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The [[carbonate compensation depth]] (CCD) is the point in the ocean where the rate of precipitation of calcium carbonate is balanced by the rate of dissolution due to the conditions present. Deep in the ocean, the temperature drops and pressure increases. Calcium carbonate is unusual in that its solubility increases with decreasing temperature. Increasing pressure also increases the solubility of calcium carbonate. The CCD can range from 4–6 km below sea level.
==Usesභාවිත==
===කාර්මික යෙදවුම්===
===Industrial applications===
The main use of calciumකැල්සියම් carbonateකාබනේට් is in the construction industry, either as a building material in its own right (e.g. marble) or limestone aggregate for roadbuilding or as an ingredient of [[cement]] or as the starting material for the preparation of builder's lime by burning in a kiln.
Calciumකැල්සියම් carbonateකාබනේට් is also used in the purification of [[iron]] from [[iron ore]] in a [[blast furnace]]. Calciumකැල්සියම් carbonateකාබනේට් is calcined ''in situ'' to give calcium oxide, which forms a slag with various impurities present, and separates from the purified iron.<ref>{{cite web|title = Blast Furnace|publisher = Science Aid|accessdate = 2007-12-30|url = http://www.scienceaid.co.uk/chemistry/industrial/blastfurnace.html}}</ref>
Calciumකැල්සියම් carbonateකාබනේට් is also used in the [[oil industry]] in [[drilling fluid]]s as a formation bridging and filtercake sealing agent and may also be used as a weighting material to increase the density of [[drilling fluid]]s to control downhole pressures.
Calciumකැල්සියම් carbonateකාබනේට් is also one of the main sources used in growing [[Seacrete]], or [[Biorock]].
Precipitated calciumකැල්සියම් carbonateකාබනේට්, pre-dispersed in slurry form, is also now widely used as filler material for latex gloves with the aim of achieving maximum saving in material and production costs.<ref name = precaco3>{{cite web|title = Precipitated Calciumකැල්සියම් Carbonateකාබනේට් uses|url = http://www.aristocratholding.com/calris-5.html}}</ref>
Calciumකැල්සියම් carbonateකාබනේට් is widely used as an extender in paints,<ref name = reade>{{cite web|title = Calcium Carbonatecarbonate Powder|publisher = Reade Advanced Materials |date=2006-02-04|accessdate = 2007-12-30|url = http://www.reade.com/Products/Minerals_and_Ores/calcium_carbonate.html}}</ref> in particular matte emulsion paint where typically 30% by weight of the paint is either chalk or marble.
Calciumකැල්සියම් carbonateකාබනේට් is also widely used as a filler in plastics.<ref name = reade/> Some typical examples include around 15 to 20% loading of chalk in [[Polyvinyl chloride|unplasticized polyvinyl chloride]] (uPVC) drain pipe, 5 to 15% loading of stearate coated chalk or marble in uPVC window profile. [[Polyvinyl chloride|PVC]] cables can use calciumකැල්සියම් carbonateකාබනේට් at loadings of up to 70 phr (parts per hundred parts of resin) to improve mechanical properties (tensile strength and elongation) and electrical properties (volume resistivity). [[Polypropylene]] compounds are often filled with calciumකැල්සියම් carbonateකාබනේට් to increase rigidity, a requirement that becomes important at high use temperatures.<ref name= Imerys>{{cite web|url=http://www.imerys-perfmins.com/calcium-carbonate/eu/calcium-carbonate-plastic.htm |title=Calciumකැල්සියම් carbonateකාබනේට් in plastic applications |accessdate=2008-08-01 |publisher=Imerys Performance Minerals}}</ref> It also routinely used as a filler in [[Thermosetting plastic|thermosetting resins]] (Sheet and Bulk moulding compounds)<ref name = Imerys/> and has also been mixed with [[acrylonitrile butadiene styrene|ABS]], and other ingredients, to form some types of compression molded "clay" Poker chips.
Fine ground calciumකැල්සියම් carbonateකාබනේට් is an essential ingredient in the microporous film used in babies' [[diapers]] and some building films as the pores are nucleated around the calciumකැල්සියම් carbonateකාබනේට් particles during the manufacture of the film by biaxial stretching.
Calciumකැල්සියම් carbonateකාබනේට් is also used in a wide range of trade and [[do it yourself]] adhesives, sealants, and decorating fillers.<ref name = reade/> Ceramic tile adhesives typically contain 70 to 80% limestone. Decorating crack fillers contain similar levels of marble or dolomite. It is also mixed with putty in setting [[stained glass]] windows, and as a resist to prevent glass from sticking to kiln shelves when firing glazes and paints at high temperature.
Calciumකැල්සියම් carbonateකාබනේට් is known as ''whiting'' in [[ceramics (art)|ceramics]]/glazing applications,<ref name = reade/> where it is used as a common ingredient for many glazes in its white powdered form. When a glaze containing this material is fired in a kiln, the whiting acts as a [[flux]] material in the glaze.
Ground Calciumකැල්සියම් Carbonateකාබනේට් (GCC) or Precipitated Calciumකැල්සියම් Carbonateකාබනේට් (PCC) is used as a filler in paper. GCC and PCC are cheaper than wood fiber, so adding it to paper is cost efficient for the paper industry. Printing and writing paper can be made of 10 - 20% calcium cabonate.
In North America, calciumකැල්සියම් carbonateකාබනේට් has begun to replace [[Kaolinite|kaolin]] in the production of glossy paper. Europe has been practicing this as alkaline [[papermaking]] or acid-free papermaking for some decades. Carbonates are available in forms: ground calciumකැල්සියම් carbonateකාබනේට් (GCC) or precipitated calciumකැල්සියම් carbonateකාබනේට් (PCC). The latter has a very fine and controlled particle size, on the order of 2 micrometres in diameter, useful in [[Coated paper|coatings for paper]].
It is used in swimming pools as a [[pH]] corrector for maintaining [[alkalinity]] "buffer" to offset the acidic properties of the disinfectant agent.
It is commonly called [[chalk]] as it has traditionally been a major component of blackboard chalk. Modern manufactured chalk is now mostly [[gypsum]], hydrated [[calcium sulfate]] CaSO<sub>4</sub>·2H<sub>2</sub>O.
Ground calciumකැල්සියම් carbonateකාබනේට් is further used as an [[abrasive]] (both as scouring powder and as an ingredient of household scouring creams), in particular in its calcite form, which has the relatively low hardness level of 3 on the [[Mohs scale of mineral hardness]], and will therefore not scratch [[glass]] and most other [[ceramics]], [[Vitreous enamel|enamel]], [[bronze]], [[iron]], and [[steel]], and have a moderate effect on softer metals like [[aluminium]] and [[copper]].
===Health and dietary applications===
[[Image:500 mg calcium supplements with vitamin D.jpg|thumb|500 milligram calcium supplements made from calciumකැල්සියම් carbonateකාබනේට්]]
Calciumකැල්සියම් carbonateකාබනේට් is widely used medicinally as an inexpensive dietary calcium supplement or [[antacid|gastric antacid]].<ref name = medline>{{cite web|publisher = [[National Institutes of Health]]|work = Medline Plus|title = Calciumකැල්සියම් Carbonateකාබනේට් |date=2005-10-01|accessdate = 2007-12-30|url = http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601032.html}}</ref> It may be used as a [[phosphate binder]] for the treatment of [[hyperphosphatemia]] (primarily in patients with [[chronic renal failure]]). It is also used in the pharmaceutical industry as an inert [[Excipients#Fillers_and_diluents|filler]] for [[tablet]]s and other pharmaceuticals.<ref>{{cite book|author = Herbert A. Lieberman, Leon Lachman, Joseph B. Schwartz|title = Pharmaceutical Dosage Forms: Tablets|year = 1990|isbn = 0824780442|page=153|publisher = Dekker|location = New York}}</ref>
Calciumකැල්සියම් carbonateකාබනේට් is used in the production of toothpaste and is also used in homeopathy as one of the constitutional remedies. Also, it has seen a resurgence as a food preservative and color retainer, when used in or with products such as organic apples or food<ref>http://chemistry.about.com/od/foodcookingchemistry/a/cadditives.htm</ref>.
Excess calcium from supplements, fortified food and high-calcium diets, can cause the "milk alkali syndrome," which has serious toxicity and can be fatal. In 1915, Bertram Sippy introduced the "Sippy regimen" of hourly ingestion of milk and cream, and the gradual addition of eggs and cooked cereal, for 10 days, combined with alkaline powders, which provided symptomatic relief for peptic ulcer disease. Over the next several decades, the Sippy regimen resulted in renal failure, alkalosis, and hypercalcemia, mostly in men with peptic ulcer disease. These adverse effects were reversed when the regimen stopped, but it was fatal in some patients with protracted vomiting. Milk alkali syndrome declined in men after effective treatments for peptic ulcer disease. During the past 15 years, it has been reported in women taking calcium supplements above the recommended range of 1.2 to 1.5 g daily, for prevention and treatment of osteoporosis, and is exacerbated by dehydration. Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake. Excessive calcium intake can lead to [[hypercalcemia]], complications of which include vomiting, abdominal pain and altered mental status.<ref>{{cite journal|url=http://content.nejm.org/cgi/content/short/358/18/1952|title=Clinical problem-solving, back to basics|author=Ilan Gabriely et al.|journal=New England Journal of Medicine|year=2008|volume=358|page=1952|pmid=18450607|doi=10.1056/NEJMcps0706188|issue=18}}</ref>
As a [[food additive]] it is designated E170.<ref>{{cite web|title=Food-Info.net : E-numbers : E170 Calciumකැල්සියම් carbonateකාබනේට්|url=http://www.food-info.net/uk/e/e170.htm}} 080419 food-info.net</ref> It is used in some [[soy milk]] products as a source of dietary calcium; one study suggests that calciumකැල්සියම් carbonateකාබනේට් might be as [[bioavailable]] as the calcium in cow's milk.<ref>{{cite journal|author = Y. Zhao, B. R. Martin and C. M. Weaver|title = Calcium Bioavailability of Calciumකැල්සියම් Carbonateකාබනේට් Fortified Soymilk Is Equivalent to Cow's Milk in Young Women|year = 2005|journal = J. Nutr.|volume = 135|issue = 10|pages = 2379–2382|pmid = 16177199}}</ref> Calciumකැල්සියම් carbonateකාබනේට් is also used as a [[firming agent]] in many canned or bottled vegetable products.
===Environmental applications===
In 1989, a researcher, Ken Simmons, introduced CaCO<sub>3</sub> into the [[Whetstone Brook]] in Massachusetts.<ref>{{cite news|author = [[Associated Press]]|title =
Limestone Dispenser Fights Acid Rain in Stream |date=1989-06-13|url = http://query.nytimes.com/gst/fullpage.html?res=950DEFD9173FF930A25755C0A96F948260|publisher = [[New York Times]]}}</ref> His hope was that the calciumකැල්සියම් carbonateකාබනේට් would counter the acid in the stream from acid rain and save the trout that had ceased to spawn. Although his experiment was a success, it did increase the amounts of aluminium ions in the area of the brook that was not treated with the limestone. This shows that CaCO<sub>3</sub> can be added to neutralize the effects of acid rain in [[river]] ecosystems. Currently calciumකැල්සියම් carbonateකාබනේට් is used to neutralize acidic conditions in both soil and water.<ref>{{cite journal|author = R. K. Schreiber|title = Cooperative federal-state liming research on surface waters impacted by acidic deposition|year = 1988|journal =Water, Air, & Soil Pollution|volume = 41|issue = 1|pages = 53–73|url=http://www.springerlink.com/content/x71m4r306055p651/}}</ref><ref>{{cite web|title = Effects of low pH and high aluminum on Atlantic salmon smolts in Eastern Maine and liming project feasibility analysis|year = 2006|author = Dan Kircheis; Richard Dill|publisher = National Marine Fisheries Service and Maine Atlantic Salmon Commission|url = http://www.mainesalmonrivers.org/pages/Liming%20Project%20Rpt.pdf|format = reprinted at Downeast Salmon Federation}}</ref>. Since the 1970s, such ''liming'' has been practiced on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly.<ref>{{cite journal|author = M. Guhren, C. Bigler and I. Renberg|title = Liming placed in a long-term perspective: A paleolimnological study of 12 lakes in the Swedish liming program|year = 2007|journal =Journal of Paleolimnology|volume = 37|pages = 247–258|doi=10.1007/s10933-006-9014-9}}</ref>
==Calcination equilibrium==
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