JP4712290B2 - Hazardous material collecting material and method of treating sewage and soil using the same - Google Patents

Description

  The present invention relates to a hazardous substance collecting material used for collecting harmful substances in waste water or soil, various waste treatments, and the like. Unless otherwise specified, parts and% in the present invention are shown on a mass basis.

  Environmental problems are becoming apparent. In particular, harmful substances in sewage and soil, such as heavy metals such as chromium, selenium, arsenic, nitrate nitrogen, nitrite nitrogen, fluorine, boron, dioxins, volatile organic compounds such as trichloroethylene and tetrachloroethylene, Environmental standards based on the Basic Environment Law are established, and it is preferable to maintain a level below this standard value. Particularly, chromium, selenium, arsenic, and volatile organic compounds, which have a high environmental impact, are efficiently and quickly captured. There is a need for materials to collect.

  As materials for collecting and reducing these harmful substances, methods using activated carbon (see Patent Documents 1 and 2, etc.), methods using zeolites (see Patent Document 3, etc.), hydrotalcites and hydrocalumite (Refer to patent documents 4-5 etc.), the method of reducing and decomposing with reducible iron powder (refer to patent documents 6 etc.), the method using ferrous sulfate (refer to patent documents 7-8 etc.) A method using apatites (see Patent Document 9 etc.), a method using calcium sulfoaluminate hydrate or a heated dehydrated calcium aluminate hydrate (see Patent Document 10 etc.), and the like are known.

  On the other hand, environmental problems are also examined from the viewpoint of volume reduction and effective use of industrial by-products. In particular, it is important to search for new uses of industrial waste that has not been effectively utilized, for example, steelmaking slag. Steelmaking slag is a general term for slag generated in the process of making pig iron into steel, and includes converter slag, various types of hot metal pretreatment slag, and refining slag. Although more than 10 million tons of these steelmaking slags are generated every year in Japan alone, the utilization rate is still low compared to blast furnace slag generated at the stage of obtaining pig iron. Finding uses of steelmaking slag generated in large quantities from the steel industry, which can be said to be representative of mass production, is a major social issue.

  A water treatment material and a water treatment method in which converter slag is used in combination with an alkali metal or an alkaline earth metal are known (see Patent Document 11, etc.). The present invention mainly relates to the treatment of phosphoric acid, but also exhibits an arsenic reduction effect.

There is known a method for stabilizing waste containing heavy metals at 60 ° C. or higher using steelmaking slag such as secondary refining slag, hot metal pretreatment slag, converter slag, and the like (see Patent Document 12, etc.). This invention can suppress elution of lead, cadmium, and zinc by using steelmaking slag such as secondary refining slag, hot metal pretreatment slag, converter slag, and the like.

  There is known a method for stabilizing waste containing chromium using calcium aluminate, calcium silicate, powder containing calcium aluminosilicate and powder containing sulfate radical (see Patent Document 13 and the like).

  It is known that secondary refining slag powder containing calcium aluminate is effective in suppressing elution of fluorine (see Patent Documents 14 to 16).

JP 05-076619 A JP 2002-239347 A JP 2001-238980 Japanese Patent Laid-Open No. 10-128313 JP 2001-252675 A Japanese Unexamined Patent Publication No. 07-108280 Japanese Unexamined Patent Publication No. 09-085224 Japanese Patent Laid-Open No. 10-034124 Japanese Unexamined Patent Publication No. 08-182984 Japanese Patent Laid-Open No. 2001-070926 Japanese Patent Laid-Open No. 2002-086139 JP 2000-037676 JP 2002-059141 A JP 2000-225383 A JP 2000-246267 A JP 2001-259570

  The present invention provides a harmful substance collecting material, and a method for treating sewage and soil using the same.

The present invention, Blaine specific surface area of 3,000 cm ² / g or more, the content of the content of SiO ₂ is _Al 2 _{O 3} less than 20% is 8.4% or more, the _Fe 2 _{O 3} and _Al 2 _{O 3} A harmful substance collecting material containing a steelmaking slag powder and a alkanolamine containing no calcium aluminate having a total content of 15% or more and a total content of fluorine, boron and sulfur of 2% or less. This is a method for treating sewage and soil using a collecting material.

 The hazardous substance collecting material of the present invention can collect many harmful substances, and has the ability to collect harmful substances quickly and efficiently even in an environment with a high concentration of various anions such as sulfate ions and carbonate ions. There are effects such as having.

  Hazardous substances as used in the present invention are not particularly limited, but environmental standards are established, and heavy metals such as chromium, selenium, arsenic, cadmium, lead, and mercury, all cyan, and nitrates, which are considered particularly harmful substances Nitrogen, nitrite nitrogen, fluorine, boron, phosphorus, volatile organic compounds such as trichlorethylene and tetrachloroethylene, dioxins, PCB, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, 1,1 1,1-trichloroethane, 1,1,2-trichloroethane, benzene, organic phosphorus, and the like. Examples of environmental standards not defined include copper, zinc, molybdenum, amine compounds, various environmental hormones, endocrine disrupting substances, and the like.

Steelmaking slag is a general term for slag generated in the ironmaking process among steel slags, and is not particularly limited. Specific examples thereof include various types of hot metal pretreatment slag and refining slag such as converter slag, desiliconization, decarburization, and dephosphorization. The chemical composition and alloy composition of the steel slag, but multifarious by steelmaking process and process, the chemical components, for _{example, CaO, SiO 2, Fe 2} O 3, Al 2 O 3, MgO, TiO 2, _{MnO, Na 2 O, K 2} O, S, P 2 O 5, B 2 O 3 and F, and the like.

Examples of compounds constituting steelmaking slag include calcium alumino such as 4CaO · Al ₂ O ₃ · Fe ₂ O ₃ and 6CaO · 2Al ₂ O ₃ · Fe ₂ O ₃ and 6CaO · Al ₂ O ₃ · 2Fe ₂ O _3. Ferrite, calcium ferrite such as CaO · Fe ₂ O ₃ and 2CaO · Fe ₂ O ₃ , free lime, calcium aluminum such as 12CaO · 7Al ₂ O ₃ and 11CaO · 7Al ₂ O ₃ · CaF ₂ , 3CaO · Al ₂ O ₃ sulfonates, gehlenite _{2CaO · Al 2 O 3 · SiO} 2, anorthite CaO · Al ₂ O calcium aluminosilicates such as ₃ · 2SiO _2, Merubinaito 3CaO · MgO · 2SiO _2, Akerumanaito 2CaO · MgO · 2SiO _2, Monte celite CaO · MgO · calcium magnesium silicate, such as SiO _2, tri-calcium silicate 3CaO · SiO ₂ or dicalcium silicate 2CaO · SiO ₂ and rankinite night 3CaO · 2SiO ₂ or calcium silicate such as wollastonite CaO · SiO _2, Kasupidin 3CaO · 2SiO ₂ · CaF _2, fluorine A Apatites, such as tight and hydroxyapatite, wustite FeO, magnetite Fe ₃ O _4, leucite _{(K 2 O, Na 2 O} ) · Al 2 O 3 · SiO 2 and the like. These compounds may be mixed in a crystalline or amorphous form.

The total content of fluorine, boron and sulfur in the steelmaking slag is preferably 2% or less. If the content of these elements is large, the harmful substance collecting effect may not be sufficient. For example, 11CaO · 7Al ₂ O ₃ · CaF ₂ , caspidine 3CaO · 2SiO ₂ · CaF ₂ , fluorine apatite, and the like, which are fluorine-containing compounds, preferably have a low content. The same is true for compounds containing boron or sulfur.

Fe ₂ O ₃ content and Al ₂ O ₃ content are important from the viewpoint of enhancing the collection effect of harmful substances, and the total of Fe ₂ O ₃ content and Al ₂ O ₃ content should be 15% or more Is preferable, and it is more preferable that it is 20 to 65%. If the total content of Fe ₂ O ₃ and Al ₂ O ₃ is outside the above range, the harmful substance collecting effect may be insufficient. The ratio of the Fe ₂ O ₃ component and the Al ₂ O ₃ component in the steelmaking slag is not particularly limited, but the Fe ₂ O ₃ content is generally larger than the Al ₂ O ₃ content.

The iron oxides contained in steelmaking slag include iron in the form of Fe ₂ O ₃ forming calcium ferrite and calcium aluminoferrite, as well as iron in the form of wustite FeO and magnetite Fe ₃ O _4. There is a case. Wustite FeO and magnetite Fe ₃ O ₄ are known as reducing agents and may coexist because they reduce or decompose harmful substances, but in the present invention, calcium ferrite or calcium aluminoferrite is formed. The presence of iron in the form of Fe ₂ O ₃ is preferred. This is considered to be due to the excellent effect of trapping harmful substances due to the interaction of calcium ferrite or calcium aluminoferrite with alkanolamine.

The CaO content in the steelmaking slag is not particularly limited, but is preferably 35% or more, more preferably 40% or more. In this case, free lime is often present, but the presence of free lime also has a preferable aspect from the viewpoint of collecting phosphoric acid and the like, specifically in a range that does not substantially impede the purpose of the present invention. Is not a problem within 15%. In addition, the content of SiO ₂ is preferably 20% or less, more preferably 15% or less, from the viewpoint of ensuring a high content of Fe ₂ O ₃ , Al ₂ O ₃ , and CaO.

The particle size of the steelmaking slag, is not particularly limited, but is preferably 3,000~9,000cm ² / g in Blaine specific surface area value, 4,000~6,000cm ² / g is more preferable. If the particle size is coarse, the effect of collecting harmful substances may be reduced, and excessive grinding is uneconomical.

Alkanolamine is a chemical formula R ₁ R ₂ N—R—OH or R ₁ R ₂ R ₃ N ⁺ —R—OH (R _{1 to} R ₃ may be any of a hydrogen atom, an alkyl group, an allyl group, etc. It may have a group, a side chain, etc. R is not particularly limited as long as R is a divalent or higher-valent compound such as a methylene group or an allyl group.

Specific examples include N-monoethanolamine, N, N-diethanolamine, N, N, N-triethanolamine, N, N, N-tris-triisopropanolamine, N, N-bis- (2-hydroxyl ) -N- (2-hydroxypropyl) -amine, tris- (2-hydroxybutyl) -amine and the like, higher trialkanolamines having hydroxyl and amino groups, 1- (bis-2-hydroxypropylamino) -2- Propyl maleate, 1- (bishydroxyethyl) amino-2-hydroxy-propylsulfonic acid, sodium 1- (bis-2-hydroxypropyl) aminopropionate and sodium 1- (bishydroxyethyl) aminopropionate Examples thereof include carboxylic acid derivatives and salts thereof, alkanolamines having ionic functional groups other than hydroxyl groups. Among these, triethanolamine and triisopropanolamine are more preferable from the viewpoint of enhancing the effect of collecting harmful substances and from the viewpoint of economy.

  Examples of carboxylic acid derivatives of alkanolamine include potassium salts, calcium salts, magnesium salts, ammonium salts and the like in addition to sodium salts.

  In the present invention, the steelmaking slag powder and alkanolamine are used in combination, but when only steelmaking slag is used or only alkanolamine is used, an excellent harmful substance collecting effect cannot be obtained. When only steelmaking slag is used, in an environment with a high concentration of various interfering anions such as sulfate ions, nitrate ions, carbonate ions, it is not possible to exert an excellent collection effect in a short time. There is no effect of collecting harmful substances. By using steelmaking slag powder in combination with alkanolamine, an excellent collection effect can be achieved in a short time even in an environment where the concentration of various anions such as sulfate ion, nitrate ion and carbonate ion is high. Alkanolamine is sorbed in steelmaking slag and is hardly released into sewage or soil.

  The ratio of the steelmaking slag powder and the alkanolamine used is not particularly limited, but usually it is preferably used in the range of 0.1 to 10 parts alkanolamine with respect to 100 parts of the steelmaking slag powder, 0.5 parts ~ 5 parts are more preferred. If the amount of alkanolamine is small, the collection effect of harmful substances may not be sufficient in an environment where the concentration of various anions such as sulfate ion, nitrate ion and carbonate ion is high, and the amount of alkanolamine is large. In some cases, excess alkanolamines may be released into sewage and soil.

  The alkanolamine may be added separately from the steelmaking slag, or may be mixed in advance with the steelmaking slag. When steelmaking slag and alkanolamine are mixed, when steelmaking slag is pulverized, it is preferable to pulverize while adding alkanolamine to steelmaking slag.

  In the present invention, calcium ferrite, calcium aluminate, calcium aluminoferrite, calcium aluminosilicate, various portland cement, filler cement mixed with limestone powder, municipal waste incineration ash and sewage sludge incineration ash were used as raw materials. Environmentally friendly cement (eco-cement), calcium oxide, ground granulated blast furnace slag, blast furnace slow-cooled slag, fly ash, etc., any water generated from hydraulic materials, latent hydraulic materials, and pozzolanic materials contained in the above powders Japanese compounds, magnesium oxide, magnesium hydroxide, magnesium compounds such as dolomite and hydrotalcite, carbonaceous materials such as activated carbon, bentonites, zeolites, sepiolite, which are layered compounds represented by montmorillonite and kaolinite, A Phosphate such as tight and zirconium phosphate, activated carbon, sulfur compounds such as polysulfides and sulfides, thiourea, thiosulfates and sulfites, amalgam, reduced iron powder, ferrous sulfate and ferrous chloride, etc. 1 type or 2 or more types of hazardous | toxic substance reduction material of water-soluble polymers, such as these iron compounds, cellulose, polyvinyl alcohol, chitosan, dialkyl dithiocarbamic acid, quinoline compounds, polyamines, saccharides, etc. of this invention They can be used in combination as long as the purpose is not substantially inhibited.

  The above hazardous substance reducing material may be used in combination with the hazardous substance collecting material of the present invention, or may be used separately. For example, after the primary treatment is performed with the hazardous substance collecting material of the present invention, the secondary treatment can be performed with the above-described hazardous substance reducing material. It is preferable to perform a plurality of such harmful substance treatments from the viewpoint of collecting harmful substances in a multifaceted and reliable manner.

  The method of using the hazardous substance collecting material of the present invention is not particularly limited. For example, if it is used for water treatment, it may be used in a powder form and then separated into solid and liquid, or processed into pellets, columns, filters, etc., and treated water may be run.

  Examples of the method for producing pellets and filters include a method for pressure-molding the harmful substance-collecting material of the present invention, a method for adding and hardening a hydraulic material such as various Portland cements and alumina cements, and a method for molding. It is done.

  In the case of using for soil, a method of using the harmful substance collection material of the present invention by mixing and stirring with soil, a method of spraying and using it, a method of injecting it into a slurry, and the like can be mentioned. At this time, various cements may be used in combination as a solidifying material or an injecting material.

To 100 parts of various steelmaking slags shown in Table 1, alkanolamine A or alkanolamine B is added in the proportions shown in Table 1, and the steelmaking slag is crushed to a Blaine specific surface area of 5,000 cm ² / g in the presence of alkanolamines. Then, a harmful substance collecting material was prepared. Using 1 g of this harmful substance collection material, it was placed in 50 ml of an aqueous solution containing the harmful substances shown in Table 1, stirred for 3 hours, and then solid-liquid separated. And the density | concentration of the harmful substance which remains in a liquid phase was measured, and the reduction rate of the harmful substance was calculated | required. At this time, sodium sulfate was allowed to coexist at a concentration of 1,000 mg / liter using sodium sulfate. The results are shown in Table 1. As a comparative example, the results of similar experiments are also shown in Table 1 in the case where only commercially available harmful substance collection materials (hazardous substance collection materials A to C) and steel slag powder are used.

<Materials used>
Steelmaking slag (1): Converter slag, SiO ₂ content 11.5%, Fe ₂ O ₃ content 19.7%, Al ₂ O ₃ content 8.4%, CaO content 46.2% (free lime content 10.7%), MgO content 7.6%, sulfur content 0.1%, fluorine content 0.1%, boron is not detected. Does not include calcium aluminate.
Steelmaking slag (2): Hot metal pretreatment slag, SiO ₂ content 23.2%, Fe ₂ O ₃ content 7.4%, Al ₂ O ₃ content 11.8%, CaO content 37.8% (free lime content is 0.8%) , MgO content 3.8%, sulfur content 0.5%, fluorine content 0.9%, boron is not detected. Does not include calcium aluminate.
Steelmaking slag (3): Refined slag, SiO ₂ content 11.3%, Fe ₂ O ₃ content 22.5%, Al ₂ O ₃ content 11.2%, CaO content 40.9% (free lime content 8.3%), MgO Content 5.8%, sulfur content 0.3%, fluorine content 0.3%, boron was not detected. Does not include calcium aluminate.
Steelmaking slag (4): Dephosphorized slag, SiO ₂ content 17.3%, Fe ₂ O ₃ content 15.7%, Al ₂ O ₃ content 2.8%, CaO content 42.3% (free lime content 8.9%), MgO Content 6.2%, sulfur content 0.1%, P ₂ O ₅ content 5.5%, fluorine content 2.2%, boron is not detected. Does not include calcium aluminate.
Alkanolamine A: Triisopropanolamine, Reagent primary alkanolamine B: Triethanolamine, Reagent primary hazardous substance collector a: Commercial zeolite hazardous substance collector b: Commercial activated carbon hazardous substance collector c: Commercial Hydrotalcite harmful substance Cr: chromium standard solution, chromium concentration 1,000mg / liter solution, Kanto Chemical's hazardous substance Se: selenium standard solution, selenium concentration 1,000mg / liter solution, Kanto Chemical's hazardous substance As: arsenic standard solution, Arsenic concentration 1,000mg / liter solution, Kanto Chemical's hazardous substance F: Sodium fluoride, powder, reagent grade 1, Wako Pure Chemical's hazardous substance B: Boric acid, powder, reagent grade 1, hazardous substance made by Wako Pure Chemical NO ₃ : Sodium nitrate, reagent grade 1, Wako Pure Chemical's hazardous substance P: Sodium orthophosphate (Na ₃ PO ₃ ), powder, reagent grade 1, Wako Pure Chemical's hazardous substance TCE (Trichloroethi Ren): Reagent grade 1, manufactured by Wako Pure Chemical

<Measurement method>
Hazardous substance concentration: Measured according to Environmental Agency Notification No. 46.
Hazardous substance reduction rate: Calculated by the following formula based on the concentration of harmful substances measured based on Environmental Agency Notification No. 46.
Hazardous substance reduction rate (%) = C / C ₀ × 100
However, C ₀ : Total amount of harmful substance elution when no hazardous substance collector is added, C: Total amount of harmful substance elution when a hazardous substance collector is added.

注：AのみはアルカノールアミンAを1g使用。TCEはトリクロロエチレン。

Note: Only A uses 1 g of alkanolamine A. TCE is trichlorethylene.

  The same procedure as in Example 1 was conducted except that 2 parts of alkanolamine A was added to 100 parts of steelmaking slag (1) to prepare a harmful substance collecting material having a specific surface area of Blane shown in Table 2. The results are shown in Table 2.

注：TCEはトリクロロエチレン。

Note: TCE is trichlorethylene.

Dissolution test based on the Environmental Agency Notification No. 46, using chromium, selenium, and arsenic containing 100 parts of steelmaking slag (1) and adding alkanolamine A as a hazardous material collector. As a result, the soil treatment effect was confirmed for the soil in which the elution amount of the heavy metal exceeds the environmental standard value. Against soil 1 m ^3, was added 150kg of hazardous substances adsorbent, and treated mixed well. The elution test based on the Environmental Agency Notification No. 46 method was performed again using the treated soil. The results are shown in Table 3. For comparison, the results obtained in the same manner using ordinary Portland cement are also shown.

<Materials used>
Soil: Contains Kanto loam soil, Cr, As, Se contaminated with harmful substances.
Ordinary Portland cement (OPC): Uses a mixture of three commercial products in equal amounts.

注：表中のN.D.は検出下限以下。

Note: ND in the table is below the detection limit.

The hazardous material collecting material of the present invention is a lot of harmful substances such as chromium, selenium, arsenic, fluorine, boron, nitrate nitrogen, and phosphorus, which are discarded from the chemical industry, electronics industry, medical facilities, and various research facilities. Regardless of its type, it has an effect that it can be collected quickly and efficiently, and is therefore suitable for collecting harmful substances contained in treated water containing various harmful substances.

Claims (3)

Blaine specific surface area is 3,000 cm ² / g or more, SiO ₂ content is 20% or less, Al ₂ O ₃ content is 8.4% or more , and the total content of Fe ₂ O ₃ and Al ₂ O ₃ Is a steel material slag powder containing 15% or more and a total content of fluorine, boron and sulfur of 2% or less , and containing alkanolamine. Hazardous substance trapping material of claim 1 wherein alkanolamine is characterized in that it comprises a triisopropanolamine. Method of processing sewage and soil, which comprises using a hazardous substance trapping material according to one of claims 1-2.