JPS63274614A - Manufacture of alpha-type gypsum hemihydrate - Google Patents
Manufacture of alpha-type gypsum hemihydrateInfo
- Publication number
- JPS63274614A JPS63274614A JP10883787A JP10883787A JPS63274614A JP S63274614 A JPS63274614 A JP S63274614A JP 10883787 A JP10883787 A JP 10883787A JP 10883787 A JP10883787 A JP 10883787A JP S63274614 A JPS63274614 A JP S63274614A
- Authority
- JP
- Japan
- Prior art keywords
- gypsum
- sodium citrate
- concentration
- slurry
- alpha
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000010440 gypsum Substances 0.000 claims abstract description 33
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 33
- 150000004683 dihydrates Chemical class 0.000 claims abstract description 30
- 239000002002 slurry Substances 0.000 claims abstract description 29
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims abstract description 22
- 239000001509 sodium citrate Substances 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims description 14
- 238000010335 hydrothermal treatment Methods 0.000 claims description 12
- 239000002994 raw material Substances 0.000 abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 238000004364 calculation method Methods 0.000 abstract description 4
- 239000000463 material Substances 0.000 abstract description 4
- 229920006395 saturated elastomer Polymers 0.000 abstract description 4
- 238000003756 stirring Methods 0.000 abstract description 2
- 238000003860 storage Methods 0.000 abstract description 2
- 238000011282 treatment Methods 0.000 abstract 4
- 238000010438 heat treatment Methods 0.000 abstract 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 229910052925 anhydrite Inorganic materials 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 238000010923 batch production Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/024—Ingredients added before, or during, the calcining process, e.g. calcination modifiers
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、建築基材やボード材あるいは模型用として用
いられるα型半水石膏の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing α-type hemihydrate gypsum used as a building base material, board material, or model.
α型半水石膏の製法としては、加圧水溶液法、加圧水蒸
気法、音圧水溶液法などが矧られているが、いずれも回
分方式で製造する方法であり、大量のα型半水石膏を製
造するには不適当な方法であつ次。There are several methods for producing α-type hemihydrate gypsum, such as the pressurized aqueous solution method, pressurized steam method, and sonic pressure aqueous solution method, but all of them are batch production methods and produce large quantities of α-type hemihydrate gypsum. In an inappropriate way.
本発明者らは従来の回分方式を連続生産方式にして工業
的に大容量のα型半水石ｉＩｒを連続的に製造する方法
として媒晶剤としてのクエン酸ナトリウム′ｔ−１ｌＬ
０１重重−以下添加した二水石膏スラリーを１４０℃以
上で処理しα型半水石膏を連続的に製造する方法を既に
提案し友。（特公昭５９〜３４０６号公報参照）
しかしながら、本発明者らは、既提案製造法では連続的
に品質の安定したα型半水石膏を製造することが難かし
く、微細粒径のα型半水石膏が混在したり′■型無水石
膏が生成したりすることをたびたび経験した。The present inventors developed a method for continuously producing α-type hemihydrate iIr in large quantities industrially by converting the conventional batch method into a continuous production method.
We have already proposed a method for continuously producing α-type hemihydrate gypsum by processing dihydrate gypsum slurry containing 0.01 weight or less at 140°C or higher. (Refer to Japanese Patent Publication No. 59-3406) However, the present inventors discovered that it is difficult to continuously produce α-type hemihydrate gypsum with stable quality using the previously proposed production method, and that I have often experienced the presence of aqueous gypsum or the formation of '■-type anhydrite.
そこで本発明は、従来方法の欠点を解消しうる微細な粒
のα型半水石膏や■型無水石膏が混在しない品質の安定
したα型半水石膏の連続的な製造法を提供しようとする
ものである。Therefore, the present invention aims to provide a method for continuously producing α-type hemihydrate gypsum with stable quality and free from the mixture of fine-grained α-type hemihydrate gypsum and ■-type anhydrite, which can eliminate the drawbacks of conventional methods. It is something.
本発明者らは前記提案方法のα型半水石膏の品質不安定
な原因を検討した結果、原料でろる二水石膏スラリー中
に含有するクエン酸ナトリウム濃度が経時的に変動し、
加圧水熱処理槽内でα型半水石膏の結晶成長速度が安定
していないことが主因であるとの結論に至り、加圧水熱
処理槽でのクエン酸す） ＩＪウム濃度を恒常的に安定
化させることによって連続して安定した品質のα警手水
石１ｆを製造し得るという知見を得たＯ
本発明はこの知見に基づいて完成されたものでろって、
二水石膏スラリーを加圧水熱処理してα型半水石膏に転
移させるにあ次り、クエン酸ナトＩＪウムをα０．０１
重量＊以下含有した二水石膏スラリーを１４０℃以上の
温度で適当時間加圧水熱処理槽で処理してα型半水石膏
を連続的に製造する方法において、上記二水石膏スラリ
ーの温度と電気伝導度を測定して、該二水石膏スラリー
に添加するクエン酸ナトリウムの添加ｔを調節すること
を特徴とするα型半水石膏の製造方法である。The present inventors investigated the cause of the unstable quality of α-type hemihydrate gypsum produced by the proposed method, and found that the concentration of sodium citrate contained in the dihydrate slurry made from the raw material fluctuates over time.
It was concluded that the main cause was that the crystal growth rate of α-type hemihydrate gypsum was not stable in the pressurized hydrothermal treatment tank. The present invention was completed based on this knowledge, and the present invention was completed based on this knowledge.
After the dihydrate gypsum slurry was subjected to pressure hydrothermal treatment to transform into α-type hemihydrate gypsum, sodium citrate was added to α0.01
In a method for continuously producing α-type hemihydrate gypsum by treating a dihydrate gypsum slurry containing not more than weight * in a pressurized hydrothermal treatment tank at a temperature of 140° C. or higher for an appropriate time, the temperature and electrical conductivity of the dihydrate gypsum slurry are This is a method for producing α-type hemihydrate gypsum, which is characterized in that the addition t of sodium citrate added to the dihydrate gypsum slurry is adjusted by measuring .
水中に溶解する二水石膏の溶解度は温度に依存して変化
し、又この溶解量は液の電気伝導度を測定すれば、測定
された電気伝導度と温度から知ることができる。さらに
これにクエン酸ナトリウムを添加すると電気伝導度は変
化するが二水石膏スラリー中へのクエンばナトリウムの
添加量に応じて変化する電気伝導度の変化とクエン酸ナ
トリウム添加量との関係を各温度との関係として予め検
量しておけば二本石膏スラリー中のクエン酸ナトリウム
量が判る。The solubility of dihydrate gypsum in water varies depending on the temperature, and the amount dissolved can be determined from the measured electrical conductivity and temperature by measuring the electrical conductivity of the liquid. Furthermore, when sodium citrate is added to this, the electrical conductivity changes, but the relationship between the change in electrical conductivity, which changes depending on the amount of sodium citrate added to the dihydrate gypsum slurry, and the amount of sodium citrate added is If it is calibrated in advance in relation to temperature, the amount of sodium citrate in the two-piece gypsum slurry can be determined.
これらの関係について第２図〜第４図に示した。＠２図
は二水石膏の水中への溶解度を温度の関数として示した
図でろり、この溶解度と温度の関係を安達らは（！）式
の３次式として蟲め、次のように示している。（Ｇｙｐ
日ｕｎ ＆ Ｌｉｎｅ 。These relationships are shown in FIGS. 2 to 4. Figure 2 shows the solubility of gypsum dihydrate in water as a function of temperature.Adachi et al. ing. (Gyp
Sun & Line.
Ｎｏ、１３５．１９７５．Ｐ６３−７２）８＝ａ ＋
ｔｉｔ ＋ ａｔ” ＋ ｄｔ”
”” Ｔｌ１Ｓ：ｌ解反 （ｆ−Ｃａ８０４／ｋｆ／
−ＨｘＯ）ａ、 ｂ、 ｃ、 （１：係数 〔−〕ｔ：
＠ 匿 （Ｃ）
第３図は各温度（４０℃、６０℃、８０℃。No. 135.1975. P63-72) 8=a +
tit + at” + dt”
"" Tl1S:l solution (f-Ca804/kf/
-HxO) a, b, c, (1: coefficient [-]t:
@ Hidden (C) Figure 3 shows various temperatures (40℃, 60℃, 80℃.
１００℃）における溶解石膏濃度と電気伝導度の関係を
示すグラフであり、縦軸は電気伝導度（Δ、単位ｍｅ／
ｃｍ）の対数値、横軸は溶解石膏濃度（Ｃａ８０４ ）
の対数値を示す。第４図はクエン酸す？Ｖクムａ度と電
気伝導度の対数値の関係を示すグラフである。This is a graph showing the relationship between dissolved gypsum concentration and electrical conductivity at 100°C), where the vertical axis is the electrical conductivity (Δ, unit: me/
cm), the horizontal axis is the dissolved gypsum concentration (Ca804)
Indicates the logarithm value of Figure 4 is citric acid? It is a graph showing the relationship between the V-cum a degree and the logarithm value of electrical conductivity.
先ず２水石膏スラリー中の石１Ｆ溶解度は、（１１式か
ら計算できるので、温度と電気伝導度の値から第３図、
第４図のグラフの関係を用いて、クエン酸ナトリウムの
濃度を求めることができ、クエン酸ナトリウムの添加ｔ
を適正濃度に管理することができる０
〔実施例〕
第１図は本発明の一実施例として、α型半水石膏製造方
法のフローを示した図でろる〇二水石膏スラリー供給槽
４から配管５ｔ−介して原料二水石膏スラリーを加圧水
熱処理槽１１へ供給し、該加圧水熱処理槽１１では攪拌
機１９で攪拌しながら連続式で二水石膏を半水石膏に転
化させ、該加圧水熱処理槽１１内滞留スラリー１８の滞
留量が一定となるようにレベル検出器２１でレベル検出
器
で制御弁２３を作動させ配管２０を介して、前記二水石
膏スラリーの供給量相当分を抜き出Ｕ液体サイクロン２
４′ｔ−介して粗粒含有スラリー２５を微粒スラリー２
６に分級させ、粗粒側２５は製品α−半水石貴回収工程
へ送ｐ１微粒側２６は前記二水石膏スラリー供給槽４へ
循環させている。該二水石膏スラリー供給槽４にはその
他に二水石膏スラリー１とクエン酸ナトリウム貯槽２か
らクエン酸ナトリウムが供給量れるが、このクエン酸ナ
トリウムの二水石膏スラリー供給槽４への供給量は、前
記加圧水熱処理槽１１へ供給している原料二本石膏スラ
リーの電気伝導度と温度を各々電気伝導度検知器６及び
温度計８で検卸し、各々の検知信号を増幅器７．９で処
理し、この信号を演算調節計１０で処理して、切出し器
３を作動させて調節している。演算調節計１０では下記
の演算を行なわせる。First, the solubility of stone 1F in dihydrate gypsum slurry can be calculated from Equation 11 (Fig. 3) using the temperature and electrical conductivity values.
Using the relationship shown in the graph in Figure 4, the concentration of sodium citrate can be determined, and the addition t of sodium citrate
[Example] Figure 1 is a diagram showing the flow of a method for producing α-type hemihydrate gypsum as an example of the present invention. The raw material dihydrate gypsum slurry is supplied to the pressurized hydrothermal treatment tank 11 through the pipe 5t, and in the pressurized hydrothermal treatment tank 11, the dihydrate gypsum is continuously converted into hemihydrate gypsum while being stirred by the stirrer 19. A control valve 23 is actuated by a level detector 21 so that the amount of retained slurry 18 retained in the interior becomes constant, and an amount equivalent to the supply amount of the dihydrate gypsum slurry is extracted via piping 20. 2
4'T - Coarse particle-containing slurry 25 is passed through fine particle slurry 2.
The coarse grain side 25 is sent to the product α-hemihydrate precious recovery process, and the fine grain side 26 is circulated to the dihydrate slurry supply tank 4. The dihydrate slurry supply tank 4 is also supplied with sodium citrate from the dihydrate slurry 1 and the sodium citrate storage tank 2, but the amount of sodium citrate supplied to the dihydrate slurry supply tank 4 is , the electrical conductivity and temperature of the two raw material gypsum slurries supplied to the pressurized hydrothermal treatment tank 11 are detected by an electrical conductivity detector 6 and a thermometer 8, and each detection signal is processed by an amplifier 7.9. This signal is processed by the arithmetic controller 10, and the cutter 3 is operated and adjusted. The calculation controller 10 performs the following calculations.
（演算調節計演算項目）
（１） 原料二水石膏スラリー中の飽和溶解石膏濃度
ｃ＋＋Ｉ を計算
（イ）（１）式に表−１の二水石膏のａ、ｂ、ｃを代入
（ロ）（１）式のｔは測定値を使用
（２） 媒晶剤濃度の計算
←） 上記からｔＣにおける飽和溶解石膏濃度が判れば
、第３図の関係が求めた次の（２）式より Ｃａ８０４
による電気伝導度が判る０Ａ” ＝ ｆｆ（ｔ）ｎ（Ｃ
’）Ｉ＋１１−＋２１、Ｘ＊ ： ＷＬ電気伝導度
〔ｍｓ／ｌＩ〕ｔ：温度 〔℃〕
Ｃ“：上記（１）項で得た飽和溶解石膏濃度１度（ｔ７
ｋｇ−Ｈ２ｏ ）
α、ｎ、ｍ：係数 〔−〕
（ロ）実測した電気伝導度ＡとＡ”の計算値の差からク
エン酸ナトリウム濃度が求まる。(Arithmetic controller calculation items) (1) Calculate the saturated dissolved gypsum concentration c++I in the raw dihydrate gypsum slurry (a) Substitute a, b, and c of dihydrate gypsum in Table 1 into equation (1) (b) Use the measured value for t in equation (1). (2) Calculate modifier concentration ←) If the saturated dissolved gypsum concentration at tC is known from the above, then from the following equation (2), which calculates the relationship in Figure 3, Ca804
The electric conductivity is determined by 0A” = ff(t)n(C
') I+11-+21, X*: WL electrical conductivity
[ms/lI] t: Temperature [℃] C": Saturated dissolved gypsum concentration 1 degree obtained in the above (1) (t7
kg-H2o) α, n, m: coefficient [-] (b) The sodium citrate concentration is determined from the difference between the calculated values of the actually measured electrical conductivity A and A''.
Ｃａｄｄ＝β（Ａ−Ａ”）
Ｃａｄａ ：クエン酸ナトリウム濃度 （ｗｔ％〕Ａ
：供給される二水石膏スラリーの電気伝導度
（ｍ８／ａｎ〕β ：係数 〔−
〕
（βは上記、α、ｎ、ｍと同様事前に測定して定める。Cadd=β(A-A”) Cada: Sodium citrate concentration (wt%) A
: Electrical conductivity of supplied dihydrate gypsum slurry
(m8/an]β: Coefficient [-
] (β is determined by measuring in advance like α, n, and m above.
）
本実施例での操作条件及び装置仕様扛次の通りでろる〇
（操作条件）
＋１１ 原料二水石膏スラリー濃度 ： １５ｗｔ
チ（２） クエン酸ナトリウム濃度 ： α０１
ｗｔチ（３） 加圧水熱処理濃度 ＝１４０
℃（４） 加圧水熱処理槽ホールド液ｉｉ ： ２０
０１（主要装置条件）
０） 二水石膏原料供給槽容積 ： ２０００ｔ（２
） 加圧水熱処理槽容積 ： ２５０ｔ（
３） 加圧水熱処理槽攪拌機 ：タービ４（４）
同上撹拌機攪拌動力 ： １ ｋＷ／ｍ”次
に本発明の効果を示すために、第５図に製品α半水石膏
の１００倍拡大写真を示した。) The operating conditions and equipment specifications in this example are as follows (Operating conditions) +11 Raw material dihydrate slurry concentration: 15wt
H (2) Sodium citrate concentration: α01
wt Chi (3) Pressurized hydrothermal treatment concentration = 140
°C (4) Pressurized hydrothermal treatment tank hold liquid II: 20
01 (Main equipment conditions) 0) Dihydrate gypsum raw material supply tank volume: 2000t (2
) Pressurized hydrothermal treatment tank volume: 250t (
3) Pressurized hydrothermal treatment tank agitator: Turbi 4 (4)
Stirring power of the same stirrer as above: 1 kW/m''Next, in order to show the effect of the present invention, FIG. 5 shows a 100 times enlarged photograph of the product α hemihydrate gypsum.
以上述べたごとく、二水石膏原料スラリー中のクエン酸
ナトリウム濃度を所望濃度に制御維持させることによっ
て、安定した品質のα警手水石貴の連続製造ができるよ
うになった。As described above, by controlling and maintaining the sodium citrate concentration in the dihydrate gypsum raw material slurry at a desired concentration, it has become possible to continuously produce α-Keite Suiseki with stable quality.
第１図は本発明方法の一実施例を示す図、第２図は二水
石膏の水中への醪解反と温度の関係を示すグラフ、第３
図は各温度における溶解石１ｆ＠度と電気伝導度の関係
を示すグラフ、第４図はクエン酸ナトリウム濃度と電気
伝導度の関係を示すグラフ、第５図は本発明の実施例で
得られ次α半水石膏の結晶構造の顕微鏡写真（１００倍
）である。Fig. 1 is a diagram showing an embodiment of the method of the present invention, Fig. 2 is a graph showing the relationship between melting of dihydrate gypsum in water and temperature, and Fig. 3
The figure is a graph showing the relationship between molten stone 1f@degree and electrical conductivity at each temperature, Figure 4 is a graph showing the relationship between sodium citrate concentration and electrical conductivity, and Figure 5 is a graph showing the relationship between the concentration of sodium citrate and electrical conductivity. This is a micrograph (100x magnification) of the crystal structure of α-hemihydrate gypsum.
Claims (1)
移させるにあたり、クエン酸ナトリウムを０．０１重量
％以下含有した二水石膏スラリーを１４０℃以上の温度
で適当時間加圧水熱処理槽で処理してα型半水石膏を連
続的に製造する方法において、上記二水石膏スラリーの
温度と電気伝導度を測定して、該二水石膏スラリーに添
加するクエン酸ナトリウムの添加量を調節することを特
徴とするα型半水石膏の製造方法。In order to transform the dihydrate gypsum slurry into α-type hemihydrate gypsum through pressure hydrothermal treatment, the dihydrate gypsum slurry containing 0.01% by weight or less of sodium citrate is treated in a pressure hydrothermal treatment tank at a temperature of 140°C or higher for an appropriate period of time. In the method for continuously producing α-type hemihydrate gypsum, the temperature and electrical conductivity of the dihydrate gypsum slurry are measured and the amount of sodium citrate added to the dihydrate gypsum slurry is adjusted. Characteristic method for producing α-type hemihydrate gypsum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10883787A JPH0686293B2 (en) | 1987-05-06 | 1987-05-06 | Method for producing α-type hemihydrate gypsum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10883787A JPH0686293B2 (en) | 1987-05-06 | 1987-05-06 | Method for producing α-type hemihydrate gypsum |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63274614A true JPS63274614A (en) | 1988-11-11 |
| JPH0686293B2 JPH0686293B2 (en) | 1994-11-02 |
Family
ID=14494818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10883787A Expired - Fee Related JPH0686293B2 (en) | 1987-05-06 | 1987-05-06 | Method for producing α-type hemihydrate gypsum |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0686293B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0379266A2 (en) * | 1989-01-17 | 1990-07-25 | Mitsubishi Jukogyo Kabushiki Kaisha | Production method for anhydrous gypsum |
| JP2006273599A (en) * | 2005-03-28 | 2006-10-12 | Tokuyama Corp | Method for treating waste gypsum |
| CN104355560A (en) * | 2014-10-21 | 2015-02-18 | 金正大生态工程集团股份有限公司 | Production method of alpha-gypsum powder with high strength |
-
1987
- 1987-05-06 JP JP10883787A patent/JPH0686293B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0379266A2 (en) * | 1989-01-17 | 1990-07-25 | Mitsubishi Jukogyo Kabushiki Kaisha | Production method for anhydrous gypsum |
| JP2006273599A (en) * | 2005-03-28 | 2006-10-12 | Tokuyama Corp | Method for treating waste gypsum |
| CN104355560A (en) * | 2014-10-21 | 2015-02-18 | 金正大生态工程集团股份有限公司 | Production method of alpha-gypsum powder with high strength |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0686293B2 (en) | 1994-11-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |