JP2020093955A

Movatterモバイル変換

Info

Publication number: JP2020093955A
Application number: JP2018233156A
Authority: JP
Inventors: 晋吾平中; Shingo Hiranaka; 健太郎松尾; Kentaro Matsuo
Original assignee: Tokuyama Corp; Tokuyama Chiyoda Gypsum Co Ltd
Current assignee: Tokuyama Corp; Tokuyama Chiyoda Gypsum Co Ltd
Priority date: 2018-12-13
Filing date: 2018-12-13
Publication date: 2020-06-18
Anticipated expiration: 2038-12-13
Also published as: JP7184622B2

Abstract

To provide a recycling method in which a color tone of dihydrate gypsum particles to be recycled from waste gypsum boards is improved.SOLUTION: A method for recycling a dihydrate gypsum from waste gypsum boards includes: calcining a gypsum derived from waste gypsum boards to convert the gypsum into hemihydrate and/or anhydrous type III gypsum granules; mixing the gypsum granules with a slurry including a gypsum or water to prepare a gypsum slurry; and subjecting dihydrate gypsum particles precipitated in the gypsum slurry to solid-liquid separation, wherein the following two steps are performed: a mixing step of mixing a granular or fibrous activated carbon with the gypsum slurry; and a separation step of separating the activated carbon from the gypsum slurry before the solid liquid separation.SELECTED DRAWING: Figure 1

Description

Translated fromJapanese

この発明は、廃石膏ボードから回収した二水石膏の色調の改善に関する。 This invention relates to improving the color tone of gypsum dihydrate recovered from waste gypsum board.

出願人は廃石膏ボードからの二水石膏の回収を工業化することに成功した。二水石膏の回収方法を、出願人の特許文献１（WO2012/176688A）に従って説明する。廃石膏ボードを粉砕し、紙片等の異物を二水石膏から分離し、二水石膏をか焼し半水石膏等に変換する。半水石膏等を混合槽で石膏スラリー等と混合し、析出槽へ移してスラリー中に二水石膏粒子を析出させると共に、スラリーを混合槽へ還流する。スラリー中に析出した二水石膏粒子を、フィルタープレス等の固液分離装置により抽出する。 Applicants have succeeded in industrializing the recovery of gypsum dihydrate from waste gypsum board. A method for recovering gypsum dihydrate will be described in accordance with the applicant's Patent Document 1 (WO2012/176688A). The waste gypsum board is crushed to separate foreign matters such as paper pieces from the dihydrate gypsum, and the dihydrate gypsum is calcined to be converted into hemihydrate gypsum and the like. Hemihydrate gypsum and the like are mixed with gypsum slurry and the like in a mixing tank and transferred to a precipitation tank to deposit gypsum dihydrate particles in the slurry, and the slurry is refluxed to the mixing tank. The gypsum dihydrate particles precipitated in the slurry are extracted with a solid-liquid separator such as a filter press.

WO2012/176688AWO2012/176688A

発明者は、この方法で回収した二水石膏が淡褐色等に僅かに着色することがあることに着目した。着色は石膏ボードのメーカー、ボードの種類等に関係なく発生し、石膏ボードの原料となる二水石膏は白色の色調が要求され、着色は好ましくない。 The inventor has noticed that the gypsum dihydrate recovered by this method may be slightly colored such as light brown. Coloring occurs regardless of the gypsum board manufacturer, type of board, etc., and gypsum dihydrate, which is a raw material for the gypsum board, is required to have a white color tone, and coloring is not preferable.

この発明の課題は、廃石膏ボードから回収する二水石膏の色調を改善することにある。 An object of the present invention is to improve the color tone of gypsum dihydrate recovered from waste gypsum board.

この発明は、廃石膏ボード由来の石膏をか焼することにより半水及び／又は無水III型の石膏粒体とし、前記石膏粒体を、石膏を含むスラリーまたは水と混合して石膏スラリーとし、石膏スラリー中に析出した二水石膏粒子を固液分離する、廃石膏ボードからの二水石膏の回収方法において、
粒状あるいは繊維状の活性炭を前記石膏スラリーと混合する混合ステップと、
前記固液分離前に、活性炭を石膏スラリーから分離する分離ステップとを行うことを特徴とする。This invention is a semi-water and/or anhydrous type III gypsum granules by calcining gypsum derived from waste gypsum board, and the gypsum granules are mixed with a slurry containing gypsum or water to form a gypsum slurry, Solid-liquid separation of dihydrate gypsum particles precipitated in the gypsum slurry, in the method of recovery of dihydrate gypsum from waste gypsum board,
A mixing step of mixing granular or fibrous activated carbon with the gypsum slurry,
Before the solid-liquid separation, a separation step of separating activated carbon from the gypsum slurry is performed.

発明者は当初石膏スラリー中のFe^３＋イオン等の金属イオンが着色の原因ではないかと疑い、イオン交換樹脂等によりスラリー中のFe^３＋イオン等を除去した。しかし着色は解消しなかった。そこで石膏スラリー中に活性炭を投入すると、脱色に成功した。これらのことは、活性炭で吸着可能な有色の有機物が石膏スラリー中に存在していることを示唆している。このような有機物の起源として、石膏ボードに広く用いられている澱粉等の糊、界面活性剤等が長期間の間にあるいは石膏のか焼時に発色した、等が考えられる。着色の正確な機構は不明であるが、活性炭で除去可能な物質が原因であることは確実である。またシリカゲルは親水性、ゼオライトは極性が強く、水性スラリー中の微量有機物の除去には適していない。The inventor initially suspected that the metal ions such as Fe³⁺ ions in the gypsum slurry were the cause of the coloring, and removed the Fe³⁺ ions in the slurry with an ion exchange resin or the like. However, coloring did not disappear. Therefore, when activated carbon was added to the gypsum slurry, decolorization was successful. These suggest that colored organic matter that can be adsorbed by activated carbon is present in the gypsum slurry. The origin of such organic substances is considered to be that pastes such as starch widely used for gypsum boards, surfactants, etc., develop color during a long period of time or during calcination of gypsum. The exact mechanism of coloring is unknown, but it is certain that it is due to a substance that can be removed with activated carbon. Further, silica gel is hydrophilic and zeolite is strongly polar, so it is not suitable for removing trace organic substances in an aqueous slurry.

着色の原因となる有機物は、二水石膏粒子の内部まで入り込んでいるか、石膏粒子への吸着等により粒子表面に存在すると考えられる。そして回収した二水石膏粒子を水洗すると、ある程度は色調を改善、即ち白色度を高める、ことができるが、充分ではない。これは二水石膏粒子の内部まで着色物質の一部が浸透し、水洗では充分に除去できないことを示唆している。 It is considered that the organic matter that causes coloring enters the inside of the gypsum dihydrate particles or exists on the surface of the particles due to adsorption to the gypsum particles. When the recovered gypsum dihydrate particles are washed with water, the color tone can be improved to some extent, that is, the whiteness can be increased, but this is not sufficient. This suggests that a part of the coloring substance penetrates into the gypsum dihydrate particles and cannot be sufficiently removed by washing with water.

粒状あるいは繊維状の活性炭を石膏スラリーと混合すると、石膏スラリーを脱色し、二水石膏粒子の白色度を高めることができる。半水及び／又は無水III型の石膏は水と接触することによりいったん溶解し、二水石膏として析出する。この過程において、活性炭を存在させることにより、前述したような着色物質（有機物）が活性炭に吸着され、析出時に二水石膏の結晶中に取り込まれる着色物質の量を大幅に減少させることができているためであると推測される。混合では、石膏スラリー中に活性炭を投入しても、水等に石膏粒体と活性炭を別々に投入しても、あるいは石膏粒体と活性炭を予め混合し、水等に投入しても良い。即ち、石膏スラリーに活性炭が混合されれば良く、混合のプロセスは任意である。 When granular or fibrous activated carbon is mixed with the gypsum slurry, the gypsum slurry can be decolorized and the whiteness of the gypsum dihydrate particles can be increased. Hemi-water and/or anhydrous type III gypsum once dissolves upon contact with water and precipitates as gypsum dihydrate. In this process, the presence of activated carbon makes it possible to significantly reduce the amount of the coloring substance (organic substance) as described above, which is adsorbed by the activated carbon and taken into the crystals of gypsum dihydrate during precipitation. It is presumed that this is because In the mixing, activated carbon may be added to the gypsum slurry, gypsum particles and activated carbon may be separately added to water or the like, or gypsum particles and activated carbon may be mixed in advance and added to water or the like. That is, the activated carbon may be mixed with the gypsum slurry, and the mixing process is arbitrary.

シート状の活性炭を石膏スラリーと接触させると、活性炭表面に二水石膏が析出し、スラリー中の着色物質の除去が困難になる。そこで活性炭は粒状あるいは繊維状とし、粒状の場合、顆粒状の成型活性炭でも不定形の破砕活性炭でも良い。そして活性炭を石膏スラリー中に混合し、言い換えると石膏スラリー中に分散させ、分離ステップにより、二水石膏粒子の固液分離前に、石膏スラリーから活性炭を分離する。以上のようにして、この発明では回収した二水石膏粒子の色調を改善することができる。 When the sheet-shaped activated carbon is brought into contact with the gypsum slurry, gypsum dihydrate is deposited on the surface of the activated carbon, which makes it difficult to remove the coloring substance in the slurry. Therefore, the activated carbon is granular or fibrous, and in the case of granular, it may be granular activated carbon or crushed irregular activated carbon. Then, the activated carbon is mixed with the gypsum slurry, in other words, dispersed in the gypsum slurry, and the separation step separates the activated carbon from the gypsum slurry before solid-liquid separation of the gypsum dihydrate particles. As described above, according to the present invention, the color tone of the recovered gypsum dihydrate particles can be improved.

好ましくは、前記分離ステップでは、二水石膏粒子を通過させるが活性炭を通過させない目開きの篩により、活性炭を石膏スラリーから篩い分けする。言い換えると、二水石膏粒子の粒度分布（最大粒径）に対して、最小粒径あるいは繊維長が大きい活性炭を用い、篩い分けにより活性炭を分離する。 Preferably, in the separating step, the activated carbon is sieved from the gypsum slurry by a sieve having an opening which allows the gypsum dihydrate particles to pass through but does not allow the activated carbon to pass through. In other words, activated carbon having a minimum particle size or a large fiber length is used for the particle size distribution (maximum particle size) of the gypsum dihydrate particles, and the activated carbon is separated by sieving.

特に好ましくは、前記篩以上の目開きの第２の篩上で予め篩い分け洗浄した活性炭を前記混合ステップで使用する。この篩い分けは、例えば篩上の活性炭を水で洗浄（水洗）するなどして、活性炭に含まれる微粉等を予め除去することにより、微粉等が石膏スラリー中に残存することを防止する。 Particularly preferably, the activated carbon which has been previously sieved and washed on the second sieve having an opening larger than that of the sieve is used in the mixing step. This sieving prevents fine powder and the like from remaining in the gypsum slurry by removing fine powder and the like contained in the activated carbon in advance by, for example, washing (washing) the activated carbon on the screen with water.

なお本発明で採用する製造方法で得られる二水石膏は、通常は実質的な最大粒径が300μm程度である。このため、前記活性炭との分離ステップで用いる篩の目開きは300μmを超えることが好ましく、350〜750μmの範囲内にあることがより好ましく、400〜700μmの範囲内にあることが特に好ましい。その際、上記の活性炭の事前篩い分けに用いる篩の目開きは800μｍ以上が好ましく、１mm以上がより好ましい。活性炭の回収率を考慮すると、該目開きは好ましくは5mm以下、より好ましくは3mm以下である。 The gypsum dihydrate obtained by the manufacturing method adopted in the present invention usually has a substantial maximum particle size of about 300 μm. For this reason, the mesh size of the sieve used in the step of separating from the activated carbon is preferably more than 300 μm, more preferably in the range of 350 to 750 μm, and particularly preferably in the range of 400 to 700 μm. In that case, the opening of the sieve used for the above-mentioned sieving of activated carbon is preferably 800 μm or more, more preferably 1 mm or more. Considering the recovery rate of activated carbon, the mesh size is preferably 5 mm or less, more preferably 3 mm or less.

実施例の二水石膏の回収方法を示す図The figure which shows the collection method of the dihydrate gypsum of an Example

以下に本発明を実施するための実施例を示す。この発明の範囲は、特許請求の範囲の記載に基づき、明細書の記載とこの分野での周知技術とを参酌し、当業者の理解に従って定められるべきである。 Examples for carrying out the present invention will be shown below. The scope of the present invention should be determined according to the understanding of those skilled in the art, taking into consideration the description of the specification and the well-known technology in this field based on the description of the claims.

図１に二水石膏の回収方法を示す。２は粉砕機で廃石膏ボードを粉砕し、篩３により紙片等の異物を除去し、か焼炉４で例えば130℃〜160℃に加熱し、半水石膏及び又は無水III型石膏に変化させる。 Fig. 1 shows a method for recovering gypsum dihydrate.Reference numeral 2 crushes the waste gypsum board with a crusher, removes foreign matters such as paper pieces with asieve 3, and heats the calcination furnace 4 to, for example, 130°C to 160°C to change into hemihydrate gypsum and/or anhydrous type III gypsum. ..

６は混合器で、半水石膏及び又は無水III型石膏の粒体と、活性炭、及び最下段の析出槽１１からの石膏スラリーを混合してスラリー原液とし、初段の析出槽８へスラリー原液を供給する。活性炭の投入量は、半水石膏換算での石膏粒体1ton当たり、１Kg以上１０Kg以下が好ましい。混合器６の構造は任意で、実施例では円筒状の槽であるが、樋状の流路として樋の上部から石膏粒体と活性炭を投入しても良い。さらに石膏スラリーの代わりに工業用水を供給しても良く、中段の析出槽９，１０等からの石膏スラリーを混合器６へ循環させて良い。石膏スラリーには二水石膏粒子が分散しており、析出槽８でスラリー原液を石膏スラリーと混合し、二水石膏の種結晶と接触させる。 6 is a mixer, which mixes hemihydrate gypsum and/or anhydrous type III gypsum granules, activated carbon, and the gypsum slurry from the lowermost precipitation tank 11 into a slurry stock solution, and the slurry stock solution is fed to the first-stage precipitation tank 8. Supply. The amount of activated carbon added is preferably 1 kg or more and 10 kg or less per 1 ton of gypsum granules in terms of hemihydrate gypsum. The structure of themixer 6 is arbitrary, and is a cylindrical tank in the embodiment, but gypsum granules and activated carbon may be charged from the upper part of the gutter as a gutter-shaped flow path. Further, industrial water may be supplied instead of the gypsum slurry, and the gypsum slurry from the middle stage precipitation tanks 9 and 10 may be circulated to themixer 6. Gypsum dihydrate particles are dispersed in the gypsum slurry, and the slurry stock solution is mixed with the gypsum slurry in theprecipitation tank 8 and brought into contact with the seed crystals of gypsum dihydrate.

投入する活性炭は好ましくは顆粒状の成型活性炭あるいは破砕活性炭であり、得られる二水石膏粒子の粒径よりも大きいものが好ましく、例えば目開き500μmの篩を通過しないものを、好ましくは目開き1mmの篩を通過しないものを用いる。そして活性炭に微粉が含まれている場合に備え、図示しない篩上（例えば振動篩）で予め水洗し、篩を通過しなかった篩上成分を用いることが好ましい。水洗に用いる篩（第２の篩）の目開きは例えば500μm以上、好ましくは1mm以上で、後述の篩２０の目開き以上であり、実施例で回収する二水石膏粒子の最大粒径（約300μm）よりも大きくする。そして篩上で水洗することにより、活性炭中の微粉を除去し、活性炭中の微粉が篩２０を通過しないようにする。また石膏ボード原料の場合、処理効率を無視して、二水石膏粒子の最大粒径を300μm超にする理由はない。 The activated carbon to be charged is preferably granular shaped activated carbon or crushed activated carbon, which is preferably larger than the particle size of the obtained dihydrate gypsum particles, for example, one which does not pass through a sieve having an opening of 500 μm, preferably an opening of 1 mm. Use one that does not pass through the sieve. Then, in preparation for the case where the activated carbon contains fine powders, it is preferable to use a sieve component that has not passed through the sieve after previously washing with water on a sieve (for example, a vibration sieve) not shown. The sieve used for washing with water (second sieve) has an opening of, for example, 500 μm or more, preferably 1 mm or more, which is equal to or more than the opening of thesieve 20 described later, and the maximum particle size of the dihydrate gypsum particles (about Larger than 300 μm). Then, the fine powder in the activated carbon is removed by washing with water on the sieve so that the fine powder in the activated carbon does not pass through thesieve 20. In the case of gypsum board raw material, there is no reason to ignore the treatment efficiency and to make the maximum particle size of dihydrate gypsum particles exceed 300 μm.

混合器６の下流側に例えば直列４段の析出槽８〜１１を設け、析出槽８〜１１を全体として析出部１２と呼ぶ。析出槽８〜１１に撹拌機１４を設けてスラリーを撹拌し、石膏スラリーのオーバーフロー等により上流側の析出槽から下流側の析出槽に導入する。なお流体ポンプにより析出槽間を移送しても良い。析出槽８〜１１の段数は任意で、１段のみの析出槽により析出部１２を構成しても良い。析出槽８〜１１の石膏スラリーは二水石膏粒子を含む水性のスラリーで、二水石膏粒子が種結晶として作用し、混合器６に投入した半水石膏等を消費し、二水石膏粒子が成長する。 For example, four stages ofprecipitation tanks 8 to 11 are provided on the downstream side of themixer 6, and theprecipitation tanks 8 to 11 are collectively referred to as aprecipitation unit 12. Anagitator 14 is provided in each of theprecipitation tanks 8 to 11 to stir the slurry, and the gypsum slurry is introduced into the downstream precipitation tank from the upstream precipitation tank due to overflow or the like. A fluid pump may be used to transfer between the precipitation tanks. The number of stages of theprecipitation tanks 8 to 11 is arbitrary, and theprecipitation section 12 may be configured by only one precipitation tank. The gypsum slurry in theprecipitation tanks 8 to 11 is an aqueous slurry containing gypsum dihydrate particles, and the gypsum dihydrate particles act as seed crystals, consuming the hemihydrate gypsum and the like charged into themixer 6, and the gypsum dihydrate particles are grow up.

混合器６で混合された活性炭はスラリー原液中の水溶性有機物と考えられる着色物質を吸着し、二水石膏粒子内に着色物質が浸透することを防止する。このため活性炭は、析出槽９〜１１に投入しても良いが、好ましくは混合器６、初段の析出槽８、あるいは後述の配管１８，１９のいずれかでスラリーと混合する。 The activated carbon mixed in themixer 6 adsorbs a coloring substance considered to be a water-soluble organic substance in the slurry stock solution and prevents the coloring substance from penetrating into the gypsum dihydrate particles. Therefore, the activated carbon may be charged into the precipitation tanks 9 to 11, but is preferably mixed with the slurry in themixer 6, the first-stage precipitation tank 8 or thepipes 18 and 19 described later.

例えば最下段の析出槽１１から、石膏スラリーを流体ポンプP1により配管１８を介して混合器６へ導入し、混合器６〜析出部１２を循環させる。なお最下段の析出槽１１以外の析出槽８〜１０から、石膏スラリーを混合器６へ循環させても良い。 For example, the gypsum slurry is introduced from the lowermost precipitation tank 11 into themixer 6 by the fluid pump P1 via thepipe 18, and themixer 6 to theprecipitation part 12 are circulated. Note that the gypsum slurry may be circulated to themixer 6 from theprecipitation tanks 8 to 10 other than the lowermost precipitation tank 11.

最下段の析出槽１１から石膏スラリーを抽出し、振動篩等の篩２０により活性炭を除去し、スラリーに紙片等の異物が含まれる場合には異物も同時に除去する。篩２０を通過した石膏スラリーをフィルタープレス１６等の固液分離装置により処理し、ろ液と二水石膏粒子に分離する。分離したろ液にフィルタープレス１６等で失われた水を補給し、流体ポンプP2と配管１９により例えば初段の析出槽８へ還流する。 The gypsum slurry is extracted from the lowermost precipitation tank 11, and activated carbon is removed by asieve 20 such as a vibration sieve. When the slurry contains foreign matter such as paper pieces, the foreign matter is also removed at the same time. The gypsum slurry that has passed through thesieve 20 is treated with a solid-liquid separator such as afilter press 16 to separate into a filtrate and gypsum dihydrate particles. The separated filtrate is supplemented with water lost by thefilter press 16 or the like, and is refluxed to, for example, the firststage precipitation tank 8 through the fluid pump P2 and thepipe 19.

篩２０の目開きは活性炭洗浄用の篩（第２の篩）の目開き以下で、実施例では篩20の目開きが例えば500μm、活性炭洗浄用の篩の目開きが1mmである。また二水石膏粒子の最大粒径は300μm程度で、二水石膏粒子は大部分篩２０を通過し、活性炭に付着している粒子等の極く一部の二水石膏粒子が篩２０で捕捉される。活性炭の篩い分けは例えば析出槽１０，１１間等で行っても良いが、析出槽１１とフィルタープレス１６の間で行うと処理スラリー量を少なくできる。 The opening of thesieve 20 is equal to or smaller than the opening of the sieve for cleaning the activated carbon (second sieve). In the embodiment, the opening of thesieve 20 is, for example, 500 μm, and the opening for cleaning the activated carbon is 1 mm. Further, the maximum particle size of the gypsum dihydrate particle is about 300 μm, most of the gypsum dihydrate particle passes through thesieve 20, and only a part of the gypsum dihydrate particle such as particles adhering to the activated carbon is captured by thesieve 20. To be done. The sieving of the activated carbon may be carried out, for example, between the precipitation tanks 10 and 11, but if it is carried out between the precipitation tank 11 and thefilter press 16, the amount of treated slurry can be reduced.

実験例
以下のようにして二水石膏粒体を調製し、得られた二水石膏粒体の色調をハンター白色度Ｗ（Lab）で評価した。即ち、二水石膏粒体を乾燥させ付着水を除いた後10Mpaで成形し、その表面に日本電色工業株式会社製のNF333簡易型分光光度計を直接接触させ、ハンター白色度を測定した。Experimental Example A dihydrate gypsum granule was prepared in the following manner, and the color tone of the obtained dihydrate gypsum granule was evaluated by Hunter whiteness W (Lab). That is, the gypsum dihydrate granules were dried to remove adhering water, then molded at 10 MPa, and the surface thereof was brought into direct contact with an NF333 simplified spectrophotometer manufactured by Nippon Denshoku Industries Co., Ltd. to measure Hunter whiteness.

実験例１
廃石膏ボードを破砕及び粉砕し平均粒径2mmの廃二水石膏を得、熱風乾燥機で130℃に加熱し、半水石膏とした。半水石膏を100g/hrで、粒径分布範囲が1〜3mmの破砕活性炭（目開き1mmの振動篩上で水洗済み）を0.8g/hrで、60℃の水を200ｍL/hrで、濃度40mass%の石膏スラリー3000mL中に40時間供給し、この間スラリーを常時撹拌し、スラリー温度を60℃に保った。Experimental example 1
The waste gypsum board was crushed and crushed to obtain waste dihydrate gypsum with an average particle size of 2 mm, and the waste gypsum board was heated to 130°C with a hot air dryer to obtain hemihydrate gypsum. Hemihydrate gypsum at 100 g/hr, crushed activated carbon with a particle size distribution range of 1 to 3 mm (washed on a vibrating sieve with 1 mm opening) at 0.8 g/hr, water at 60°C at 200 mL/hr, concentration The mixture was fed into 3000 mL of 40 mass% gypsum slurry for 40 hours, during which the slurry was constantly stirred and the slurry temperature was kept at 60°C.

40時間熟成後のスラリーを採取し、目開き0.5mmの篩で活性炭と石膏スラリーを分離し、分離した石膏スラリーをろ過し、二水石膏粒体を抽出した。二水石膏粒体の乾燥後に上記のようにして白色度を測定したところ、ハンター白色度は89.7であった。 The slurry after aging for 40 hours was collected, the activated carbon and the gypsum slurry were separated with a sieve having an opening of 0.5 mm, and the separated gypsum slurry was filtered to extract gypsum dihydrate granules. When the whiteness was measured as described above after drying the gypsum dihydrate granules, the Hunter whiteness was 89.7.

比較例１
活性炭を投入せず、他は実験例１と同様にして二水石膏粒体を得、ハンター白色度を測定した。ハンター白色度は78.5で、実験例１よりも低かった。Comparative Example 1
Gypsum dihydrate gypsum was obtained in the same manner as in Experimental Example 1 except that activated carbon was not added, and the whiteness of Hunter was measured. The Hunter whiteness was 78.5, which was lower than that of Experimental Example 1.

比較例２
比較例１で抽出した二水石膏粒体50gを100mLのイオン交換水で洗浄し、ろ過と乾燥を施した後に、ハンター白色度を測定した。ハンター白色度は78.8で、水洗による白色度の改善は僅かであった。
Comparative example 2
50 g of gypsum dihydrate gypsum extracted in Comparative Example 1 was washed with 100 mL of ion-exchanged water, filtered and dried, and then the whiteness of Hunter was measured. The Hunter whiteness was 78.8, and the whiteness improvement by washing with water was slight.

２粉砕機
３,２０篩
４か焼炉
６混合器
８〜１１析出槽
１２析出部
１４撹拌機
１６フィルタープレス
１８，１９配管
P1,P2 流体ポンプ2Crusher 3,20 Sieve 4Calcination furnace 6 Mixer 8-11Precipitator 12Precipitator 14Stirrer 16Filter press 18, 19 Piping
P1,P2 fluid pump

Claims

Translated fromJapanese

廃石膏ボード由来の石膏をか焼することにより半水及び／又は無水III型の石膏粒体とし、前記石膏粒体を、石膏を含むスラリーまたは水と混合して石膏スラリーとし、石膏スラリー中に析出した二水石膏粒子を固液分離する、廃石膏ボードからの二水石膏の回収方法において、
粒状あるいは繊維状の活性炭を前記石膏スラリーと混合する混合ステップと、
前記固液分離前に、活性炭を石膏スラリーから分離する分離ステップとを行うことを特徴とする、廃石膏ボードからの二水石膏の回収方法。The gypsum derived from the waste gypsum board is calcined to form semi-water and/or anhydrous type III gypsum granules, and the gypsum granules are mixed with a slurry containing gypsum or water to form a gypsum slurry. Solid-liquid separation of the precipitated dihydrate gypsum particles, in the method of recovering dihydrate gypsum from waste gypsum board,
A mixing step of mixing granular or fibrous activated carbon with the gypsum slurry,
A method for recovering gypsum dihydrate from waste gypsum board, characterized in that a separation step of separating activated carbon from the gypsum slurry is performed before the solid-liquid separation.

前記分離ステップでは、二水石膏粒子を通過させるが活性炭を通過させない目開きの篩により、活性炭を石膏スラリーから篩い分けすることを特徴とする、請求項１の廃石膏ボードからの二水石膏の回収方法。 In the separation step, the activated carbon is sieved from the gypsum slurry by a sieve having an opening that allows the gypsum particles to pass through but does not pass the activated carbon. The gypsum dihydrate gypsum from the waste gypsum board according to claim 1, wherein Recovery method.

前記篩以上の目開きの第２の篩上で予め洗浄した活性炭を前記混合ステップで使用することを特徴とする、請求項２の廃石膏ボードからの二水石膏の回収方法。 The method for recovering gypsum dihydrate from waste gypsum board according to claim 2, characterized in that activated carbon previously washed on the second sieve having an opening larger than that of the sieve is used in the mixing step.