Gypsum, CaSO

NSP is produced by the reaction of phosphate rock and sulfuric acid. This reaction quickly yields a soHd mass containing monocalcium phosphate monohydrate and gypsum, CaSO 2H20, according to the simplified equation... 

Some of the economic hurdles and process cost centers of this conventional carbohydrate fermentation process, schematically shown in Eigure 1, are in the complex separation steps which are needed to recover and purify the product from the cmde fermentation broths. Eurthermore, approximately a ton of gypsum, CaSO, by-product is produced and needs to be disposed of for every ton of lactic acid produced by the conventional fermentation and recovery process (30). These factors have made large-scale production by this conventional route economically and ecologically unattractive. 

Sulfates and Sulfites. Calcium sulfate [7778-18-9] occurs in large deposits as CaSO and as gypsum, CaSO -2H20. The dihydrate is a... 

In order for normal set to occur in Portland cement paste, mortar, or concrete, calcium sulfate must be present in the cement-water system. In today s cements, most of the calcium sulfate introduced into the system as a component of the cement, can be present in one or more forms gypsum (CaSO, 2H O), hemihydrate (CaSO. 1/2H O), soluble anhydrite (or natural anhydrite4 (CaSO ). It is very... 

Figure 2.6. Gypsum (CaSO F Os) solubility data demonstrating the common ion effect (from Tanji, 1969b, with permission).

Gypsum CaSO ZHjO Hemihydrate y-CaS04 CaS04<0.05H20 Syngenite K CalSOJjH O... 

Heating limestone, CaC03, produces quicklime, CaO, which can then be treated with water to form slaked lime, Ca(OH)2, an inexpensive base for which industry finds many uses. When slaked lime is mixed with sand and exposed to the CO2 of the air, it hardens to form mortar. Heating gypsum, CaSO - 2H2O, produces plaster of Paris, 2CaS04... 

Sulfur occurs as the free element—predominantly Sg molecules—and in metal sulfides such as galena, PbS iron pyrite, FeS2 and cinnabar, HgS. To a lesser extent, it occurs as metal sulfates such as barite, BaSO, and gypsum, CaSO - 2H2O, and in volcanic gases as H2S and SO2. 

The single crystal method of (4.) can be repeated with other host crystals which are transparent in the visible or infrared. Since NaCl is isomorphous with AgBr and AgCl and has a lattice parameter intermediate between the two silver halides, it is a model host of choice for studies on the (100) face (22). It must, of course, be dyed out of nonaqueous media. Gypsum (CaSO t O) has also been... 

Suppose, for example, that CaC03 (i.e., limestone— relatively abundant) is available in the environment, then the SO2 can combine with the CaC03 (and other components of the environment) to produce gypsum, CaSO/ O, which is very inert. There is a calculable (12,13) available energy attainable. from this reaction. 

The exceptionally light carbonates (5 C= i8.9%o) in the Medjounes structure result from sulfate reduction by sulfate-reducing bacteria in the presence of hydrocarbons, leading eventually to the formation of elemental (native) sulfur. In view of the presence of thick layers of gypsum (CaSO x zH O) and anhydrite (CaSO ) in the succession at the above-mentioned site (sample 27a), a potential for the presence of a native sulfur deposit is indicated. 

Sulfur is a component of numerous minerals. Sulfides include iron pyrite ( fool s gold, FeS ), zinc blende (ZnS), galena (PbS), and cinnabar (HgS). Sulfates include gypsum (CaSO H O) and barite (BaSO ). These ores are among industry s principal sources of copper, zinc, lead. 

Sulfates Gypsum CaSO,j 2 HgO Cement, plaster of paris. 

Monoclinic 2/m Rhomboidal prismatic (= holohedral) Gypsum, CaSO, 5... 

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