Calcium carbonat

Kunz, B., and W. Stumm (1984), "Kinetik der Bildung und des Wachstums von Calcium-Carbonat", Vom Wasser 62, 279-293. 

Als Reduktionsmittel werden Natriumhydrogensulfi t1, Hydrazin2, Hy drazinj Raney-NickeP und Palladium-calcium-carbonat mit Ameisensaure als H-Donator4, s. a. Tab. 78 (S. 139), verwendet. 

HUttig, G., u. H. Kappel Die Kinetik des thermischen Zerfalls von Calcium-carbonat. Angew. Chem. 53, 57/59 (1940). 

Nach der Vorschrift in ds. Handb., BA V/3, S. 620 betragt die Ausbente 64% d.Th. Calcium-carbonat wird als Ncutralisationsmittel verwendet. 

Filtration. Any type of clarification is foUowed by filtration through leaf-type vertical or horizontal pressure filters. Carbonatated Hquors, containing calcium carbonate, may require addition of diatomaceous earth as a filter precoat. Phosphatated Hquors are generally filtered with the addition of diatomaceous earth as precoat and body feed. 

CARBONATATION The process of purifying juice by adding an excess of calcium hydroxide (lime) at 75°C and removing the surplus by precipitation with carbon dioxide and filtering the resulting calcium carbonate. 

Clarification. All clarification treatments include the addition of lime. Lime increases the pH, stabilizing the sucrose against hydrolysis at high temperatures, and the calcium forms insoluble precipitates with many of the impurities in the raw liquor. Simple liming is rarely used in refining. The important clarification processes are phosphatation and carbonatation, which include combinations of lime with either phosphoric acid or carbon dioxide. 

Very simply, a sandstone has a grain composition of stone detritus (quartz, feldspar, detritic mica/clays) and a binder that may be clayey, quartzitic, or carbonatic (or mixtures thereof) [51, 55]. The mineral composition of limestone is mostly calcium carbonate, often derived fi om precipitated calcium carbonate and fossil shell remnants fi-om marine organisms and a calcitic binder matrix [51, 56, 57]. 

Part of the calcium content, which was formerly present as hydroxide, is now carbonatized. It can be expected that cadmium and lead are present as carbonates, since these compounds are less soluble than the respective hydroxides. Zinc concentrations are widely unchanged. Chromium contents, however, wUl depend on sorption processes on iron oxide (Ker-sten et al. 1998) or barium sulfate (Johnson et al. 1999). 

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