JPH0217228B2 - - Google Patents
Info
- Publication number
- JPH0217228B2 JPH0217228B2 JP61026620A JP2662086A JPH0217228B2 JP H0217228 B2 JPH0217228 B2 JP H0217228B2 JP 61026620 A JP61026620 A JP 61026620A JP 2662086 A JP2662086 A JP 2662086A JP H0217228 B2 JPH0217228 B2 JP H0217228B2
- Authority
- JP
- Japan
- Prior art keywords
- coal ash
- iron
- pressure steam
- stabilizing
- iron chloride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010883 coal ash Substances 0.000 claims description 74
- 238000000034 method Methods 0.000 claims description 31
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 claims description 24
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 229910000358 iron sulfate Inorganic materials 0.000 claims description 23
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 239000000843 powder Substances 0.000 claims description 15
- 230000000087 stabilizing effect Effects 0.000 claims description 14
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 13
- 239000011593 sulfur Substances 0.000 claims description 13
- 229910052717 sulfur Inorganic materials 0.000 claims description 13
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 238000004898 kneading Methods 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 7
- 239000003245 coal Substances 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 claims description 6
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 claims 1
- 229910001385 heavy metal Inorganic materials 0.000 description 20
- 239000000126 substance Substances 0.000 description 19
- 238000010828 elution Methods 0.000 description 17
- 230000007774 longterm Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 239000011651 chromium Substances 0.000 description 7
- 230000007613 environmental effect Effects 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 239000002956 ash Substances 0.000 description 6
- -1 iron ions Chemical class 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000007922 dissolution test Methods 0.000 description 4
- 229960002089 ferrous chloride Drugs 0.000 description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 150000002505 iron Chemical class 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 239000011812 mixed powder Substances 0.000 description 3
- 230000006641 stabilisation Effects 0.000 description 3
- 238000011105 stabilization Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 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 1
- 229910001653 ettringite Inorganic materials 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
Description
〔産業上の利用分野〕
本発明は、石炭燃焼時に排出される石炭灰の安
定化方法、詳しくは石炭灰に、塩化鉄処理また
は／および硫酸鉄処理と、常圧水蒸気処理とを組
み合わせた処理を施し、また石炭灰にアルカリ物
質が多い際には、イオウもしくは硫化物の添加ま
たは炭酸ガス処理を付加する石炭灰の安定化方法
に関するものである。
〔従来の技術〕
従来、我国においては、フライアツシユの約20
％はセメント混和材、セメント原料などに再利用
されており、残りは埋立地などに処分されてい
る。しかしながら、従来の方式による再利用だけ
では、将来発生するであろう膨大な石炭灰量に対
応し得るだけの需要の増加は期待できない。一
方、現行の石炭灰の埋立地などへの処分について
は、石炭灰溶出水が高アルカリであり、かつ場合
によつては、環境基準値を越える重金属の溶出が
認められるゆえ、環境保全に係わる規制の強化に
伴い、石炭灰処分用地の確保が難しくなりつつあ
り、本格的な石炭火力発電所の稼動の際には、現
状の石炭灰の有効利用方式ならびに処分方法によ
つては、発生する全ての石炭灰を処理することは
難しくなる見通しである。また石炭灰の大量処理
方式の検討に際しては、国家資源に乏しい我国に
おいては、単なる投棄処分ではなく、石炭灰を資
源として再利用を図ることが重要である。
従来、石炭灰の安定化方法として、石炭灰を炭
酸ガス処理、または硫酸処理する方法が知られて
いる。
また特開昭51−78078号公報には、塵芥焼却灰
に硫酸第一鉄を添加して、脱臭および重金属イオ
ンの溶出の防止を図る方法が記載されている。
さらに特開昭56−44085号公報には、電気炉製
鋼の際に発生するクロムを含有するダストに、塩
化第１鉄などを添加し、水を加えて混練する方法
が記載されている。
〔発明が解決しようとする課題〕
上記の特開昭51−78078号公報記載の発明は、
塵芥焼却灰を対象とし、処理温度が常温である。
また上記の特開昭56−44085号公報記載の発明は、
電気炉製鋼の際に発生するクロムを含有するダス
トを対象とし、処理温度が常温であるとともに、
溶出液PHが11.9〜13.5と環境基準値を満足せず、
また短期〜長期において、Cr6+溶出が検出限界値
以下となつていないという問題点がある。
石炭灰は一部の地域で土木材料として利用され
ている。しかしながら、石炭灰は溶出水が高アル
カリ性であり、また場合によつては重金属、特に
Cr6+の溶出が環境基準値を越えるため、土木材料
として利用するには地下水状況に留意し、施工方
法を配慮する必要がある。
また上記のように、石炭灰を炭酸ガス、硫酸な
どによつて常温下で中和処理を行う提案も見られ
るが、溶出水のPHを初期に低くできても、経時的
にPHが上昇し、いずれ高アルカリ性を呈するとと
もに、重金属の中で特にCr6+または／およびAs
の溶出が、無処理の石炭灰よりも増大するように
なる。
そこで本発明者らは、石炭灰からのアルカリ物
質、重金属の溶出を長期的に抑制する方法、すな
わち長期的な安定化方法について種々の研究を行
い、その結果、石炭灰に塩化鉄粉体もしくは／お
よび硫酸鉄粉体を加え水で混練するか、または塩
化鉄水溶液もしくは／および硫酸鉄水溶液で混練
した後、常圧水蒸気で処理する方法、石炭灰を水
で混練し、常圧水蒸気で処理した後、塩化鉄粉体
もしくは／および硫酸鉄粉体またはこれらの水溶
液を加えて常温処理することによつて、さらに石
炭灰中にアルカリ物質が多い際には、イオウもし
くは硫化物の添加または炭酸ガス処理を付加する
ことによつて、長期的に石炭灰を安定化すること
が可能であることを見出した。
本発明は上記の諸点に鑑み、上記の知見に基づ
いてなされたもので、石炭灰の大量消費を可能な
らしめるとともに、長期的に安定な石炭灰を得る
方法の提供を目的とするものである。
〔課題を解決するための手段および作用〕
本願の第１の発明は、石炭燃焼時に排出される
石炭灰に塩化鉄粉体もしくは／および硫酸鉄粉体
を加え水で混練するか、または塩化鉄水溶液もし
くは／および硫酸鉄水溶液で混練した後、40〜
100℃の常圧水蒸気で処理することを特徴として
いる。
また本願の第２の発明は、石炭燃焼時に排出さ
れる石炭灰に水を加えて混練し、40〜100℃の常
圧水蒸気で処理した後、塩化鉄粉体もしくは／お
よび硫酸鉄粉体を加えるか、または塩化鉄水溶液
もしくは／および硫酸鉄水溶液を加えて常温処理
することを特徴としている。
また石炭灰中にアルカリ物質が多い際には、石
炭灰にイオウもしくは硫化物を添加したり、また
は常圧水蒸気処理後に濃度１％以上の炭酸ガスを
含有する雰囲気下で処理を行う。
石炭灰中のアルカリ物質、重金属は石炭灰表
面、内部に均一に分布しているため、長期にわた
つてアルカリ物質および重金属の溶出を抑制する
には、特に石炭灰内部のアルカリ物質、重金属を
初期に溶出させる必要があり、それには処理温度
を常温よりも高くし、より高い温度の水蒸気下で
処理することが効果的である。また処理温度を高
くすることによつてアルカリ物質、重金属の一部
はエトリンガイト、ケイ酸カルシウム水和物など
の水和反応生成物中に固定されるため、可溶性の
アルカリ物質、重金属化合物が減少することにな
る。このため、処理水蒸気の温度を40〜100℃と
することが必要なのである。なお水蒸気として加
圧水蒸気を用いると、各設備を耐圧構造としなけ
ればならないのでコスト的に好ましくなく、この
ため常圧水蒸気を用いる。
一方、石炭灰からの重金属の溶出は、一般にPH
を低くすることによつて増大するが、塩化鉄また
は／および硫酸鉄を加えることによつて、重金属
は鉄イオン等で固定されるか、または還元（例え
ばCr6+→Cr3+）された後、固定されることによつ
て、無処理の石炭灰よりも重金属の溶出は少な
く、かつ環境基準値以下となる。また塩化鉄、硫
酸鉄水溶液は強酸性であるために、CaOを主とす
るフリーなアルカリ物質は中和され、溶出水PHは
低くなる。しかしながら、石炭灰によつては多量
のアルカリ物質を含有しているものがあり、その
ような灰に対して、常圧水蒸気処理と塩化鉄また
は／および硫酸鉄処理との組合わせのみで安定化
を図るには、多量の塩化鉄または／および硫酸鉄
で処理をしなければ十分な効果がない。したがつ
て、そのような灰の安定化に対して、イオウもし
くは硫化物の添加または炭酸ガス処理を付加する
ことによつて、塩化鉄または／および硫酸鉄によ
る安定化効果が向上し、長期にわたつてアルカリ
物質ならびに重金属の溶出抑制ができる。
イオウもしくは硫化物の添加は、石炭灰を水と
混練する時に行うか、あるいは予め石炭灰にイオ
ウもしくは硫化物を加えておいた後、水と混練す
る方法が好適である。また炭酸ガス処理は、常圧
水蒸気処理後に実施するのが好適で、常圧水蒸気
処理前では十分な安定化効果が期待できない。
イオウまたは硫化物の添加量が0.01重量％未満
の場合は、重金属の固定が不十分となるととも
に、アルカリ物質の溶出を経時的に抑制できなく
なり、長期的に安定化を図ることが難しくなる。
添加量が３重量％以上の場合は、石炭灰からの溶
出水のPHが低くなりすぎて、溶出条件によつて環
境基準値を満足しないことがある。したがつてイ
オウまたは硫化物の添加量は、石炭灰からのアル
カリ物質ならびに重金属の経時的な溶出特性によ
つて異なるが、通常は0.05〜２重量％の範囲が適
正である。イオウまたは硫化物の添加は特に石炭
灰を炭酸ガスあるいは酸性水溶液で中和処理した
際には、より長期的な安定化に対して効果的とな
る。
塩化鉄または／および硫酸鉄を石炭灰中あるい
は混練水中に添加して混練する方法は、安定化プ
ロセスが簡素となる点で好適である。一方、常圧
水蒸気処理後に添加する方法は、鉄塩添加量を低
くできるメリツトがある。なおこの方法は、鉄塩
処理までは強アルカリ性であるため、石炭灰を十
分に固化できるとともに、アンモニアを含有して
いる場合には、脱アンモニアが可能である。なお
石炭灰、石灰・セメント・スラグなどの石灰源材
料、石こうからなる混合粉体を用い、石炭灰を固
化し、かつ安定化させる方法では、塩化鉄また
は／および硫酸鉄を石炭灰中に、あるいは混練水
中に添加して混練する方法は、塩化鉄または／お
よび硫酸鉄が石灰源材料および石こうと反応を起
こし、固化反応が大幅に抑制され、かつ安定化効
果が不十分となり、安定化された高強度の固化体
とならないため、必ず常圧水蒸気処理後に実施す
る必要がある。
本発明の方法において用いる硫酸鉄または／お
よび塩化鉄はFe2+、Fe3+のいずれでもよく、ま
た添加量は石炭灰からのアルカリ物質ならびに重
金属の溶出特性によつて異なるが、通常は石炭灰
に対して２〜６％になるように、粉体あるいは水
溶液で添加することが適正である。また石炭灰に
よつては、混練物が常圧水蒸気処理によつて固化
するため、20〜30％の水にて撹拌造粒などの方法
で粒状とすれば、土木材料としての付加価値が向
上する。
上記のように、本発明によると、石炭火力発電
所などで大量に発生する石炭灰を、塩化鉄また
は／および硫酸鉄で処理した後、常圧水蒸気で処
理を行うことによつて、さらに石炭灰中のアルカ
リ物質が多い際には、イオウもしくは硫化物の添
加、あるいは炭酸ガス処理を付加することによつ
て、石炭灰からのアルカリ物質ならびに重金属の
溶出を長期的に抑制でき、環境保全性が長期的に
良好となり、土木材料としての利用が可能とな
る。
〔実施例〕
つぎに実施例および比較例について説明する。
実施例および比較例における石炭灰の性状を第
１表に示す。石炭灰の化学成分としては、Ｘ線回
析によれば大量の石英、中量のムライト、少量の
マグネタイトが認められた。石炭灰溶出水のPH、
重金属の測定は、処理後の石炭灰を１mm以下に粉
砕した後、環境庁告示13号の陸上埋立処分方法
（固化体／水＝10％、PH＝5.8〜6.3）によつた。
ブレーン比表面積測定は、島津製作所製の粉体
比表面積測定器SS−100形を使用し、空気透過法
によつた。
[Industrial Application Field] The present invention relates to a method for stabilizing coal ash discharged during coal combustion, and more specifically, to a method of stabilizing coal ash discharged during coal combustion. The present invention relates to a method for stabilizing coal ash, which involves adding sulfur or sulfide or treating with carbon dioxide gas when the coal ash contains a large amount of alkaline substances. [Conventional technology] Conventionally, in Japan, approximately 20
% is reused as cement admixtures and cement raw materials, and the rest is disposed of in landfills. However, it is not possible to expect demand to increase enough to cope with the enormous amount of coal ash that will be generated in the future by reusing it using conventional methods. On the other hand, with regard to the current disposal of coal ash in landfills, it is difficult to preserve the environment because coal ash leached water is highly alkaline and, in some cases, heavy metals exceeding environmental standard values have been leached. With the tightening of regulations, it is becoming difficult to secure land for coal ash disposal, and when a full-scale coal-fired power plant goes into operation, the current effective utilization and disposal methods of coal ash will result in the generation of coal ash. It is expected that it will be difficult to process all of the coal ash. Furthermore, when considering methods for mass disposal of coal ash, it is important to reuse coal ash as a resource, rather than simply dumping it, as our country is poor in national resources. Conventionally, methods of treating coal ash with carbon dioxide gas or sulfuric acid are known as methods for stabilizing coal ash. Further, JP-A-51-78078 describes a method of adding ferrous sulfate to garbage incineration ash to deodorize it and prevent the elution of heavy metal ions. Further, JP-A-56-44085 describes a method in which ferrous chloride or the like is added to chromium-containing dust generated during electric furnace steelmaking, and water is added and kneaded. [Problem to be solved by the invention] The invention described in JP-A-51-78078 mentioned above is
The target is garbage incineration ash, and the processing temperature is room temperature.
Moreover, the invention described in the above-mentioned Japanese Patent Application Laid-Open No. 56-44085 is
Targeting chromium-containing dust generated during electric furnace steelmaking, the treatment temperature is room temperature and
The eluate pH was 11.9 to 13.5, which did not meet the environmental standards.
Furthermore, there is a problem that Cr 6+ elution is not below the detection limit value in the short to long term. Coal ash is used as a civil engineering material in some areas. However, the leached water of coal ash is highly alkaline, and in some cases heavy metals, especially
Since the elution of Cr 6+ exceeds the environmental standard value, it is necessary to pay attention to the groundwater situation and consider the construction method when using it as a civil engineering material. In addition, as mentioned above, there are proposals to neutralize coal ash with carbon dioxide gas, sulfuric acid, etc. at room temperature, but even if the pH of the leached water can be lowered initially, the pH will increase over time. , eventually exhibits high alkalinity, and among heavy metals, especially Cr 6+ or/and As
The elution of coal ash becomes greater than that of untreated coal ash. Therefore, the present inventors conducted various studies on methods for long-term suppression of the elution of alkaline substances and heavy metals from coal ash, that is, long-term stabilization methods, and as a result, found that iron chloride powder or iron chloride powder or A method of adding / and iron sulfate powder and kneading with water, or kneading with an aqueous iron chloride solution or/and an aqueous iron sulfate solution, and then treating with atmospheric pressure steam, kneading coal ash with water and treating with atmospheric pressure steam After that, by adding iron chloride powder and/or iron sulfate powder or an aqueous solution thereof and treating at room temperature, if there are many alkaline substances in the coal ash, addition of sulfur or sulfide or carbonation can be performed. We have found that it is possible to stabilize coal ash in the long term by adding gas treatment. The present invention has been made in view of the above points and based on the above knowledge, and aims to enable mass consumption of coal ash and provide a method for obtaining coal ash that is stable over a long period of time. . [Means and effects for solving the problem] The first invention of the present application is to add iron chloride powder or/and iron sulfate powder to coal ash discharged during coal combustion and knead it with water, or After kneading with aqueous solution or/and iron sulfate aqueous solution, 40~
It is characterized by being treated with normal pressure steam at 100℃. In addition, the second invention of the present application is to add water to coal ash discharged during coal combustion, knead it, treat it with atmospheric pressure steam at 40 to 100°C, and then add iron chloride powder or/and iron sulfate powder. It is characterized by adding or adding an aqueous iron chloride solution or/and an aqueous iron sulfate solution and treating at room temperature. Further, when coal ash contains a large amount of alkaline substances, sulfur or sulfide is added to the coal ash, or treatment is performed in an atmosphere containing carbon dioxide gas at a concentration of 1% or more after treatment with atmospheric pressure steam. Alkaline substances and heavy metals in coal ash are uniformly distributed on the surface and inside the coal ash. Therefore, in order to suppress the elution of alkali substances and heavy metals over a long period of time, it is necessary to remove the alkali substances and heavy metals from the inside of coal ash at the initial stage. For this purpose, it is effective to raise the treatment temperature higher than room temperature and to perform the treatment under steam at a higher temperature. In addition, by increasing the treatment temperature, some of the alkaline substances and heavy metals are fixed in the hydration reaction products such as ettringite and calcium silicate hydrate, which reduces the amount of soluble alkaline substances and heavy metal compounds. It turns out. For this reason, it is necessary to set the temperature of the treated steam to 40 to 100°C. Note that if pressurized steam is used as the steam, each piece of equipment must have a pressure-resistant structure, which is not preferable in terms of cost, and therefore normal pressure steam is used. On the other hand, the elution of heavy metals from coal ash is generally caused by PH
However, by adding iron chloride and/or iron sulfate, heavy metals are fixed with iron ions, etc., or reduced (e.g. Cr 6+ →Cr 3+ ). After that, by being fixed, the elution of heavy metals is lower than that of untreated coal ash, and it is below environmental standard values. Furthermore, since iron chloride and iron sulfate aqueous solutions are strongly acidic, free alkaline substances, mainly CaO, are neutralized and the PH of the eluted water is lowered. However, some coal ash contains large amounts of alkaline substances, and such ash can be stabilized only by a combination of atmospheric steam treatment and iron chloride or/and iron sulfate treatment. In order to achieve this, the treatment will not be sufficiently effective unless treated with a large amount of iron chloride and/or iron sulfate. Therefore, by adding sulfur or sulfide or carbon dioxide treatment to stabilize such ash, the stabilizing effect of iron chloride and/or iron sulfate can be improved and it can be stabilized for a long time. It can suppress the elution of alkaline substances and heavy metals. It is preferable that sulfur or sulfide be added when coal ash is kneaded with water, or that sulfur or sulfide be added to coal ash in advance and then kneaded with water. Further, the carbon dioxide treatment is preferably carried out after the atmospheric pressure steam treatment, and a sufficient stabilizing effect cannot be expected before the atmospheric pressure steam treatment. If the amount of sulfur or sulfide added is less than 0.01% by weight, the fixation of heavy metals will be insufficient, and the elution of alkaline substances will not be suppressed over time, making it difficult to achieve long-term stability.
When the amount added is 3% by weight or more, the pH of the water eluted from the coal ash becomes too low and may not meet the environmental standard values depending on the elution conditions. Therefore, the amount of sulfur or sulfide added varies depending on the elution characteristics of alkaline substances and heavy metals from coal ash over time, but is usually in the range of 0.05 to 2% by weight. Addition of sulfur or sulfide is particularly effective for long-term stabilization when coal ash is neutralized with carbon dioxide gas or acidic aqueous solution. A method in which iron chloride or/and iron sulfate is added to coal ash or kneading water and kneaded is preferred in that the stabilization process is simple. On the other hand, the method of adding iron salt after normal pressure steam treatment has the advantage that the amount of iron salt added can be reduced. Note that this method is strongly alkaline until the iron salt treatment, so the coal ash can be sufficiently solidified, and if it contains ammonia, it can be deammoniated. In addition, in the method of solidifying and stabilizing coal ash using a mixed powder consisting of coal ash, lime source materials such as lime, cement, and slag, and gypsum, iron chloride or/and iron sulfate is added to the coal ash. Alternatively, in the method of adding iron chloride and/or iron sulfate to the mixing water and kneading, iron chloride and/or iron sulfate react with the lime source material and gypsum, and the solidification reaction is greatly suppressed and the stabilizing effect is insufficient. This process must be carried out after normal pressure steam treatment, as it does not result in a solidified product with high strength. The iron sulfate and/or iron chloride used in the method of the present invention may be either Fe 2+ or Fe 3+ , and the amount added varies depending on the elution characteristics of alkaline substances and heavy metals from coal ash, but usually it is It is appropriate to add it in the form of powder or aqueous solution in an amount of 2 to 6% based on the ash. In addition, with coal ash, the kneaded material solidifies through atmospheric pressure steam treatment, so if it is made into granules using a method such as agitation granulation with 20 to 30% water, its added value as a civil engineering material will increase. do. As described above, according to the present invention, coal ash, which is generated in large quantities at coal-fired power plants, is treated with iron chloride and/or iron sulfate, and then treated with atmospheric pressure steam to further improve the coal ash. When the ash contains a large amount of alkaline substances, adding sulfur or sulfide or carbon dioxide treatment can suppress the elution of alkaline substances and heavy metals from the coal ash over the long term, improving environmental protection. will be in good condition over the long term, making it possible to use it as a civil engineering material. [Example] Next, Examples and Comparative Examples will be described. Table 1 shows the properties of coal ash in Examples and Comparative Examples. As for the chemical components of the coal ash, X-ray diffraction revealed a large amount of quartz, a medium amount of mullite, and a small amount of magnetite. PH of coal ash elution water,
Heavy metals were measured by crushing the treated coal ash into pieces of 1 mm or less, and then using the Land Landfill Disposal Method (solidified solids/water = 10%, PH = 5.8 to 6.3) as stipulated in Environment Agency Notification No. 13. The Blaine specific surface area was measured using a powder specific surface area measuring instrument SS-100 manufactured by Shimadzu Corporation, and by an air permeation method.
【表】
比較例 １
石炭灰100重量部を水10重量部を加えて混練し、
さらに温度20℃、濃度10重量％の炭酸ガスを含有
するガスで10時間処理した後、ポリエチレン製袋
に密閉し、１日後、28日後に溶出試験を行つた。
試験結果を第２表に示す。
比較例 ２
石炭灰100重量部に硫酸2.5重量部、水10重量部
を加えて混練し、98℃の常圧水蒸気下で２時間処
理を行つた後、ポリエチレン製袋に密閉し、１日
後、28日後に溶出試験を行つた。試験結果を第２
表に示す。
実施例 １
石炭灰100重量部に、塩化第一鉄４重量部を添
加した混合粉体を、水20重量部で混練し、98℃の
常圧水蒸気下で２時間処理を行つた後、ポリエチ
レン製袋に密閉し、１日後、28日後に溶出試験を
行つた。試験結果を第２表に示す。
実施例 ２
石炭灰100重量部にイオウ１重量部を添加した
混合粉体を、濃度20％の塩化第一鉄水溶液20重量
部で混練し、98℃の常圧水蒸気で２時間処理を行
つた後、ポリエチレン袋に密閉し、１日後、28日
後に溶出試験を行つた。試験結果を第２表に示
す。
実施例 ３
石炭灰100重量部を水で撹拌造粒し、98℃の常
圧水蒸気下で２時間処理を行つた後、塩化第一鉄
３重量部を混合し、ポリエチレン袋に密閉し、１
日後、28日後に溶出試験を行つた。試験結果を第
２表に示す。[Table] Comparative Example 1 100 parts by weight of coal ash was mixed with 10 parts by weight of water,
After further treatment for 10 hours with a gas containing carbon dioxide gas at a concentration of 10% by weight at a temperature of 20°C, the sample was sealed in a polyethylene bag, and an elution test was conducted 1 day later and 28 days later.
The test results are shown in Table 2. Comparative Example 2 100 parts by weight of coal ash was mixed with 2.5 parts by weight of sulfuric acid and 10 parts by weight of water, treated under normal pressure steam at 98°C for 2 hours, sealed in a polyethylene bag, and after 1 day, A dissolution test was conducted after 28 days. Second test result
Shown in the table. Example 1 A mixed powder obtained by adding 4 parts by weight of ferrous chloride to 100 parts by weight of coal ash was kneaded with 20 parts by weight of water and treated under normal pressure steam at 98°C for 2 hours. The bag was sealed and a dissolution test was conducted 1 day and 28 days later. The test results are shown in Table 2. Example 2 A mixed powder prepared by adding 1 part by weight of sulfur to 100 parts by weight of coal ash was kneaded with 20 parts by weight of an aqueous ferrous chloride solution with a concentration of 20%, and treated with atmospheric pressure steam at 98°C for 2 hours. After that, the bag was sealed in a polyethylene bag, and a dissolution test was conducted after 1 day and 28 days. The test results are shown in Table 2. Example 3 100 parts by weight of coal ash was stirred and granulated with water, treated under normal pressure steam at 98°C for 2 hours, mixed with 3 parts by weight of ferrous chloride, sealed in a polyethylene bag, and granulated with water.
A dissolution test was conducted after 28 days. The test results are shown in Table 2.
以上説明したように、本発明によれば、石炭灰
に塩化鉄または／および硫酸鉄処理と、40〜100
℃の常圧水蒸気処理とを組合せた処理を行うこと
によつて、石炭灰からのアルカリ物質ならびに重
金属の溶出を短期〜長期的に抑制し、水質汚濁に
係る環境基準値を満足させることができるため、
本発明は石炭灰を土木分野における材料としての
有効利用に寄与する技術としてきわめて有益であ
る。
As explained above, according to the present invention, coal ash is treated with iron chloride or/and iron sulfate, and
By performing treatment in combination with atmospheric pressure steam treatment at ℃, the elution of alkaline substances and heavy metals from coal ash can be suppressed in the short to long term, and environmental standard values related to water pollution can be satisfied. For,
The present invention is extremely useful as a technology that contributes to the effective use of coal ash as a material in the civil engineering field.
Claims (1)
もしくは／および硫酸鉄粉体を加え水で混練する
か、または塩化鉄水溶液もしくは／および硫酸鉄
水溶液で混練した後、40〜100℃の常圧水蒸気で
処理することを特徴とする石炭灰の安定化方法。 ２ 石炭灰にイオウまたは硫化物を加える特許請
求の範囲第１項記載の石炭灰の安定化方法。 ３ 常圧水蒸気処理後に濃度１％以上の炭酸ガス
を含有する雰囲気下で処理する特許請求の範囲第
１項記載の石炭灰の安定化方法。 ４ 石炭燃焼時に排出される石炭灰に水を加えて
混練し、40〜100℃の常圧水蒸気で処理した後、
塩化鉄粉体もしくは／および硫酸鉄粉体を加える
か、または塩化鉄水溶液もしくは／および硫酸鉄
水溶液を加えて常温処理することを特徴とする石
炭灰の安定化方法。 ５ 石炭灰にイオウまたは硫化物を加える特許請
求の範囲第４項記載の石炭灰の安定化方法。 ６ 常圧水蒸気処理後に濃度１％以上の炭酸ガス
を含有する雰囲気下で処理した後、塩化鉄また
は／および硫化鉄を加えて処理する特許請求の範
囲第４項記載の石炭灰の安定化方法。[Claims] 1. After adding iron chloride powder or/and iron sulfate powder to coal ash discharged during coal combustion and kneading it with water, or kneading it with an aqueous iron chloride solution or/and an aqueous iron sulfate solution, A method for stabilizing coal ash, characterized by treatment with normal pressure steam at 40 to 100°C. 2. The method for stabilizing coal ash according to claim 1, which comprises adding sulfur or sulfide to coal ash. 3. The method for stabilizing coal ash according to claim 1, which comprises treating the coal ash in an atmosphere containing carbon dioxide gas at a concentration of 1% or more after the atmospheric pressure steam treatment. 4 After adding water and kneading the coal ash emitted during coal combustion and treating it with atmospheric pressure steam at 40 to 100°C,
A method for stabilizing coal ash, which comprises adding iron chloride powder or/and iron sulfate powder, or adding an iron chloride aqueous solution or/and iron sulfate aqueous solution and treating at room temperature. 5. The method for stabilizing coal ash according to claim 4, which comprises adding sulfur or sulfide to coal ash. 6. The method for stabilizing coal ash according to claim 4, which comprises treating it in an atmosphere containing carbon dioxide gas at a concentration of 1% or more after the atmospheric pressure steam treatment, and then treating it by adding iron chloride or/and iron sulfide. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61026620A JPS62183896A (en) | 1986-02-07 | 1986-02-07 | Method for stabilizing coal ash |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61026620A JPS62183896A (en) | 1986-02-07 | 1986-02-07 | Method for stabilizing coal ash |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62183896A JPS62183896A (en) | 1987-08-12 |
| JPH0217228B2 true JPH0217228B2 (en) | 1990-04-19 |
Family
ID=12198514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61026620A Granted JPS62183896A (en) | 1986-02-07 | 1986-02-07 | Method for stabilizing coal ash |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62183896A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2741645B2 (en) * | 1992-09-08 | 1998-04-22 | 新日本製鐵株式会社 | Treatment method for heavy metal-containing ash |
| NL9202033A (en) * | 1992-11-23 | 1994-06-16 | Tauw Milieu Bv | Process for the treatment of combustion residues and their use as an adsorbent. |
| JP3969617B2 (en) * | 1998-07-21 | 2007-09-05 | 不二倉業株式会社 | Hazardous substance immobilization material |
| JP4789411B2 (en) * | 2003-11-10 | 2011-10-12 | 川崎重工業株式会社 | Waste stabilization treatment and treatment equipment |
| JP4835359B2 (en) * | 2005-09-30 | 2011-12-14 | 宇部興産株式会社 | Coal ash granulated sand and method for producing coal ash granulated sand |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5178078A (en) * | 1974-12-28 | 1976-07-07 | Betsuku Kk | Jinkaishokyakubainoshorihoho |
| JPS5644085A (en) * | 1979-06-29 | 1981-04-23 | Nippon Jiryoku Senko Kk | Processing method of chromium-containing dust |
-
1986
- 1986-02-07 JP JP61026620A patent/JPS62183896A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5178078A (en) * | 1974-12-28 | 1976-07-07 | Betsuku Kk | Jinkaishokyakubainoshorihoho |
| JPS5644085A (en) * | 1979-06-29 | 1981-04-23 | Nippon Jiryoku Senko Kk | Processing method of chromium-containing dust |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62183896A (en) | 1987-08-12 |
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