硫酸カルシウム(か焼) 化学特性,用途語,生産方法
外観
白色の粉末
定義
本品は、硫酸(*)のカルシウム塩であり、次の化学式で表される。
参照表示名称：硫酸
溶解性
水及びエタノールにほとんど溶けない。
解説
ギプス，主として四肢，軀幹を一定の位置に保持するために用いる固定材料。その成分は硫酸カルシウム(焼セッコウ)の白い粉末で，これが水と反応して硬化する性質を利用している。この場合，加える水の温度が高いほど硬化は速い。 普通はガーゼ包帯の間にギプス粉末を挟みギプス包帯として用いる。布にギプス粉を特殊加工して固着させたものもある。これを温水または水に浸し一定の位置をとった四肢の軀幹に幾重にも巻きつけ，肢位を保持しながら硬化を待つ。
用途
石膏ブラスター、石膏ボード、鋳型、接着剤、充填剤。
用途
薄層クロマトグラフ用バインダー、石膏型材料等。
化粧品の成分用途
不透明化剤、研磨.スクラブ剤、増量剤
化学的特性
white or slightly off-white powder or granules
一般的な説明
Gypsum is a naturally hydrated calcium sulfate. It can also be easily synthesized in a partially hydrated or anhydrous form. The partially hydrated form is called hemihydrate calcium sulfate, while the anhydrous form is called anhydrite (Jorgensen 1994). In the past, a gypsum fiber product made of long, strong, and thin fibers that had good reinforcing properties was used. These fibers were nonabrasive and stable up to a temperature of 1,000°C. They were also stable in mild acids and bases (Virta 1994).
工業用途
Gypsum is the most common sulfate mineral,characterized by the chemical formulaCaSO
4 · 2H
2O; it shows little variation from thiscomposition.
Gypsum is one of the several evaporite minerals.This mineral group includes chlorides,carbonates, borates, nitrates, and sulfates. Theseminerals precipitate in seas, lakes, caves, andsalt flats due to concentration of ions by evaporation.When heated or subjected to solutionswith very large salinities, gypsum converts tobassanite (CaSO
4.H
2O) or anhydrite (CaSO
4).Under equilibrium conditions, this conversionto anhydrite is direct. The conversion occursabove 42°C in pure water.
Gypsum is used for making building plaster,wallboard tiles, as an absorbent for chemicals,as a paint pigment and extender, and forcoating papers. Natural gypsum of California,containing 15 to 20% sulfur, is used for producingammonium sulfate for fertilizer. Gypsumis also used to make sulfuric acid by heatingto 1093°C in an air-limited furnace. Theresultant calcium sulfide is reacted to yield limeand sulfuric acid. Raw gypsum is also used tomix with portland cement to retard the set.Compact massive types of the mineral are usedas building stones.
Solubility in water
Gypsum
is slightly soluble in water. Gypsum is readily
soluble in glycerol and sugar solutions and in
aqueous solutions of chelating agents, such as
EDTA.
純化方法
Its solubility in H2O is 0.2parts/100 at 18.75o. It dehydrates completely >650o. Dry it below 300o to give a solid with estimated pore size ca 38% of volume. Anhydrous CaSO4 (Drierite) has a high affinity for H2O and will absorb 6.6% of its weight of H2O to form the hemihydrate (gypsum). It sets to a hard mass with H2O; hence it should be kept in a tightly sealed container. The solubility of gypsum in H2O is unusual: 0.176% at 0o, 0.209% at 30o, 0.210 at 40o, 0.204 at 50o and 0.200 at 60o. [Hulett J Am Chem Soc 27 49 1905, James & Partington J Chem Soc 107 1019 1915, Namba J Soc Chem Ind 40 2797 1920.]
硫酸カルシウム(か焼) 上流と下流の製品情報
原材料
準備製品