Calcium carbonate synthetically precipitated

Calcium carbonate, synthetic n. CaC03. Pigment white 18 (77220). Calcium carbonate manufactured by a precipitation process in order to obtain a finer or more uniform particle size range. Four commercial processes are known. Density, 2.65 g/ cm (22.07Ib/gal) O.A., 28-58 particle size, 0.6-30 pm. Syn precipitated calcium carbonate. 

Precipitated calcium carbonate See calcium carbonate, synthetic. 

Precipitated Calcium Carbonate See Calcium Carbonate, Synthetic. 

Calcium carbonate [471-34-1]—Cl Pigment White 18, Cl No. 77220, EEC No. E 170. A fine, white, synthetically prepared powder consisting essentially of precipitated calcium carbonate, CaCO. ... 

Type of dryer tions, extracts, milk, blood, waste liquors, rubber latex, etc. gents, calcium carbonate, bentonite, clay sbp, lead concentrates, etc. trifuged sobds, starch, etc. dry. Examples centrifuged precipitates, pigments, clay, cement. ores, potato strips, synthetic rubber. objects, rayon skeins, lumber. sheets. her sheets. 

Not all mine drainage or natural runoff from rock outcrops are acidic, even when extensive sulfide oxidation is present. Synthetic cyanide solutions, which are often used to extract gold and other metals from ores, can greatly increase the alkalinity of mining wastes and neutralize sulfuric acid (Craw et al., 1999). In other cases, the sulfuric acid is effectively neutralized by alkaline soils, limestones, dolostones, marbles, shams, or other carbonate-rich rocks (Pfeifer et al., 2004, 219 Razo et al., 2004 Lee, Lee and Lee, 2001, 491 Mendoza et al., 2006). Reactions between calcium carbonate and sulfuric acid may precipitate gypsum (CaS04 2H20). 

The most complete study of the inhibition of calcium carbonate precipitation by organic matter was carried out by Berner et al. (1978), where primary concern was the lack of carbonate precipitation from supersaturated seawater. Both synthetic organic compounds and organic-rich pore waters from Long Island Sound were used to measure the inhibition of aragonite precipitation. Natural marine humic substances and certain aromatic acids were found to be the strongest inhibitors. The rate of precipitation in pore waters was also found to be strongly inhibited. 

The primary particle size of Winnofil stearate coated precipitated calcium carbonate from Zeneca Resins is in the region of 0.075 micron. When compounded into natural and synthetic elastomers, the hydrophobic surface coating assists wetting and aids dispersion. When compounded into plasticised PVC for cable sheathing, the PCC allows for formulations with minimal potential for acid gas release in combustion conditions. In rigid PVC, stearate coated PCC has been used in compounding as an alternative to conventional acrylic processing aids and as a means to reduce impact modifier levels. 

Aizenberg, J. 1996. Stabilization of amorphous calcium carbonate by specialized macromolecules in biological and synthetic precipitates. Advanced Materials, 8 222-5. 

Extracellular calcium carbonate formation by some cyanobacteria and algae, which are photo synthetic autotrophs that obtain their carbon from CO2, can be explained by Eq. (1.5) above. In that instance, the uptake and fixation of CO2 by the cyanobacteria and algae promotes C03 formation needed for precipitation of extracellular CaC03. In the cyanobacterium Synechococcus, the Ca precipitated by C03 from photosynthesis is derived from that bound to the cell surface of Synechococcus (Thompson et al., 1990). 

Economic Importance The current worldwide extraction of limestone and other calcium carbonate-containing minerals such as dolomite is estimated to be ca. 3-10 t/a, of which 950 10 t/a is in the USA. In the rock and earth extraction industry, limestone is in second place, only the mining of sand and gravel being more important. The extraction of limestone in 1995 in Western Europe was 850 10 t. The 1995 production of synthetic (precipitated) calcium carbonate in the USA was 1.483 10 t/a. 

The only synthetic sulfate manufactured as a filler is barium sulfate and it is known as blanc fixe . As with calcium carbonate it is produced by precipitation reactions ... 

Figure 2.16 shows a schematic diagram of the production of precipitated calcium carbonate. Such grades are also termed synthetic calcium carbonate since several chemical operations are performed. The first operation is calcination which is performed in a kiln at 900°C. At this stage, calcium carbonate is decomposed to... 

Precipitated Extenders. Precipitated extenders such as calcium carbonate (calcium carbonicum praecipitatum), barium sulfate (blanc fixe), and silica have been known for a fairly long time. When natural minerals are micronized, a minimum particle size limit is encountered. Lower particle sizes (< 1 pm) can only be obtained with considerable technical effort and expense. Extenders with finer particle sizes are produced synthetically by precipitation. The structure of one and the same extender can be modified by controlling the precipitation conditions. Particularly pure and thus bright extenders can be produced by a suitable choice of starting substances [4.12]. 

Polypropylene (PP500P, SABIC) has melt flow rate of 3.1 (2.16 kg at 230 °C) and density of 905 kg/m3 was used as matrix resin. Nano-sized synthetic ultrafine surface treated precipitated calcium carbonate (Socal 312, Solvay, France) with mean particle diameter of 70 nm used as filler phase. PP-g-MAH compatibiliser (Priex 20097, Solvay, France) with a maleic anhydride content of 0.05 wt % and MFI of 15 (2.16 kg at 230 °C) was employed to promote the interfacial interaction between nano-CaC03 and PP, and to extend the dispersion of nanoparticles in polymer matrix. Compounds used as processing materials are listed in the table 1. 

The choice of antiblocking additive depends on the polymer, the desired film quality, and whether there is a pigment. Several inorganic substances are used, including synthetic amorphous precipitated silica, diatomaceous earths, nepheline syenite, calcined clay, coated calcium carbonate, magnesium carbonate, magnesium sulphate, mica, talc and various zeolites. Calcium carbonate particles are approximately spherical, but silica ones are irregular mica forms sheets and talc is plate-like. 

Precipitated calcium carbonate is a synthetic form obtained by the recarbonization process. This type is available in high purity grades with very fine particle sizes. It has the same or higher specific gravity, and median particle sizes range from 0.7 to 2 p.m. Very fine particle sizes are used for high-viscosity nonsag plastisols and polyesters. 

Precipitated calcium carbonates CaCOj (chalk) are additives used in numerous applications. They are one of the most commonly used dental abrasives for toothpaste formulations. They are synthetic products from the decomposition and resynthesis of lime after purification. 

In other cases, homemade matrix-matched standards have been prepared. For instance, Ulens et al. used CaCOs pellets doped with known amounts of the analytes for marble analysis [9]. Pereira et al. prepared synthetic obsidian standards based on the coprecipitation of trace elements in alumina and calcium carbonate, followed by the incorporation of the precipitates into a glass frit, for analysis of natural obsidian... 

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