JP2016221472A - Screening method of coal ash - Google Patents
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- 239000010883 coal ash Substances 0.000 title claims abstract description 193
- 238000000034 method Methods 0.000 title claims abstract description 58
- 238000012216 screening Methods 0.000 title claims abstract description 5
- 238000010828 elution Methods 0.000 claims abstract description 64
- 239000002245 particle Substances 0.000 claims abstract description 53
- 239000000126 substance Substances 0.000 claims abstract description 39
- 239000011737 fluorine Substances 0.000 claims abstract description 33
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 33
- 229910052785 arsenic Inorganic materials 0.000 claims abstract description 25
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims abstract description 25
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000011669 selenium Substances 0.000 claims abstract description 7
- 229910052711 selenium Inorganic materials 0.000 claims abstract description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 239000011651 chromium Substances 0.000 claims abstract description 6
- 239000011133 lead Substances 0.000 claims abstract description 5
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 claims abstract 2
- 239000003440 toxic substance Substances 0.000 claims description 11
- 239000000383 hazardous chemical Substances 0.000 claims description 5
- 231100000167 toxic agent Toxicity 0.000 claims description 4
- 238000010187 selection method Methods 0.000 claims description 3
- 238000011084 recovery Methods 0.000 abstract description 12
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 31
- 238000012360 testing method Methods 0.000 description 15
- 230000007613 environmental effect Effects 0.000 description 12
- 239000002994 raw material Substances 0.000 description 12
- 239000000463 material Substances 0.000 description 11
- 239000002956 ash Substances 0.000 description 10
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 10
- 231100000614 poison Toxicity 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000007689 inspection Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 239000002689 soil Substances 0.000 description 6
- 239000004568 cement Substances 0.000 description 5
- 239000003245 coal Substances 0.000 description 5
- 239000004567 concrete Substances 0.000 description 5
- 239000010881 fly ash Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 238000000691 measurement method Methods 0.000 description 4
- 239000002893 slag Substances 0.000 description 4
- 238000009835 boiling Methods 0.000 description 3
- 238000002386 leaching Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000003818 cinder Substances 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- FZFYOUJTOSBFPQ-UHFFFAOYSA-M dipotassium;hydroxide Chemical compound [OH-].[K+].[K+] FZFYOUJTOSBFPQ-UHFFFAOYSA-M 0.000 description 1
- 238000007922 dissolution test Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000012717 electrostatic precipitator Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 238000007726 management method Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
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- 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)
Abstract
Description
本発明は、有害物質の含有量又は溶出量が所定のしきい値以下となる石炭灰を選別することができる石炭灰の選別方法に関する。 The present invention relates to a coal ash sorting method capable of sorting coal ash having a harmful substance content or elution amount equal to or less than a predetermined threshold value.
電気事業連合会（２０１４）によれば、関係各社の石炭火力発電所の石炭灰発生量の合計は２０１３年度で８７７万トン／年に達し、その量は今後も石炭火力発電所の新設・増設に伴い増加する見込みである。このため石炭灰の有効利用量を拡大することが急務になっている。 According to the Federation of Electric Power Companies (2014), the total amount of coal ash generated from coal-fired power plants of related companies reached 8.77 million tons / year in 2013, and the amount will continue to be newly established and expanded. It is expected to increase along with. For this reason, there is an urgent need to increase the effective use of coal ash.
石炭灰は、セメント原料、コンクリート混和材、土工材、建材などに有効利用されている。この中でも、土工材は、コンクリート混和材への利用が難しい非ＪＩＳ灰の有効利用先として特に重要である。 Coal ash is used effectively for cement raw materials, concrete admixtures, earthwork materials, building materials, and the like. Among these, earthwork materials are particularly important as an effective use destination of non-JIS ash which is difficult to be used as a concrete admixture.
土工材用途における石炭灰の利用法に関しては、現在、石炭エネルギーセンター（ＪＣＯＡＬ）において有効利用ガイドラインが整備されており（石炭エネルギーセンター、２０１４）、この中では製品の環境安全品質の確保のため、製品出荷時には製品の有害物質（ヒ素、セレン、六価クロム、フッ素、ホウ素）の溶出量検査（環境安全受渡検査）が導入されている。環境安全受渡検査を含む環境安全品質及びその検査方法については、ＪＩＳ Ａ５０１１−１：２０１３（コンクリート用スラグ骨材−第１部：高炉スラグ骨材）とＪＩＳ Ａ５０１１−４（コンクリート用スラグ骨材−第４部：電気炉酸化スラグ骨材）において既に導入されており、石炭灰についても今後のＪＩＳ改正時には導入が検討される可能性が高い。 Regarding the use of coal ash in earthwork materials, the Coal Energy Center (JCOAL) currently has an effective use guideline (Coal Energy Center, 2014), in which to ensure the environmental safety quality of products, At the time of product shipment, an elution amount inspection (environmental safety delivery inspection) of harmful substances (arsenic, selenium, hexavalent chromium, fluorine, boron) is introduced. Regarding environmental safety quality including environmental safety delivery inspection and its inspection method, JIS A5011-1: 2013 (Concrete slag aggregate-Part 1: Blast furnace slag aggregate) and JIS A5011-4 (Concrete slag aggregate- Part 4: Electric furnace oxidation slag aggregate) has already been introduced, and there is a high possibility that the introduction of coal ash will be considered in the future JIS revision.
当該検査工程が普及した場合には、土工材の製造者は、石炭灰を原料として使用した製品を出荷する際に上記検査工程を実施する必要があり、製品の歩留りが悪くなるリスクを抱えることになる。このリスクを抑止するためには、石炭火力発電所や土工材の製造者において有害物質の溶出量あるいは含有量（溶出量と相関がある場合）が小さい石炭灰をあらかじめ選別し、それを原料として用いることが有効である。 When the inspection process becomes widespread, the earthwork material manufacturer must carry out the above inspection process when shipping a product using coal ash as a raw material, and there is a risk that the yield of the product will deteriorate. become. In order to suppress this risk, coal ash with a small amount of toxic substance elution or content (if there is a correlation with the elution amount) is selected in advance in coal-fired power plants and earthworks manufacturers, and this is used as a raw material. It is effective to use.
通常、石炭灰に含まれる有害物質の含有量及び溶出性を判定するには時間とコストがかかることから、より効率的な選別技術を整備しておく必要がある。このような選別技術としては、石炭火力発電所の電気集塵機の前段から、有害物質の溶出量が少ない石炭灰を得ることができる技術が提案されている（例えば特許文献１参照）。 Usually, since it takes time and cost to determine the content and elution property of harmful substances contained in coal ash, it is necessary to develop a more efficient sorting technique. As such a sorting technique, a technique has been proposed that can obtain coal ash with a small amount of toxic substance elution from the front stage of an electrostatic precipitator of a coal-fired power plant (see, for example, Patent Document 1).
しかしながら、特許文献１に係る技術は、電気集塵機前段のホッパから直接回収する過程でのみ適用可能な方法であり、石炭灰の回収手段が限定される。例えば、石炭火力発電所の貯蔵サイロ内にある石炭灰を検査又は分別する方法として使用することはできない。また、各所の石炭火力発電所から石炭灰を回収し、その石炭灰から土工材を製造する工場においても、特許文献１に係る技術を使用することはできない。 However, the technique according to Patent Document 1 is a method that can be applied only in the process of direct recovery from the hopper upstream of the electric dust collector, and the coal ash recovery means is limited. For example, it cannot be used as a method for inspecting or sorting coal ash in a storage silo of a coal-fired power plant. Moreover, the technique which concerns on patent document 1 cannot be used also in the factory which collects coal ash from each coal-fired power plant, and manufactures earthwork material from the coal ash.
また、石炭灰に含まれる有害物質のうち、ヒ素、セレン、クロムの含有量に関しては蛍光Ｘ線法により定量することが可能である（電力中央研究所報告 Ｖ１３０２３、 ２０１４）。しかし、当該方法には高価な測定機器が必要となる。さらに、有害物質量が既知の標準試料を用いた検量線を予め作成する必要があり、当該方法の実施にあたっては高度な技量を要する。 In addition, among toxic substances contained in coal ash, the contents of arsenic, selenium, and chromium can be quantified by the fluorescent X-ray method (Electric Power Research Institute Report V13023, 2014). However, this method requires expensive measuring equipment. Furthermore, it is necessary to prepare a calibration curve using a standard sample with a known amount of harmful substances in advance, and a high level of skill is required to implement the method.
石炭灰に含まれるフッ素の含有量は、現状、非破壊で定量することは困難である。このため、石炭灰の溶出試験を実施し、石炭灰からフッ素の溶出量を定量する必要がある。この溶出操作と分析操作には最低二日程度の時間が必要である。 At present, it is difficult to determine the content of fluorine contained in coal ash in a non-destructive manner. For this reason, it is necessary to conduct a coal ash elution test to quantify the amount of fluorine eluted from the coal ash. The elution operation and the analysis operation require a time of at least about 2 days.
本発明は、上記事情に鑑み、回収手段に限定されず、簡易な方法により、効率よく有害物質の含有量又は溶出量が少ない石炭灰を選別することができる石炭灰の選別方法を提供することを目的とする。 In view of the above circumstances, the present invention is not limited to a recovery means, and provides a coal ash sorting method that can efficiently sort coal ash with a low content of harmful substances or a small amount of elution by a simple method. With the goal.
本発明者は、石炭灰試料の有害物質の溶出性と、その他の物理・化学的特性値との関係を鋭意調査・検討した結果、有害物質の含有量及び溶出量が石炭灰試料の密度との間に関係があることを見いだし、一定の密度以下の石炭灰を選別することで、有害物質の含有量及び溶出量の少ない石炭灰を得る方法を新たに発明するに至った。なお、密度により石炭灰を選別できる原理については後述する。 As a result of earnest investigation and examination of the relationship between the leaching properties of harmful substances in coal ash samples and other physical and chemical characteristic values, the present inventor has found that the content and leaching amount of toxic substances is the density of coal ash samples. As a result, the inventors have invented a new method for obtaining coal ash having a low content of harmful substances and a small amount of elution by selecting coal ash having a certain density or less. The principle of selecting coal ash based on density will be described later.
上記目的を達成するための第１の態様は、石炭灰の密度を測定し、当該密度が第１しきい値よりも小さい石炭灰を有害物質の含有量又は溶出量が所定量以下となる石炭灰であると選別する石炭灰の選別方法にある。 The first aspect for achieving the above object is to measure the density of coal ash, and to reduce the content or elution amount of harmful substances from coal ash whose density is lower than the first threshold value to a predetermined amount or less. There is a method for sorting coal ash which is sorted as ash.
かかる第１の態様は、石炭灰の密度を測定しさえすれば、有害物質が所定量以下の含有量又は溶出量の石炭灰を選別することができる。これにより、石炭灰に含まれる有害物質の含有量又は溶出量を得るために、従来の蛍光Ｘ線法や溶出試験などのように高価な測定装置が不要であり、特別な技量をも要さず、試験に掛かる時間も大幅に削減することができる。さらに、従来では非破壊迅速定量が困難なフッ素についても、簡易な操作で迅速に溶出量及び含有量の多寡を分別可能である。また、石炭灰は、石炭灰の回収手段について特に限定はなく、任意の回収手段により回収された石炭灰について本発明を適用することができる。 In the first aspect, as long as the density of coal ash is measured, it is possible to select coal ash whose content or elution is less than a predetermined amount of harmful substances. Thus, in order to obtain the content or elution amount of harmful substances contained in coal ash, an expensive measuring device such as the conventional fluorescent X-ray method and elution test is unnecessary, and a special skill is also required. In addition, the time required for the test can be greatly reduced. Furthermore, with regard to fluorine, which is difficult to measure rapidly in a conventional manner, it is possible to quickly separate the amount of elution and content by simple operations. The coal ash is not particularly limited with respect to the coal ash recovery means, and the present invention can be applied to the coal ash recovered by any recovery means.
本発明の第２の態様は、第１の態様に記載する石炭灰の選別方法において、前記有害物質は、フッ素、ヒ素、セレン、クロム、及び鉛からなる群より選択される少なくとも一種を含むことを特徴とする石炭灰の選別方法にある。 According to a second aspect of the present invention, in the coal ash sorting method according to the first aspect, the harmful substance includes at least one selected from the group consisting of fluorine, arsenic, selenium, chromium, and lead. In the method for sorting coal ash.
かかる第２の態様では、有害物質としてフッ素、ヒ素、セレン、クロム、及び鉛が所定量以下である含有量又は溶出量の石炭灰を選別することができる。 In the second aspect, coal ash whose content or elution amount is less than a predetermined amount of fluorine, arsenic, selenium, chromium, and lead as harmful substances can be selected.
本発明の第３の態様は、第１又は第２の態様に記載する石炭灰の選別方法において、前記第１しきい値は２．１ｇ／ｃｍ３以上２．２ｇ／ｃｍ３以下の範囲であることを特徴とする石炭灰の選別方法にある。 According to a third aspect of the present invention, in the coal ash sorting method described in the first or second aspect, the first threshold value is in a range of 2.1 g / cm 3 or more and 2.2 g / cm 3 or less. There exists in the sorting method of coal ash characterized by.
かかる第３の態様では、当該密度を指標することで、容易に、有害物質が所定量以下の含有量又は溶出量の石炭灰を選別することができる。 In the third aspect, by using the density as an index, it is possible to easily select coal ash whose content or elution amount is less than a predetermined amount of harmful substances.
本発明の第４の態様は、第３の態様に記載する石炭灰の選別方法において、石炭灰の中央粒径に対する第２しきい値として２０μｍ以上２５μｍ以下の範囲の値を設定し、前記第１しきい値より密度が小さく、かつ前記第２しきい値より粒径が大きい石炭灰を有害物質の含有量又は溶出量が所定量以下となる石炭灰であると選別することを特徴とする石炭灰の選別方法にある。 According to a fourth aspect of the present invention, in the coal ash sorting method described in the third aspect, a value in a range of 20 μm to 25 μm is set as the second threshold value with respect to the median particle size of the coal ash, The coal ash having a density smaller than one threshold and a particle diameter larger than the second threshold is selected as coal ash having a harmful substance content or elution amount equal to or less than a predetermined amount. It is in the sorting method of coal ash.
かかる第４の態様では、より確実に、有害物質の含有量や溶出量が所定量以下の石炭灰を選別することができる。 In the fourth aspect, it is possible to more reliably select coal ash having a hazardous substance content or elution amount of a predetermined amount or less.
本発明の第５の態様は、第１から第４の何れか一つの態様に記載する石炭灰の選別方法において、前記石炭灰は、石炭火力発電所で生じた石炭灰であることを特徴とする石炭灰の選別方法にある。 According to a fifth aspect of the present invention, in the coal ash sorting method according to any one of the first to fourth aspects, the coal ash is coal ash generated in a coal-fired power plant. There is a method for sorting coal ash.
かかる第５の態様では、電気集塵機の前段などの特定の回収手段に限定されず、石炭火力発電所で生じた石炭灰について本発明を適用することができる。 In the fifth aspect, the present invention can be applied to coal ash generated in a coal-fired power plant, without being limited to a specific recovery means such as a front stage of an electric dust collector.
本発明によれば、石炭灰の回収手段に限定されず、簡易な方法で効率よく有害物質の含有量又は溶出量が少ない石炭灰を選別することができる石炭灰の選別方法が提供される。 According to the present invention, there is provided a coal ash sorting method that is not limited to coal ash recovery means, and that can efficiently sort coal ash with a low content or elution amount of harmful substances by a simple method.
〈実施形態１〉
本発明の石炭灰の選別方法は、石炭灰の密度を測定し、当該密度が第１しきい値よりも小さい石炭灰を有害物質の含有量又は溶出量が所定量以下となる石炭灰であると選別することを特徴とする。
<Embodiment 1>
The method for sorting coal ash according to the present invention is a coal ash in which the density of coal ash is measured, and the coal ash whose density is lower than the first threshold is a content or elution amount of a hazardous substance or less. It is characterized by sorting.
石炭灰とは、広義のフライアッシュをいい、シンダーアッシュ（粒径０．１〜１ｍｍ）と、より粒径の小さいフライアッシュ（粒径０．１ｍｍ以下）を含む。フライアッシュは、微粉砕した石炭を石炭火力発電所のボイラで燃焼させ、電気集塵機で捕集することができる。 Coal ash refers to fly ash in a broad sense, and includes cinder ash (particle size 0.1 to 1 mm) and fly ash having a smaller particle size (particle size 0.1 mm or less). In fly ash, finely pulverized coal can be burned in a boiler of a coal-fired power plant and collected by an electric dust collector.
石炭灰の密度は、通常は液相置換法（ＪＩＳ−Ａ−１２０２、 ＪＩＳ−Ｒ−５２０１）あるいは懸ちょう（吊）法及び気体置換法（ＪＩＳ−Ｒ−１６２０）により得ることができる。もちろん、石炭灰の粒子の密度を計測可能な方法であれば、それらの方法には限定されない。 The density of coal ash can be usually obtained by a liquid phase replacement method (JIS-A-1202, JIS-R-5201) or a suspension method and a gas replacement method (JIS-R-1620). Of course, as long as the density of coal ash particles can be measured, the method is not limited to these methods.
石炭灰に含まれる有害物質とは、石炭灰から溶出して環境に悪影響を与える物質であり、具体的には、フッ素、ヒ素、セレン、クロム、鉛などである。有害物質は、これらの元素からなる群より選択される少なくとも一種を含む。 The harmful substances contained in the coal ash are substances that are eluted from the coal ash and adversely affect the environment, and specifically include fluorine, arsenic, selenium, chromium, lead, and the like. The harmful substance includes at least one selected from the group consisting of these elements.
石炭灰に含まれる有害物質の含有量とは、石炭灰の単位重量当たりに含まれる上記有害物質の重量である。含有量は、特に限定はないが、例えば、環境省の底質調査方法や環境省告示１９号による方法などにより測定することができる。 The content of harmful substances contained in coal ash is the weight of the harmful substances contained per unit weight of coal ash. The content is not particularly limited, but can be measured, for example, by the Ministry of the Environment's bottom sediment survey method or the method according to Ministry of the Environment Notification No. 19.
石炭灰に含まれる有害物質の溶出量とは、環境庁告示第４６号，環境庁告示１３号，ＥＮ−１２４５７（ＥＵ規格）、ＡＳＴＭ Ｄ ３９８７（米国規格）等に基づく溶出試験における、石炭灰の単位重量当たりの有害物質の溶出量をいう。 The amount of toxic substances contained in coal ash is the amount of coal ash in the dissolution tests based on Environmental Agency Notification No. 46, Environmental Agency Notification 13, EN-12457 (EU standard), ASTM D 3987 (US standard), etc. This refers to the amount of harmful substances eluted per unit weight.
有害物質の溶出量と比較される所定量は、石炭灰を原料とした用いた製品（土工材等）が土壌環境基準（環境庁告示第４６号）等に定められた基準値を超過しないために製造者が設定した石炭灰の溶出量の管理上限値である。製造者は、石炭灰の溶出量が管理上限値を超えれば、石炭灰を原料とした製品から土壌環境基準に適合しない量の有害物質が溶出する虞があると判断する。石炭灰を原料とした製品の多くにはセメントが添加されるが、有害物質の溶出量の大きい石炭灰を原料として用いた場合には、製品からの溶出を土壌環境基準値以下にするためには、セメントの添加量を多くする必要がある。セメントの添加量を多くすると製造コストが上昇するため、製造者は経済的観点から、製品へ添加可能なセメント量に応じて、原料として用いる石炭灰の溶出量値の管理上限値を設定する必要がある。 The specified amount compared with the leaching amount of toxic substances is because the products (earthwork materials etc.) using coal ash as the raw material do not exceed the standard value set in the soil environmental standards (Environment Agency Notification No. 46) etc. This is the upper limit of coal ash elution set by the manufacturer. If the elution amount of coal ash exceeds the control upper limit value, the manufacturer determines that there is a risk that a harmful substance in an amount not conforming to the soil environmental standards may be eluted from a product using coal ash as a raw material. Cement is added to many products made from coal ash, but when coal ash with a large amount of toxic substance elution is used as a raw material, in order to keep the elution from the product below the soil environmental standard value Therefore, it is necessary to increase the amount of cement added. Since the manufacturing cost increases when the amount of cement added is increased, the manufacturer needs to set a control upper limit for the elution amount of coal ash used as a raw material according to the amount of cement that can be added to the product from an economic viewpoint. There is.
また、有害物質の含有量と比較される所定量は、石炭灰を原料とした製品（土工材等）が前記土壌環境基準に基づいて定められた基準値を超過しないために設定した石炭灰含有量の管理上限値である。製造者は、石炭灰の含有量が含有量の管理上限値を超えれば、石炭灰を原料とした製品から前記土壌環境基準の基準値を超える量の有害物質が溶出する虞があると判断する。 In addition, the predetermined amount compared with the content of harmful substances is the coal ash content set so that products made from coal ash (such as earthwork materials) do not exceed the standard value determined based on the soil environmental standards. This is the upper limit value for the quantity. If the content of coal ash exceeds the control upper limit of content, the manufacturer determines that there is a risk that harmful substances in an amount exceeding the reference value of the soil environment standard may be eluted from the product using coal ash as a raw material. .
石炭灰の密度と比較される第１しきい値は、石炭灰を原料とした製品の製造者が設定した管理上限値に適合する石炭灰であるか否かを判定するしきい値である。この第１しきい値は、石炭灰の密度と、石炭灰の含有量又は溶出量との関係を予め試験により求めることにより得られる。例えば、第１しきい値は、２．１ｇ／ｃｍ３以上２．２ｇ／ｃｍ３以下の範囲から設定することが好ましい。たとえば、含有量又は溶出量が顕著に大きい石炭灰を除外するために最も効果的な第１しきい値は、２．２ｇ／ｃｍ３である。また、誤選別の危険性を低減させる必要がある場合には、第１しきい値を２．１ｇ/ｃｍ３以上２．２ｇ/ｃｍ3以下の範囲内に設定することが好ましい。 The 1st threshold value compared with the density of coal ash is a threshold value which judges whether it is coal ash which meets the control upper limit set by the manufacturer of the product which uses coal ash as a raw material. The first threshold value is obtained by obtaining a relationship between the density of coal ash and the content or elution amount of coal ash in advance by a test. For example, the first threshold value is preferably set from a range of 2.1 g / cm 3 or more and 2.2 g / cm 3 or less. For example, the most effective first threshold value for removing coal ash having a significantly large content or elution amount is 2.2 g / cm 3 . Moreover, when it is necessary to reduce the risk of misselection, it is preferable to set the first threshold value within a range of 2.1 g / cm 3 or more and 2.2 g / cm 3 or less.
石炭灰の密度が第１しきい値の一例である２．２ｇ／ｃｍ３以下であれば、当該石炭灰の有害物質の含有量又は溶出量の小さい石炭灰を最も効果的に選別できる。これは後述するように、石炭灰の密度と有害物質の含有量又は溶出量には相関があり、有害物質の含有量又は溶出量が顕著に大きい石炭灰が、密度２．２ｇ/ｃｍ3以上の範囲に存在するためである。したがって、石炭灰の密度を測定しさえすれば、有害物質の含有量又は溶出量が所定量以下の石炭灰を選別することができる。 If the density of coal ash is 2.2 g / cm 3 or less, which is an example of the first threshold value, coal ash having a small content of toxic substances or a small amount of elution can be selected most effectively. As will be described later, there is a correlation between the density of coal ash and the content or elution amount of toxic substances, and coal ash having a significantly large content or elution amount of toxic substances has a density of 2.2 g / cm 3 or more. It is because it exists in the range. Therefore, as long as the density of coal ash is measured, it is possible to select coal ash having a hazardous substance content or elution amount of a predetermined amount or less.
また、第１しきい値として２．１ｇ／ｃｍ３未満とした場合においては、しきい値より小さい値を示す石炭灰の量が、現状の石炭灰の性状分布から判断して著しく少なくなることが明らかなため、土工材製造に必要な量を確保することは困難である。 In addition, when the first threshold value is less than 2.1 g / cm 3 , the amount of coal ash showing a value smaller than the threshold value is significantly reduced as judged from the current coal ash property distribution. Therefore, it is difficult to secure an amount necessary for manufacturing the earthwork material.
これにより、石炭灰に含まれる有害物質の含有量又は溶出量を得るために、従来の蛍光Ｘ線法や溶出試験などのように高価な測定装置が不要であり、また、特別な技量をも要さず、試験に掛かる時間も大幅に削減することができる。 As a result, in order to obtain the content or elution amount of harmful substances contained in coal ash, an expensive measuring device such as the conventional fluorescent X-ray method or elution test is not required, and a special skill is required. The time required for the test can be greatly reduced.
また、従来では非破壊迅速定量が困難なフッ素についても、簡易な方法で迅速に溶出量及び含有量の多寡を分別可能である。また、ヒ素の含有量、六価クロムの溶出量に関しても適用が可能である。 In addition, it is possible to quickly separate the amount of elution and content of fluorine, which is difficult to determine rapidly and nondestructively by a simple method. The present invention can also be applied to the arsenic content and the elution amount of hexavalent chromium.
また、石炭灰は、石炭灰の回収手段について特に限定はない。例えば、石炭火力発電所の電気集塵機の前段部分を回収手段として使用する場合に限定されない。すなわち、任意の回収手段により回収された石炭灰について本発明を適用することができる。 Moreover, there is no limitation in particular about coal ash collection | recovery means of coal ash. For example, the present invention is not limited to the case where the front part of the electric dust collector of the coal-fired power plant is used as the recovery means. That is, the present invention can be applied to coal ash recovered by any recovery means.
このように石炭灰の回収手段に限定がないので、本発明に係る石炭灰の選別方法は、石炭火力発電所の貯蔵サイロ内にある石炭灰を検査又は分別する方法として使用することができる。 Thus, since there is no limitation in the recovery means of coal ash, the coal ash selection method according to the present invention can be used as a method for inspecting or separating coal ash in a storage silo of a coal-fired power plant.
また、石炭火力発電所から石炭灰を回収し、その石炭灰から土工材を製造する工場においても、本発明は有用である。例えば、各所から回収した石炭灰について本発明の選別方法を適用し、選別された石炭灰のみを原料として用いることで、土壌環境基準に適合した土工材を製造することができる。 The present invention is also useful in a factory that collects coal ash from a coal-fired power plant and manufactures earthwork materials from the coal ash. For example, by applying the sorting method of the present invention to coal ash collected from various places and using only the sorted coal ash as a raw material, an earthwork material that conforms to the soil environmental standards can be produced.
〈実施形態２〉
実施形態１では、石炭灰の密度に基づいて選別を行う選別方法について説明したが、石炭灰の中央粒径（メジアン；５０％値）を併用して選別を行ってもよい。詳細は後述するが、中央粒径が第２しきい値よりも小さい石炭灰は、特にフッ素の含有量や溶出量が多いからである。
<Embodiment 2>
In the first embodiment, the sorting method for sorting based on the density of coal ash has been described. However, sorting may be performed using the median particle size (median; 50% value) of coal ash. Although details will be described later, coal ash having a median particle size smaller than the second threshold value has a particularly large fluorine content and elution amount.
第２しきい値は、第１しきい値と同様に、石炭灰を原料とした製品の製造者が設定した管理上限値に適合する石炭灰であるか否かを判定するしきい値である。ただし、石炭灰の選別に際して、第２しきい値は単独で用いられず、第１しきい値と共に用いられる。 Similar to the first threshold value, the second threshold value is a threshold value for determining whether or not the coal ash conforms to the management upper limit set by the manufacturer of the product using coal ash as a raw material. . However, when sorting coal ash, the second threshold value is not used alone, but is used together with the first threshold value.
第２しきい値の具体的な値としては、２０μｍ以上２５μｍ以下の範囲であることが好ましく、量を多く確保するためには２０μｍが最も好ましい。石炭灰の粒径は、例えばレーザー粒度計を用いて測定するが、測定方法はこれに限定されない。 The specific value of the second threshold value is preferably in the range of 20 μm or more and 25 μm or less, and 20 μm is most preferable for securing a large amount. Although the particle size of coal ash is measured using, for example, a laser particle size meter, the measurement method is not limited to this.
具体的には、石炭灰を目開き２０μｍの篩にかけ、篩上に得られた石炭灰を収集する。これにより、中央粒径が２０μｍ以上（第２しきい値）の石炭灰を得ることができる。そして、収集した石炭灰について実施形態１で説明したように密度を測定する。当該密度が第１しきい値以下であれば、有害物質が所定量以下の含有量又は溶出量の石炭灰を選別することができる。 Specifically, the coal ash is passed through a sieve having an opening of 20 μm, and the coal ash obtained on the sieve is collected. Thereby, coal ash having a median particle diameter of 20 μm or more (second threshold value) can be obtained. Then, the density of the collected coal ash is measured as described in the first embodiment. If the density is equal to or lower than the first threshold value, coal ash having a hazardous substance content or elution amount equal to or less than a predetermined amount can be selected.
このように、密度の測定に先立ち、中央粒径が小さな石炭量を除外することで所定量を超える含有量又は溶出量の有害物質を含む石炭灰の混入を防ぐことができる。そして、中央粒径による石炭灰の分別を行った後に、密度による石炭灰の選別を行うことで、より確実に、有害物質の含有量や溶出量が所定量以下の石炭灰を選別することができる。 Thus, prior to the measurement of the density, by excluding the amount of coal having a small median particle size, it is possible to prevent coal ash containing a harmful substance having a content exceeding the predetermined amount or an elution amount from being contained. And after sorting coal ash by median particle size, by sorting coal ash by density, it is possible to more reliably sort coal ash whose content and elution amount of harmful substances are below a predetermined amount. it can.
〈密度により選別できる原理〉
フッ素やヒ素の分別が密度により可能になる原理については以下のように考えられる。
<Principle that can be sorted by density>
The principle that enables separation of fluorine and arsenic by density is considered as follows.
フッ素は揮発温度が低く、またヒ素も硫化物あるいは硫酸塩の形態で存在する場合は低沸点の物質である。このため、含有量は石炭灰生成時の温度が関係しており、高温で生成された石炭灰では、これら低沸点の物質はガス側に移行するため、灰中の含有量は小さくなり、一方比較的低温で生成された灰中の含有量は大きくなる。一方、石炭灰の密度は石炭灰粒子中の独立した微小空隙の内包量に影響される。この空隙は石炭中の灰分が完全に溶解した時に、内部からガスが発生したことによる空隙である。既往の研究では灰の融点が上昇すると中空粒子の割合が多くなることが知られており、このことから一般に灰の融点が高く、高温条件下で生成した灰ほど密度は小さくなると考えられる。このため密度と低沸点の物質の含有量には一定の相関性があり、密度を指標にして石炭灰の分別を行うことが可能になると考えられる。 Fluorine has a low volatility temperature, and arsenic is a low-boiling substance when it exists in the form of sulfide or sulfate. For this reason, the content is related to the temperature at the time of coal ash generation, and in coal ash generated at high temperatures, these low-boiling substances move to the gas side, so the content in ash is reduced, The content in the ash produced at a relatively low temperature increases. On the other hand, the density of coal ash is affected by the amount of inclusion of independent microvoids in the coal ash particles. This void is due to the generation of gas from the inside when the ash in the coal is completely dissolved. In past studies, it is known that the proportion of hollow particles increases as the melting point of ash increases. From this, the melting point of ash is generally high, and the ash produced under high temperature conditions is considered to have a lower density. For this reason, there is a certain correlation between the density and the content of low-boiling substances, and it is considered that the coal ash can be separated using the density as an index.
〈実施例〉
石炭火力発電所の石炭灰２２種類を本発明の選別方法の対象とした。なお、この石炭灰には有害物質の含有量や溶出量が大きい試料も一部含まれるが、本試料はプラント内でスポット的に少量採取した試料であり、現在販売されている石炭灰（貯蔵サイロで混合されている石炭灰）の性状を代表するものではない。
<Example>
Twenty-two types of coal ash from a coal-fired power plant were targeted for the sorting method of the present invention. This coal ash includes some samples with a large amount of harmful substances and large amounts of elution, but this sample is a sample collected in a small spot in the plant, and is currently sold in coal ash (storage It does not represent the properties of coal ash mixed in silos.
図１は、蛍光Ｘ線法により測定された石炭灰試料の主成分組成割合を示す図である。試料番号１はシンダーアッシュであり、残りは狭義のフライアッシュである。 FIG. 1 is a diagram showing a main component composition ratio of a coal ash sample measured by a fluorescent X-ray method. Sample number 1 is cinder ash and the rest is fly ash in a narrow sense.
同図には、各試料の石炭灰に含まれる、酸化カリウム（Ｋ２Ｏ）、酸化ナトリウム（Ｎａ２Ｏ）、酸化カルシウム（ＣａＯ）、酸化マグネシウム（ＭｇＯ）、酸化鉄（Ｆｅ２Ｏ３）、酸化アルミニウム（Ａｌ２Ｏ３）、二酸化珪素（シリカ、ＳｉＯ２）の重量の比率が示されている。測定は島津製作所ＸＲＦ−１５００を用い、測定法はＪＩＳ−Ｒ５２０４に準拠した。 The figure shows potassium oxide (K 2 O), sodium oxide (Na 2 O), calcium oxide (CaO), magnesium oxide (MgO), and iron oxide (Fe 2 O 3 ) contained in the coal ash of each sample. The weight ratio of aluminum oxide (Al 2 O 3 ) and silicon dioxide (silica, SiO 2 ) is shown. The measurement used Shimadzu Corporation XRF-1500, and the measurement method was based on JIS-R5204.
表１は、試料の強熱減量、比表面積、１０％粒径、５０％粒径、密度の測定結果を示す表である。強熱減量はＪＩＳ Ａ ６２０１（コンクリート用フライアッシュ）に準じて測定した。比表面積はＢＥＴ一点法による測定を実施し、測定法はＪＩＳ−Ｚ−８８３０：ガス吸着による粉体（固体）の比表面積測定方法に準拠した。粒度はレーザー粒度計で測定し、測定は島津製作所製レーザー粒度計ＳＡＬＤ３０００シリーズを用いた。密度の測定は、液相置換法（ＪＩＳ−Ａ−１２０２）により行った。 Table 1 is a table showing the measurement results of ignition loss, specific surface area, 10% particle size, 50% particle size, and density of the sample. The ignition loss was measured according to JIS A 6201 (Fly Ash for Concrete). The specific surface area was measured by the BET single point method, and the measurement method was based on JIS-Z-8830: Method for measuring specific surface area of powder (solid) by gas adsorption. The particle size was measured with a laser particle size meter, and the measurement was performed using a laser particle size meter SALD3000 series manufactured by Shimadzu Corporation. The density was measured by a liquid phase replacement method (JIS-A-1202).
〈試験例１〉
各試料について密度を測定した。密度の測定は、液相置換法（ＪＩＳ−Ａ−１２０２）により行った。また、各試料についてフッ素含有量を燃焼イオンクロマトグラフ法により測定した。これらの測定結果を図２に示す。
<Test Example 1>
The density was measured for each sample. The density was measured by a liquid phase replacement method (JIS-A-1202). Further, the fluorine content of each sample was measured by combustion ion chromatography. The measurement results are shown in FIG.
図２は、密度とフッ素含有量の関係を示す図である。横軸は密度［ｇ／ｃｍ３］であり、縦軸はフッ素含有量［ｍｇ／ｋｇ］である。同図に示すように、密度が２．２ｇ／ｃｍ３を超えると、フッ素含有量が１００ｍｇ／ｋｇを超える石炭灰が存在することが分かる。 FIG. 2 is a diagram showing the relationship between density and fluorine content. The horizontal axis represents density [g / cm 3 ], and the vertical axis represents fluorine content [mg / kg]. As shown in the figure, it can be seen that when the density exceeds 2.2 g / cm 3 , coal ash having a fluorine content exceeding 100 mg / kg exists.
したがって、石炭灰の密度を測定し、当該密度が第１しきい値の一例である２．２ｇ／ｃｍ３以下の石炭灰を、フッ素の含有量が所定量の一例である１００ｍｇ／ｋｇ以下の石炭灰として選別することができる。 Therefore, the density of the coal ash is measured, and the density is 2.2 g / cm 3 or less, which is an example of the first threshold value, and the fluorine content is 100 mg / kg or less, which is an example of a predetermined amount. Can be sorted as coal ash.
〈試験例２〉
各試料についてフッ素の溶出量を測定した。溶出量の測定は、環境庁告示第４６号に基づく溶出試験により行った。これらの測定結果を図３に示す。
<Test Example 2>
The elution amount of fluorine was measured for each sample. The elution amount was measured by an elution test based on Notification No. 46 of the Environment Agency. The measurement results are shown in FIG.
図３は、密度と石炭灰のフッ素の溶出量の関係を示す図である。横軸は密度［ｇ／ｃｍ３］であり、縦軸はフッ素溶出量［ｍｇ／Ｌ］である。同図に示すように、密度が２．２ｇ／ｃｍ３を超えると、フッ素の溶出量が１ｍｇ／Ｌを超える石炭灰が存在することが分かる。 FIG. 3 is a diagram showing the relationship between the density and the elution amount of fluorine from coal ash. The horizontal axis is density [g / cm 3 ], and the vertical axis is fluorine elution amount [mg / L]. As shown in the figure, it can be seen that when the density exceeds 2.2 g / cm 3 , coal ash having a fluorine elution amount exceeding 1 mg / L exists.
したがって、石炭灰の密度を測定し、当該密度が第１しきい値の一例である２．２ｇ／ｃｍ３以下の石炭灰を、フッ素の溶出量が所定量の一例である１ｍｇ／Ｌ以下の石炭灰として選別することができる。 Therefore, the density of coal ash is measured, and the density is 2.2 g / cm 3 or less, which is an example of the first threshold, and the amount of elution of fluorine is 1 mg / L or less, which is an example of a predetermined amount. Can be sorted as coal ash.
〈試験例３〉
各試料について粒径を測定した。粒径の測定は、レーザー粒度計を用いて測定した。図４は、レーザー粒度計を用いて得られた粒径の中央粒径（メジアン；５０％値）と、試験例１のフッ素の含有量と、密度との関係を示す図である。横軸は密度［ｇ／ｃｍ３］であり、縦軸は５０％粒径（中央粒径）［μｍ］である。また、プロットされた数字は、各試料のフッ素含有量［ｍｇ／ｋｇ］を表し、座標上の試料の位置はフッ素含有量に対応した大きさの円の中心である。
<Test Example 3>
The particle size was measured for each sample. The particle size was measured using a laser particle size meter. FIG. 4 is a graph showing the relationship between the median particle size (median; 50% value) of the particle size obtained using the laser particle size meter, the fluorine content of Test Example 1, and the density. The horizontal axis represents density [g / cm 3 ], and the vertical axis represents 50% particle size (median particle size) [μm]. The plotted numbers represent the fluorine content [mg / kg] of each sample, and the position of the sample on the coordinates is the center of a circle having a size corresponding to the fluorine content.
同図に示すように、中央粒径が２０μｍ未満の石炭灰は、フッ素を相対的に多く含んでいることが分かる。また少なくとも中央粒径が２５μｍを超える石炭灰は、フッ素含有量が相対的に少ない。このことから、中央粒径が２０μｍ以上２５μｍ以下の範囲で第２しきい値を設定することで、フッ素含有量が所定量以下となる石炭灰を選別できる。 As shown in the figure, it can be seen that the coal ash having a median particle size of less than 20 μm contains a relatively large amount of fluorine. Moreover, at least the coal ash having a median particle size exceeding 25 μm has a relatively small fluorine content. Therefore, by setting the second threshold value in the range where the median particle size is 20 μm or more and 25 μm or less, coal ash having a fluorine content of a predetermined amount or less can be selected.
したがって、石炭灰を篩にかけるなどして、中央粒径が第２のしきい値の一例として２０μｍ以上のものを回収し、当該石炭灰の密度が第１のしきい値の一例として２．２ｇ／ｃｍ３以下のものを選別する。このようにして選別された石炭灰は、フッ素含有量が所定量１００ｍｇ／ｋｇ以下（最大６７ｍｇ／ｋｇ）となる。 Accordingly, the coal ash is sieved to collect particles having a median particle size of 20 μm or more as an example of the second threshold, and the density of the coal ash is set as an example of the first threshold. Screening for 2 g / cm 3 or less. The coal ash thus selected has a fluorine content of a predetermined amount of 100 mg / kg or less (maximum 67 mg / kg).
このように、石炭灰の粒径を用いることで、密度のみを用いて選別するよりもより確実に、有害物質が所定量以下となる石炭灰を選別することができる。 Thus, by using the particle size of coal ash, it is possible to more reliably sort coal ash whose harmful substances are equal to or less than a predetermined amount than sorting using only the density.
〈試験例４〉
各試料についてヒ素の含有量を測定した。ヒ素の含有量は、環境庁告示１９号に定める測定方法により測定した。石炭灰の密度とヒ素の含有量を図５に示す。
<Test Example 4>
The arsenic content was measured for each sample. The arsenic content was measured by the measurement method specified in Environmental Agency Notification No. 19. The density of coal ash and the content of arsenic are shown in FIG.
図５は、石炭灰の密度とヒ素の含有量を示す図である。横軸は密度［ｇ／ｃｍ３］であり、縦軸はヒ素の含有量［ｍｇ／ｋｇ］である。 FIG. 5 is a diagram showing the density of coal ash and the content of arsenic. The horizontal axis represents density [g / cm 3 ], and the vertical axis represents arsenic content [mg / kg].
同図に示すように、密度が２．２ｇ／ｃｍ３を超えると、ヒ素含有量が１５ｍｇ／ｋｇを超える石炭灰が存在することが分かる。 As shown in the figure, it is understood that when the density exceeds 2.2 g / cm 3 , coal ash having an arsenic content exceeding 15 mg / kg exists.
したがって、石炭灰の密度を測定し、当該密度が第１しきい値の一例である２．２ｇ／ｃｍ３以下の石炭灰を、ヒ素の含有量が所定量の一例である１５ｍｇ／ｋｇ以下の石炭灰として選別することができる。 Therefore, the density of coal ash is measured, and the density is 2.2 g / cm 3 or less, which is an example of the first threshold, and the arsenic content is 15 mg / kg or less, which is an example of a predetermined amount. Can be sorted as coal ash.
図６は、石炭灰の粒径とヒ素含有量との関係を示す図である。横軸は５０％粒径（中央粒径）［μｍ］であり、縦軸はヒ素の含有量［ｍｇ／ｋｇ］である。 FIG. 6 is a diagram showing the relationship between the particle size of coal ash and the arsenic content. The horizontal axis represents 50% particle size (median particle size) [μm], and the vertical axis represents arsenic content [mg / kg].
同図に示すように、石炭灰の粒径はほぼ５〜３０μｍの範囲にあるが、ヒ素の含有量は５〜６５ｍｇ／ｋｇの範囲に分布している。すなわち、石炭灰の粒径が特定されても、石炭灰に含まれるヒ素の含有量が１５ｍｇ／ｋｇ以下とはならず、粒径と有害物質の含有量との間に相関がないことが分かる。粒径と溶出量についても同様に相関がないと推定される。 As shown in the figure, the particle size of coal ash is in the range of about 5 to 30 μm, but the arsenic content is distributed in the range of 5 to 65 mg / kg. That is, even if the particle size of coal ash is specified, the content of arsenic contained in coal ash does not become 15 mg / kg or less, and it is understood that there is no correlation between the particle size and the content of harmful substances. . Similarly, it is estimated that there is no correlation between the particle size and the elution amount.
一般に、密度は粒径に相関関係があると考えられる。しかし、密度と粒径に相関関係があったとしても、本試験例では、粒径を指標としてはヒ素の含有量が所定量以下となるか否かを判別できないことが示された。つまり、密度を指標とすることで、粒径では判別できないヒ素含有量の多寡が判別できることが示され、密度は粒径とは代替できないことが分かる。 Generally, density is considered to be correlated with particle size. However, even if there was a correlation between the density and the particle size, it was shown that in this test example, it was not possible to determine whether or not the arsenic content was a predetermined amount or less using the particle size as an index. In other words, it is shown that by using density as an index, it is possible to determine the amount of arsenic content that cannot be determined by particle size, and it is understood that density cannot be substituted for particle size.
〈試験例５〉
各試料について六価クロムの溶出量を測定した。六価クロムの溶出量は、環境庁告示第４６号に基づく溶出試験により行った。六価クロムの溶出量と密度の関係を図７に示す。
<Test Example 5>
The elution amount of hexavalent chromium was measured for each sample. The elution amount of hexavalent chromium was determined by an elution test based on Notification No. 46 of the Environment Agency. FIG. 7 shows the relationship between the elution amount of hexavalent chromium and the density.
図７は、密度と石炭灰の六価クロムの溶出量の関係を示す図である。横軸は密度［ｇ／ｃｍ３］であり、縦軸は六価クロム溶出量［ｍｇ／Ｌ］である。同図に示すように、密度が２．２ｇ／ｃｍ３を超えると、六価クロムの溶出量が０．１５ｍｇ／Ｌを超える石炭灰が存在することが分かる。 FIG. 7 is a diagram showing the relationship between the density and the elution amount of hexavalent chromium in coal ash. The horizontal axis represents density [g / cm 3 ], and the vertical axis represents hexavalent chromium elution amount [mg / L]. As shown in the figure, it can be seen that when the density exceeds 2.2 g / cm 3 , coal ash having an elution amount of hexavalent chromium exceeding 0.15 mg / L exists.
したがって、石炭灰の密度を測定し、当該密度が第１しきい値の一例である２．２ｇ／ｃｍ３以下の石炭灰を、六価クロムの溶出量が所定量の一例である０．１５ｍｇ／Ｌ以下の石炭灰として選別することができる。 Therefore, the density of coal ash is measured, and the density is 2.2 g / cm 3 or less, which is an example of the first threshold, and the elution amount of hexavalent chromium is 0.15 mg, which is an example of a predetermined amount. / L or less as coal ash.
本発明は、石炭灰を原料として土工材等の有効利用品を製造する産業分野で利用することができる。
INDUSTRIAL APPLICATION This invention can be utilized in the industrial field | area which manufactures effective utilization goods, such as earthwork materials, using coal ash as a raw material.
Claims (5)
前記有害物質は、フッ素、ヒ素、セレン、クロム、及び鉛からなる群より選択される少なくとも一種を含む
ことを特徴とする石炭灰の選別方法。 In the coal ash sorting method according to claim 1,
The toxic substance includes at least one selected from the group consisting of fluorine, arsenic, selenium, chromium, and lead.
前記第１しきい値は２．１ｇ／ｃｍ３以上２．２ｇ／ｃｍ３以下の範囲である
ことを特徴とする石炭灰の選別方法。 In the selection method of coal ash according to claim 1 or claim 2,
Method of screening coal ash, characterized in that said first threshold is in the range of less 2.1 g / cm 3 or more 2.2 g / cm 3.
石炭灰の中央粒径に対する第２しきい値として２０μｍ以上２５μｍ以下の範囲の値を設定し、
前記第１しきい値より密度が小さく、かつ前記第２しきい値より粒径が大きい石炭灰を有害物質の含有量又は溶出量が所定量以下となる石炭灰であると選別する
ことを特徴とする石炭灰の選別方法。 In the coal ash sorting method according to claim 3,
A value in the range of 20 μm or more and 25 μm or less is set as the second threshold value for the median particle size of coal ash,
The coal ash having a density smaller than the first threshold value and a particle size larger than the second threshold value is selected as coal ash having a harmful substance content or elution amount equal to or less than a predetermined amount. Coal ash sorting method.
前記石炭灰は、石炭火力発電所で生じた石炭灰である
ことを特徴とする石炭灰の選別方法。
In the selection method of coal ash according to any one of claims 1 to 4,
The coal ash is coal ash generated in a coal-fired power plant.
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