Calcium global production

From the anionic surfactants (Table 1.1) the most relevant is LAS with an annual global production volume of more than 3 X 1061 in 2001. LAS has a wide application because of its excellent detersive properties and cost-performance ratio. Commercial LAS is applied mainly in the formulation of powder and liquid laundry detergents. The calcium salts are used as an emulsifier in pesticide formulations their amine salts are used in dry cleaning and as degreasing agents in the metal industry [14]. 

Citric acid and its citrate compounds are widely used in hundreds of applications. Global production of citric acid in 2005 was 1.6 million tons, with China producing approximately 40% of the world supply. In the United States, approximately 65% of citric acid use is in the food and beverage industry. Citric acid is used as an acidulant to impart tartness, to control pH, as a preservative and antioxidant, as a metal chelator, and to stabilize color and taste. Citrate salts can be used as mineral and metal dietary supplement for example, calcium citrate... 

The rate of global production of bicarbonate by weathering can be determined because we loiow approximately the flow of HCO J in the world s major rivers. This represents a drain of the CO2 of the atmosphere, which must be balanced by resupply to maintain a steady One is tempted to estimate the vulnerability of atmospheric/co to the imbalance between the atmospheric CO2 drain by weathering and resupply by CaCOs precipitation by focusing on the CO2 fluxes from and to the atmosphere. This, however, would be incorrect because the ocean and atmosphere carbon reservoirs are approximately in chemical equilibrium on time scales greater than the circulation of the ocean (see Chapter 11). In order to emphasize the severity of the HCOs imbalance estimated in Fig. 2.4 one should focus on the fluxes of DlC and alkalinity between the land and ocean. Because we have not yet discussed alkalinity and DIC relationships (Chapter 4) a simple approximation can be made by considering the fluxes of bicarbonate and calcium. 

In general, there is relatively little data available on the relative contributions made by different planktonic calcifying organisms (i.e. coccolithophores, foraminifera, pteropods) to the global production of calcium carbonate. Estimates of the coccoUth contribution to pelagic marine carbonate... 

The thermal decomposition of limestone - which was reported by Cato in 184 bc -at about 900 °C produces calcium oxide (lime, technically called quicklime ) (CaCOj CO2 + CaO). This is an important basic step in glass and ceramics production, and quicklime in combination with clay is also a cheap essential raw material for the cement industry. For the estimated worldwide production of cement in 1994, the consumption of limestone was about 1420x10 (metric) tons. Quicklime reacts with water to calcium hydroxide Ca(OH)2. Hydrated lime is a dry calcium hydroxide powder, while slaked lime is an aqueous suspension of calcium hydroxide particles in water. Both forms are the cheapest industrial alkaline chemical and are frequently used together with limestone as a neutralizer for acids, for example in flue gas desulfurization (see below) (Oates 1998). The annual global production of lime and lime compounds is estimated to exceed 300x10 tons, with highest amounts in China, followed by the USA, the former Soviet Union, Germany, Japan, Mexico and Brazil (Oates 2002). 

While limestone is not an essential raw material for the production of cement, it is generally the cheapest source of calcium oxide. On the basis of the global production of cement, the limestone used in its production probably amounts to about 1,500 million tpa, or one third of the total extracted. 

Only about 360,000 tonnes of mineral filler of any sort are used in polyolefins. Most of it is either calcium carbonate or talc. Globally, talc has 7% of the fillers-for-plastics market, and China is the world s largest producer. Consumption of talc in plastics is mainly in PP, but there is also considerable demand from the coatings, paper, pharmaceuticals, agricidtmal and water treatment chemicals sectors, as well as for ceramics and refractories. Estimates of consumption depend considerably on which minerals are counted some estimates have put global production at 2.4 M toimes in 2002, for all purposes. 

Milliman JD (1993) Production and accumulation of calcium carbonate in the ocean budget of a non-steady state. Global Geochem Cycles 7 927-957... 

In the preceding sections, we have discussed the marine processes that control calcium carbonate s formation, dissolution, and delivery to the seafloor. Their combined effects determine the geographic distribution of calcium carbonate in marine sediments seen in Figure 15.5. As noted earlier, the global distribution of calcareous sediments does not seem to follow that of plankton production. This points to the overriding importance of the processes that control the dissolution and sedimentation of calcium carbonate. 

Figure 6 Compilation of reconstructed variations in the depth of the CCD from selected studies covering the last 50 million years for different oceanic regions. The overall similarity of the CCD behavior between regions suggests a common forcing mechanism, such as global sea level or a long-term change in the supply of calcium to the ocean. Variations between the oceans are probably the result of differences in regional surface productivity and deep circulation patterns. Cited CCD studies include V75, van Andel (1975) B75, Berger and Roth (1975) S77, Sclater et al. (1977) P92, Peterson et al. (1992).

---