JP2008297172A - Method of treating gypsum for reducing elution of contained fluorine, and gypsum reduced in elution of contained fluorine - Google Patents

Method of treating gypsum for reducing elution of contained fluorine, and gypsum reduced in elution of contained fluorine Download PDF

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JP2008297172A
JP2008297172A JP2007146594A JP2007146594A JP2008297172A JP 2008297172 A JP2008297172 A JP 2008297172A JP 2007146594 A JP2007146594 A JP 2007146594A JP 2007146594 A JP2007146594 A JP 2007146594A JP 2008297172 A JP2008297172 A JP 2008297172A
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gypsum
fluorine
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JP4752038B2 (en
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Masamoto Tafu
昌幹 袋布
Tetsuji Choji
哲治 丁子
Takumi Fujita
巧 藤田
Masaya Hiwasa
雅哉 日和佐
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Chiyoda Ute Co Ltd
Institute of National Colleges of Technologies Japan
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of treating gypsum capable of economically and surely reducing the elution amount of fluorine from a gypsum containing fluorine up to a value of 0.8 mg/L or less of environmental quantity standards for soil by a simple work, and a gypsum obtainable by this treating method. <P>SOLUTION: The gypsum containing fluorine is recovered after being aged for a required time in water in the presence of calcium hydrogen phosphate dihydrate to be an amount in the ratio of 1-5 pts.mass to 100 pts.mass of calcium sulfate dihydrate in the gypsum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は含有フッ素の溶出を低減させる石膏の処理方法及び含有フッ素の溶出を低減させた石膏に関する。例えば建築材料として用いた石膏ボードの廃材を埋立処分する場合、環境保全の観点から、かかる廃材からのフッ素の溶出量は土壌環境基準の０．８mg／Ｌ以下であることが求められる。石膏ボードの主原料はいうまでもなく石膏であり、石膏には天然のものと人工的に製造又は副生したものとがあるが、程度の差はあるもののこれらの石膏中には、なかでもリン酸石膏のように人工的に副生した石膏中には、相応量のフッ素が含まれており、かかるフッ素が製品である石膏ボードに持ち込まれ、更にその廃材にも持ち込まれて、結果としてそのような廃材からのフッ素の溶出が問題となるのである。本発明は各種石膏製品の主原料である石膏それ自体からのこれに含まれるフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させることができる石膏の処理方法及びこの処理方法によって得られる石膏に関する。   The present invention relates to a method for treating gypsum that reduces the elution of contained fluorine, and a gypsum that reduces the elution of contained fluorine. For example, when a gypsum board waste material used as a building material is disposed of in landfill, the amount of fluorine eluted from the waste material is required to be 0.8 mg / L or less of the soil environment standard from the viewpoint of environmental conservation. Needless to say, the main raw material of gypsum board is gypsum, and there are natural gypsum and artificially produced or by-produced gypsum. Artificial by-product gypsum like phosphate gypsum contains a certain amount of fluorine, and such fluorine is brought into the gypsum board that is the product, and is also brought into the waste material, resulting in The elution of fluorine from such waste material becomes a problem. INDUSTRIAL APPLICABILITY The present invention is a gypsum treatment method capable of reducing the elution amount of fluorine contained in gypsum itself, which is the main raw material of various gypsum products, to 0.8 mg / L or less of the soil environment standard, and this treatment method Relates to the gypsum obtained.

従来、含有フッ素の溶出を低減させる石膏の処理方法として、フッ素を含有する石膏にアルミン酸ナトリウムのようなアルミニウム化合物を加える方法（例えば特許文献１参照）、フッ素を含有する石膏スラリーにアルカリを加えてｐＨを９以上に上げた後、酸を加えてｐＨを下げ幅１以上の６以上に調整し、必要に応じて第三リン酸カルシウムのようなリン酸カルシウムを加える方法（例えば特許文献２参照）、フッ素を含有する石膏にリン酸水素カルシウム二水和物を加える方法（例えば非特許文献１参照）等が知られている。   Conventionally, as a method for treating gypsum to reduce the elution of contained fluorine, a method of adding an aluminum compound such as sodium aluminate to gypsum containing fluorine (see, for example, Patent Document 1), an alkali is added to a gypsum slurry containing fluorine. After raising the pH to 9 or more, a method of adding an acid to lower the pH to adjust to 6 or more with a width of 1 or more, and adding calcium phosphate such as tricalcium phosphate as necessary (for example, see Patent Document 2), fluorine A method of adding calcium hydrogen phosphate dihydrate to gypsum containing bismuth (see, for example, Non-Patent Document 1) is known.

しかし、特許文献１のようにアルミン酸ナトリウムのようなアルミニウム化合物を加える従来法には、加える薬剤の性質上、その取扱いが厄介という問題があり、また特許文献２のようにｐＨを一定の値や幅で上下させて調整する従来法には、工数が多く、操作が煩雑という問題があって、更に非特許文献１のように単にリン酸水素カルシウム二水和物を加えるだけの従来法には、所期の効果を発現させようとすると相応に多量のリン酸水素ナトリウム二水和物が必要となり、非経済的という問題がある。
特開２００１−２５３７５５号公報 特開２００３−２０６１３３号公報 ジャナル オブ ザ ヨーロピアン セラミック ソサエティ（Ｊｏｕｒａｌ ｏｆ ｔｈｅ Ｅｕｒｏｐｅａｎ Ｃｅｒａｍｉｃ Ｓｏｃｉｅｔｙ）２６（２００６）７６７−７７０ However, the conventional method of adding an aluminum compound such as sodium aluminate as in Patent Document 1 has a problem that it is difficult to handle due to the nature of the drug to be added, and the pH is a constant value as in Patent Document 2. In the conventional method of adjusting by moving up and down with a width, there are problems of many man-hours and complicated operations. Further, as in Non-Patent Document 1, the conventional method of simply adding calcium hydrogen phosphate dihydrate is used. In order to achieve the desired effect, a correspondingly large amount of sodium hydrogenphosphate dihydrate is required, which is uneconomical.
JP 2001-253755 A JP 2003-206133 A Janal of the European Ceramic Society 26 (2006) 767-770

本発明が解決しようとする課題は、簡単な作業で経済的に且つ確実にフッ素を含有する石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させることができる石膏の処理方法及びこの処理方法によって得られる石膏を提供する処にある。   The problem to be solved by the present invention is a gypsum capable of reducing the amount of fluorine eluted from gypsum containing fluorine economically and reliably to 0.8 mg / L or less of the soil environment standard by simple work. And a gypsum obtained by this treatment method.

前記の課題を解決する本発明は、フッ素を含有する石膏を、該石膏中の硫酸カルシウム二水和物１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で所要期間養生した後、回収することを特徴とする含有フッ素の溶出を低減させる石膏の処理方法に係る。また本発明は、フッ素を含有する石膏スラリーを、該石膏スラリー中の硫酸カルシウム二水和物１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で所要期間養生した後、石膏を回収することを特徴とする含有フッ素の溶出を低減させる石膏の処理方法に係る。更に本発明は、以上のような処理方法によって得られる含有フッ素の溶出を低減させた石膏に係る。   The present invention for solving the above-mentioned problems is that the calcium hydrogen phosphate dihydrate is used in an amount of 1 to 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum containing fluorine. In the presence of the present invention, the present invention relates to a method for treating gypsum that reduces elution of contained fluorine, which is recovered after curing in water for a required period of time. The present invention also provides a gypsum slurry containing fluorine in the presence of calcium hydrogen phosphate dihydrate in an amount of 1 to 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum slurry. Furthermore, the present invention relates to a method for treating gypsum that reduces elution of contained fluorine, characterized in that gypsum is recovered after curing in water for a required period of time. Furthermore, the present invention relates to a gypsum with reduced elution of contained fluorine obtained by the above processing method.

先ず、本発明に係る石膏の処理方法（以下単に本発明の処理方法という）について説明する。本発明の処理方法では、フッ素を含有する石膏を、リン酸水素カルシウム二水和物（ＣａＨＰＯ４・２Ｈ２Ｏ）の存在下に、水中で養生する。ここで用いるフッ素を含有する石膏は、それがフッ素を含有するものであれば、その種類を特に制限されず、これには例えば、リン鉱石から湿式リン酸法によりリン酸を生成させる際の副産物として得られる石膏、石灰法により排煙脱硫する際の副産物として得られる石膏、これらの石膏を用いて製造した石膏ボードの廃材から得られる石膏等が挙げられる。またここで用いる薬剤はリン酸水素カルシウム二水和物である。例えばリン酸三カルシウム（Ｃａ３（ＰＯ４）２）でも相応の効果を発現するが、その程度はリン酸水素カルシウム二水和物に比べて著しく劣る。 First, a method for treating gypsum according to the present invention (hereinafter simply referred to as the treatment method of the present invention) will be described. In the treatment method of the present invention, gypsum containing fluorine is cured in water in the presence of calcium hydrogen phosphate dihydrate (CaHPO 4 .2H 2 O). The type of gypsum containing fluorine is not particularly limited as long as it contains fluorine. For example, this is a by-product when phosphoric acid is produced from phosphorous ore by a wet phosphoric acid method. , Gypsum obtained as a by-product when flue gas is desulfurized by the lime method, gypsum obtained from waste materials of gypsum board produced using these gypsum, and the like. The drug used here is calcium hydrogen phosphate dihydrate. For example, tricalcium phosphate (Ca 3 (PO 4 ) 2 ) exhibits a corresponding effect, but the degree is significantly inferior to calcium hydrogen phosphate dihydrate.

本発明の処理方法において、フッ素を含有する石膏のリン酸水素カルシウム二水和物の存在下における水中での養生は、双方の混合物に水を加える方法、一方の水スラリーに他方を加えて混合する方法、双方の水スラリーを混合する方法等、いずれの方法で行なってもよい。いずれの方法で行なうにしても、フッ素を含有する石膏及びリン酸水素カルシウム二水和物としてはそれらの粉状物を用いるのが好ましい。具体的に水中での養生は、適宜に加温しながら行なうこともできるが、所謂室温下で行なうこともでき、また撹拌しながら行なうこともできるが、当初は撹拌するもののその後は静置して行なうこともできる。尚、ここで水中というのは、フッ素を含有する石膏及びリン酸水素カルシウム二水和物が共に水で少なくとも浸漬された状態を意味する。   In the treatment method of the present invention, curing of gypsum containing fluorine in water in the presence of calcium hydrogen phosphate dihydrate is carried out by adding water to the mixture of both, adding one to the water slurry and mixing. It may be performed by any method such as a method of mixing and a method of mixing both water slurries. Whichever method is used, it is preferable to use a powdery product as the gypsum containing fluorine and calcium hydrogen phosphate dihydrate. Specifically, curing in water can be performed while appropriately heating, but can also be performed at a so-called room temperature, and can be performed with stirring. Can also be done. The term “water” as used herein means a state in which both gypsum containing fluorine and calcium hydrogen phosphate dihydrate are at least immersed in water.

フッ素を含有する石膏を、リン酸水素カルシウム二水和物を単にそのまま存在させた状態下で養生しても、例えば双方の粉状物を混合したものをそのまま養生しても、そのような石膏からのフッ素の溶出量を相応に低減させることができるが、フッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させようとすると、高価なリン酸水素カルシウム二水和物が多量に必要となる。しかし、フッ素を含有する石膏を、リン酸水素カルシウム二水和物の存在下に水中で養生すると、比較的少量のリン酸水素カルシウム二水和物の使用で、そのような石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させることができる。リン酸水素カルシウム二水和物の粉状物を水に懸濁した状態で数時間〜数十時間置くと、リン酸水素カルシウム二水和物の粒子はその表面に大きさが数十ｎｍ程度の多数の微細結晶を均一に析出した構造のものとなって活性化する。フッ素を含有する石膏を、リン酸水素カルシウム二水和物の存在下に水中で養生すると、前記のように粒子表面が活性化したリン酸水素カルシウム二水和物が石膏中のフッ素をフッ素アパタイトとして効率的に不溶化するのである。かかるリン酸水素カルシウム二水和物の特徴的な作用効果は、他のリン酸カルシウム化合物、例えばリン酸三カルシウムでは得られない。   Even if the gypsum containing fluorine is cured in a state where calcium hydrogen phosphate dihydrate is simply present, for example, a mixture of both powders is cured as it is, such gypsum. The amount of fluorine eluted from the soil can be reduced accordingly, but if the amount of fluorine eluted is reduced to 0.8 mg / L or less of the soil environment standard, the expensive calcium hydrogen phosphate dihydrate is A large amount is required. However, when gypsum containing fluorine is cured in water in the presence of calcium hydrogen phosphate dihydrate, the use of a relatively small amount of calcium hydrogen phosphate dihydrate can reduce the amount of fluorine from such gypsum. The amount of elution can be reduced to 0.8 mg / L or less of the soil environment standard. When the powder of calcium hydrogen phosphate dihydrate is suspended in water for several hours to several tens of hours, the particles of calcium hydrogen phosphate dihydrate are about tens of nanometers in size on the surface. It becomes a structure in which a large number of fine crystals are uniformly deposited and activated. When gypsum containing fluorine is cured in water in the presence of calcium hydrogen phosphate dihydrate, the calcium hydrogen phosphate dihydrate whose particle surface is activated as described above converts the fluorine in the gypsum to fluorine apatite. It is effectively insolubilized. The characteristic effects of such calcium hydrogen phosphate dihydrate cannot be obtained with other calcium phosphate compounds such as tricalcium phosphate.

本発明の処理方法では、フッ素を含有する石膏を、該石膏中の硫酸カルシウム二水和物（ＣａＳＯ４・２Ｈ２Ｏ）１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で養生する。リン酸水素カルシウム二水和物の使用量を、フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たり、１質量部未満の割合となる量にすると、そのような条件下で養生した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にするためには、著しく長い養生期間が必要となり、実用的でない。逆にリン酸水素カルシウム二水和物の使用量を、フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たり、５質量部超の割合となる量にしても、フッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にするための必要な養生期間はそれ程には変わらない。 In the treatment method of the present invention, fluorine-containing gypsum is used in an amount of 1 to 5 parts by mass of hydrogen phosphate per 100 parts by mass of calcium sulfate dihydrate (CaSO 4 .2H 2 O) in the gypsum. Curing in water in the presence of calcium dihydrate. When the amount of calcium hydrogen phosphate dihydrate used is an amount that is less than 1 part by mass per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine, curing is performed under such conditions. In order to reduce the amount of fluorine eluted from the gypsum to 0.8 mg / L or less of the soil environment standard, a considerably long curing period is required, which is not practical. Conversely, even if the amount of calcium hydrogen phosphate dihydrate used is an amount that exceeds 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine, the amount of eluted fluorine The required curing period to reduce the soil environmental standard to 0.8 mg / L or less is not so different.

本発明の処理方法では、フッ素を含有する石膏を、該石膏中の硫酸カルシウム二水和物１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で所要期間養生する。水中で養生する所要期間は、養生後に回収した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させるために必要な期間であり、これは主にリン酸水素カルシウム二水和物の使用量によって影響を受ける。具体的にかかる養生期間は、フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たり、リン酸水素カルシウム二水和物の使用量が１質量部の場合に５日、３質量部の場合に２日、５質量部の場合に１日となる。   In the treatment method of the present invention, fluorine-containing gypsum is present in the presence of calcium hydrogen phosphate dihydrate in an amount of 1 to 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum. Then, cure underwater for the required period. The required period of curing in water is the period necessary to reduce the amount of fluorine elution from gypsum collected after curing to 0.8 mg / L or less of the soil environmental standard, which is mainly calcium hydrogen phosphate. It is affected by the amount of dihydrate used. Specifically, the curing period is 5 days, 3 parts by mass for 1 part by mass of calcium hydrogen phosphate dihydrate per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine. 2 days in the case of 1 and 1 day in the case of 5 parts by mass.

養生期間について詳しくは後述するが、本発明の処理方法では、前記したような水中での養生を、リン酸水素カルシウム二水和物の使用量との関係で、下記の数１を満足する期間行なうのが好ましい。養生後に回収した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで確実に低減させることができるからである。   Although the curing period will be described in detail later, in the treatment method of the present invention, the above-described curing in water is a period in which the following number 1 is satisfied in relation to the amount of calcium hydrogen phosphate dihydrate used. It is preferred to do so. This is because the elution amount of fluorine from gypsum collected after curing can be reliably reduced to 0.8 mg / L or less of the soil environment standard.

Figure 2008297172
Figure 2008297172

数１において、
Ｙ：水中での養生期間（日）
Ｘ：フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たりのリン酸水素カルシウム二水和物の使用量（質量部、但しＸは１〜５） In Equation 1,
Y: Curing period in water (days)
X: Amount of calcium hydrogen phosphate dihydrate used per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine (part by mass, where X is 1 to 5)

次に、本発明に係る石膏（以下単に本発明の石膏という）について説明する。本発明の石膏は、以上説明した本発明の処理方法によって得られるフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで低減させた石膏である。かかる本発明の石膏は、石膏ボード、プラスター、土壌固化材等の原料として使用できる。   Next, the plaster according to the present invention (hereinafter simply referred to as the plaster of the present invention) will be described. The gypsum of the present invention is a gypsum in which the elution amount of fluorine obtained by the treatment method of the present invention described above is reduced to 0.8 mg / L or less of the soil environment standard. Such gypsum of the present invention can be used as a raw material for gypsum board, plaster, soil solidifying material and the like.

本発明の処理方法によると、簡単な作業で経済的に且つ確実にフッ素を含有する石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下に低減させることができる。   According to the treatment method of the present invention, the elution amount of fluorine from gypsum containing fluorine can be reduced to 0.8 mg / L or less of the soil environment standard with simple operations economically and reliably.

フッ素を含有する石膏として、リン鉱石から湿式リン酸法によりリン酸を生成させる際の副産物として得られる石膏を用いた。この石膏からのフッ素の溶出量は７．７２mg／Ｌであった。尚、フッ素の溶出量は、石膏５０ｇに純水５００mlを加え、毎分２００回で６時間振盪し、１０分間静置した後、上澄液を０．４５ｎｍのメンブレンフィルターで濾過して溶出液を得、この溶出液中のフッ素濃度をイオン選択性電極で測定した（定量下限は０．０２mg／Ｌ）。以下の各例についても、フッ素の溶出量は同様の方法で測定した。   As the gypsum containing fluorine, gypsum obtained as a by-product in producing phosphoric acid from phosphorus ore by a wet phosphoric acid method was used. The amount of fluorine eluted from this gypsum was 7.72 mg / L. The amount of elution of fluorine is 500 g of pure water added to 50 g of gypsum, shaken at 200 times per minute for 6 hours, allowed to stand for 10 minutes, and the supernatant is filtered through a 0.45 nm membrane filter. The fluorine concentration in the eluate was measured with an ion selective electrode (lower limit of quantification was 0.02 mg / L). In each of the following examples, the elution amount of fluorine was measured by the same method.

実施例
内容２Ｌのビーカーに、粉状の石膏１００ｇと、該石膏中の硫酸カルシウム二水和物１００質量部当たり１、３又は５質量部の割合となる量の粉状のリン酸水素カルシウム二水和物を加え、更に純水１Ｌを加えて、毎分２００回で５分間振盪した後（ｐＨ５．３）、水分が蒸発しないようにして室温下に静置し、一定期間（最長で６日間）、水中で養生した。かくして養生したものから、脱水し、乾燥して回収した石膏について、フッ素の溶出量を測定した。結果を図１に示した。図１において、リン酸水素カルシウム二水和物の使用量が、石膏中の硫酸カルシウム二水和物１００質量部当たり、１質量部の割合となる量の場合の結果を白抜き丸印を結ぶ曲線１で示し、この場合には養生期間が５日でフッ素の溶出量が０．４９mg／Ｌとなっており、また３質量部の割合となる量の場合の結果を白抜き四角印を結ぶ曲線２で示し、この場合には養生期間が２日でフッ素の溶出量が０．７５mg／Ｌとなっていて、更に５質量部の割合となる量の場合の結果を白抜き三角印を結ぶ曲線３で示し、この場合には養生期間が１日でフッ素の溶出量が０．４９mg／Ｌとなっている。 Example Content In a 2 L beaker, 100 g of powdery gypsum and 1, 3 or 5 parts by mass of powdered calcium hydrogen phosphate per 100 parts by mass of calcium sulfate dihydrate in the gypsum Add hydrate, add 1 L of pure water, shake at 200 times per minute for 5 minutes (pH 5.3), and leave it at room temperature to prevent water from evaporating. Days). The amount of elution of fluorine was measured for gypsum collected after being dehydrated, dried and recovered. The results are shown in FIG. In FIG. 1, the results when the amount of calcium hydrogen phosphate dihydrate used is a ratio of 1 part by mass per 100 parts by mass of calcium sulfate dihydrate in gypsum are marked with white circles. It is shown by curve 1, and in this case, the curing period is 5 days, the amount of elution of fluorine is 0.49 mg / L, and the result in the amount of 3 parts by mass is marked with a white square mark This is shown by curve 2, and in this case, the curing period is 2 days, the elution amount of fluorine is 0.75 mg / L, and the result in the amount of 5 parts by mass is connected with a white triangle mark. In this case, the curing period is one day and the elution amount of fluorine is 0.49 mg / L.

図１は、水中での養生後に回収した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下（図１中の点線）にまで低減させるために必要な期間はリン酸水素カルシウム二水和物の使用量によって大きな影響を受け、かかる養生期間は、フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たり、リン酸水素カルシウム二水和物の使用量が１質量部の場合に５日、３質量部の場合に２日、５質量部の場合に１日となることを示している。図２は、図１について以上説明したような、フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たりのリン酸水素カルシウム二水和物の使用量（質量部、横軸のＸ）と、水中での養生後に回収した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで確実に低減させるための必要な期間（日、縦軸のＹ）との関係を示すもので、図２中の曲線５は前記の数１に相当している。   Fig. 1 shows the period of time required to reduce the amount of fluorine eluted from gypsum recovered after curing in water to 0.8 mg / L or less of the soil environment standard (dotted line in Fig. 1). It is greatly affected by the amount of dihydrate used, and during this curing period, the amount of calcium hydrogen phosphate dihydrate used is 1 mass per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine. 5 days for 3 parts, 2 days for 3 parts by mass, and 1 day for 5 parts by mass. FIG. 2 shows the amount of calcium hydrogen phosphate dihydrate used per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine as described above for FIG. 1 (parts by mass, X on the horizontal axis). ) And the required period (days, Y on the vertical axis) to reliably reduce the amount of fluorine elution from gypsum recovered after curing in water to 0.8 mg / L or less of the soil environment standard The curve 5 in FIG. 2 corresponds to the above formula 1.

数１において、Ｘが２のとき、Ｙは３．２５となり、必要な養生期間は３．２５日（７８時間）となるが、実際、この条件で石膏を前記した実施例のように水中養生すると、養生後に回収した石膏からのフッ素溶出量は０．７５mg／Ｌとなっていた。また数１において、Ｘが４のとき、Ｙは１．２５となり、必要な養生期間は１．２５日（３０時間）となるが、実際、この条件で石膏を前記した実施例のように水中養生すると、養生後に回収した石膏からのフッ素の溶出量は０．４９mg／Ｌとなっていた。   In Equation 1, when X is 2, Y is 3.25, and the necessary curing period is 3.25 days (78 hours). Actually, under this condition, the gypsum is cured underwater as in the above-described embodiment. Then, the fluorine elution amount from the gypsum collected after curing was 0.75 mg / L. In addition, in Formula 1, when X is 4, Y is 1.25, and the necessary curing period is 1.25 days (30 hours). When cured, the elution amount of fluorine from gypsum recovered after curing was 0.49 mg / L.

比較例
粉状の石膏１００ｇに、該石膏中の硫酸カルシウム二水和物１００質量部当たり０、１、３、５又は１０質量部の割合となる量の粉状のリン酸水素カルシウム二水和物を加え、毎分２００回で５分間振盪した後、室温下に１日間静置した。かくして処理した石膏について、フッ素の溶出量を測定し、結果を図３に示した。図３の曲線５は、水中養生をしないと、処理後の石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下（図中の点線）にすることが著しく難しいことを示している。 Comparative Example Powdery calcium hydrogen phosphate dihydrate in an amount of 0, 1, 3, 5 or 10 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum was added to 100 g of powdered gypsum. The product was added, shaken at 200 times per minute for 5 minutes, and then allowed to stand at room temperature for 1 day. For the gypsum thus treated, the amount of fluorine eluted was measured, and the results are shown in FIG. Curve 5 in FIG. 3 shows that it is extremely difficult to reduce the amount of fluorine eluted from the treated gypsum to 0.8 mg / L or less of the soil environment standard (dotted line in the figure) without water curing. Yes.

本発明において、リン酸水素カルシウム二水和物の使用量毎に、水中での養生期間（日）と、養生後に回収した石膏からのフッ素の溶出量（mg／Ｌ）との関係を示すグラフ。In this invention, the graph which shows the relationship between the curing period in water (day) for every usage-amount of calcium hydrogenphosphate dihydrate, and the elution amount (mg / L) of the fluorine from the gypsum collect | recovered after curing. . 本発明において、リン酸水素カルシウム二水和物の使用量と、水中での養生後に回収した石膏からのフッ素の溶出量を土壌環境基準の０．８mg／Ｌ以下にまで確実に低減させるための必要な養生期間（日）との関係を示すグラフ。In the present invention, the amount of calcium hydrogen phosphate dihydrate used and the elution amount of fluorine from gypsum recovered after curing in water are reliably reduced to 0.8 mg / L or less of the soil environment standard. The graph which shows the relationship with a required curing period (days). 本発明との比較をするため、水中での養生をしない場合について、リン酸水素カルシウム二水和物の使用量と、処理後の石膏からのフッ素の溶出量（mg／Ｌ）との関係を示すグラフ。For comparison with the present invention, the relationship between the amount of calcium hydrogen phosphate dihydrate used and the amount of fluorine eluted from the treated gypsum (mg / L) when not cured in water. Graph showing.

Claims (4)

フッ素を含有する石膏を、該石膏中の硫酸カルシウム二水和物１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で所要期間養生した後、回収することを特徴とする含有フッ素の溶出を低減させる石膏の処理方法。   Curing gypsum containing fluorine in water in the presence of calcium hydrogen phosphate dihydrate in an amount of 1 to 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum After that, a method for treating gypsum that reduces the elution of contained fluorine, which is recovered. フッ素を含有する石膏スラリーを、該石膏スラリー中の硫酸カルシウム二水和物１００質量部当たり１〜５質量部の割合となる量のリン酸水素カルシウム二水和物の存在下に、水中で所要期間養生した後、石膏を回収することを特徴とする含有フッ素の溶出を低減させる石膏の処理方法。   A gypsum slurry containing fluorine is required in water in the presence of calcium hydrogen phosphate dihydrate in an amount of 1 to 5 parts by mass per 100 parts by mass of calcium sulfate dihydrate in the gypsum slurry. A method for treating gypsum that reduces elution of contained fluorine, wherein gypsum is recovered after curing for a period of time. 水中での養生を、用いるリン酸水素カルシウム二水和物の量との関係で、下記の数１を満足する期間行なう請求項１又は２記載の含有フッ素の溶出を低減させる石膏の処理方法。
Figure 2008297172
 （数１において、
Ｙ：水中での養生期間（日）
Ｘ：フッ素を含有する石膏中の硫酸カルシウム二水和物１００質量部当たりのリン酸水素カルシウム二水和物の使用量（質量部、但しＸは１〜５）） The method for treating gypsum that reduces elution of contained fluorine according to claim 1 or 2, wherein the curing in water is performed for a period satisfying the following formula 1 in relation to the amount of calcium hydrogen phosphate dihydrate used.
Figure 2008297172
 (In Equation 1,
Y: Curing period in water (days)
X: Amount of calcium hydrogen phosphate dihydrate used per 100 parts by mass of calcium sulfate dihydrate in gypsum containing fluorine (part by mass, where X is 1 to 5)) 請求項１〜３のいずれか一つの項記載の処理方法によって得られる含有フッ素の溶出を低減させた石膏。   The gypsum which reduced elution of the containing fluorine obtained by the processing method of any one of Claims 1-3.
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JP5582141B2 (en) * 2009-05-21 2014-09-03 ダイキン工業株式会社 Treatment agent, method for producing the same, and treatment method
JP2017095287A (en) * 2015-11-18 2017-06-01 株式会社トクヤマ Method for producing dihydrate gypsum with decreased amount of fluorine elution

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JP2003206133A (en) * 2002-01-15 2003-07-22 Shimonoseki Mitsui Chemicals Inc Gypsum wherein eluted fluorine is reduced
JP2004016852A (en) * 2002-06-13 2004-01-22 Kawasaki Heavy Ind Ltd Stabilization treating method for waste and stabilization treated material for waste
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JP2001253755A (en) * 2000-03-10 2001-09-18 Natl Inst Of Advanced Industrial Science & Technology Meti Gypsum composition eluting no fluorine and its manufacturing method
JP2003206133A (en) * 2002-01-15 2003-07-22 Shimonoseki Mitsui Chemicals Inc Gypsum wherein eluted fluorine is reduced
JP2004016852A (en) * 2002-06-13 2004-01-22 Kawasaki Heavy Ind Ltd Stabilization treating method for waste and stabilization treated material for waste
JP2004299962A (en) * 2003-03-31 2004-10-28 Central Res Inst Of Electric Power Ind Method for removing fluorine in gypsum

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5582141B2 (en) * 2009-05-21 2014-09-03 ダイキン工業株式会社 Treatment agent, method for producing the same, and treatment method
JP2017095287A (en) * 2015-11-18 2017-06-01 株式会社トクヤマ Method for producing dihydrate gypsum with decreased amount of fluorine elution

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