hours at ³ / hr.

As a result, the concentration of trichlorethylene at five places (set at random) in the soil changed as described below one month after the injection.

Silt layer (before injection → one month later (unit: pp)
m)): 1) 1.85 → less than 0.0005, 2) 0.01 → 0.
3) 3.22 → less than 0.0005 4) 1.97 → 0.
5) 0.08 → less than 0.0005.

Clay layer (before injection → one month later (unit: pp)
m)): 1) 5.06 → less than 0.0005, 2) 1.03 → 0.
3) 3.08 → less than 0.0005, 4) 1.53 → 0.
5) 2.93 → less than 0.0005.

Further, of the five locations in the soil, the position furthest from the injection port was a horizontal distance of 5 m and a depth of 2 m, and the purifying agent was effective at this position. It can be seen that it has good permeability to soil.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an embodiment of a method for producing an iron fine particle slurry of the present invention.

FIG. 2 is a sectional view showing an example of an embodiment of the purification method of the present invention.

FIG. 3 is a graph showing the particle size distribution of the iron fine particle slurry obtained in Example 1.

[Explanation of symbols]

 2 Air-permeable columnar part 3 Air-permeable material 3 4 Horizontal air-permeable layer 5 Intake pipe 6 Impermeable sheet 9 Injection pipe 11 Underground impermeable ground 12 Impermeable layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) C09K 103: 00 (72) Inventor Terunobu Maeda 2-5-8 Kitaaoyama, Minato-ku, Tokyo Co., Ltd. (72) Inventor Yasunori Kimura 2-3-13 Kyobashi, Chuo-ku, Tokyo Inside Toyo Ink Manufacturing Co., Ltd. (72) Inventor Junji Igawa 1-1 Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation F term in Yawata Works (reference) 4D004 AA41 AB03 AB06 AC07 CA34 CC11 DA03 DA10 DA20 4H026 CA05 CC06 4K001 AA10 BA14 GB09

Claims (18)

[Claims] 1. An iron fine particle slurry in which spherical iron fine particles having an average particle diameter of less than 10 μm are dispersed in water. 2. The iron fine particle slurry according to claim 1, wherein the average particle size is 0.1 to 6 μm. 3. The iron fine particle slurry according to claim 1, further comprising an antioxidant. 4. The iron fine particle slurry according to claim 1, wherein the solid content is 20 to 80% by mass. 5. The iron fine particles according to claim 1, wherein exhaust gas generated during refining is collected from the steelmaking oxygen blowing furnace and the gas is removed to obtain slurry-like steelmaking dust. A method for producing a slurry. 6. The dust collection is performed by wet dust collection.
5. The method for producing the iron fine particle slurry according to the above. 7. The method for producing iron fine particle slurry according to claim 5, wherein after the dust collection, steelmaking dust is settled and collected by a thickener to obtain an iron powder sludge slurry. 8. A soil purifying agent for purifying contaminated soil, comprising an aqueous suspension containing the iron fine particle slurry according to claim 1. Description: 9. The soil remediation agent according to claim 8, wherein the contaminants of the contaminated soil are organic halides and / or hexavalent chromium. 10. The soil purifying agent according to claim 8, wherein the aqueous suspension further contains a hydrophilic binder. 11. The soil purification agent according to claim 8, wherein the aqueous suspension further contains a metal halide. 12. The soil purification agent according to claim 8, wherein the aqueous suspension further contains a metal sulfate as a reducing agent. 13. The soil purifying agent according to claim 8, wherein the aqueous suspension further contains an inorganic carbonate or a carbonate mineral. 14. A soil purification method comprising permeating the soil purification agent according to any one of claims 8 to 13 into contaminated soil. 15. The pollutant of the contaminated soil is an organic halide and / or hexavalent chromium.
5. The soil purification method according to item 4. 16. The soil purifying agent is permeated by spraying the soil purifying agent over substantially the entire surface of the soil.
16. The soil purification method according to 4 or 15. 17. A soil purification method comprising: inserting an injection pipe for supplying the soil purification agent according to claim 8; and injecting the soil purification agent into the injection pipe. 18. The soil purification method according to claim 14, wherein the surface of the contaminated soil is further covered with a sheet.