JP2019001696A - Coal ash-cured substance - Google Patents
Coal ash-cured substance Download PDFInfo
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- JP2019001696A JP2019001696A JP2017120201A JP2017120201A JP2019001696A JP 2019001696 A JP2019001696 A JP 2019001696A JP 2017120201 A JP2017120201 A JP 2017120201A JP 2017120201 A JP2017120201 A JP 2017120201A JP 2019001696 A JP2019001696 A JP 2019001696A
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- coal ash
- chlorine bypass
- bypass dust
- hardened
- mass
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- 239000003245 coal Substances 0.000 title abstract description 9
- 239000000126 substance Substances 0.000 title abstract description 7
- 239000010883 coal ash Substances 0.000 claims abstract description 194
- 239000000460 chlorine Substances 0.000 claims abstract description 118
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 118
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 116
- 239000000428 dust Substances 0.000 claims abstract description 108
- 239000000463 material Substances 0.000 claims abstract description 44
- 239000004568 cement Substances 0.000 claims abstract description 37
- 238000005406 washing Methods 0.000 claims description 94
- 238000010828 elution Methods 0.000 claims description 76
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 60
- 239000011669 selenium Substances 0.000 claims description 33
- 229910052711 selenium Inorganic materials 0.000 claims description 29
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 claims description 28
- 239000010440 gypsum Substances 0.000 claims description 20
- 229910052602 gypsum Inorganic materials 0.000 claims description 20
- 239000003638 chemical reducing agent Substances 0.000 claims description 15
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 12
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 12
- 239000004571 lime Substances 0.000 claims description 12
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 9
- 229910001385 heavy metal Inorganic materials 0.000 abstract description 59
- 239000005447 environmental material Substances 0.000 abstract description 10
- AFHJQYHRLPMKHU-XXWVOBANSA-N Aloin Natural products O=C1c2c(O)cc(CO)cc2[C@H]([C@H]2[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O2)c2c1c(O)ccc2 AFHJQYHRLPMKHU-XXWVOBANSA-N 0.000 abstract 1
- CPUHNROBVJNNPW-UHFFFAOYSA-N aloin A Natural products OC1C(O)C(O)C(CO)OC1OC1C2=CC(CO)=CC(O)=C2C(=O)C2=C(O)C=CC=C21 CPUHNROBVJNNPW-UHFFFAOYSA-N 0.000 abstract 1
- AFHJQYHRLPMKHU-WEZNYRQKSA-N aloin B Chemical compound O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@H]1[C@H]1C2=CC(CO)=CC(O)=C2C(=O)C2=C(O)C=CC=C21 AFHJQYHRLPMKHU-WEZNYRQKSA-N 0.000 abstract 1
- AFHJQYHRLPMKHU-UHFFFAOYSA-N isobarbaloin Natural products OC1C(O)C(O)C(CO)OC1C1C2=CC(CO)=CC(O)=C2C(=O)C2=C(O)C=CC=C21 AFHJQYHRLPMKHU-UHFFFAOYSA-N 0.000 abstract 1
- 238000000034 method Methods 0.000 description 32
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 29
- 229910001653 ettringite Inorganic materials 0.000 description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 16
- 229910052796 boron Inorganic materials 0.000 description 16
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 15
- 239000000292 calcium oxide Substances 0.000 description 15
- 235000012255 calcium oxide Nutrition 0.000 description 15
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 14
- 239000002689 soil Substances 0.000 description 13
- 238000002441 X-ray diffraction Methods 0.000 description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 11
- 239000011575 calcium Substances 0.000 description 11
- 229910052791 calcium Inorganic materials 0.000 description 11
- 230000000694 effects Effects 0.000 description 11
- 229910052731 fluorine Inorganic materials 0.000 description 11
- 239000011737 fluorine Substances 0.000 description 11
- 229910052785 arsenic Inorganic materials 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 9
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 9
- 230000007613 environmental effect Effects 0.000 description 8
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 7
- 239000000920 calcium hydroxide Substances 0.000 description 7
- 235000011116 calcium hydroxide Nutrition 0.000 description 7
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 7
- 150000004683 dihydrates Chemical class 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 229910010413 TiO 2 Inorganic materials 0.000 description 6
- 239000002956 ash Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000011651 chromium Substances 0.000 description 5
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000006703 hydration reaction Methods 0.000 description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 5
- 229910052863 mullite Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000010453 quartz Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000001629 suppression Effects 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 239000003112 inhibitor Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000010998 test method Methods 0.000 description 4
- 208000005156 Dehydration Diseases 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000011400 blast furnace cement Substances 0.000 description 3
- 210000004556 brain Anatomy 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 239000010881 fly ash Substances 0.000 description 3
- -1 hydroxide ions Chemical class 0.000 description 3
- 238000004898 kneading Methods 0.000 description 3
- 239000000395 magnesium oxide Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 238000009614 chemical analysis method Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 150000004677 hydrates Chemical class 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000012085 test solution Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229940043430 calcium compound Drugs 0.000 description 1
- 150000001674 calcium compounds Chemical class 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 1
- JGIATAMCQXIDNZ-UHFFFAOYSA-N calcium sulfide Chemical compound [Ca]=S JGIATAMCQXIDNZ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical group 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 230000003100 immobilizing effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 150000002505 iron Chemical class 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 150000002681 magnesium compounds Chemical class 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- PSZYNBSKGUBXEH-UHFFFAOYSA-N naphthalene-1-sulfonic acid Chemical compound C1=CC=C2C(S(=O)(=O)O)=CC=CC2=C1 PSZYNBSKGUBXEH-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000005077 polysulfide Substances 0.000 description 1
- 229920001021 polysulfide Polymers 0.000 description 1
- 150000008117 polysulfides Polymers 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229940082569 selenite Drugs 0.000 description 1
- MCAHWIHFGHIESP-UHFFFAOYSA-L selenite(2-) Chemical compound [O-][Se]([O-])=O MCAHWIHFGHIESP-UHFFFAOYSA-L 0.000 description 1
- 238000007655 standard test method Methods 0.000 description 1
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical compound NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 235000020681 well water Nutrition 0.000 description 1
- 239000002349 well water Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Processing Of Solid Wastes (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
Description
本発明は、石炭灰硬化物に関する。 The present invention relates to a cured coal ash.
石炭火力発電所から発生する石炭灰は、SiO2やAl2O3を主成分とする鉱物である石英やムライトで主に構成されており、従来、セメント原料やコンクリート混和材、埋戻し材や盛土材などの土木資材、底質改善材、水質浄化材などの環境資材として利用されている。中でも、近年の石炭灰発生量の増加に伴い、石炭灰を大量に有効利用が可能であると見込まれる土木資材や環境資材への利用が有望視されている。しかし、石炭灰は石炭由来の重金属類を含んでおり、石炭灰から土壌環境基準を超過する重金属類が溶出することが報告されている。したがって、石炭灰を土木資材あるいは環境資材に有効利用するためには、石炭灰に含まれる重金属類の溶出を抑制する必要がある。 Coal ash generated from coal-fired power plants is mainly composed of quartz and mullite, which are minerals mainly composed of SiO 2 and Al 2 O 3. Conventionally, cement raw materials, concrete admixtures, backfill materials, It is used as environmental materials such as civil engineering materials such as embankment materials, bottom quality improvement materials, and water purification materials. Among them, with the recent increase in the amount of coal ash generated, it is considered promising to use it for civil engineering materials and environmental materials that are expected to be able to effectively use a large amount of coal ash. However, coal ash contains coal-derived heavy metals, and it has been reported that heavy metals exceeding soil environmental standards are eluted from coal ash. Therefore, in order to effectively use coal ash for civil engineering materials or environmental materials, it is necessary to suppress elution of heavy metals contained in coal ash.
石炭灰中の重金属類の溶出を抑制する方法として、特許文献1には石炭灰にセメントと還元剤と消石灰とを添加して硬化させる方法が開示されている。特許文献2には、石炭灰に還元剤とセメント、石灰、石膏等を添加して造粒する方法が開示されている。 As a method for suppressing elution of heavy metals in coal ash, Patent Document 1 discloses a method in which cement ash, a reducing agent, and slaked lime are added to coal ash and hardened. Patent Document 2 discloses a method of granulating by adding a reducing agent and cement, lime, gypsum and the like to coal ash.
他方、セメント工場では近年、高塩素含有廃棄物のセメント原燃料化が拡大してきており,セメントキルン内の塩素を除去するために設置されている塩素バイパス設備から発生する塩素バイパスダストの発生量が増加している。塩素バイパスダストは従来、水洗処理して塩素等を除去した水洗残渣をセメントに添加する方法やセメント系固化材に添加する方法で処理されてきたが、発生量の増加に伴い新たな処理方法や有効利用方法の開発が望まれている。 On the other hand, in cement factories, the use of high chlorine-containing waste as a raw material for cement has been increasing in recent years, and the amount of chlorine bypass dust generated from chlorine bypass facilities installed to remove chlorine in cement kilns has increased. It has increased. Chlorine bypass dust has been treated by the method of adding water washing residue, which has been treated with water to remove chlorine, etc., to cement or the method of adding it to cement-based solidified materials. Development of effective use methods is desired.
特許文献1及び2に開示される方法では、石炭灰と、セメント、石灰及び石膏のうち少なくとも一種以上とを含む材料を用いているため、石炭灰に含まれるフッ素、ホウ素、ヒ素及びセレンといった重金属類の不溶化効果は期待されるが、六価クロムの溶出抑制効果は期待できない。また、六価クロムの溶出を抑制するには高価な還元剤を必要とするため、材料コスト及び製品単価が高くなり、安価な材料が要求される土木資材や環境資材等への有効利用が困難となる。更に、特許文献1のように、還元剤として酸性の鉄塩のみを用いると、石炭灰硬化物のpHが低下し、ホウ素等の溶出抑制効果に悪影響を及ぼすことが懸念される。 In the methods disclosed in Patent Documents 1 and 2, since a material containing coal ash and at least one of cement, lime, and gypsum is used, heavy metals such as fluorine, boron, arsenic, and selenium contained in coal ash are used. The effect of insolubilization of hexavalent chromium is expected, but the effect of inhibiting elution of hexavalent chromium cannot be expected. In addition, since an expensive reducing agent is required to suppress the elution of hexavalent chromium, the material cost and the unit price of the product increase, making it difficult to effectively use it for civil engineering and environmental materials that require inexpensive materials. It becomes. Furthermore, like patent document 1, when only an acidic iron salt is used as a reducing agent, there exists a concern that the pH of coal ash hardened | cured material may fall and it may have a bad influence on the elution suppression effect, such as a boron.
したがって、本発明の課題は、石炭灰中の重金属類の溶出が抑制され、かつ土木資材や環境資材として安価に利用可能な石炭灰硬化物を提供することにある。さらに、近年発生量が増加している塩素バイパスダストの水洗残渣の有効な利用方法を提供することにある。 Therefore, the subject of this invention is providing the coal ash hardened | cured material which can suppress the elution of heavy metals in coal ash, and can be utilized cheaply as a civil engineering material or an environmental material. It is another object of the present invention to provide an effective method for using water residue of chlorine bypass dust, which has been generated in recent years.
本発明者は、塩素バイパスダストの水洗残渣はカルシウム、アルミニウム及び硫酸分を含み、水洗残渣中にエトリンガイトが生成していることを見出した。エトリンガイトはその構造中に含まれる硫酸イオンや水酸化物イオンと重金属アニオンとが置換して重金属類を不溶化すること、表面に重金属類を吸着する性質があり、石炭灰中の重金属類を不溶化し、その溶出を低減できることを見出した。また、塩素バイパスダストの水洗残渣には塩素バイパスダスト中のフリーライム(以下「f.CaO」とも言う。)が水和して生成した水酸化カルシウムが含まれていることを見出した。 The present inventor has found that the washing residue of chlorine bypass dust contains calcium, aluminum and sulfuric acid, and ettringite is produced in the washing residue. Ettringite has the property of insolubilizing heavy metals by replacing sulfate ions and hydroxide ions contained in its structure with heavy metal anions, and adsorbing heavy metals on the surface, insolubilizing heavy metals in coal ash. And found that the elution can be reduced. Moreover, it discovered that the water washing residue of the chlorine bypass dust contained calcium hydroxide produced by hydration of free lime (hereinafter also referred to as “f.CaO”) in the chlorine bypass dust.
本発明者はこれらの知見に基づき、石炭灰と塩素バイパスダストの水洗残渣とセメントとを混合し、水と混練して養生することで得られた石炭灰硬化物は、塩素バイパスダストの水洗残渣無添加の場合に比べ、石炭灰硬化物からの重金属類の溶出量を低減できることを見出し、本発明を完成させるに至った。 Based on these findings, the present inventor mixed coal ash and water washing residue of chlorine bypass dust and cement, and cured coal ash obtained by curing by kneading with water is water washing residue of chlorine bypass dust. It has been found that the amount of elution of heavy metals from the hardened coal ash can be reduced as compared with the case where no additive is added, and the present invention has been completed.
すなわち、本発明は、石炭灰と、塩素バイパスダストの水洗残渣と、セメントとを含む石炭灰硬化物に関する。
本発明は、石炭灰100質量部に対して塩素バイパスダストの水洗残渣を0.1〜20質量部含む石炭灰硬化物に関する。
本発明は、前記塩素バイパスダストの水洗残渣のAl2O3含有量が1〜10質量%である石炭灰硬化物に関する。
本発明は、前記塩素バイパスダストの水洗残渣のSO3含有量が3〜25質量%である石炭灰硬化物に関する。本発明は、前記塩素バイパスダストの水洗残渣のf.CaO含有量が0.1〜45質量%である石炭灰硬化物に関する。本発明は、前記塩素バイパスダストの水洗残渣のセレン溶出量が0.001〜1.0mg/Lである石炭灰硬化物に関する。
本発明は、前記塩素バイパスダストの水洗残渣のセレン含有量が10〜250mg/kgである石炭灰硬化物に関する。
That is, this invention relates to the hardened coal ash containing coal ash, the washing residue of chlorine bypass dust, and cement.
The present invention relates to a cured coal ash containing 0.1 to 20 parts by mass of chlorine bypass dust washing residue with respect to 100 parts by mass of coal ash.
The present invention relates to a cured coal ash having an Al 2 O 3 content of 1 to 10% by mass in the water washing residue of the chlorine bypass dust.
The present invention relates to a cured coal ash having a SO 3 content of 3 to 25% by mass of the water washing residue of the chlorine bypass dust. The present invention relates to f. The present invention relates to a cured coal ash having a CaO content of 0.1 to 45% by mass. This invention relates to the hardened | cured coal ash whose selenium elution amount of the water washing residue of the said chlorine bypass dust is 0.001-1.0 mg / L.
The present invention relates to a hardened coal ash having a selenium content of the water washing residue of the chlorine bypass dust of 10 to 250 mg / kg.
本発明は、石炭灰100質量部に対してセメントを3〜25質量部含む石炭灰硬化物に関する。
本発明は、前記塩素バイパスダストの水洗残渣が塩素バイパスダストを水洗し、脱水したものである石炭灰硬化物に関する。
本発明は、前記石炭灰硬化物が石炭灰100質量部に対して、石膏を1〜15質量部含む石炭硬化物に関する。本発明は、前記石炭灰硬化物が石炭灰100質量部に対して、石灰を1〜15質量部含む石炭灰硬化物に関する。
本発明は、更に減水剤を含む石炭灰硬化物に関する。
The present invention relates to a cured coal ash containing 3 to 25 parts by mass of cement with respect to 100 parts by mass of coal ash.
The present invention relates to a hardened coal ash in which the water washing residue of the chlorine bypass dust is obtained by washing and dewatering the chlorine bypass dust.
The present invention relates to a hardened coal product in which the hardened coal ash contains 1 to 15 parts by weight of gypsum with respect to 100 parts by weight of coal ash. The present invention relates to a cured coal ash containing 1 to 15 parts by mass of lime with respect to 100 parts by mass of the coal ash.
The present invention further relates to a cured coal ash containing a water reducing agent.
本発明の石炭灰硬化物は、石炭灰と、塩素バイパスダストの水洗残渣と、セメントとを含むことにより、重金属類の溶出量が土壌環境基準以下まで低減されているため、土木資材や環境資材として好適に利用することができる。 The hardened coal ash of the present invention contains coal ash, washing residue of chlorine bypass dust, and cement, so that the amount of elution of heavy metals is reduced to below the soil environmental standard, so civil engineering materials and environmental materials Can be suitably used.
また、本発明の石炭灰硬化物は重金属類の溶出抑制材として産業廃棄物である塩素バイパスダストの水洗残渣を利用していることから、従来の市販の重金属類の溶出抑制材を利用した場合に比較して安価な土木資材、あるいは環境資材として利用でき、石炭灰の有効利用量の拡大を図ることができるとともに、塩素バイパスダストの水洗残渣の有効利用を図ることができる。 In addition, since the hardened coal ash of the present invention uses the washing residue of chlorine bypass dust, which is industrial waste, as an elution inhibitor for heavy metals, when using a conventional commercially available heavy metal elution inhibitor Compared to the above, it can be used as an inexpensive civil engineering material or environmental material, so that the effective use of coal ash can be expanded and the washing residue of chlorine bypass dust can be used effectively.
以下、本発明の好適な実施形態について詳細に説明する。なお、本発明は以下の実施形態に限定されるものではない。 Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment.
本発明の石炭灰硬化物は、石炭灰と、塩素バイパスダストの水洗残渣と、セメントとを含むものである。 The hardened coal ash according to the present invention includes coal ash, a residue of washing water of chlorine bypass dust, and cement.
本発明で用いられる石炭灰は、石炭の燃焼によって生成したものであれば特に限定されない。例えば、石炭火力発電所にて微粉炭を燃焼した際に生成する灰であって、電気集塵機等で回収されるフライアッシュや燃焼ボイラから落下採取されるクリンカアッシュ等が挙げられる。特にフライアッシュは、クリンカアッシュに比べて重金属類を多く含有し、その溶出量も多いため、本発明の石炭灰硬化物の原料として好適に有効利用される。 The coal ash used in the present invention is not particularly limited as long as it is generated by coal combustion. Examples include ash produced when pulverized coal is burned at a coal-fired power plant, and fly ash collected by an electric dust collector or the like and clinker ash collected by dropping from a combustion boiler. In particular, fly ash contains a large amount of heavy metals compared to clinker ash and has a large amount of elution, so that it is suitably used effectively as a raw material for the hardened coal ash of the present invention.
石炭灰は、例えばヒ素(As)、セレン(Se)及び六価クロム(Cr6+)等の石炭由来の重金属を含んでいる。重金属以外にも石炭灰はフッ素(F)及びホウ素(B)などの元素を含んでいる。以下の説明においては、これらの重金属及びそれ以外の元素であるフッ素やホウ素を総称して「重金属類」と言う。重金属類は石炭灰から土壌環境基準を超過して溶出する恐れがある。これらの重金属類を不溶化する方法として、セメントを添加して硬化させることで硬化物内に物理的に封じ込めて不溶化する方法や、石炭灰のポゾラン反応やセメントの水和反応により生成する水和物に固定化して不溶化する方法が知られている。フッ素、ヒ素及びセレンはこれらの方法を用いることにより、石炭灰からの溶出を十分に抑制することができる。 Coal ash contains heavy metals derived from coal such as arsenic (As), selenium (Se), and hexavalent chromium (Cr 6+ ). In addition to heavy metals, coal ash contains elements such as fluorine (F) and boron (B). In the following description, these heavy metals and other elements such as fluorine and boron are collectively referred to as “heavy metals”. Heavy metals may leach out of coal ash in excess of soil environmental standards. As a method for insolubilizing these heavy metals, cement is added and cured, and it is physically contained in the cured product and insolubilized, and coal ash pozzolanic reaction and cement hydration reaction. There is known a method of immobilizing and insolubilizing. Fluorine, arsenic and selenium can sufficiently suppress elution from coal ash by using these methods.
一方、ホウ素は、セメントの水和反応や石炭灰のポゾラン反応により生成する水和物によって不溶化されるが、中性化等によりpHが低下すると溶出量が増加しやすい元素である。また六価クロムは、還元剤を添加して三価クロムの形態に還元することで不溶化されるが、三価クロムの形態に還元する方法以外では溶出抑制が難しい元素である。本発明の石炭灰硬化物は、塩素バイパスダストの水洗残渣を含有することにより、重金属類を不溶化するエトリンガイトを生成し、中性化等によりpHが低下しにくく、六価クロムの溶出抑制効果をも有するため、フッ素、ホウ素、ヒ素、セレン及び六価クロムのうち少なくとも一種以上を溶出する石炭灰を好適に有効利用でき、ホウ素及び六価クロムのうち少なくとも一種以上を溶出する石炭灰をより好適に有効利用できる。 On the other hand, boron is insolubilized by a hydrate produced by cement hydration reaction or coal ash pozzolanic reaction, but it is an element whose elution amount tends to increase when pH is lowered due to neutralization or the like. Hexavalent chromium is insolubilized by adding a reducing agent and reducing it to the form of trivalent chromium, but it is difficult to suppress elution except by the method of reducing to the form of trivalent chromium. The hardened coal ash of the present invention contains rind residue of chlorine bypass dust to produce ettringite that insolubilizes heavy metals, and is less susceptible to pH reduction due to neutralization, etc., and has an effect of suppressing elution of hexavalent chromium. Therefore, coal ash eluting at least one or more of fluorine, boron, arsenic, selenium and hexavalent chromium can be effectively used, and coal ash eluting at least one or more of boron and hexavalent chromium is more suitable. Can be used effectively.
本発明で用いられる石炭灰のホウ素溶出量は、0.001〜15mg/Lが好ましく、0.001〜10mg/Lがより好ましく、0.001〜7.5mg/Lが更に好ましい。石炭灰のホウ素溶出量がこれらの範囲であれば、本発明の石炭灰硬化物からのホウ素溶出量を土壌環境基準以下に抑制することができる。 The boron elution amount of coal ash used in the present invention is preferably 0.001 to 15 mg / L, more preferably 0.001 to 10 mg / L, and still more preferably 0.001 to 7.5 mg / L. If the boron elution amount of coal ash is within these ranges, the boron elution amount from the hardened coal ash of the present invention can be suppressed to a soil environment standard or less.
本発明で用いられる石炭灰のヒ素溶出量は、0.0001〜0.5mg/Lが好ましく、0.0001〜0.4mg/Lがより好ましく、0.0001〜0.3mg/Lが更に好ましい。石炭灰のヒ素溶出量がこれらの範囲であれば、本発明の石炭灰硬化物からのヒ素溶出量を土壌環境基準以下に抑制することができる。 The arsenic elution amount of coal ash used in the present invention is preferably 0.0001 to 0.5 mg / L, more preferably 0.0001 to 0.4 mg / L, and still more preferably 0.0001 to 0.3 mg / L. . If the arsenic elution amount of coal ash is within these ranges, the arsenic elution amount from the cured coal ash of the present invention can be suppressed to a soil environment standard or less.
本発明で用いられる石炭灰のセレン溶出量は、0.0001〜0.3mg/Lが好ましく、0.0001〜0.2mg/Lがより好ましく、0.0001〜0.1mg/Lが更に好ましい。セレンは、本発明の石炭灰硬化物に含有される塩素バイパスダストの水洗残渣からも溶出するが、石炭灰のセレン溶出量が前述の範囲であれば、本発明の石炭灰硬化物からのセレン溶出量を土壌環境基準以下に抑制することができる。 The selenium elution amount of coal ash used in the present invention is preferably 0.0001 to 0.3 mg / L, more preferably 0.0001 to 0.2 mg / L, and still more preferably 0.0001 to 0.1 mg / L. . Selenium is also eluted from the washing residue of the chlorine bypass dust contained in the hardened coal ash of the present invention. If the amount of selenium eluted from the coal ash is within the above range, the selenium from the hardened coal ash of the present invention The amount of elution can be suppressed below the soil environmental standard.
本発明で用いられる石炭灰の六価クロム溶出量は、0.001〜0.3mg/Lが好ましく、0.001〜0.2mg/Lがより好ましく、0.001〜0.1mg/Lが更に好ましい。石炭灰の六価クロム溶出量がこれらの範囲であれば、本発明の石炭灰硬化物からの六価クロム溶出量を土壌環境基準以下に抑制することができる。 The hexavalent chromium elution amount of coal ash used in the present invention is preferably 0.001 to 0.3 mg / L, more preferably 0.001 to 0.2 mg / L, and 0.001 to 0.1 mg / L. Further preferred. If the elution amount of hexavalent chromium in the coal ash is within these ranges, the elution amount of hexavalent chromium from the hardened coal ash of the present invention can be suppressed below the soil environmental standard.
本発明で用いられる石炭灰のフッ素溶出量は、0.001〜15mg/Lが好ましく、0.001〜12.5mg/Lがより好ましく、0.001〜10mg/Lが更に好ましい。石炭灰のフッ素溶出量がこれらの範囲であれば、本発明の石炭灰硬化物からのフッ素溶出量を土壌環境基準以下に抑制することができる。 0.001-15 mg / L is preferable, as for the fluorine elution amount of coal ash used by this invention, 0.001-12.5 mg / L is more preferable, and 0.001-10 mg / L is still more preferable. If the fluorine elution amount of coal ash is within these ranges, the fluorine elution amount from the hardened coal ash of the present invention can be suppressed to a soil environment standard or less.
石炭灰からのホウ素溶出量、ヒ素溶出量、セレン溶出量、六価クロム溶出量及びフッ素溶出量は、後述する実施例に記載の方法によって測定される。 The boron elution amount, the arsenic elution amount, the selenium elution amount, the hexavalent chromium elution amount and the fluorine elution amount from coal ash are measured by the methods described in Examples described later.
塩素バイパスダストとは、セメント製造工程において塩素含有量の多い原燃料を使用した際に、セメント工場設備のセメントキルン内に生じる塩素分を含む排ガスの一部を塩素バイパス設備により抽気し、その抽気した排ガスを冷却した際に発生するダスト(粉状物)のことである。塩素バイパスダストは、塩化カリウムなどの塩化物、f.CaOなどのセメント原料の仮焼物や、塩素、アルミニウム、硫酸分等により構成される。 Chlorine bypass dust means that when raw fuel with a high chlorine content is used in the cement manufacturing process, part of the exhaust gas containing chlorine contained in the cement kiln of the cement factory equipment is extracted by the chlorine bypass equipment. It is dust (powder) generated when the exhaust gas is cooled. Chlorine bypass dust is a chloride such as potassium chloride, f. It is composed of a calcined material of cement raw material such as CaO, chlorine, aluminum, sulfuric acid and the like.
本発明で用いられる塩素バイパスダストの水洗残渣は、上述の塩素バイパスダストを水洗処理した際に発生する不溶残渣のことである。水洗処理とは、水洗し、脱水する処理のことを指す。 The washing residue of chlorine bypass dust used in the present invention is an insoluble residue generated when the above-described chlorine bypass dust is washed with water. The water washing treatment refers to a treatment of washing with water and dehydrating.
塩素バイパスダストには、塩素、カルシウムなどの複数の成分が含まれていることに起因して、塩素バイパスダストを水洗後濾過することによって得られる塩素バイパスダストの水洗残渣は、塩素バイパスダストと同様に、塩化物、カルシウム、アルミニウム、硫酸分などを含んでいる。一方、塩素バイパスダストの水洗残渣は、水洗処理を経ていることに起因して、水洗前の塩素バイパスダストに比べてセレン溶出量や塩素量が低減されている。これらの理由から、本発明において、塩素バイパスダストの水洗残渣は重金属類の溶出抑制材として石炭灰硬化物に好適に含有される。 Due to the fact that chlorine bypass dust contains a plurality of components such as chlorine and calcium, the washing residue of the chlorine bypass dust obtained by filtering the chlorine bypass dust after washing with water is the same as the chlorine bypass dust. In addition, it contains chloride, calcium, aluminum and sulfuric acid. On the other hand, the washing residue of chlorine bypass dust has a reduced amount of selenium and chlorine as compared with the chlorine bypass dust before washing due to the fact that it has undergone a washing treatment. For these reasons, in the present invention, the washing residue of chlorine bypass dust is suitably contained in the hardened coal ash as a heavy metal elution inhibitor.
塩素バイパスダストの水洗残渣が重金属類の溶出抑制材としての効果を有する理由は明らかではないが、本発明者は以下(1)〜(4)のように推測している。 Although the reason why the washing residue of chlorine bypass dust has an effect as an elution inhibitor of heavy metals is not clear, the present inventor presumes as follows (1) to (4).
(1)塩素バイパスダストの水洗残渣にはカルシウム、アルミニウム、硫酸分を含むことに起因して、塩素バイパスダストの水洗残渣中のカルシウム及びアルミニウムと、硫酸分とが水和して重金属類を取込むエトリンガイト(3CaO・Al2O3・3CaSO4・32H2O)が生成する。塩素バイパスダストの水洗残渣を添加することによって、石炭灰硬化物中にエトリンガイトを良好に生成させることができ、ホウ素やその他重金属類が石炭灰硬化物中に不溶化される効果が高まるものと考えられる。
(2)塩素バイパスダストの水洗残渣に含まれるf.CaO(水酸化カルシウム)が石炭灰のポゾラン反応及び/又はセメントの水和反応を促進することによって石炭灰硬化物の硬化が促進され、石炭灰に含まれる重金属類が硬化物内に物理的に封じ込められる効果が向上するとともに、重金属類を固定化する水和物の生成量が増加することで溶出抑制効果が向上するものと考えられる。また、水酸化カルシウムは石炭灰硬化物のpHを上昇させ、pHの高い領域で不溶化されやすいホウ素の溶出抑制効果が向上するものと考えられる。
(1) Due to the fact that the washing residue of chlorine bypass dust contains calcium, aluminum, and sulfuric acid, the calcium and aluminum in the washing residue of chlorine bypass dust and the sulfuric acid content are hydrated to remove heavy metals. writing ettringite (3CaO · Al 2 O 3 · 3CaSO 4 · 32H 2 O) is produced. It is considered that ettringite can be generated satisfactorily in the hardened coal ash by adding the washing residue of chlorine bypass dust, and the effect of insolubilizing boron and other heavy metals in the hardened coal ash is expected to increase. .
(2) f. Contained in washing residue of chlorine bypass dust. CaO (calcium hydroxide) accelerates the pozzolanic reaction of coal ash and / or the hydration reaction of cement, thereby promoting the hardening of the hardened coal ash, and the heavy metals contained in the coal ash are physically contained in the hardened material. It is considered that the effect of containment is improved and the elution suppression effect is improved by increasing the amount of hydrates that immobilize heavy metals. Further, it is considered that calcium hydroxide increases the pH of the hardened coal ash and improves the boron elution suppression effect that is easily insolubilized in a high pH region.
(3)本発明者は検討を進めたところ、前記セメントキルンの窯尻近傍から抽気された排ガスのガス雰囲気は酸素濃度が低く、還元性物質が生成しやすいことに起因して、塩素バイパスダストおよびその水洗残渣中に還元性物質が含まれていることが判った。この還元性物質によって、六価クロムが三価クロムに還元されることにより溶出抑制効果が向上するものと考えられる。なお、塩素バイパスダストには、六価のセレン酸と四価の亜セレン酸が共存していることを本発明者は実測しており、塩素バイパスダストが還元雰囲気に曝されていることを本発明者は確認している。
(4)塩素バイパスダストの水洗残渣は、TiO2やMnO等の多価金属を微量成分として含有することから、重金属類がこれらの多価金属に収着しやすいことによって、石炭灰硬化物からの重金属類の溶出が抑制されるものと考えられる。
(3) As a result of investigations by the inventor, chlorine bypass dust is caused by the fact that the gas atmosphere of the exhaust gas extracted from the vicinity of the kiln bottom of the cement kiln has a low oxygen concentration and is likely to generate reducing substances. It was also found that reducing substances were contained in the washing residue. It is considered that this reducing substance improves the elution suppression effect by reducing hexavalent chromium to trivalent chromium. In addition, the present inventors have actually measured that hexavalent selenate and tetravalent selenite coexist in the chlorine bypass dust, and it has been confirmed that the chlorine bypass dust is exposed to a reducing atmosphere. The inventor has confirmed.
(4) Since the water washing residue of chlorine bypass dust contains polyvalent metals such as TiO 2 and MnO as trace components, heavy metals easily sorb on these polyvalent metals, resulting in a coal ash cured product. It is thought that elution of heavy metals is suppressed.
塩素バイパスダストの水洗残渣を製造する際の、水洗に用いられる水の種類は特に制限はなく、水道水、井戸水、イオン交換水、雨水などを使用することができる。水洗に用いられる水の量は、塩素バイパスダストに対して質量比で1〜20倍量が好ましく、3〜15倍量がより好ましく、5〜10倍量が更に好ましい。水の使用量が前記範囲であれば、石炭灰硬化物からの重金属類の溶出がより低減されるため好ましい。 There is no particular limitation on the type of water used for washing when producing the washing residue of chlorine bypass dust, and tap water, well water, ion-exchanged water, rain water, and the like can be used. The amount of water used for water washing is preferably 1 to 20 times, more preferably 3 to 15 times, and still more preferably 5 to 10 times the mass of chlorine bypass dust. If the usage-amount of water is the said range, since elution of heavy metals from a coal ash hardened | cured material is reduced more, it is preferable.
塩素バイパスダストの水洗残渣を製造する際の水洗方法は特に制限されず、例えば塩素バイパスダストと水とをブレンダ等の公知の装置を用いて撹拌し、その混合物を濾過等の脱水処理することができる。また脱水処理後の塩素バイパスダストの水洗残渣は、乾燥させて粉末状にしたものを用いてもよく、脱水処理後の湿潤状態のものを用いてもよい。 There is no particular restriction on the washing method when producing the washing residue of chlorine bypass dust, and for example, the chlorine bypass dust and water can be stirred using a known apparatus such as a blender, and the mixture can be subjected to dehydration treatment such as filtration. it can. Moreover, the water-washing residue of the chlorine bypass dust after the dehydration treatment may be dried and powdered, or may be in a wet state after the dehydration treatment.
本発明の石炭灰硬化物に含有される塩素バイパスダストの水洗残渣の量は、石炭灰100質量部に対して0.1〜20質量部が好ましく、0.5〜15質量部がより好ましく、1〜10質量部が更に好ましい。塩素バイパスダストの水洗残渣の含有量を前記範囲とすることで、石炭灰に含まれる重金属類の溶出抑制効果が得られ、石炭灰硬化物からのセレン溶出量を土壌環境基準以下とすることができる。 0.1-20 mass parts is preferable with respect to 100 mass parts of coal ash, and, as for the quantity of the washing residue of the chlorine bypass dust contained in the hardened coal ash of this invention, 0.5-15 mass parts is more preferable, 1-10 mass parts is still more preferable. By making the content of the washing residue of the chlorine bypass dust within the above range, an effect of suppressing elution of heavy metals contained in coal ash can be obtained, and the amount of selenium eluted from the coal ash cured product can be made to be below the soil environment standard. it can.
塩素バイパスダストの水洗残渣のAl2O3含有量は、1〜10質量%が好ましく、2〜8質量%がより好ましく、3〜6質量%が更に好ましい。Al2O3含有量が前記範囲であれば、重金属類を固定化するエトリンガイトの生成により、石炭灰硬化物からの重金属類の溶出量が低減されるため好ましい。塩素バイパスダストの水洗残渣のAl2O3含有量は、後述する実施例に記載の方法によって測定される。 The content of Al 2 O 3 in the washing residue of chlorine bypass dust is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and still more preferably 3 to 6% by mass. If the Al 2 O 3 content is in the above range, the production of ettringite that immobilizes heavy metals reduces the elution amount of heavy metals from the hardened coal ash, which is preferable. The Al 2 O 3 content of the washing residue of chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のSO3含有量は、3〜25質量%が好ましく、4〜20質量%がより好ましく、5〜15質量%が更に好ましい。SO3含有量が前記範囲であれば、塩素バイパスダストの水洗残渣、石炭灰およびセメントに含まれるカルシウム、アルミニウム等と反応して重金属類を固定化するエトリンガイトを生成することにより、石炭灰硬化物からの重金属類の溶出量が低減されるため好ましい。塩素バイパスダストの水洗残渣のSO3含有量は、後述する実施例に記載の方法によって測定される。 SO 3 content of the washing residue chlorine bypass dust is preferably 3 to 25 wt%, more preferably from 4 to 20 mass%, still more preferably 5 to 15 wt%. If the SO 3 content is in the above range, the coal ash hardened product is produced by generating ettringite that immobilizes heavy metals by reacting with water washing residue of chlorine bypass dust, calcium ash and calcium contained in cement, aluminum, and the like. Since the elution amount of heavy metals from is reduced, it is preferable. The SO 3 content of the washing residue of chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のf.CaO含有量は、0.1〜45質量%が好ましく、5〜40質量%がより好ましく、10〜35質量%が更に好ましい。f.CaO含有量が前記範囲であることによって、重金属類を固定化するエトリンガイトを十分に生成することができ、また、石炭灰のポゾラン反応及び/又はセメントの水和反応の促進及び/又は石炭灰硬化物のpHが上昇することによる石炭灰硬化物からの重金属類の溶出抑制効果を効果的に発揮できる。塩素バイパスダストの水洗残渣のf.CaO含有量は、後述する実施例に記載の方法によって測定される。 Chlorine bypass dust washing residue f. The CaO content is preferably 0.1 to 45% by mass, more preferably 5 to 40% by mass, and still more preferably 10 to 35% by mass. f. When the CaO content is within the above range, ettringite that immobilizes heavy metals can be sufficiently generated, and the pozzolanic reaction of coal ash and / or the hydration reaction of cement and / or the hardening of coal ash The elution inhibitory effect of heavy metals from the hardened coal ash due to the increase in the pH of the product can be effectively exhibited. Chlorine bypass dust washing residue f. The CaO content is measured by the method described in Examples described later.
本発明の石炭灰硬化物に含有される塩素バイパスダストの水洗残渣のセレン溶出量は、0.001〜1.0mg/Lが好ましく、0.001〜0.75mg/Lがより好ましく、0.001〜0.5mg/Lが更に好ましい。塩素バイパスダストの水洗残渣のセレン溶出量が前記範囲にあることによって、石炭灰硬化物からのセレン溶出量を土壌環境基準以下とすることができる。塩素バイパスダストの水洗残渣のセレン溶出量は、後述する実施例に記載の方法によって測定される。 0.001 to 1.0 mg / L is preferable, 0.001 to 0.75 mg / L is more preferable, and 0.001 to 0.75 mg / L is more preferable as the selenium elution amount of the chlorine bypass dust washing residue contained in the hardened coal ash of the present invention. 001 to 0.5 mg / L is more preferable. When the selenium elution amount of the water washing residue of the chlorine bypass dust is within the above range, the selenium elution amount from the hardened coal ash can be made to be the soil environment standard or less. The amount of selenium eluted from the water washing residue of chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のセレン含有量は、10〜250mg/kgが好ましく、10〜200mg/kgがより好ましく、10〜150mg/kgが更に好ましい。塩素バイパスダストの水洗残渣のセレン含有量が前記範囲であることによって、塩素バイパスダストの水洗残渣のセレン溶出量が上述の溶出範囲を超えることなく、かつ石炭灰硬化物からのセレン溶出量を土壌環境基準以下とすることができる。塩素バイパスダストの水洗残渣のセレン含有量は、後述する実施例に記載の方法によって測定される。 The selenium content of the water washing residue of the chlorine bypass dust is preferably 10 to 250 mg / kg, more preferably 10 to 200 mg / kg, still more preferably 10 to 150 mg / kg. When the selenium content of the washing residue of the chlorine bypass dust is in the above range, the selenium elution amount of the washing residue of the chlorine bypass dust does not exceed the above elution range, and the selenium elution amount from the coal ash cured product is reduced to the soil. Can be below environmental standards. The selenium content of the water washing residue of the chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のTiO2含有量は、0.05〜0.5質量%が好ましく、0.1〜0.4質量%がより好ましく、0.15〜0.35質量%が更に好ましい。TiO2含有量が前記範囲であれば、石炭灰硬化物からの重金属類の溶出がより低減されるため好ましい。塩素バイパスダストの水洗残渣のTiO2含有量は、後述する実施例に記載の方法によって測定される。 The content of TiO 2 in the water washing residue of the chlorine bypass dust is preferably 0.05 to 0.5% by mass, more preferably 0.1 to 0.4% by mass, and still more preferably 0.15 to 0.35% by mass. . If the content of TiO 2 is the range is preferable because elution of heavy metals from coal ash cured product is further reduced. The TiO 2 content of the washing residue of chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のMnO含有量は、0.001〜0.2質量%が好ましく、0.005〜0.15質量%がより好ましく、0.01〜0.1質量%が更に好ましい。MnO含有量が前記範囲であれば、石炭灰硬化物からの重金属類の溶出がより低減されるため好ましい。塩素バイパスダストの水洗残渣のMnO含有量は、後述する実施例に記載の方法によって測定される。 0.001-0.2 mass% is preferable, as for the MnO content of the water washing residue of chlorine bypass dust, 0.005-0.15 mass% is more preferable, and 0.01-0.1 mass% is still more preferable. If MnO content is the said range, since elution of heavy metals from coal ash hardened | cured material is reduced more, it is preferable. The MnO content of the water washing residue of the chlorine bypass dust is measured by the method described in the examples described later.
塩素バイパスダストの水洗残渣のブレーン比表面積は、2000〜20000cm2/gが好ましく、3000〜15000cm2/gがより好ましく、4000〜10000cm2/gが更に好ましい。ブレーン比表面積が前記範囲であれば、塩素バイパスダストの水洗残渣は石炭灰硬化物中で十分に反応することができ、石炭灰硬化物からの重金属類の溶出がより低減されるため好ましい。ブレーン比表面積の測定方法は後述する実施例において詳述する。 Blaine specific surface area of the washing residue chlorine bypass dust is preferably 2000~20000cm 2 / g, more preferably 3000~15000cm 2 / g, more preferably 4000~10000cm 2 / g. If the Blaine specific surface area is in the above-mentioned range, the water washing residue of chlorine bypass dust can react sufficiently in the hardened coal ash, and the elution of heavy metals from the hardened coal ash is further reduced, which is preferable. The method for measuring the specific surface area of branes will be described in detail in the examples described later.
本発明に用いられるセメントは、特に限定されるものではなく、普通ポルトランドセメント、高炉セメント、早強セメント等が挙げられる。塩素バイパスダストの水洗残渣中の硫酸分やカルシウムと反応し、エトリンガイトを多く生成させる観点から、高炉スラグを含有し、アルミニウムを多く含む高炉セメントを用いることが好ましい。石炭灰硬化物に含有されるセメント量は、石炭灰100質量部に対して3〜25質量部が好ましく、5〜20質量部がより好ましく、10〜15質量部が更に好ましい。石炭灰硬化物に含有されるセメント量が前記範囲にあることによって、材料コストを低減しつつ、石炭灰硬化物からの重金属類の溶出抑制効果を十分に得ることができる。 The cement used in the present invention is not particularly limited, and examples thereof include ordinary Portland cement, blast furnace cement, and early strength cement. From the viewpoint of reacting with sulfuric acid or calcium in the water washing residue of chlorine bypass dust and generating a large amount of ettringite, it is preferable to use a blast furnace cement containing blast furnace slag and containing a lot of aluminum. 3-25 mass parts is preferable with respect to 100 mass parts of coal ash, and, as for the amount of cement contained in hardened coal ash, 5-20 mass parts is more preferable, and 10-15 mass parts is still more preferable. When the amount of cement contained in the hardened coal ash is in the above range, it is possible to sufficiently obtain the effect of suppressing elution of heavy metals from the hardened coal ash while reducing the material cost.
本発明の石炭灰硬化物には、更に石膏が含まれていてもよい。本発明で使用される石膏としては、例えば二水石膏、半水石膏、無水石膏が挙げられる。石炭灰硬化物に含有される石膏の量は、石炭灰100質量部に対して二水石膏換算で1〜15質量部が好ましく、3〜12.5質量部がより好ましく、5〜10質量部が更に好ましい。二水石膏換算の石膏量が前記範囲にあることによって、材料コストを低減しつつ、石炭灰硬化物からの重金属類の溶出抑制効果を十分に得ることができる。 The hardened coal ash of the present invention may further contain gypsum. Examples of the gypsum used in the present invention include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. The amount of gypsum contained in the hardened coal ash is preferably 1 to 15 parts by weight, more preferably 3 to 12.5 parts by weight, and more preferably 5 to 10 parts by weight with respect to 100 parts by weight of coal ash. Is more preferable. When the amount of gypsum converted to dihydrate gypsum is within the above range, the effect of suppressing the elution of heavy metals from the hardened coal ash can be sufficiently obtained while reducing the material cost.
本発明の石炭灰硬化物には、更に石灰が含まれていてもよい。本発明で使用される石灰としては、消石灰及び生石灰が挙げられる。石炭灰硬化物に含有される石灰の量は、消石灰を例にすると、石炭灰100質量部に対して1〜15質量部が好ましく、3〜12.5質量部がより好ましく、5〜10質量部が更に好ましい。また、石炭灰硬化物に含有される石灰の量は、生石灰を例にすると、石炭灰100質量部に対して1〜11.5質量部が好ましく、2〜9.5質量部がより好ましく、3〜7.5質量部が更に好ましい。いずれの石灰を用いた場合でも、石灰の量が前記範囲にあることによって、材料コストを低減しつつ、石炭灰硬化物からの重金属類の溶出抑制効果を十分に得ることができる。 The hardened coal ash of the present invention may further contain lime. Examples of lime used in the present invention include slaked lime and quicklime. When slaked lime is taken as an example, the amount of lime contained in the hardened coal ash is preferably 1 to 15 parts by weight, more preferably 3 to 12.5 parts by weight, and more preferably 5 to 10 parts by weight with respect to 100 parts by weight of coal ash. Part is more preferred. The amount of lime contained in the hardened coal ash is preferably 1 to 11.5 parts by weight, more preferably 2 to 9.5 parts by weight, based on quick lime as an example. 3-7.5 mass parts is still more preferable. Even when any lime is used, the amount of lime in the above range can sufficiently obtain the effect of suppressing elution of heavy metals from the hardened coal ash while reducing the material cost.
本発明の石炭灰硬化物には、更に減水剤が含まれていてもよい。本発明で使用される減水剤としては、ポリカルボン酸系、リグニン系、ナフタレンスルホン酸系、アミノスルホン酸系の減水剤等が挙げられる。石炭灰硬化物製造時の水/粉体比を低減し、より緻密な構造で重金属類が溶出しにくい石炭灰硬化物を得る観点から、ポリカルボン酸系減水剤を使用することが好ましい。石炭灰硬化物に含有される減水剤の量は、石炭灰100質量部に対して0.1〜10質量部が好ましく、1〜5質量部がより好ましい。 The hardened coal ash of the present invention may further contain a water reducing agent. Examples of the water reducing agent used in the present invention include polycarboxylic acid-based, lignin-based, naphthalenesulfonic acid-based, and aminosulfonic acid-based water reducing agents. From the viewpoint of reducing the water / powder ratio at the time of producing the coal ash cured product and obtaining a coal ash cured product having a denser structure and preventing heavy metals from eluting, it is preferable to use a polycarboxylic acid-based water reducing agent. 0.1-10 mass parts is preferable with respect to 100 mass parts of coal ash, and, as for the quantity of the water reducing agent contained in hardened coal ash, 1-5 mass parts is more preferable.
また、本発明の石炭灰硬化物は、本発明の効果を阻害しない範囲で塩化第一鉄、硫酸第一鉄、多硫化カルシウム、硫化カルシウムなどの還元剤、高炉スラグ、炭酸カルシウムなどのカルシウム化合物、酸化マグネシウム、水酸化マグネシウム、ドロマイトなどのマグネシウム化合物等を更に含んでいてもよい。 In addition, the hardened coal ash of the present invention is a reducing compound such as ferrous chloride, ferrous sulfate, calcium polysulfide, and calcium sulfide as long as the effects of the present invention are not impaired, and calcium compounds such as blast furnace slag and calcium carbonate. Further, magnesium compounds such as magnesium oxide, magnesium hydroxide and dolomite may be further contained.
本発明の石炭灰硬化物の粒度は、石炭灰硬化物からの重金属類の溶出を抑制する観点からは粒度が大きい方が好ましいが、その用途に応じて適宜調製されることが好ましい。例えば、土木資材として利用する場合、石炭灰硬化物の粒度は0.01〜100mmであることが好ましく、0.075〜75mmであることがより好ましく、2〜40mmであることが更に好ましい。 The particle size of the hardened coal ash according to the present invention is preferably larger from the viewpoint of suppressing elution of heavy metals from the hardened coal ash, but is preferably prepared as appropriate according to the application. For example, when used as a civil engineering material, the particle size of the hardened coal ash is preferably 0.01 to 100 mm, more preferably 0.075 to 75 mm, and still more preferably 2 to 40 mm.
本発明の石炭灰硬化物の製造方法は、特に限定されることはなく、例えば石炭灰、塩素バイパスダストの水洗残渣及びセメントと、必要に応じて石膏、石灰及び/又は減水剤と、水とを混練し、得られた混練物を養生して硬化させる方法や、混練物をさらに造粒して得られた造粒物を養生して硬化させる方法などの公知の方法を適用することができる。石炭灰硬化物からの重金属類の溶出を抑制する観点からは、混練物がスラリー状になる量の水を添加して混練した後、得られたスラリー状の混練物を養生して硬化させる方法が好ましい。前記方法で得られた石炭灰硬化物が前記粒度範囲に適合しない場合は、更に分級機や破砕機等を用いて粒度を調整することができる。 The method for producing the hardened coal ash according to the present invention is not particularly limited. For example, coal ash, washing residue and cement of chlorine bypass dust, gypsum, lime and / or water reducing agent, and water as necessary. Known methods such as a method of curing and curing the obtained kneaded product, and a method of curing and curing the granulated product obtained by further granulating the kneaded product can be applied. . From the viewpoint of suppressing the elution of heavy metals from the hardened coal ash, a method of curing and curing the obtained slurry-like kneaded material after adding and kneading an amount of water in which the kneaded material becomes a slurry. Is preferred. When the hardened coal ash obtained by the above method does not conform to the particle size range, the particle size can be further adjusted using a classifier or a crusher.
前記製造方法で得られた石炭灰硬化物中に、エトリンガイトが存在していることは、石炭灰硬化物をX線回折測定することによって確認することができる。例えば、石炭灰硬化物のX線回折測定の条件を、X線回折装置としてD2PHASER(BRUKER社製、X線源:CuKα線)を用いて、測定範囲:2θ=5〜25°、スキャンスピード:0.5秒/ステップ、ステップ幅:0.02°としたときに、2θ=8°以上10°以下の範囲にエトリンガイトの(010)面に由来するピークが観察された場合、及び/又は2θ=15°以上17°以下の範囲にエトリンガイトの(110)面に由来するピークが観察された場合、石炭灰硬化物にエトリンガイトが存在しているといえる。石炭灰硬化物中にエトリンガイトが存在していることによって、石炭灰硬化物からの重金属類の溶出抑制効果をより高めることができる。 The presence of ettringite in the cured coal ash obtained by the above production method can be confirmed by X-ray diffraction measurement of the cured coal ash. For example, the conditions for X-ray diffraction measurement of the hardened coal ash are as follows. Using D2PHASER (manufactured by BRUKER, X-ray source: CuKα ray) as an X-ray diffractometer, measurement range: 2θ = 5 to 25 °, scan speed: When a peak derived from the (010) plane of ettringite is observed in the range of 2θ = 8 ° or more and 10 ° or less when 0.5 second / step and step width: 0.02 °, and / or 2θ When a peak derived from the (110) plane of ettringite is observed in the range of 15 ° to 17 °, it can be said that ettringite is present in the hardened coal ash. By the presence of ettringite in the hardened coal ash, the elution suppression effect of heavy metals from the hardened coal ash can be further enhanced.
前記製造方法で得られた石炭灰硬化物中に、ムライトが存在していることは、エトリンガイトの存在確認の場合と同様に、石炭灰硬化物をX線回折測定することによって確認することができる。例えば、石炭灰硬化物のX線回折測定の条件を上述と同一の条件としたときに、2θ=15°以上17°以下の範囲にムライトの(110)面に由来するピークが観察された場合、石炭灰硬化物中にムライトが存在しているといえる。 The presence of mullite in the hardened coal ash obtained by the above production method can be confirmed by X-ray diffraction measurement of the hardened coal ash as in the case of confirming the presence of ettringite. . For example, when the X-ray diffraction measurement conditions of the hardened coal ash are the same as those described above, a peak derived from the (110) plane of mullite is observed in the range of 2θ = 15 ° to 17 °. It can be said that mullite is present in the hardened coal ash.
同様に、前記製造方法で得られた石炭灰硬化物中に、石英が存在していることは、石炭灰硬化物のX線回折測定において、石炭灰硬化物のX線回折測定の条件を上述と同一の条件としたときに、2θ=20°以上22°以下の範囲に石英の(010)面に由来するピークが観察された場合、石炭灰硬化物中に石英が存在しているといえる。 Similarly, the presence of quartz in the hardened coal ash obtained by the above production method indicates that the conditions for the X-ray diffraction measurement of the hardened coal ash in the X-ray diffraction measurement of the hardened coal ash are described above. When a peak derived from the (010) plane of quartz is observed in the range of 2θ = 20 ° to 22 ° in the same condition as above, it can be said that quartz is present in the hardened coal ash. .
前記製造方法で得られた石炭灰硬化物中に石膏を含む場合は、上述と同様に石炭灰硬化物をX線回折測定することによって石膏の存在を確認することができる。例えば、石炭灰硬化物中に二水石膏を含む場合、石炭灰硬化物のX線回折測定において、石炭灰硬化物のX線回折測定の条件を上述と同一の条件としたときに、2θ=11°以上13°以下の範囲に二水石膏の(020)面に由来するピークが観察された場合、石炭灰硬化物中に二水石膏が存在しているといえる。 When gypsum is included in the cured coal ash obtained by the production method, the presence of gypsum can be confirmed by X-ray diffraction measurement of the cured coal ash as described above. For example, when dihydrate gypsum is included in the coal ash cured product, in the X-ray diffraction measurement of the coal ash cured product, when the condition of the X-ray diffraction measurement of the coal ash cured product is the same as described above, 2θ = When a peak derived from the (020) plane of dihydrate gypsum is observed in the range of 11 ° to 13 °, it can be said that dihydrate gypsum is present in the hardened coal ash.
本発明の石炭灰硬化物は重金属類の溶出が環境基準以下に抑制されていることから、土木資材や環境資材として好適に利用することができる。土木資材の用途例としては、埋戻し材、路盤材、盛土材、埋立材、地盤改良材、裏込め材等が挙げられる。環境資材の用途例としては、底質改善材や水質浄化材等が挙げられる。 Since the elution of heavy metals is suppressed below the environmental standard, the hardened coal ash of the present invention can be suitably used as a civil engineering material or an environmental material. Examples of uses of civil engineering materials include backfill materials, roadbed materials, embankment materials, landfill materials, ground improvement materials, backfill materials and the like. Examples of uses of environmental materials include bottom quality improving materials and water purification materials.
以下に、本発明について実施例及び比較例を挙げて詳細に説明する。なお、本発明はこれらの例によって限定されるものではない。 Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. Note that the present invention is not limited to these examples.
1.石炭灰
石炭灰には、石炭火力発電所の電気集塵機で回収されたフライアッシュを使用した。使用した石炭灰の重金属類溶出量を表1に示す。表1に示す分析値は、平成3年環境庁告示第46号付表に準拠して溶出試験を行って得た検液の重金属類濃度を、JIS K 0012「工場排水試験方法」に準拠して測定した値である。なお、以下の土壌環境基準は、平成3年環境庁告示第46号別表の記載を用いた。
1. Coal ash For the coal ash, fly ash recovered with an electric dust collector at a coal-fired power plant was used. Table 1 shows the amount of heavy metals eluted from the coal ash used. Analytical values shown in Table 1 are based on JIS K 0012 “Factory drainage test method” for the concentration of heavy metals in the test solution obtained from the elution test in accordance with Appendix No. 46 of the 1991 Environment Agency Notification. It is a measured value. In addition, the following soil environment standard used the description of the 1991 Environment Agency notification 46 separate table.
2.塩素バイパスダストの水洗残渣
使用した塩素バイパスダストの水洗残渣は、塩素バイパスダストに対して質量比で10倍量の水を添加し、30分間攪拌した後、ブフナー漏斗及び濾紙(アドバンテック社製、No.5A)を用いて吸引濾過し、濾紙上に残った残渣を40℃、24時間乾燥することで得た。使用した塩素バイパスダストの水洗残渣及び水洗前の塩素バイパスダストの性状を、以下の表2に示す。表2に示す分析値は以下の方法(i)〜(v)で測定した値である。
2. Washing residue of chlorine bypass dust Washing residue of chlorine bypass dust used was added 10 times the amount of water by weight with respect to chlorine bypass dust, stirred for 30 minutes, and then Buchner funnel and filter paper (manufactured by Advantech, No. The residue remaining on the filter paper was dried at 40 ° C. for 24 hours. Table 2 below shows the washing residue of the chlorine bypass dust used and the properties of the chlorine bypass dust before washing. The analysis values shown in Table 2 are values measured by the following methods (i) to (v).
(i)SiO2、Al2O3、Fe2O3、CaO、MgO、SO3、Na2O、K2O、R2O、TiO2、MnO含有量
SiO2、Al2O3、Fe2O3、CaO、MgO、SO3、Na2O、K2O、TiO2、MnO含有量は、JIS M 8853「セラミックス用アルミノけい酸塩質原料の化学分析方法」を参考にして測定した。
R2O含有量は、上記の方法により測定したNa2O及びK2Oの含有量(質量%)から、下記の式(1)により算出した。なお、「0.658」はK2OをNa2Oのモル当量に換算する係数である。
R2O含有量(質量%)=Na2O含有量+(0.658×K2O含有量)・・・(1)
(I) SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, SO 3 , Na 2 O, K 2 O, R 2 O, TiO 2 , MnO content SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, SO 3 , Na 2 O, K 2 O, TiO 2 and MnO content were measured with reference to JIS M 8853 “Chemical analysis method of aluminosilicate materials for ceramics”. .
The R 2 O content was calculated from the Na 2 O and K 2 O content (% by mass) measured by the above method according to the following formula (1). “0.658” is a coefficient for converting K 2 O into a molar equivalent of Na 2 O.
R 2 O content (mass%) = Na 2 O content + (0.658 × K 2 O content) (1)
(ii)f.CaO含有量
f.CaO含有量は、セメント協会標準試験方法のJCAS I−01:1997「遊離酸化カルシウムの定量方法」に準拠して測定した。
(iii)Cl、Se含有量
Cl、Se含有量は、JIS R 5202「セメントの化学分析方法」に準拠して測定した。
(iv)Se溶出量
Se溶出量は、平成3年環境庁告示第46号付表に準拠して検液を作製し、その検液のSe濃度をJIS K 0102「工場排水試験方法」に準拠して測定した。
(v)ブレーン比表面積
ブレーン比表面積は、JIS R 5201:1997「セメントの物理試験方法」に従い、ブレーン空気透過装置を用いて測定した。
(Ii) f. CaO content f. The CaO content was measured in accordance with JCAS I-01: 1997 “Method for Quantifying Free Calcium Oxide” of the Cement Association Standard Test Method.
(Iii) Cl and Se contents Cl and Se contents were measured in accordance with JIS R 5202 "Cement chemical analysis method".
(Iv) Se elution amount The Se elution amount was prepared in accordance with the Appendix of Environment Agency Notification No. 46 in 1991, and the Se concentration of the test solution was determined in accordance with JIS K 0102 “Factory drainage test method”. Measured.
(V) Brain specific surface area The brain specific surface area was measured using a brain air permeation apparatus in accordance with JIS R 5201: 1997 “Cement physical test method”.
表2に示すように、塩素バイパスダストの水洗残渣はカルシウム、アルミニウム、硫酸分を含んでいる。また塩素バイパスダストの水洗残渣は、塩素バイパスダストに比べて塩素分、セレンの溶出量及び含有量が低減されていることが判る。 As shown in Table 2, the washing residue of chlorine bypass dust contains calcium, aluminum, and sulfuric acid. It can also be seen that the chlorine washing dust washing residue is reduced in chlorine content, selenium elution amount and content as compared with chlorine bypass dust.
3.石炭灰硬化物の作製
石炭灰、塩素バイパスダストの水洗残渣、高炉セメントB種(宇部三菱セメント社製)、二水石膏(排煙脱硫石膏)及び消石灰(宇部マテリアルズ社製、JIS特号)を混合して混合物を得た後、ポリカルボン酸系減水剤(BASF社製、マスターグレニウムSP8SV)と前記混合物がスラリー化する量の水を添加してホバートミキサー(ホバート・ジャパン株式会社製、型番:N50)を用いて591rpmで10分間混練した。得られた混練物を長方形の容器に投入し、振動を加えてスラリー状にして容器内に均一に充填した後、1日密封養生して硬化させた。硬化体を容器から脱型し、10〜15mmの粒度に切断して石炭灰硬化物を得た。石炭灰硬化物は石炭灰に対する塩素バイパスダストの水洗残渣の添加量を変化させて、石炭灰硬化物AないしDの4種類を作製した。作製した石炭灰硬化物の配合割合を表3に示す。
3. Preparation of hardened coal ash Coal ash, residual residue of chlorine bypass dust, blast furnace cement type B (manufactured by Ube-Mitsubishi Cement), dihydrate gypsum (exhaust gas desulfurization gypsum) and slaked lime (manufactured by Ube Materials, JIS special name) To obtain a mixture, a polycarboxylic acid-based water reducing agent (manufactured by BASF, master glenium SP8SV) and an amount of water in which the mixture is slurried are added to a Hobart mixer (manufactured by Hobart Japan Co., Ltd., And kneading at 591 rpm for 10 minutes. The obtained kneaded material was put into a rectangular container, and was shaken to form a slurry, which was uniformly filled in the container, and then cured by sealing for one day. The cured product was removed from the container and cut to a particle size of 10 to 15 mm to obtain a hardened coal ash. Coal ash hardened | cured material changed the addition amount of the washing residue of the chlorine bypass dust with respect to coal ash, and produced four types of hardened coal ash A thru | or D. Table 3 shows the blending ratio of the produced hardened coal ash.
4.石炭灰硬化物の重金属類の溶出量の評価 4). Evaluation of elution amount of heavy metals in hardened coal ash
〔実施例1〕
石炭灰100質量部に対して塩素バイパスダストの水洗残渣を5質量部添加して作製した石炭灰硬化物Aを3日、7日、あるいは28日間湿空養生した後、重金属類の溶出量を評価した。重金属類の溶出量の評価は、JIS K 0058−1の5「スラグ類の化学物質試験方法」に準拠して検液を作製し、その検液のpH及びB、As、Se、Cr6+、及びF濃度をJIS K 0102「工場排水試験方法」に準拠して測定した。結果を表4に示す。
[Example 1]
Coal ash hardened material A prepared by adding 5 parts by mass of water washing residue of chlorine bypass dust to 100 parts by mass of coal ash was cured for 3 days, 7 days, or 28 days, and then the elution amount of heavy metals was reduced. evaluated. The evaluation of the elution amount of heavy metals was made according to JIS K 0058-1 5 “Testing method for chemical substances of slags”, and the pH and B, As, Se, Cr 6+ , And F concentration were measured in accordance with JIS K 0102 “Factory drainage test method”. The results are shown in Table 4.
〔実施例2〕
石炭灰100質量部に対して塩素バイパスダストの水洗残渣を10質量部添加して作製した石炭灰硬化物Bを用いた以外は、実施例1と同様の方法で石炭灰硬化物からの重金属類の溶出量を評価した。結果を表4に示す。
[Example 2]
Heavy metals from hardened coal ash by the same method as in Example 1 except that hardened coal ash B prepared by adding 10 parts by weight of washing residue of chlorine bypass dust to 100 parts by weight of coal ash was used. The elution amount of was evaluated. The results are shown in Table 4.
〔実施例3〕
石炭灰100質量部に対して塩素バイパスダストの水洗残渣を15質量部添加して作製した石炭灰硬化物Cを用いた以外は、実施例1と同様の方法で石炭灰硬化物からの重金属類の溶出量を評価した。結果を表4に示す。
Example 3
Heavy metals from hardened coal ash by the same method as in Example 1 except that the hardened coal ash C produced by adding 15 parts by weight of washing residue of chlorine bypass dust to 100 parts by weight of coal ash was used. The elution amount of was evaluated. The results are shown in Table 4.
〔比較例1〕
塩素バイパスダストの水洗残渣を添加せずに作製した石炭灰硬化物Dを用いた以外は、実施例1と同様の方法で石炭灰硬化物からの重金属類の溶出量を評価した。結果を表4に示す。
[Comparative Example 1]
The amount of elution of heavy metals from the hardened coal ash was evaluated in the same manner as in Example 1 except that the hardened coal ash D prepared without adding the water washing residue of chlorine bypass dust was used. The results are shown in Table 4.
5.石炭灰硬化物のX線回折測定
実施例1〜3及び比較例1の石炭灰硬化物A〜Dについて、X線回折測定装置を用いて得られた回折ピークから、石炭灰硬化物A〜D中に含まれるエトリンガイト、石膏(二水石膏)、ムライト及び石英の存在を確認した。X線回折測定は上述の方法と同様に行った。結果を図1に示す。
5. X-ray diffraction measurement of hardened coal ash About hardened coal ash of Examples 1 to 3 and Comparative Example 1 from the diffraction peaks obtained using an X-ray diffractometer, the hardened coal ash AD The presence of ettringite, gypsum (dihydrate gypsum), mullite and quartz contained therein was confirmed. X-ray diffraction measurement was performed in the same manner as described above. The results are shown in FIG.
表4に示す実施例1〜3及び比較例1より、塩素バイパスダストの水洗残渣を添加した石炭灰硬化物A〜C(実施例1〜3)は、塩素バイパスダストの水洗残渣無添加の石炭灰硬化物D(比較例1)と比較して、ホウ素,ヒ素,六価クロム及びフッ素の溶出量が低減された。これは、塩素バイパスダストの水洗残渣に含まれるカルシウム、アルミニウム、硫酸分が水和して重金属類を固定化するエトリンガイトが生成したこと、及び塩素バイパスダストの水洗残渣に含まれるf.CaOにより石炭灰硬化物のpHが上昇したためと考えられる。 From Examples 1 to 3 and Comparative Example 1 shown in Table 4, the hardened coal ash A to C (Examples 1 to 3) to which the water washing residue of the chlorine bypass dust was added is the coal with no water washing residue added to the chlorine bypass dust. Compared with the ash cured product D (Comparative Example 1), the elution amounts of boron, arsenic, hexavalent chromium and fluorine were reduced. This is because the ettringite that hydrates calcium, aluminum, and sulfuric acid contained in the chlorine bypass dust washing residue and immobilizes heavy metals was formed, and in the chlorine washing dust washing residue f. It is considered that the pH of the hardened coal ash was increased by CaO.
特に、塩素バイパスダストの水洗残渣の含有量を多くした石炭灰硬化物B及びC(実施例2及び3)では、表4に示すとおり、材齢28日における石炭灰硬化物からのホウ素、六価クロム及びフッ素の溶出量がより低減できることが判る。これらの結果は、エトリンガイトの存在が確認されている図1に示す結果からも支持される。 In particular, in the coal ash cured products B and C (Examples 2 and 3) in which the content of the water washing residue of the chlorine bypass dust was increased, as shown in Table 4, boron from the coal ash cured product at the age of 28 days, six It can be seen that the elution amount of valent chromium and fluorine can be further reduced. These results are supported by the results shown in FIG. 1 in which the presence of ettringite is confirmed.
石炭灰硬化物からのセレン溶出量は塩素バイパスダストの水洗残渣の添加量に伴って増加傾向であるものの、石炭灰硬化物に含まれる塩素バイパスダストの水洗残渣の量を特定の範囲内に設定することで、セレン溶出量を土壌環境基準以下に抑制できることが判った。
Although the amount of selenium eluted from hardened coal ash tends to increase with the addition of water washing residue of chlorine bypass dust, the amount of water washing residue of chlorine bypass dust contained in hardened coal ash is set within a specific range. By doing so, it was found that the amount of selenium eluted could be suppressed below the soil environmental standard.
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