JP2019011223A - Gypsum and manufacturing method therefor, cement composition and manufacturing method therefor, and foundation improvement material - Google Patents
Gypsum and manufacturing method therefor, cement composition and manufacturing method therefor, and foundation improvement material Download PDFInfo
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- 239000010440 gypsum Substances 0.000 title claims abstract description 122
- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 122
- 239000004568 cement Substances 0.000 title claims abstract description 94
- 239000000203 mixture Substances 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 239000000463 material Substances 0.000 title claims description 13
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims abstract description 78
- 239000002002 slurry Substances 0.000 claims abstract description 74
- 238000000034 method Methods 0.000 claims abstract description 50
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 30
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 29
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 29
- 239000007788 liquid Substances 0.000 claims abstract description 13
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 34
- 239000002245 particle Substances 0.000 claims description 22
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 20
- 150000004683 dihydrates Chemical class 0.000 claims description 17
- 238000002156 mixing Methods 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 13
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 13
- 239000000347 magnesium hydroxide Substances 0.000 claims description 13
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 13
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 10
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 10
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 10
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 9
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 9
- QAOWNCQODCNURD-UHFFFAOYSA-M hydrogensulfate Chemical compound OS([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 claims description 8
- 150000002500 ions Chemical class 0.000 claims description 8
- 239000002893 slag Substances 0.000 claims description 8
- 238000010298 pulverizing process Methods 0.000 claims description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 claims description 5
- 238000007254 oxidation reaction Methods 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 5
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 claims description 4
- 239000011651 chromium Substances 0.000 abstract description 16
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 abstract description 16
- 238000010828 elution Methods 0.000 abstract description 15
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 9
- 229910052804 chromium Inorganic materials 0.000 abstract description 9
- JGIATAMCQXIDNZ-UHFFFAOYSA-N calcium sulfide Chemical compound [Ca]=S JGIATAMCQXIDNZ-UHFFFAOYSA-N 0.000 abstract 2
- 230000000052 comparative effect Effects 0.000 description 14
- 239000011777 magnesium Substances 0.000 description 13
- 239000011398 Portland cement Substances 0.000 description 7
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 6
- 229910052749 magnesium Inorganic materials 0.000 description 6
- 239000000395 magnesium oxide Substances 0.000 description 6
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 6
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000003546 flue gas Substances 0.000 description 3
- 239000002689 soil Substances 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000011400 blast furnace cement Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000007655 standard test method Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 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
- 210000004556 brain Anatomy 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- GBAOBIBJACZTNA-UHFFFAOYSA-L calcium sulfite Chemical compound [Ca+2].[O-]S([O-])=O GBAOBIBJACZTNA-UHFFFAOYSA-L 0.000 description 1
- 235000010261 calcium sulphite Nutrition 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000005649 metathesis reaction Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Abstract
Description
本発明は、石膏及びその製造方法、セメント組成物及びその製造方法、ならびに地盤改良材に関する。 The present invention relates to gypsum and a manufacturing method thereof, a cement composition and a manufacturing method thereof, and a ground improvement material.
セメント系の地盤改良材を用いて地盤の固化処理を行う場合、土質や添加量、強度発現性などの使用条件によっては六価クロムが溶出するおそれがあり、環境への影響が懸念される。セメント系固化材を用いた固化処理土からの六価クロムの溶出抑制方法については、多くの検討がなされており、基本的にはセメントに各種還元剤を添加することで固化処理土からの六価クロムの溶出を低減する方法が知られている（特許文献１〜５参照）。 When solidifying the ground using a cement-based ground improvement material, hexavalent chromium may be eluted depending on the use conditions such as soil quality, amount added, strength development, etc., and there is concern about the impact on the environment. Many studies have been made on methods for suppressing elution of hexavalent chromium from solidified soil using cement-based solidified material. Basically, various reducing agents are added to cement to reduce the amount of hexavalent chromium from solidified soil. Methods for reducing elution of valent chromium are known (see Patent Documents 1 to 5).
ところで、特定種類の石膏を還元剤として使用することも検討されている。例えば、地盤改良材に配合する還元剤として、特許文献１、３，４には、亜硫酸カルシウム（亜硫酸石膏）を使用し得ることが記載されている。しかし、亜硫酸石膏は、二水石膏に比べて、セメントの凝結遅延や強度発現の低下を生じることが知られ、セメントへの利用はされておらず、地盤改良材への利用に限られている。
By the way, the use of a specific type of gypsum as a reducing agent has also been studied. For example,
本発明は、セメントクリンカーに添加され、セメントクリンカーとともにセメント組成物を構成し得る石膏の製造方法であって、セメントクリンカーのクロム含有量が比較的高くても、セメント組成物の硬化体から六価クロムの溶出を十分に抑制するのに有用な石膏の製造方法を提供することを目的とする。また、本発明は、かかる石膏、これを含むセメント組成物及びその製造方法、ならびに当該石膏を含む地盤改良材を提供することを目的とする。 The present invention relates to a method for producing gypsum that can be added to a cement clinker and constitute a cement composition together with the cement clinker, and the hexavalent valence of the cement composition from a cured product, even if the chromium content of the cement clinker is relatively high. An object of the present invention is to provide a method for producing gypsum useful for sufficiently suppressing elution of chromium. Moreover, an object of this invention is to provide this gypsum, the cement composition containing this, its manufacturing method, and the ground improvement material containing the said gypsum.
本発明に係る石膏の製造方法は、二酸化硫黄を含有するガスと、硫酸カルシウム及び水酸化カルシウムを少なくとも含むスラリーとの気液接触工程を経て石膏を製造する方法であり、上記スラリーに含まれる硫酸カルシウムの量を１００質量部とすると、スラリーに含まれる水酸化カルシウムの量が０．２〜１０質量部であり、製造される石膏はＪＩＳ Ｒ９１０１−１９９５に記載の方法に準拠して定量される二酸化硫黄の含有率が０．５〜１５質量％である。 The method for producing gypsum according to the present invention is a method for producing gypsum through a gas-liquid contact process between a gas containing sulfur dioxide and a slurry containing at least calcium sulfate and calcium hydroxide, and sulfuric acid contained in the slurry. When the amount of calcium is 100 parts by mass, the amount of calcium hydroxide contained in the slurry is 0.2 to 10 parts by mass, and the gypsum produced is quantified in accordance with the method described in JIS R9101-1995. The content of sulfur dioxide is 0.5 to 15% by mass.
上記製造方法の気液接触工程は、硫酸カルシウムと、硫酸カルシウムの量を基準として所定量の水酸化カルシウムが共存するスラリーに二酸化硫黄を吸収させる工程である。この工程を実施することにより、上記ＪＩＳの方法に準拠して定量される二酸化硫黄の含有率（以下、場合により、単に「二酸化硫黄の含有率」という。）が０．５〜１５質量％の石膏が得られる。石膏の二酸化硫黄の含有率が０．５質量％以上であることで、当該石膏とセメントクリンカーとを混合してセメント組成物を製造したときに、セメントクリンカーのクロム含有量が比較的高くても、セメントの硬化体から六価クロムが溶出することを十分に抑制できる。他方、石膏の二酸化硫黄の含有率が１５質量％以下であることで、セメントの凝結遅延や強度発現の低下を十分に抑制できる。 The gas-liquid contact step of the production method is a step of absorbing sulfur dioxide in a slurry in which calcium sulfate and a predetermined amount of calcium hydroxide coexist based on the amount of calcium sulfate. By carrying out this step, the sulfur dioxide content determined in accordance with the above JIS method (hereinafter, simply referred to as “sulfur dioxide content” in some cases) is 0.5 to 15% by mass. Gypsum is obtained. When the content of sulfur dioxide in the gypsum is 0.5% by mass or more, when the cement composition is produced by mixing the gypsum and the cement clinker, the chromium content of the cement clinker is relatively high. It is possible to sufficiently suppress the elution of hexavalent chromium from the hardened cement. On the other hand, when the content of sulfur dioxide in gypsum is 15% by mass or less, it is possible to sufficiently suppress the setting delay of cement and a decrease in strength.
本発明に係る石膏の製造方法は、水酸化マグネシウムを使用する以下の態様であってもよい。すなわち、本発明に係る石膏の製造方法は、水酸化マグネシウムと、硫酸カルシウムと、水酸化カルシウムとを少なくとも含む第１のスラリーを調製する第１工程と、二酸化硫黄を含有するガスと、第１のスラリーとを気液接触させることによって、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンと、石膏とを含む第２のスラリーを得る第２工程と、第２のスラリーを固液分離することによって、石膏を回収するとともに、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンとを含む第３のスラリーを得る第３工程とを含み、第１のスラリーに含まれる硫酸カルシウムの量を１００質量部とすると、第１のスラリーに含まれる水酸化カルシウムの量が０．２〜１０質量部であり、第３工程で得られる石膏は、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準じて定量される二酸化硫黄の含有率が０．５〜１５質量％である。 The method for producing gypsum according to the present invention may be the following embodiment using magnesium hydroxide. That is, the method for producing gypsum according to the present invention includes a first step of preparing a first slurry containing at least magnesium hydroxide, calcium sulfate, and calcium hydroxide, a gas containing sulfur dioxide, A second step of obtaining a second slurry containing magnesium ion, at least one ion of sulfate ion, sulfite ion and hydrogensulfate ion, and gypsum by bringing the slurry into gas-liquid contact; A third step of recovering gypsum by solid-liquid separation and obtaining a third slurry containing magnesium ions and at least one ion of sulfate ions, sulfite ions and hydrogen sulfate ions, When the amount of calcium sulfate contained in the slurry is 100 parts by mass, calcium hydroxide contained in the first slurry The amount is 0.2 to 10 parts by mass, and the gypsum obtained in the third step has a sulfur dioxide content determined in accordance with the method described in JIS R9101-1995 of 0.5 to 15% by mass. .
この製造方法は、排煙脱硫プロセスの一態様である「水酸化マグネシウム−石膏法」を変形し、六価クロムの溶出を抑制し得る石膏を製造できるようにしたものである。すなわち、この製造方法の第２工程は、硫酸カルシウムと、この硫酸カルシウムの量を基準として所定量の水酸化カルシウムが共存する第１のスラリーに二酸化硫黄を吸収させる工程である。この工程を実施することにより、二酸化硫黄の含有率が０．５〜１５質量％の石膏が得られる。 This production method is a modification of the “magnesium hydroxide-gypsum method”, which is an embodiment of the flue gas desulfurization process, and can produce gypsum that can suppress elution of hexavalent chromium. That is, the second step of the manufacturing method is a step of absorbing sulfur dioxide in the first slurry in which calcium sulfate and a predetermined amount of calcium hydroxide coexist based on the amount of calcium sulfate. By carrying out this step, a gypsum having a sulfur dioxide content of 0.5 to 15% by mass is obtained.
水酸化マグネシウムを使用する上記態様の石膏の製造方法は、二酸化硫黄との接触によって硫酸マグネシウムとなった水酸化マグネシウムを再生する工程をさらに含むことが好ましい。かかる態様の石膏の製造方法は、第３のスラリーの少なくとも一部に対して酸化処理を施すことを経ることによって、硫酸マグネシウムを含む第４のスラリーを得る第４工程と、第４のスラリーに水酸化カルシウムを添加することによって、硫酸マグネシウムから再生された水酸化マグネシウムと、二水石膏と、水酸化カルシウムとを含む第５のスラリーを得る第５工程とを含み、第１のスラリーに含まれる硫酸カルシウムは、第５のスラリーに含まれる二水石膏の少なくとも一部である。 It is preferable that the method for producing gypsum of the above aspect using magnesium hydroxide further includes a step of regenerating magnesium hydroxide which has been converted to magnesium sulfate by contact with sulfur dioxide. The gypsum manufacturing method of this aspect includes a fourth step of obtaining a fourth slurry containing magnesium sulfate by subjecting at least a part of the third slurry to an oxidation treatment, and a fourth slurry. A fifth step of obtaining a fifth slurry containing magnesium hydroxide regenerated from magnesium sulfate, dihydrate gypsum, and calcium hydroxide by adding calcium hydroxide is included in the first slurry. Calcium sulfate is at least part of dihydrate gypsum contained in the fifth slurry.
本発明はＪＩＳ Ｒ９１０１−１９９５に記載の方法に準拠して定量される二酸化硫黄の含有率が０．５〜１５質量％である石膏を提供する。また、本発明は、この石膏と、セメントクリンカーとを含む、セメント組成物を提供する。さらに、本発明は、この石膏と、セメントクリンカーとを混合する工程を含む、セメント組成物の製造方法を提供する。六価クロムの溶出をより一層低減する観点から、石膏とセメントクリンカーとを混合する工程において、混合処理とともに粉砕処理も実施することが好ましい。 This invention provides the gypsum whose content rate of sulfur dioxide quantified based on the method as described in JISR9101-1995 is 0.5-15 mass%. The present invention also provides a cement composition comprising the gypsum and a cement clinker. Furthermore, this invention provides the manufacturing method of a cement composition including the process of mixing this gypsum and a cement clinker. From the viewpoint of further reducing the elution of hexavalent chromium, it is preferable to perform a pulverization process as well as a mixing process in the step of mixing gypsum and cement clinker.
本発明に係るセメント組成物は、ＪＩＳ Ｒ５２０２：２０１０に記載の方法に準じて定量されるＳＯ３量が１．５〜１５質量％であり、当該セメント組成物を構成する粒子が粒径１０μｍ以下の粒子を含み、当該セメント組成物の全体に含まれるＳＯ３量を１００質量部とすると、粒径１０μｍ以下の粒子に含まれるＳＯ３量が３０質量部以上であることが好ましい。これらの条件を満たすセメント組成物によれば、六価クロムの溶出をより一層低減することができる。 In the cement composition according to the present invention, the amount of SO 3 quantified according to the method described in JIS R5202: 2010 is 1.5 to 15% by mass, and the particles constituting the cement composition have a particle size of 10 μm or less. When the amount of SO 3 contained in the cement composition is 100 parts by mass, the amount of SO 3 contained in particles having a particle size of 10 μm or less is preferably 30 parts by mass or more. According to the cement composition satisfying these conditions, the elution of hexavalent chromium can be further reduced.
本発明は、上記セメント組成物と、無水石膏及び高炉スラグの少なくとも一方とを含む地盤改良材を提供する。 The present invention provides a ground improvement material comprising the cement composition and at least one of anhydrous gypsum and blast furnace slag.
本発明によれば、セメントクリンカーに添加され、セメントクリンカーとともにセメント組成物を構成し得る石膏の製造方法であって、セメントクリンカーのクロム含有量が比較的高くても、セメント組成物の硬化体から六価クロムの溶出を十分に抑制するのに有用な石膏の製造方法が提供される。また、本発明によれば、かかる石膏、これを含むセメント組成物及びその製造方法、ならびに当該石膏を含む地盤改良材が提供される。 According to the present invention, there is provided a method for producing gypsum that can be added to a cement clinker and constitute a cement composition together with the cement clinker, even if the cement clinker has a relatively high chromium content. A method for producing gypsum useful for sufficiently suppressing elution of hexavalent chromium is provided. Moreover, according to this invention, this gypsum, the cement composition containing this, its manufacturing method, and the ground improvement material containing the said gypsum are provided.
以下、本発明の実施形態について説明する。なお、本発明は以下の実施形態に限定されるものではない。 Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment.
＜石膏の製造方法＞
図１は、本実施形態に係る石膏の製造方法のフローを示す模式図である。この製造方法は、排煙脱硫プロセスの一態様である「水酸化マグネシウム−石膏法」を変形し、六価クロムの溶出を抑制し得る石膏を製造できるようにしたものであって、以下の工程を含む。
・水酸化マグネシウムと、二水石膏（硫酸カルシウム）と、水酸化カルシウムとを少なくとも含む第１のスラリーを調製する第１工程。
・二酸化硫黄を含有するガスと、第１のスラリーとを気液接触させることによって、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンと、石膏とを含む第２のスラリーを得る第２工程。
・第２のスラリーを固液分離することによって、石膏を回収するとともに、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンとを含む第３のスラリーを得る第３工程。
・第３のスラリーの少なくとも一部に対して酸化処理を施すことを経ることによって、硫酸マグネシウムを含む第４のスラリーを得る第４工程。
・第４のスラリーに水酸化カルシウムを添加することによって、硫酸マグネシウムから再生された水酸化マグネシウムと、二水石膏と、水酸化カルシウムとを含む第５のスラリーを得る第５工程。
<Gypsum production method>
Drawing 1 is a mimetic diagram showing the flow of the manufacturing method of gypsum concerning this embodiment. This production method is a modification of the “magnesium hydroxide-gypsum method”, which is an aspect of the flue gas desulfurization process, and is capable of producing gypsum that can suppress elution of hexavalent chromium. including.
A first step of preparing a first slurry containing at least magnesium hydroxide, dihydrate gypsum (calcium sulfate), and calcium hydroxide.
A second slurry containing magnesium ion, at least one ion of sulfate ion, sulfite ion and hydrogen sulfate ion, and gypsum by bringing the gas containing sulfur dioxide into contact with the first slurry in a gas-liquid contact. A second step of obtaining
-The 3rd process of obtaining the 3rd slurry containing magnesium ion and at least 1 sort of ion of sulfate ion, sulfite ion, and hydrogen sulfate ion while collecting gypsum by carrying out solid-liquid separation of the 2nd slurry.
A fourth step of obtaining a fourth slurry containing magnesium sulfate by subjecting at least a part of the third slurry to an oxidation treatment.
A fifth step of obtaining a fifth slurry containing magnesium hydroxide regenerated from magnesium sulfate, dihydrate gypsum, and calcium hydroxide by adding calcium hydroxide to the fourth slurry.
（第１工程）
第１工程は、水酸化マグネシウム（Ｍｇ（ＯＨ）２）と、二水石膏（ＣａＳＯ４・２Ｈ２Ｏ）と、水酸化カルシウム（Ｃａ（ＯＨ）２）とを少なくとも含む第１のスラリーを調製する工程である。本実施形態に係る第１のスラリーは、第５工程で得られる第５のスラリーの成分を必要に応じて調整して得られるものであって、ガスに含まれる二酸化硫黄を吸収させるためのものである（第２工程における反応式（１）〜（４）参照）。なお、二酸化硫黄を含むガスの一例として、石炭火力発電所の排ガスが挙げられる。
(First step)
The first step prepares a first slurry containing at least magnesium hydroxide (Mg (OH) 2 ), dihydrate gypsum (CaSO 4 .2H 2 O), and calcium hydroxide (Ca (OH) 2 ). It is a process to do. The first slurry according to this embodiment is obtained by adjusting the components of the fifth slurry obtained in the fifth step as necessary, and is for absorbing sulfur dioxide contained in the gas. (Refer to the reaction formulas (1) to (4) in the second step). An example of the gas containing sulfur dioxide is exhaust gas from a coal-fired power plant.
第１のスラリーに含まれる水の質量を１００質量部とすると、第２工程において二酸化硫黄を効率的に吸収する観点から、水酸化マグネシウムの量は３〜４０質量部であることが好ましく、４〜２０質量部であることがより好ましく、４〜１０質量部であることがさらに好ましい。 When the mass of water contained in the first slurry is 100 parts by mass, the amount of magnesium hydroxide is preferably 3 to 40 parts by mass from the viewpoint of efficiently absorbing sulfur dioxide in the second step. More preferably, it is -20 mass parts, and it is further more preferable that it is 4-10 mass parts.
第１のスラリーに含まれる二水石膏の量を１００質量部とすると、第１のスラリーに含まれる水酸化カルシウムの量は、第２工程においてＪＩＳ Ｒ９１０１−１９９５に記載の方法に準じて定量される二酸化硫黄の含有率（ＳＯ２量）が所定量である石膏を得る観点から、０．２〜１０質量部であり、０．５〜７質量部が好ましく、１．０〜５質量部がより好ましい。 When the amount of dihydrate gypsum contained in the first slurry is 100 parts by mass, the amount of calcium hydroxide contained in the first slurry is quantified in the second step according to the method described in JIS R9101-1995. From the viewpoint of obtaining gypsum whose sulfur dioxide content (SO 2 amount) is a predetermined amount, it is 0.2 to 10 parts by mass, preferably 0.5 to 7 parts by mass, and 1.0 to 5 parts by mass. More preferred.
（第２工程）
第２工程は、二酸化硫黄を含有するガスと、第１のスラリーとを気液接触させることによって、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンと、石膏とを含む第２のスラリーを得る工程である。換言すれば、第２工程は「水酸化マグネシウム−石膏法」における吸収工程に相当するものであり、ガスに含まれる二酸化硫黄を理論的には（１）〜（４）の反応と、（５）の反応が同時に進むことによってスラリーに吸収させる工程である。この工程は、水酸化マグネシウム−石膏法で用いられる吸収塔にガス及び第１のスラリーをそれぞれ供給することで実施することができる。なお、理論的には（５）のように亜硫酸石膏が生成する反応が進むが、本実施形態のプロセスではスラリー中に含まれる二水石膏を核として、亜硫酸イオンはこの二水石膏の結晶中にＳＯ４ ２−イオンとＳＯ３ ２−イオンとが置換する形で取り込まれ、セメント品質に悪影響を及ぼさない形態となると推測される。
Ｈ２Ｏ＋ＳＯ２→Ｈ２ＳＯ３ （１）
Ｈ２ＳＯ３＋Ｍｇ（ＯＨ）２→ＭｇＳＯ３＋２Ｈ２Ｏ （２）
ＭｇＳＯ３＋ＳＯ２＋Ｈ２Ｏ→Ｍｇ（ＨＳＯ３）２ （３）
Ｍｇ（ＨＳＯ３）２＋Ｍｇ（ＯＨ）２→２ＭｇＳＯ３＋２Ｈ２Ｏ （４）
ＳＯ２＋Ｃａ（ＯＨ）２→ＣａＳＯ３・１／２Ｈ２Ｏ＋１／２Ｈ２Ｏ （５）
(Second step)
The second step includes magnesium ion, at least one ion of sulfate ion, sulfite ion, and hydrogen sulfate ion, and gypsum by bringing the gas containing sulfur dioxide into contact with the first slurry in a gas-liquid contact. This is a step of obtaining a second slurry. In other words, the second step corresponds to the absorption step in the “magnesium hydroxide-gypsum method”, and the sulfur dioxide contained in the gas is theoretically converted to the reactions (1) to (4) and (5 ) Is absorbed in the slurry by proceeding simultaneously. This step can be carried out by supplying the gas and the first slurry to the absorption tower used in the magnesium hydroxide-gypsum method. Theoretically, the reaction for generating sulfite gypsum proceeds as in (5). In the process of this embodiment, dihydrate gypsum contained in the slurry is used as a nucleus, and sulfite ions are contained in the crystal of this dihydrate gypsum. It is presumed that SO 4 2− ions and SO 3 2− ions are incorporated in the form of substitution, and the form does not adversely affect the cement quality.
H 2 O + SO 2 → H 2 SO 3 (1)
H 2 SO 3 + Mg (OH) 2 → MgSO 3 + 2H 2 O (2)
MgSO 3 + SO 2 + H 2 O → Mg (HSO 3 ) 2 (3)
Mg (HSO 3 ) 2 + Mg (OH) 2 → 2MgSO 3 + 2H 2 O (4)
SO 2 + Ca (OH) 2 → CaSO 3 · 1 / 2H 2 O + 1 / 2H 2 O (5)
（第３工程）
第３工程は、第２のスラリーを固液分離することによって、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準じて定量される二酸化硫黄の含有率（ＳＯ２量）が０．５〜１５質量％である石膏を回収するとともに、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンとを含む第３のスラリーを得る工程である。固液分離処理は、例えば、ハイドロサイクロン、脱水機、フィルタープレスなどを用いて実施することができ、これらのうち、一種を単独で用いてもよく、一種を複数直列に配置して用いてもよく、二種以上を併用してもよい。
(Third step)
In the third step, the second slurry is subjected to solid-liquid separation so that the sulfur dioxide content (SO 2 amount) quantified in accordance with the method described in JIS R9101-1995 is 0.5 to 15% by mass. This is a step of collecting a certain gypsum and obtaining a third slurry containing magnesium ions and at least one ion of sulfate ions, sulfite ions and hydrogen sulfate ions. The solid-liquid separation treatment can be performed using, for example, a hydrocyclone, a dehydrator, a filter press, and the like. Among these, one type may be used alone, or a plurality of types may be arranged in series. Well, you may use 2 or more types together.
第３工程で得られる石膏は、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準じて定量される二酸化硫黄の含有率（ＳＯ２量）が０．５〜１５質量％であり、１．５〜５質量％であることが好ましく、１．６〜４質量％であることがより好ましく、２〜３質量％であることがさらに好ましい。石膏の二酸化硫黄の含有率が０．５質量％以上であることで、当該混合物を洗浄等して得た石膏とセメントクリンカーとを混合してセメント組成物を製造したときに、セメントクリンカーのクロム含有量が比較的高くても、セメントの硬化体から六価クロムが溶出することを十分に抑制できる。他方、石膏の二酸化硫黄の含有率が１５質量％以下であることで、セメントの凝結遅延や強度発現の低下を十分に抑制できる。 The gypsum obtained in the third step has a sulfur dioxide content (SO 2 amount) quantified according to the method described in JIS R9101-1995 of 0.5 to 15% by mass, and 1.5 to 5% by mass. %, More preferably 1.6 to 4% by mass, and still more preferably 2 to 3% by mass. When the content of sulfur dioxide in the gypsum is 0.5% by mass or more, when the cement composition is manufactured by mixing the gypsum obtained by washing the mixture and the cement clinker, the chromium of the cement clinker Even if the content is relatively high, the elution of hexavalent chromium from the hardened cement can be sufficiently suppressed. On the other hand, when the content of sulfur dioxide in gypsum is 15% by mass or less, it is possible to sufficiently suppress the setting delay of cement and a decrease in strength.
（第４工程）
第４工程は、第３のスラリーの少なくとも一部に対して酸化処理を施すことを経ることによって、硫酸マグネシウム（マグネシウムイオン及び硫酸イオン）を含む第４のスラリーを得る工程である。この工程は、水酸化マグネシウム−石膏法で用いられる酸化塔に第３のスラリーを供給することで実施することができる。
ＭｇＳＯ３＋１／２Ｏ２→ＭｇＳＯ４ （６）
（ＳＯ３ ２−＋１／２Ｏ２→ＳＯ４ ２−）
Ｍｇ（ＨＳＯ３）２＋Ｏ２→ＭｇＳＯ４＋Ｈ２ＳＯ４ （７）
（２ＨＳＯ３ −＋Ｏ２→ＳＯ４ ２−＋Ｈ２ＳＯ４）
(4th process)
The fourth step is a step of obtaining a fourth slurry containing magnesium sulfate (magnesium ions and sulfate ions) by subjecting at least a part of the third slurry to an oxidation treatment. This step can be performed by supplying the third slurry to the oxidation tower used in the magnesium hydroxide-gypsum method.
MgSO 3 + 1 / 2O 2 → MgSO 4 (6)
(SO 3 2− + 1 / 2O 2 → SO 4 2− )
Mg (HSO 3 ) 2 + O 2 → MgSO 4 + H 2 SO 4 (7)
(2HSO 3 − + O 2 → SO 4 2− + H 2 SO 4 )
（第５工程）
第５工程は、第４のスラリーに水酸化カルシウムを添加することによって、硫酸マグネシウムから再生された水酸化マグネシウムと、二水石膏と、水酸化カルシウムとを含む第５のスラリーを得る工程である。この工程は、水酸化マグネシウム−石膏法で用いられる複分解槽に第４のスラリーを供給することで実施することができる。
ＭｇＳＯ４＋Ｃａ（ＯＨ）２＋Ｈ２Ｏ→ＣａＳＯ４・２Ｈ２Ｏ＋Ｍｇ（ＯＨ）２ （８）
(5th process)
The fifth step is a step of obtaining a fifth slurry containing magnesium hydroxide regenerated from magnesium sulfate, dihydrate gypsum, and calcium hydroxide by adding calcium hydroxide to the fourth slurry. . This step can be performed by supplying the fourth slurry to the metathesis tank used in the magnesium hydroxide-gypsum method.
MgSO 4 + Ca (OH) 2 + H 2 O → CaSO 4 .2H 2 O + Mg (OH) 2 (8)
第５工程において、第４のスラリー中の硫酸マグネシウムに対してモル比で過剰量の水酸化カルシウムを添加することによって、水酸化マグネシウムと、二水石膏と、水酸化カルシウムとを含む第５のスラリーを得ることができる。この第５のスラリーに含まれる成分量を必要に応じて調整することで第１のスラリーを得ることができる。 In the fifth step, by adding an excessive amount of calcium hydroxide in a molar ratio with respect to magnesium sulfate in the fourth slurry, a fifth step containing magnesium hydroxide, dihydrate gypsum, and calcium hydroxide is performed. A slurry can be obtained. The first slurry can be obtained by adjusting the amount of components contained in the fifth slurry as necessary.
＜石膏＞
本実施形態に係る石膏は、上記の第３工程において固形分として回収され、二水石膏を主成分として含有するものである。この石膏は、上述のとおり、二酸化硫黄の含有率が所定の範囲（０．５〜１５質量％）であり、石膏とセメントクリンカーとを混合してセメント組成物を製造したときに、セメントクリンカーのクロム含有量が比較的高くても、セメントの硬化体から六価クロムが溶出することを十分に抑制できる。なお、石膏全体における二酸化硫黄の含有率が所定の範囲（０．５〜１５質量％）となる限りにおいては、二酸化硫黄の含有率が０．５質量％未満の石膏や１５質量％超の石膏を更に加えてもよい。
<Gypsum>
The gypsum according to the present embodiment is recovered as a solid content in the third step and contains dihydrate gypsum as a main component. As described above, this gypsum has a sulfur dioxide content in a predetermined range (0.5 to 15% by mass), and when a cement composition is produced by mixing gypsum and a cement clinker, Even if the chromium content is relatively high, the elution of hexavalent chromium from the hardened cement can be sufficiently suppressed. In addition, as long as the content rate of sulfur dioxide in the whole gypsum falls within a predetermined range (0.5 to 15% by mass), the content rate of sulfur dioxide is less than 0.5% by mass and gypsum exceeding 15% by mass. May be further added.
本実施形態に係る石膏は、酸化マグネシウム（ＭｇＯ）の含有量が０．３質量％未満であることが好ましく、０．２質量％未満であることがより好ましい。酸化マグネシウムの含有量が０．３質量％未満であることにより、凝結遅延などの悪影響が回避されるという効果が奏される。 In the gypsum according to this embodiment, the content of magnesium oxide (MgO) is preferably less than 0.3% by mass, and more preferably less than 0.2% by mass. When the content of magnesium oxide is less than 0.3% by mass, there is an effect that adverse effects such as setting delay can be avoided.
＜セメント組成物＞
上記石膏と、セメントクリンカーとを混合することによってセメント組成物を製造することができる。六価クロムの溶出をより一層低減する観点から、石膏とセメントクリンカーとを混合する工程において、混合処理とともに粉砕処理も実施することが好ましい。セメントクリンカー１００質量部に対し、石膏の配合量は１．５〜２０．０質量部程度、好ましくは１．５〜６．０質量部程度とすればよい。上述のとおり、本実施形態に係る石膏によれば、セメントの硬化体から六価クロムが溶出することを十分に抑制できるため、セメントクリンカーの全クロム含有量は、例えば、５０〜２５０ｍｇ／ｋｇであってもよく、１００〜２００ｍｇ／ｋｇであってもよく、水溶性六価クロム量は、例えば、３〜４０ｍｇ／ｋｇであってもよく、１０〜４０ｍｇ／ｋｇであってもよく、２０〜３０ｍｇ／ｋｇであってもよい。
<Cement composition>
A cement composition can be produced by mixing the gypsum and a cement clinker. From the viewpoint of further reducing the elution of hexavalent chromium, it is preferable to perform a pulverization process as well as a mixing process in the step of mixing gypsum and cement clinker. The blending amount of gypsum is about 1.5 to 20.0 parts by mass, preferably about 1.5 to 6.0 parts by mass with respect to 100 parts by mass of cement clinker. As described above, according to the gypsum according to the present embodiment, the elution of hexavalent chromium from the hardened cement can be sufficiently suppressed, and therefore the total chromium content of the cement clinker is, for example, 50 to 250 mg / kg. The amount of water-soluble hexavalent chromium may be, for example, 3 to 40 mg / kg, 10 to 40 mg / kg, or 20 to 20 mg / kg. It may be 30 mg / kg.
本実施形態に係るセメント組成物は、ＪＩＳ Ｒ５２０２：２０１０に記載の方法に準じて定量されるＳＯ３量が１．５〜１５質量％であり、当該セメント組成物を構成する粒子が粒径１０μｍ以下の粒子を含み、当該セメント組成物の全体に含まれるＳＯ３量を１００質量部とすると、粒径１０μｍ以下の粒子に含まれるＳＯ３量が３０質量部以上であることが好ましい。これらの条件を満たすセメント組成物によれば、六価クロムの溶出をより一層低減することができる。 In the cement composition according to this embodiment, the amount of SO 3 quantified according to the method described in JIS R5202: 2010 is 1.5 to 15% by mass, and the particles constituting the cement composition have a particle size of 10 μm. When the amount of SO 3 contained in the cement composition including the following particles is 100 parts by mass, the amount of SO 3 contained in particles having a particle size of 10 μm or less is preferably 30 parts by mass or more. According to the cement composition satisfying these conditions, the elution of hexavalent chromium can be further reduced.
粉砕処理後のセメント組成物のブレーン比表面積は２５００〜６０００ｃｍ２／ｇが好ましく、３０００〜５０００ｃｍ２／ｇがより好ましい。ブレーン比表面積が２５００ｃｍ２／ｇ以上であることで、優れた強度発現性を達成しやすく、他方、６０００ｃｍ２／ｇ以下であることで、コンクリートや固化材スラリーとして使用したときの粘性が施工上問題ない範囲に制御しやすい。 Blaine specific surface area of the cement composition after pulverization treatment 2500~6000cm 2 / g are preferred, 3000~5000cm 2 / g is more preferable. By Blaine specific surface area of 2500 cm 2 / g or more, excellent strength development of easy to achieve, on the other hand, it is less 6000 cm 2 / g, viscosity on construction when used as a concrete or solidifying material slurry Easy to control within a safe range.
なお、セメント組成物の種類としては特に制限はなく、普通ポルトランドセメント、早強ポルトランドセメント、超早強ポルトランドセメント、耐硫酸塩ポルトランドセメント、中庸熱ポルトランドセメント、低熱ポルトランドセメント、高炉セメント、フライアッシュセメント、シリカフュームセメント、アルミナセメント等のいずれであってもよい。 In addition, there is no restriction | limiting in particular as a kind of cement composition, Ordinary Portland cement, early strength Portland cement, super early strength Portland cement, sulfate-resistant Portland cement, moderately hot Portland cement, low heat Portland cement, blast furnace cement, fly ash cement Any of silica fume cement, alumina cement and the like may be used.
＜地盤改良材＞
本実施形態に係る地盤改良材は、上記セメント組成物と、無水石膏及び高炉スラグの少なくとも一方とを含むものである。無水石膏及び高炉スラグの一方を配合する場合、セメント組成物の量を１００質量部とすると、無水石膏の配合量は３〜２０質量部であることが好ましく、５〜１５質量部であることが好ましく、高炉スラグの配合量は２〜５０質量部であることが好ましく、５〜３０質量部であることが好ましい。無水石膏と高炉スラグとを併用する場合、セメント組成物の量を１００質量部とすると、両者の合計の配合量は５〜６０質量部であることが好ましく、２０〜５０質量部であることが好ましく、高炉スラグの配合量は２〜４０質量部であることが好ましく、５〜３０質量部であることが好ましい。
<Ground improvement material>
The ground improvement material according to the present embodiment includes the cement composition and at least one of anhydrous gypsum and blast furnace slag. When blending one of anhydrous gypsum and blast furnace slag, when the amount of the cement composition is 100 parts by mass, the amount of anhydrous gypsum is preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass. Preferably, the blending amount of the blast furnace slag is preferably 2 to 50 parts by mass, and more preferably 5 to 30 parts by mass. When anhydrous gypsum and blast furnace slag are used in combination, when the amount of the cement composition is 100 parts by mass, the total amount of both is preferably 5 to 60 parts by mass, and preferably 20 to 50 parts by mass. Preferably, the blending amount of blast furnace slag is preferably 2 to 40 parts by mass, and more preferably 5 to 30 parts by mass.
以上、本発明の実施形態について詳細に説明したが、本発明は上記実施形態に限定されるものではない。 As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment.
＜石膏の製造＞
（実施例１，２）
上記実施形態に係る製造方法により、石炭火力発電所からの二酸化硫黄を含む排ガスから排煙脱硫石膏を連続的に製造した。実施例１，２に係る石膏は、第１のスラリーに含まれる二水石膏１００質量部に対し、第１のスラリーに含まれる水酸化カルシウムの量が１〜１０質量部の範囲内となるように、第５工程において水酸化カルシウムの添加量を調整して操業しているときに、別々のタイミングで採取したものである。なお、主に、排ガスに含まれる二酸化硫黄の量の変動に応じて、添加する水酸化カルシウムの量を調整した。
<Manufacture of gypsum>
(Examples 1 and 2)
By the manufacturing method which concerns on the said embodiment, flue gas desulfurization gypsum was continuously manufactured from the waste gas containing sulfur dioxide from a coal thermal power plant. In the gypsum according to Examples 1 and 2, the amount of calcium hydroxide contained in the first slurry is within the range of 1 to 10 parts by mass with respect to 100 parts by mass of dihydrate gypsum contained in the first slurry. In addition, the sample was collected at different timings when the calcium hydroxide was added and operated in the fifth step. The amount of calcium hydroxide to be added was adjusted mainly in accordance with the variation in the amount of sulfur dioxide contained in the exhaust gas.
（比較例１〜３）
比較例１〜３に係る石膏は、第１のスラリーに含まれる二水石膏１００質量部に対し、第１のスラリーに含まれる水酸化カルシウムの量が０．５質量部未満となるように、第５工程において水酸化カルシウムの添加量を調整して操業しているときに、別々のタイミングで採取したものである。
(Comparative Examples 1-3)
The gypsum according to Comparative Examples 1 to 3 is such that the amount of calcium hydroxide contained in the first slurry is less than 0.5 parts by mass with respect to 100 parts by mass of dihydrate gypsum contained in the first slurry. The sample was collected at different timings when the calcium hydroxide was added and operated in the fifth step.
（比較例４〜１２）
比較例４〜１２に係る石膏は、いわゆる石灰・石膏法によってそれぞれ製造したものである。すなわち、石灰の微粉を含むスラリーに、二酸化硫黄を含む排ガスを通し、これを空気で酸化して二水石膏を得た。
(Comparative Examples 4 to 12)
The gypsum according to Comparative Examples 4 to 12 is produced by a so-called lime / gypsum method. That is, exhaust gas containing sulfur dioxide was passed through a slurry containing lime fine powder, and this was oxidized with air to obtain dihydrate gypsum.
＜石膏の評価＞
実施例及び比較例に係る石膏について以下の評価を行った。表１に結果を示す。
（１）強熱減量（ｉｇ．ｌｏｓｓ）の測定
石膏の強熱減量（ｉｇ．ｌｏｓｓ）は、ＪＩＳ Ｒ ５２０２：２０１０の「５．強熱減量の定量方法」における「５．２ 高炉セメント及び高炉スラグ以外の場合」に記載の方法に準拠して測定した。
（２）ＳＯ３量の測定
石膏のＳＯ３量は、ＪＩＳ Ｒ ５２０２：２０１０に記載の方法に準拠して測定した。
（３）二酸化硫黄含有率（ＳＯ２量）の測定
石膏のＳＯ２量は、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準拠して定量した。なお、実施例及び比較例に係る全ての石膏のＸ線回折をＸ線回折装置（リガク社製、型番ＲＩＮＴ２０００）で確認したところ、明確な回折ピークは認められなかった（図２参照）。
（４）酸化マグネシウム含有率（ＭｇＯ量）の測定
ＭｇＯ量は、ＪＩＳ Ｒ５２０２：２０１０に記載の方法に準拠して測定した。
<Evaluation of gypsum>
The following evaluation was performed about the gypsum which concerns on an Example and a comparative example. Table 1 shows the results.
(1) Measurement of ignition loss (ig.loss) The ignition loss (ig.loss) of gypsum is described in "5.2 Blast furnace cement and blast furnace" in "5. Determination method of ignition loss" of JIS R 5202: 2010. The measurement was performed in accordance with the method described in “Other than Slag”.
(2) SO 3 content of SO 3 of the measurement gypsum, JIS R 5202: This was measured according to the method described in 2010.
(3) SO 2 amount measured gypsum sulfur dioxide content (SO 2 amount) was quantified according to the method described in JIS R9101-1995. In addition, when X-ray diffraction of all the gypsum which concerns on an Example and a comparative example was confirmed with the X-ray-diffraction apparatus (the Rigaku company make, type | model number RINT2000), the clear diffraction peak was not recognized (refer FIG. 2).
(4) Measurement of magnesium oxide content (MgO amount) The MgO amount was measured according to the method described in JIS R5202: 2010.
＜セメント組成物の製造＞
（実施例１，２及び比較例１〜１２）
全Ｃｒ含有量が１０１ｍｇ／ｋｇ、石膏無添加時の水溶性Ｃｒ（ＶＩ）量が１３ｍｇ／ｋｇであるセメントクリンカーに、実施例及び比較例に係る石膏をそれぞれ内割りで３．５質量部添加し、計１４種類のセメント組成物を製造した。セメントの粉砕は、５ｍｍ以下のクリンカーと、石膏とを、振動ミルで混合粉砕した。ブレーン比表面積は３２００±１５０ｃｍ２／ｇとした。
<Manufacture of cement composition>
(Examples 1 and 2 and Comparative Examples 1 to 12)
The cement clinker having a total Cr content of 101 mg / kg and a water-soluble Cr (VI) content of 13 mg / kg when no gypsum is added is added with 3.5 parts by mass of the gypsum according to Examples and Comparative Examples. A total of 14 cement compositions were manufactured. Crushing of the cement was performed by mixing and grinding a clinker of 5 mm or less and gypsum with a vibration mill. The Blaine specific surface area was 3200 ± 150 cm 2 / g.
（実施例３）
粉砕方法を変更したこと以外は実施例１と同様にして実施例３に係るセメント組成物を作製した。すなわち、本実施例においては、クリンカーと石膏とを混合粉砕するのではなく、まず、石膏とクリンカーとを別々にブレーン比表面積３２００±１５０ｃｍ２／ｇとなるように粉砕し、その後で両者を混合した。
(Example 3)
A cement composition according to Example 3 was produced in the same manner as Example 1 except that the pulverization method was changed. That is, in this example, the clinker and gypsum are not mixed and pulverized, but first, the gypsum and clinker are separately pulverized so as to have a brain specific surface area of 3200 ± 150 cm 2 / g, and then both are mixed. did.
セメント組成物の全体に含まれるＳＯ３量を１００質量部とすると、実施例１に係るセメント組成物は粒径１０μｍ以下の粒子に含まれるＳＯ３量が３０質量部以上であったのに対し、実施例３に係るセメント組成物は粒径１０μｍ以下の粒子に含まれるＳＯ３量が２０質量部未満であった。なお、粒径１０μｍ以下の粒子は目開き１０μｍのふるい網にセメント組成物を通過させることによって得た。粒径１０μｍ以下の粒子に含まれるＳＯ３量はＪＩＳ Ｒ５２０２：２０１０に記載の方法に準拠して測定した。 If the SO 3 content in the whole of the cement composition to 100 parts by weight, while the cement composition of Example 1 is SO 3 content in the following particles with particle sizes of 10μm was 30 parts by mass or more In the cement composition according to Example 3, the amount of SO 3 contained in the particles having a particle size of 10 μm or less was less than 20 parts by mass. The particles having a particle size of 10 μm or less were obtained by passing the cement composition through a sieve screen having an opening of 10 μm. The amount of SO 3 contained in particles having a particle size of 10 μm or less was measured according to the method described in JIS R5202: 2010.
＜水溶性Ｃｒ（ＶＩ）の定量＞
セメント協会標準試験方法Ｉ-５１−１９８１に記載の方法に準拠し、セメント中の水溶性Ｃｒ（ＶＩ）量を測定した。表１に結果を示す。
<Quantification of water-soluble Cr (VI)>
The amount of water-soluble Cr (VI) in the cement was measured according to the method described in Cement Association Standard Test Method I-51-1981. Table 1 shows the results.
（実施例４〜７及び比較例１３〜１７）
実施例１，２と同様の方法で製造した石膏と、一般的な方法で製造された石膏（ＳＯ２量：０質量％以上０．５質量％未満）とを準備し、これら二種類の石膏の混合比率等が異なる計９種類の石膏の混合物を連続的に作製した。次に、普通ポルトランドセメントクリンカーの組成となるよう焼成したクリンカーにそれぞれ内割りで前記石膏の混合物を３．５質量％と、石灰石を４．５質量％とを混合し、ブレーン比表面積が３１５０±１５０ｃｍ２／ｇとなるように粉砕し、実施例４〜７及び比較例１３〜１７のセメント組成物を製造した。得られたセメント組成物について、水溶性Ｃｒ（ＶＩ）量をセメント協会標準試験方法Ｉ−５１−１９８１に記載の方法に準拠して、凝結及びモルタル圧縮強さをＪＩＳ Ｒ５２０１「セメントの物理試験方法」に準拠してそれぞれ測定した。水溶性Ｃｒ（ＶＩ）量と石膏中のＳＯ２量との関係を実施例１，２及び比較例１〜３より導き、当該関係から実施例４〜７及び比較例１３〜１７のセメント組成物中の石膏混合物に含まれるＳＯ２量を推定した。結果を表２に示す。表２より、実施例４〜７のセメント組成物は、水溶性Ｃｒ（ＶＩ）の低減効果が見られない比較例１３〜１７と遜色ない凝結時間、圧縮強さが得られていることが判る。
(Examples 4-7 and Comparative Examples 13-17)
Gypsum produced by the same method as in Examples 1 and 2 and gypsum produced by a general method (SO 2 content: 0% by mass or more and less than 0.5% by mass) were prepared, and these two types of gypsum A total of nine types of gypsum mixtures having different mixing ratios were continuously prepared. Next, 3.5% by mass of the above-mentioned gypsum mixture and 4.5% by mass of limestone are mixed with each of the clinkers fired to have a composition of ordinary Portland cement clinker, and the specific surface area of branes is 3150 ±. The cement compositions of Examples 4 to 7 and Comparative Examples 13 to 17 were manufactured by pulverizing to 150 cm 2 / g. For the obtained cement composition, the amount of water-soluble Cr (VI) was determined according to the method described in Cement Association Standard Test Method I-51-1981, and the setting and mortar compressive strength was determined according to JIS R5201 “Cement Physical Test Method”. ”In accordance with the measurement. The relationship between the amount of water-soluble Cr (VI) and the amount of SO 2 in gypsum was derived from Examples 1 and 2 and Comparative Examples 1 to 3, and from this relationship, the cement compositions of Examples 4 to 7 and Comparative Examples 13 to 17 The amount of SO 2 contained in the gypsum mixture therein was estimated. The results are shown in Table 2. From Table 2, it can be seen that the cement compositions of Examples 4 to 7 have a setting time and compressive strength comparable to those of Comparative Examples 13 to 17 in which the effect of reducing water-soluble Cr (VI) is not observed. .
Claims (9)
前記スラリーに含まれる硫酸カルシウムの量を１００質量部とすると、前記スラリーに含まれる水酸化カルシウムの量が０．２〜１０質量部であり、
前記石膏は、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準拠して定量される二酸化硫黄の含有率が０．５〜１５質量％である、石膏の製造方法。 It is a method for producing gypsum through a gas-liquid contact step between a gas containing sulfur dioxide and a slurry containing at least calcium sulfate and calcium hydroxide,
When the amount of calcium sulfate contained in the slurry is 100 parts by mass, the amount of calcium hydroxide contained in the slurry is 0.2 to 10 parts by mass,
The said gypsum is a manufacturing method of gypsum whose content rate of the sulfur dioxide quantified based on the method of JISR9101-1995 is 0.5-15 mass%.
二酸化硫黄を含有するガスと、前記第１のスラリーとを気液接触させることによって、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンと、石膏とを含む第２のスラリーを得る第２工程と、
前記第２のスラリーを固液分離することによって、石膏を回収するとともに、マグネシウムイオンと、硫酸イオン、亜硫酸イオン及び硫酸水素イオンの少なくとも一種のイオンとを含む第３のスラリーを得る第３工程と、
を含み、
前記第１のスラリーに含まれる硫酸カルシウムの量を１００質量部とすると、前記第１のスラリーに含まれる水酸化カルシウムの量が０．２〜１０質量部であり、
前記石膏は、ＪＩＳ Ｒ９１０１−１９９５に記載の方法に準じて定量される二酸化硫黄の含有率が０．５〜１５質量％である、石膏の製造方法。 A first step of preparing a first slurry comprising at least magnesium hydroxide, calcium sulfate, and calcium hydroxide;
A second slurry containing magnesium ion, at least one ion of sulfate ion, sulfite ion and hydrogen sulfate ion, and gypsum by bringing the gas containing sulfur dioxide into contact with the first slurry in a gas-liquid contact. A second step of obtaining
A third step of recovering gypsum by solid-liquid separation of the second slurry, and obtaining a third slurry containing magnesium ions and at least one ion of sulfate ions, sulfite ions and hydrogen sulfate ions; ,
Including
When the amount of calcium sulfate contained in the first slurry is 100 parts by mass, the amount of calcium hydroxide contained in the first slurry is 0.2 to 10 parts by mass,
The said gypsum is a manufacturing method of gypsum whose sulfur dioxide content rate quantified according to the method of JISR9101-1995 is 0.5-15 mass%.
前記第４のスラリーに水酸化カルシウムを添加することによって、硫酸マグネシウムから再生された水酸化マグネシウムと、二水石膏と、水酸化カルシウムとを含む第５のスラリーを得る第５工程と、
を含み、
前記第１のスラリーに含まれる硫酸カルシウムは、前記第５のスラリーに含まれる二水石膏の少なくとも一部である、請求項２に記載の石膏の製造方法。 A fourth step of obtaining a fourth slurry containing magnesium sulfate by subjecting at least a part of the third slurry to an oxidation treatment;
A fifth step of obtaining a fifth slurry containing magnesium hydroxide regenerated from magnesium sulfate, dihydrate gypsum, and calcium hydroxide by adding calcium hydroxide to the fourth slurry;
Including
The method for producing gypsum according to claim 2, wherein the calcium sulfate contained in the first slurry is at least a part of dihydrate gypsum contained in the fifth slurry.
当該セメント組成物を構成する粒子は、粒径１０μｍ以下の粒子を含み、
当該セメント組成物の全体に含まれる前記ＳＯ３量を１００質量部とすると、前記粒径１０μｍ以下の粒子に含まれる前記ＳＯ３量が３０質量部以上である、請求項６に記載のセメント組成物。 The amount of SO 3 quantified according to the method described in JIS R5202: 2010 is 1.5 to 15% by mass,
The particles constituting the cement composition include particles having a particle size of 10 μm or less,
The cement composition according to claim 6, wherein the amount of SO 3 contained in the particles having a particle size of 10 µm or less is 30 parts by mass or more, assuming that the amount of SO 3 contained in the whole cement composition is 100 parts by mass. object.
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