JP7570596B2 - Method for recovering desalted washed ash from chlorine-containing ash - Google Patents
Method for recovering desalted washed ash from chlorine-containing ash Download PDFInfo
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- 239000000460 chlorine Substances 0.000 title claims description 69
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims description 61
- 229910052801 chlorine Inorganic materials 0.000 title claims description 61
- 238000000034 method Methods 0.000 title claims description 29
- 238000005406 washing Methods 0.000 claims description 63
- 239000003513 alkali Substances 0.000 claims description 52
- 239000011575 calcium Substances 0.000 claims description 39
- 239000007788 liquid Substances 0.000 claims description 38
- 229910052791 calcium Inorganic materials 0.000 claims description 28
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 19
- 239000000920 calcium hydroxide Substances 0.000 claims description 19
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 19
- 239000002002 slurry Substances 0.000 claims description 13
- 238000011033 desalting Methods 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 11
- 150000001805 chlorine compounds Chemical class 0.000 claims description 8
- 239000000843 powder Substances 0.000 claims description 4
- 239000012670 alkaline solution Substances 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 239000002956 ash Substances 0.000 description 88
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 16
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 12
- 239000004568 cement Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000011084 recovery Methods 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 description 6
- 235000010216 calcium carbonate Nutrition 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000010612 desalination reaction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 235000002918 Fraxinus excelsior Nutrition 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- -1 Friedel's salt Chemical class 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000010881 fly ash Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000002440 industrial waste Substances 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910018626 Al(OH) Inorganic materials 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000010882 bottom ash Substances 0.000 description 1
- 150000001669 calcium Chemical class 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 235000011148 calcium chloride Nutrition 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003818 cinder Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 238000005443 coulometric titration Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000003100 immobilizing effect Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
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Description
本発明は、塩素含有灰を脱塩洗浄してカルシウムを効果的に回収する方法に関する。 The present invention relates to a method for effectively recovering calcium by desalting and washing chlorine-containing ash.
一般廃棄物や産業廃棄物の焼却によって発生した焼却灰（主灰、飛灰、燃え殻、煤塵）や最終処分場に埋め立て処分された焼却灰、あるいはセメント工場から発生するクリンカダスト等をセメント原料等として再利用することが進められている。一方、これらの焼却灰等には十数％程度の塩素が含まれているので、これらの塩素を含む上記各種の焼却灰やクリンカダスト等（以下、これらを塩素含有灰と云う）を再資源化するには用途に応じた程度まで脱塩する必要がある。 Incident ash (bottom ash, fly ash, cinders, soot) generated by incineration of general waste and industrial waste, incineration ash disposed of in landfills at final disposal sites, and clinker dust generated from cement plants are being reused as cement raw materials. However, since these incineration ashes contain approximately 10% chlorine, in order to recycle the above-mentioned various incineration ashes and clinker dusts that contain chlorine (hereinafter referred to as chlorine-containing ash), they need to be desalted to a degree appropriate to their intended use.
また、上記塩素含有灰にはカルシウム分が酸化物換算で概ね２０％～５０％程度と豊富に含まれおり、このカルシウム分を有効に回収できれば、塩素含有灰の再資源化を拡大することができる。 The chlorine-containing ash also contains a large amount of calcium, approximately 20% to 50% in oxide equivalent, and if this calcium can be effectively recovered, it will be possible to expand the recycling of chlorine-containing ash.
上記塩素含有灰の脱塩について、該塩素含有灰に含まれる塩素化合物の大部分は水溶性なので水洗浄して脱塩できるが、塩素化合物の一部は水に難溶性のフリーデル氏塩（3CaO・Al２O３・CaCl２・10H２O）等を形成しており、水洗浄だけでは十分に脱塩することができない。一方、フリーデル氏塩等に酸を加えてｐＨを低下させることで脱塩する方法が知られている。ただし、この方法ではｐＨの低下に伴い、塩素と一緒にカルシウムも溶出するので、酸洗浄だけではカルシウムを十分に回収することができない。 Regarding the desalting of the chlorine-containing ash, most of the chlorine compounds contained in the chlorine-containing ash are water-soluble and can be desalted by washing with water, but some of the chlorine compounds form Friedel 's salt ( 3CaO.Al2O3.CaCl2.10H2O ) which is poorly soluble in water, and therefore cannot be desalted sufficiently by washing with water alone . On the other hand, a method of desalting by adding an acid to Friedel's salt etc. to lower the pH is known. However, in this method, calcium is eluted together with chlorine as the pH decreases, so calcium cannot be sufficiently recovered by washing with acid alone.
また、塩素含有灰に炭酸塩を含む水を加えて洗浄する方法（特開２００６－３２６４６２公報）、あるいは塩素含有灰の水スラリーに炭酸ガスを吹き込んで洗浄する方法が知られている（特許第３９２４８２２号公報）。しかし、炭酸塩や炭酸ガスを用いて洗浄すると、フリーデル氏塩は分解して脱塩されるので脱塩洗浄灰を得ることができるが、カルシウムの一部は水に難溶性の炭酸カルシウムになり、これが洗浄後の固液分離によって固形分として洗浄灰と共に回収される。この炭酸カルシウムを含む洗浄灰をセメント原料に用いると、その製造工程で多量のＣＯ２が発生する問題がある。 Also known is a method of washing chlorine-containing ash by adding water containing carbonate (JP Patent Publication 2006-326462 A) or a method of washing chlorine-containing ash by blowing carbon dioxide gas into a water slurry (JP Patent Publication 3924822 A). However, when washing is performed using carbonate or carbon dioxide gas, Friedel's salt is decomposed and desalted, so that desalted washed ash can be obtained, but part of the calcium becomes calcium carbonate, which is poorly soluble in water, and this is recovered as a solid content together with the washed ash by solid-liquid separation after washing. If this washed ash containing calcium carbonate is used as a cement raw material, there is a problem that a large amount of CO2 is generated during the production process.
このように、塩素含有灰をセメント原料として再利用するには、十分に脱塩すると共にセメント成分になるカルシウムを有効に回収できることが求められる。さらに、セメント製造時の低炭素化（ＣＯ２排出量削減）の要求に従うには、カルシウムは炭酸塩（ＣａＣＯ３、ＣａＭｇ(ＣＯ３)２など）以外の形態であることが望まれる。 Thus, in order to reuse chlorine-containing ash as a cement raw material, it is necessary to fully demineralize it and effectively recover calcium, which is a cement component. Furthermore, in order to comply with the demand for low carbonization (reduced CO2 emissions) during cement production, it is desirable for calcium to be in a form other than carbonate ( CaCO3 , CaMg( CO3 ) 2 , etc.).
本発明は、上記問題を解決したものであり、塩素含有灰を十分に脱塩すると共に灰に含まれるカルシウムを効果的に回収することができる処理方法を提供する。 The present invention solves the above problems and provides a treatment method that can fully demineralize chlorine-containing ash and effectively recover the calcium contained in the ash.
本発明の方法は、以下の構成によって上記問題を解決した処理方法であり、塩素含有灰を脱塩して水酸化カルシウムを含む洗浄灰を回収する方法である。
〔１〕塩素含有灰にアルカリを加え、アルカリ濃度１.０mol/L以上の液性でアルカリ洗浄することによって脱塩すると共に該塩素含有灰に含まれるカルシウムを水酸化カルシウムにするアルカリ洗浄工程と、該アルカリ洗浄工程の後に、固液分離して該水酸化カルシウムを含む固形分を回収する固液分離工程を有する脱塩洗浄灰の回収方法において、上記塩素含有灰が難溶性塩素化合物を含むものであり、液温１０℃以上～４０℃未満において、ｐＨ１３.０以上の液性でアルカリ洗浄し、液温４０℃以上～８０℃以下において、ｐＨ１２.５以上の液性でアルカリ洗浄することによって、脱塩洗浄灰の塩素濃度を０.６質量％以下に低減することを特徴とする脱塩洗浄灰の回収方法。
〔２〕塩素含有灰または塩素含有灰の水スラリーに、密閉雰囲気下または不活性ガス雰囲気下で、アルカリ濃度が１.０mol/L以上になるようにアルカリ溶液またはアルカリ粉末または粒状アルカリを加えてアルカリ洗浄する上記[１]に記載する塩素含有灰の脱塩洗浄灰の回収方法。
The method of the present invention is a treatment method which solves the above problems by the following constitution, and which is a method for desalting chlorine-containing ash and recovering washed ash containing calcium hydroxide.
[1] A method for recovering desalted washed ash, comprising an alkali washing step of adding an alkali to chlorine-containing ash, and desalting the chlorine-containing ash by alkali washing with a liquid having an alkali concentration of 1.0 mol/L or more , while converting calcium contained in the chlorine-containing ash into calcium hydroxide, and a solid-liquid separation step of recovering a solid content containing the calcium hydroxide by solid-liquid separation after the alkali washing step, wherein the chlorine-containing ash contains sparingly soluble chlorine compounds, and the chlorine concentration of the desalted washed ash is reduced to 0.6 mass% or less by performing alkali washing at a liquid temperature of 10°C or more but less than 40°C with a liquid pH of 13.0 or more, and by performing alkali washing at a liquid temperature of 40°C or more but less than 80°C with a liquid pH of 12.5 or more .
[2] A method for recovering desalted washed ash from chlorine-containing ash as described in [1] above, in which an alkaline solution, alkaline powder or granular alkali is added to chlorine-containing ash or a water slurry of chlorine-containing ash under a sealed atmosphere or an inert gas atmosphere so that the alkali concentration becomes 1.0 mol/L or more to perform alkaline washing.
〔具体的な説明〕
本発明の処理方法は、塩素含有灰にアルカリを加え、アルカリ濃度１.０mol/L以上の液性でアルカリ洗浄することによって脱塩すると共に該塩素含有灰に含まれるカルシウムを水酸化カルシウムにするアルカリ洗浄工程と、該アルカリ洗浄工程の後に、固液分離して該水酸化カルシウムを含む固形分を回収する固液分離工程を有する脱塩洗浄灰の回収方法において、上記塩素含有灰が難溶性塩素化合物を含むものであり、液温１０℃以上～４０℃未満において、ｐＨ１３.０以上の液性でアルカリ洗浄し、液温４０℃以上～８０℃以下において、ｐＨ１２.５以上の液性でアルカリ洗浄することによって、脱塩洗浄灰の塩素濃度を０.６質量％以下に低減することを特徴とする脱塩洗浄灰の回収方法である。
本発明の処理方法の概略を図１の工程図に示す。
[Specific explanation]
The treatment method of the present invention is a method for recovering desalted washed ash, which comprises an alkali washing step in which chlorine-containing ash is desalted by adding an alkali and washing with an alkali solution having an alkali concentration of 1.0 mol/L or more, and converting calcium contained in the chlorine-containing ash into calcium hydroxide, and a solid-liquid separation step in which solids containing the calcium hydroxide are recovered by solid-liquid separation after the alkali washing step, wherein the chlorine-containing ash contains sparingly soluble chlorine compounds, and the method is characterized in that the chlorine concentration of the desalted washed ash is reduced to 0.6 mass% or less by performing alkali washing at a liquid temperature of 10°C or more and less than 40°C, with a pH of 13.0 or more, and by performing alkali washing at a liquid temperature of 40°C or more and less than 80°C, with a pH of 12.5 or more.
The process of the present invention is outlined in the flow chart of FIG.
本発明の処理方法は塩素含有灰の脱塩と共にカルシウムを固定化して有効に回収する処理方法である。本発明の処理方法において、塩素含有灰は一般廃棄物や産業廃棄物の焼却灰や最終処分場に埋め立て処分された焼却灰あるいはセメント工場から発生するダストなどの塩素を含む灰類を広く含む。 The treatment method of the present invention is a treatment method that demineralizes chlorine-containing ash and simultaneously fixes and effectively recovers calcium. In the treatment method of the present invention, chlorine-containing ash broadly includes chlorine-containing ashes such as incineration ash from general waste or industrial waste, incineration ash landfilled at final disposal sites, or dust generated from cement factories.
＜アルカリ洗浄工程＞
本発明の処理方法は、塩素含有灰に、アルカリ濃度が１.０mol/L以上になるようにアルカリを加えて洗浄することによって、脱塩すると共に該塩素含有灰に含まれるカルシウムを水酸化カルシウムの状態で固形化するアルカリ洗浄工程を有する。
<Alkaline cleaning process>
The treatment method of the present invention includes an alkali washing step in which the chlorine-containing ash is desalted by washing it with an alkali so that the alkali concentration is 1.0 mol/L or more, and the calcium contained in the chlorine-containing ash is solidified in the form of calcium hydroxide.
塩素含有灰に加えるアルカリは溶液でもよく粉末状ないし粒状でもよい。アルカリの種類は水酸化ナトリウム、水酸化カリウムなどの一般的なアルカリ金属の水酸化物を用いることができる。塩素含有灰に洗浄水を加えてスラリー化した後に、アルカリ溶液あるいはアルカリ粉末、粒状アルカリを加えてもいいし、塩素含有灰にアルカリ溶液を直接加えても良い。 The alkali to be added to the chlorine-containing ash may be in the form of a solution, powder, or granules. The type of alkali that can be used may be a common alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. After adding wash water to the chlorine-containing ash to form a slurry, an alkali solution, alkali powder, or granular alkali may be added, or the alkali solution may be added directly to the chlorine-containing ash.
アルカリを加えた塩素含有灰スラリーの液固比は２～２０（液体：固体＝２：１～２０：１）が好ましく、３～１０（液体：固体＝３：１～１０：１）がより好ましい。液固比が２０を超えるとアルカリの添加量が過剰となる。一方、液固比が２未満では液量が少な過ぎて洗浄が不十分になる。液固比が３～１０程度であれば、十分に洗浄して脱塩効果を高めることができ、またフリーデル氏塩などの溶出も進むので、水酸化カルシウムを十分に回収することができる。 The liquid-solid ratio of the chlorine-containing ash slurry to which alkali has been added is preferably 2 to 20 (liquid:solid = 2:1 to 20:1), and more preferably 3 to 10 (liquid:solid = 3:1 to 10:1). If the liquid-solid ratio exceeds 20, the amount of alkali added will be excessive. On the other hand, if the liquid-solid ratio is less than 2, the amount of liquid will be too small and washing will be insufficient. If the liquid-solid ratio is around 3 to 10, sufficient washing can be achieved to improve the desalting effect, and Friedel's salt and other substances will also be eluted, allowing sufficient recovery of calcium hydroxide.
アルカリ濃度が１.０mol/L以上になるようにアルカリを加えて洗浄を行う。アルカリ濃度１.０mol/L以上でアルカリ洗浄することによって塩素含有灰の脱塩が進む。これは、ＯＨ－イオンとフリーデル氏塩などの難溶性塩素化合物に含まれるＣｌ－イオンとのイオン交換反応が起き、塩素の溶出が促進されることによると推察される。Ａｌ(ＯＨ)４－イオン（アルミン酸イオン）が存在すれば同様に脱塩が進む。また強アルカリによって塩素を含むケイ酸化合物が溶解して脱塩が進むことも考えられる。 Washing is performed by adding an alkali so that the alkali concentration becomes 1.0 mol/L or more. By washing with an alkali concentration of 1.0 mol/L or more, desalting of chlorine - containing ash proceeds. This is presumably due to an ion exchange reaction between OH- ions and Cl- ions contained in poorly soluble chlorine compounds such as Friedel's salt, promoting the dissolution of chlorine. If Al(OH) 4- ions (aluminate ions) are present, desalting proceeds in the same way. It is also thought that strong alkali may dissolve chlorine-containing silicate compounds, further promoting desalting.
また、アルカリ濃度が１.０mol/L以上になるようにアルカリを加えて洗浄することによって、塩素含有灰に含まれるカルシウムを水酸化カルシウムの状態で固形化することができる。焼却灰や焼却飛灰などの塩素含有灰に含まれるカルシウムは水酸化カルシウム、炭酸カルシウム、硫酸カルシウムなどの形態で存在しているが、アルカリ濃度１.０mol/L以上のアルカリ洗浄することによって大部分が水酸化カルシウムになる。 In addition, by washing with an alkali added so that the alkali concentration is 1.0 mol/L or more, the calcium contained in the chlorine-containing ash can be solidified in the form of calcium hydroxide. Calcium contained in chlorine-containing ash such as incineration ash and incineration fly ash exists in the form of calcium hydroxide, calcium carbonate, calcium sulfate, etc., but most of it becomes calcium hydroxide when washed with an alkali concentration of 1.0 mol/L or more.
洗浄時のアルカリ濃度が１.０mol/L未満では脱塩が不十分になる。さらにｐＨ７前後では塩素含有灰に含まれる水酸化カルシウムや炭酸カルシウムはｐＨの低下によって溶解して液中に含まれるので、カルシウムを固形化して回収するのが難しくなり、カルシウムの回収率が大幅に低下する。 If the alkali concentration during washing is less than 1.0 mol/L, desalination will be insufficient. Furthermore, at a pH of around 7, the calcium hydroxide and calcium carbonate contained in the chlorine-containing ash will dissolve and be contained in the liquid due to the drop in pH, making it difficult to solidify and recover the calcium, resulting in a significant drop in the calcium recovery rate.
アルカリ濃度が１.０mol/L以上の液性下において、液温が１０℃以上～４０℃未満においてはｐＨ１３.０以上でアルカリ洗浄を行い、液温が４０℃以上～８０℃以下においてはｐＨ１２.５以上でアルカリ洗浄を行うことによって、洗浄灰の塩素濃度を概ね０.６質量％以下に脱塩することがき、また塩素含有灰に含まれるカルシウムを水酸化カルシウムにして固形化することができる。水酸化カルシウムの溶解度は液温の上昇に伴って低下するので、上記液温にすることによって水酸化カルシウムの回収量を増やすことができる。また、ＣＯ２ガスの溶解度も温度の上昇に伴い低下するので、上記液温にすることによってカルシウムの炭酸化を抑制することができる。なお、液温を８０℃より高くする必要はない。 In a liquid having an alkali concentration of 1.0 mol/L or more, when the liquid temperature is 10°C or more but less than 40°C, alkaline washing is performed at pH 13.0 or more, and when the liquid temperature is 40°C or more but less than 80°C, alkaline washing is performed at pH 12.5 or more, whereby the chlorine concentration of the washed ash can be desalted to approximately 0.6 mass% or less, and calcium contained in the chlorine-containing ash can be converted to calcium hydroxide and solidified. Since the solubility of calcium hydroxide decreases with an increase in the liquid temperature, the amount of calcium hydroxide recovered can be increased by setting the liquid temperature at the above range. In addition, since the solubility of CO2 gas also decreases with an increase in temperature, the carbonation of calcium can be suppressed by setting the liquid temperature at the above range. It is not necessary to set the liquid temperature higher than 80°C.
アルカリ洗浄工程は大気中の二酸化炭素の混入によるカルシウムの炭酸化を防ぐために、密閉雰囲気にし、あるいは窒素ガスなどの不活性ガス雰囲気にすることが好ましい。 The alkaline cleaning process is preferably carried out in a sealed atmosphere or in an inert gas atmosphere such as nitrogen gas to prevent carbonation of calcium due to contamination with carbon dioxide from the air.
＜固液分離工程＞
アルカリ洗浄したスラリーを固液分離して固形分を回収する。この固形分には脱塩洗浄灰と共に水酸化カルシウムが含まれている。塩素含有灰に含まれるカルシウム分を水酸化カルシウムにして固定化することによって、概ね８５質量％以上のカルシウム分を回収することができる。
<Solid-liquid separation process>
The alkali-washed slurry is subjected to solid-liquid separation to recover the solids. The solids contain calcium hydroxide together with the desalted washed ash. By converting the calcium contained in the chlorine-containing ash into calcium hydroxide and immobilizing it, it is possible to recover approximately 85% by mass or more of the calcium.
固液分離装置として、フィルタープレス、真空ベルトフィルター、遠心脱水機などを用いることができる。フィルタープレスが使用しやすい。例えば、フィルタープレスで固液分離して得た洗浄灰ケーキを洗浄水で貫通洗浄することによって、脱塩効果をさらに高めることができる。なお、フィルタープレスによって得られる洗浄灰ケーキの含水率は２５～４０％程度と低く、余剰な水分が付着していないため、重量が軽減されてハンドリング性も向上する。発生した洗浄排水は塩素を含むので排水処理して放流するが、フィルタープレスを貫通洗浄して発生した洗浄排水は塩素濃度が低いため、アルカリ洗浄時の洗浄水として循環利用してもよい。 As solid-liquid separation equipment, a filter press, a vacuum belt filter, a centrifugal dehydrator, etc. can be used. A filter press is easy to use. For example, the desalination effect can be further improved by passing the washed ash cake obtained by solid-liquid separation with a filter press through and washing it with washing water. The water content of the washed ash cake obtained by the filter press is low at about 25 to 40%, and since there is no excess water attached, the weight is reduced and handling is improved. The washing wastewater generated contains chlorine and is treated and then discharged, but the washing wastewater generated by passing through and washing the filter press has a low chlorine concentration and can be recycled and reused as washing water for alkaline washing.
本発明の処理方法において、アルカリ洗浄する前に、塩素含有灰を粉砕することによって効率よく脱塩することができる。粉砕装置としては、例えば、振動ミル、ハンマーミルなどがある。粉砕とアルカリ洗浄を同時に行っても良い。また、洗浄処理は多段洗浄でもよく、例えば、まず水洗浄して水に可溶な塩素化合物（ＮａＣｌ、ＫＣｌ、ＣａＣｌ(ＯＨ)、ＣａＣｌ２等）を除去した後に、アルカリ洗浄を行っても良い。 In the treatment method of the present invention, the chlorine-containing ash can be efficiently desalted by crushing it before alkaline washing. Examples of crushing devices include a vibration mill and a hammer mill. Crushing and alkaline washing may be performed simultaneously. The washing process may be a multi-stage washing process, for example, first washing with water to remove water-soluble chlorine compounds (NaCl, KCl, CaCl(OH), CaCl2 , etc.), and then alkaline washing may be performed.
〔処理設備〕
本発明の方法を実施する処理設備の一例を図２に示す。図示する処理設備では、塩素含有灰と洗浄水を受け入れる振動ミル１が設けられている。該振動ミル１において塩素含有灰が適度に粉砕される。該振動ミル１から排出された塩素含有灰スラリーは撹拌洗浄槽２に送られる。該撹拌洗浄槽２にはアルカリ濃度が１.０mol/L以上になるようにアルカリ溶液が供給されて撹拌洗浄される。洗浄後のスラリーはフィルタープレス３に送られる。該フィルタープレス３で脱水処理され、発生した洗浄排水は排水処理設備４に送られる。なお、この洗浄排水をアルカリ洗浄の洗浄水として利用しても良い。一方、脱水ケーキ（脱塩洗浄灰）はセメント製造設備５に送られて再利用される。
[Treatment equipment]
An example of a treatment facility for carrying out the method of the present invention is shown in FIG. 2. The treatment facility shown in the figure is provided with a vibration mill 1 for receiving chlorine-containing ash and washing water. The chlorine-containing ash is appropriately pulverized in the vibration mill 1. The chlorine-containing ash slurry discharged from the vibration mill 1 is sent to an
本発明の方法によれば、アルカリ濃度１.０mol/L以上でアルカリ洗浄することによって、難溶性塩素化合物に含まれる塩素の溶出を促進させて脱塩効果を高めることができ、かつ塩素含有灰中のカルシウムを水酸化カルシウムの状態で固形化することによって、カルシウム分を豊富に含む脱塩洗浄灰を回収することができる。この脱塩洗浄灰はセメント原料の代替物として使用することができる。また、この脱塩洗浄灰に含まれるカルシウムは水酸化物であるため、この脱塩洗浄灰をセメント原料に用いた場合に、ＣＯ２をほとんど排出しないためセメント製造時の低炭素化に大きく貢献する。 According to the method of the present invention, by washing with an alkali at an alkali concentration of 1.0 mol/L or more, it is possible to promote the dissolution of chlorine contained in poorly soluble chlorine compounds and enhance the desalting effect, and by solidifying calcium in the chlorine-containing ash in the form of calcium hydroxide, it is possible to recover desalted washed ash rich in calcium. This desalted washed ash can be used as a substitute for cement raw material. Furthermore, since the calcium contained in this desalted washed ash is hydroxide, when this desalted washed ash is used as a cement raw material, it emits almost no CO2 , which greatly contributes to low carbonization during cement production.
以下、本発明の実施例を比較例と共に示す。回収した洗浄灰のＣｌ濃度は洗浄灰を酸溶解後に溶解液中のＣｌ濃度を電量滴定装置で測定して分析した。回収した洗浄灰のＣａ濃度は蛍光Ｘ線分析（ＸＲＦ）にて測定した。この結果を表１に示す。また、回収した洗浄灰のＸＲＤパターンを図３に示す。 Below, examples of the present invention are shown together with comparative examples. The Cl concentration of the recovered washed ash was analyzed by dissolving the washed ash in acid and then measuring the Cl concentration in the solution using a coulometric titration device. The Ca concentration of the recovered washed ash was measured using X-ray fluorescence analysis (XRF). The results are shown in Table 1. The XRD pattern of the recovered washed ash is also shown in Figure 3.
〔実施例〕
焼却飛灰（Ｃｌ濃度１２.５質量％、Ｃａ濃度２５.９質量％）を１０５℃で乾燥した後に篩分けし、１mm以下の灰１０ｇに純水１００mLを加えて一次洗浄した。この一次洗浄した灰１０ｇに１.０mol/L～３.０mol/Lの水酸化ナトリウム（ＮａＯＨ）溶液１００mLを加えてスラリーにし、液温１０℃～８０℃で振とうし、アルカリ洗浄を行った。このアルカリ洗浄したスラリーを濾過し、洗浄ケーキを回収した。この洗浄ケーキに純水５０mLを加えてケーキ洗浄を行い、脱塩洗浄灰を回収した。この脱塩洗浄灰を１０５℃に乾燥して乾燥脱塩洗浄灰６.１４ｇ～６.５８ｇを回収した（No.Ａ１～Ａ８）。
[Example]
Incineration fly ash (Cl concentration 12.5 mass%, Ca concentration 25.9 mass%) was dried at 105°C and sieved, and 100 mL of pure water was added to 10 g of ash with a size of 1 mm or less for primary washing. 100 mL of 1.0 mol/L to 3.0 mol/L sodium hydroxide (NaOH) solution was added to 10 g of this primary washed ash to make a slurry, and the slurry was shaken at a liquid temperature of 10°C to 80°C for alkaline washing. This alkaline washed slurry was filtered and the washed cake was collected. 50 mL of pure water was added to this washed cake for cake washing, and the desalted washed ash was collected. This desalted washed ash was dried at 105°C and 6.14 g to 6.58 g of dried desalted washed ash was collected (No. A1 to A8).
〔比較例〕
実施例の一次洗浄した灰について、０.１mol/L～０.８mol/Lの水酸化ナトリウム溶液を加えて、液温２５℃でアルカリ洗浄を行った（No.Ｂ１、Ｂ２、Ｂ３）。
実施例の一次洗浄した灰について、水酸化ナトリウム溶液に代えて純水を加え、ｐＨ１２.３の液性下、液温２５℃で水洗浄を行った（No.Ｂ４）。
実施例の一次洗浄した灰について、水酸化ナトリウム溶液に代えて０.７mol/L塩酸を加えてｐＨ７.１に調整し、液温２５℃で塩酸洗浄を行った（No.Ｂ５）。
実施例の一次洗浄した灰について、水酸化ナトリウム溶液に代えて０.１mol/L炭酸ソーダ溶液を加えてｐＨ１２.８の液性下、液温２５℃で炭酸ソーダ洗浄を行った（No.Ｂ６）。
Comparative Example
The primary washed ash of the examples was subjected to alkaline washing at a liquid temperature of 25° C. by adding 0.1 mol/L to 0.8 mol/L of sodium hydroxide solution (Nos. B1, B2, and B3).
The primary washed ash of the example was washed with water at 25° C. under a pH of 12.3 by adding pure water instead of the sodium hydroxide solution (No. B4).
The primary washed ash of the example was adjusted to pH 7.1 by adding 0.7 mol/L hydrochloric acid instead of the sodium hydroxide solution, and was then washed with hydrochloric acid at a liquid temperature of 25° C. (No. B5).
The primary washed ash of the example was subjected to sodium carbonate washing at a liquid temperature of 25° C. and a pH of 12.8 by adding 0.1 mol/L sodium carbonate solution instead of the sodium hydroxide solution (No. B6).
表１に示すように、アルカリ濃度１.０mol/Lでアルカリ洗浄した本発明の試料Ａ１～Ａ８は、何れも洗浄灰のＣｌ濃度は０.６質量％以下に脱塩されており、Ｃａ濃度は３５質量％以上であって、Ｃａ回収率は８５％以上である。
一方、アルカリ洗浄時のアルカリ濃度が１.０mol/L未満の比較試料Ｂ１～Ｂ３は、洗浄灰のＣａ濃度は３５.１～３６.２質量％であり、Ｃａ回収率は８８％～９０％であるが、Ｃｌ濃度は０.６９～０.８６質量％であり脱塩効果が大幅に低い。
さらに、アルカリ洗浄に代えて水洗浄を行った試料Ｂ４は、洗浄灰のＣａ濃度は３２.１質量％であり、Ｃａ回収率は８６％であるが、Ｃｌ濃度は０.８６質量％であり脱塩効果が大幅に低い。
また、アルカリ洗浄に代えて塩酸洗浄を行った試料Ｂ５は、洗浄灰のＣｌ濃度は０.３６質量％であり脱塩効果が高いものの、Ｃａ濃度は２４.４質量％であり、Ｃａ回収率は３８％と大幅に低い。
アルカリ洗浄に代えて炭酸ソーダ洗浄を行った試料Ｂ６は、洗浄灰のＣｌ濃度は０.５４質量％であり脱塩効果が高い。また洗浄灰のＣａ濃度は３３.９質量％であり、Ｃａ回収率は９０％であるが、図３のＸＲＤに示すように、カルシウムの大分部は炭酸カルシウムであるため、回収した洗浄灰をセメント原料に用いると、その製造工程で多量のＣＯ２が発生する。
As shown in Table 1, in all of the samples A1 to A8 of the present invention which were washed with an alkali concentration of 1.0 mol/L, the Cl concentration of the washed ash was desalted to 0.6 mass% or less, the Ca concentration was 35 mass% or more, and the Ca recovery rate was 85% or more.
On the other hand, in the comparative samples B1 to B3 in which the alkali concentration during alkaline washing was less than 1.0 mol/L, the Ca concentration in the washed ash was 35.1 to 36.2 mass%, and the Ca recovery rate was 88% to 90%, but the Cl concentration was 0.69 to 0.86 mass%, and the desalination effect was significantly low.
Furthermore, in sample B4, which was washed with water instead of with alkali, the Ca concentration in the washed ash was 32.1 mass % and the Ca recovery rate was 86%, but the Cl concentration was 0.86 mass %, indicating a significantly low desalination effect.
In addition, in sample B5, which was washed with hydrochloric acid instead of alkaline washing, the Cl concentration in the washed ash was 0.36 mass%, which was a high desalting effect, but the Ca concentration was 24.4 mass%, and the Ca recovery rate was 38%, which was significantly low.
In sample B6, which was washed with sodium carbonate instead of alkali, the Cl concentration in the washed ash was 0.54 mass%, which is a high desalination effect. The Ca concentration in the washed ash was 33.9 mass%, and the Ca recovery rate was 90%. However, as shown in the XRD of Figure 3, most of the calcium is calcium carbonate, so if the recovered washed ash is used as a cement raw material, a large amount of CO2 will be generated during the production process.
Claims (2)
2. A method for recovering desalted washed ash from chlorine-containing ash as described in claim 1, in which alkaline washing is carried out by adding an alkaline solution, alkaline powder or granular alkali to chlorine-containing ash or a water slurry of chlorine-containing ash in a sealed atmosphere or an inert gas atmosphere so that the alkali concentration is 1.0 mol/L or more.
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| JP2003181413A (en) | 2001-12-21 | 2003-07-02 | Dowa Mining Co Ltd | Fly ash treatment method |
| JP2003236497A (en) | 2002-02-15 | 2003-08-26 | Taiheiyo Cement Corp | Waste treatment method |
| JP2005021774A (en) | 2003-06-30 | 2005-01-27 | Taiheiyo Cement Corp | Method and system for treating waste gas from heating furnace for treating waste |
| JP2006334539A (en) | 2005-06-03 | 2006-12-14 | Taiheiyo Cement Corp | Treating method of fine powder containing calcium component and lead component |
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