Calcium carbonate, sulfur absorption

Fillers. The buffering action of an alkaline filler is necessary to ensure permanence in filled paper. Retained alkalinity in the paper as it ages would resist any drop in pH that might result from absorption of either carbon dioxide or sulfur dioxide from the air. Acidic fillers, such as certain types of clay, accelerate the aging process. Calcium carbonate is an ideal filling material for permanent paper as well as for some grades not requiring permanency. In fact, the work of Barrow made the use of calcium carbonate a requirement in the manufacture of permanent book papers (1). 

The principal absorption reactions for the calcium carbonate system are shovm in Reactions 5, 6, and 7. Sulfur dioxide reacts with the relatively soluble bicarbonate to form calcium bisulfite. In addition, solid... 

The reagent stream must be controlled to permit calcium salt desupersaturation external to the scrubber and absorber while maintaining adequate concentration levels for good absorption efficiency. In order to do this a reagent stream containing 8-15% solids is circulated. The solid portion is composed of some fly ash components but mainly calcium carbonate, sulfite, and sulfate. Sulfur dioxide removal efficiency dictates the carbonate level. Sulfite crystals enhance and control desupersaturation of calcium sulfate while providing nucleation sites for crystal growth... 

Kouyoumdjian H, Saliba NA (2006) Mass concentration and ion composition of coarse and fine particles in an urban area in Beimt effect of calcium carbonate on the absorption of nitric and sulfuric acids and the depletion of chlmide. Atmos Chem Phys 6 1865—1877... 

A) 2-Bromophthalide.—The apparatus shown in Fig. 6 is used for the bromination. Flasks A and B are of 200-cc. capacity. Bromine is introduced by means of a current of carbon dioxide, which passes through mineral oil or sulfuric acid in the bubble counter, then through the bromine in flask B, and finally through the drying tower. The tower is conveniently made from a condenser jacket and is filled with anhydrous calcium chloride. Flask A is surrounded by an oil bath and is equipped with a thermometer, an outlet tube of wide bore connected to a gas absorption trap, and a gas inlet tube having an inside diameter of 2 mm. The inlet tube reaches to the bottom of the flask. 

Examples of eq. (6.14) include the roasting of metal sulfides the absorption of sulfur dioxide by calcium oxide that is formed by simultaneous calcination of limestone the formation of silicon nitride from silica, carbon and nitrogen. Examples of eq. (6.15) the baking of clay the burning of limestone the pyrolysis of coal, lignite, wood, peat, or other organic materials the calcination of sodium bicarbonate and similar salts. 

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