Calcium carbonate, production

Many plants outside of North America pfill or granulate a mixture of ammonium nitrate and calcium carbonate. Production of this mixture, often called calcium ammonium nitrate, essentially removes any explosion hazard. In many cases calcium nitrate recovered from acidulation of phosphate rock (see Phosphoric acid and the phosphates) is reacted with ammonia and carbon dioxide to give a calcium carbonate—ammonium nitrate mixture containing 21 to 26% nitrogen (23). 

The use of calcium carbonate in paint, paper, and plastics make up the principal part of the market. In the paper industry calcium carbonate products find two uses as a filler in the papermaking process and as a part of the coating on paper. 

Eloneva, S. (2008) Co-utilization of C02 and steelmaking slags for precipitated calcium carbonate production, Lie. tech, thesis, Helsinki University of Technology, Espoo, Finland. 

Fig. 12.8. Simplified sketch showing main relationships inside the coupled calcium and carbon cycles of the oxalate-carbonate pathway in a hypothetical ecosystem. Plants and fungi are oxalate producers. Oxalotrophic bacteria (in the soil or animal guts) use oxalate as carbon, energy and electron sources, leading to CO2 and calcium carbonate production. Calcium carbonate can accumulate inside the soils. Because the carbon of the carbonate originates from organic carbon, its fossilization in the soil constitutes a carbon sink.

The balance between calcium carbonate production and dissolution is the major pH buffering mechanism of seawater over periods of time at least on the order of thousands of years ( ). The atmospheric carbon dioxide reservoir is less than 2 percent the size of the seawater reservoir ( ) and there is active exchange between these two reservoirs across the air-water interface. Consequently, the carbon dioxide content of the atmosphere and accumulation of calcium carbonate in the deep oceans are closely coupled. 

Fig. 2.3.5. Calcium and carbonate ions may not react spontaneously but require an energy of activation before they form the calcium carbonate product and release their energy of reaction . The broken line indicates that certain materials (e.g. organic matter) may reduce the energy of activation and thus facilitate calcification.

Smith, S.V. and Harrison, J.T., 1977. Calcium carbonate production of the Mare incogni-tum, the upper windward reef slope, at Enewetak Atoll. Science, 197 556—559. 

Smith, S.V. and Kinsey, D.W., 1976. Calcium carbonate production, coral reef growth, and sea level change. Science, 194 937—939. 

Socal. Precipitated Calcium Carbonate. Production, Properties and Applications. Solvay, 11.96. 

Limestone and calcium carbonate products are used in a wide range of industries... 

Commercial calcium carbonate products typically contain 95%-98% CaCOa, with the remainder being various metal oxides. The material is typically ground from limestone (such as dolomite) or chemically precipitated into fine uniform particles wdth, unfortunately for processors, high moisture take-up. CaCOs s specific gravity is 2.7, and particle sizes may vary from 1 to 100 pm, with the median size usually being from 3 to 20pm [7-5, 7-6]. 

Some large-scale lime-soda softening plants make use of the precipitated calcium carbonate product as a source of additional lime. The calcium carbonate is first heated to at least 825°C to produce quicklime, CaO ... 

A high brightness calcium carbonate product made from handpicked stone designed for high loading and minimum black specks for cultured marble applications. 

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