Ground calcite

CAN is produced by mixing concentrated ammonium nitrate solution with ground calcitic or dolomitic limestone, chalk marl, or precipitated calcium carbonate from nitrophosphate production. The mixing should be done quickly to avoid deccxnpoation of the ammonium nitrate ... 

Polyethylene Ground calcite Low and high density polyethylene. 

Chemical diffusion of the rare-earth element was measured in natural calcite under anhydrous conditions, using rare-earth carbonate powders as the sources. Experiments were run in sealed silica capsules together with finely ground calcite to ensure stability of the single-crystal samples during diffusion anneals. Rutherford back-scattering spectroscopy was used to measure diffusion profiles. The Arrhenius relationship at 600 to 850C was ... 

Texture. All limestones are crystalline, but there is tremendous variance in the size, uniformity, and arrangement of their crystal lattices. The crystals of the minerals calcite, magnesite, and dolomite are rhombohedral those of aragonite are orthorhombic. The crystals of chalk and of most quick and hydrated limes are so minute that these products appear amorphous, but high powered microscopy proves them to be cryptocrystalline. Hydrated lime is invariably a white, fluffy powder of micrometer and submicrometer particle size. Commercial quicklime is used in lump, pebble, ground, and pulverized forms. 

The reaction of C2S with CaO to form C S depends on dissolution of the lime Hi the clinker Hquid. When sufficient Hquid is present, the rate of solution is controUed by the size of the CaO particles, which depends Hi turn on the sizes of the particles of ground limestone. Coarse particles of siHca or calcite fail to react completely under commercial burning conditions. The reaction is governed by the rate of solution (10) ... 

By this reaction, we can expect the modeled fluid to be rather acidic, since it is rich in potassium. We could have chosen to fix pH by equilibrium with the siderite, which also occurs in the veins. It is not clear, however, that the siderite was deposited during the same paragenetic stages as the fluorite. It is difficult on chemical grounds, furthermore, to reconcile coexistence of the calcium-rich ore fluid and siderite with the absence of calcite (CaCOs ) in the district. In any event, assuming equilibrium with kaolinite leads to a fluid rich in fluorine and, hence, to an attractive mechanism for forming fluorite ore. 

Not all fibers yield fibers on comminution. Fibrous varieties of quartz (Si02), for example, are formed from tightly bonded, aligned helical fibers that cannot be separated mechanically (Frondel, 1978). Fibrous calcite (CaCOa), when crushed or ground, breaks into equant grains of rhombic shape. The fragments reflect the cleavage characteristics of the mineral. 

Fig. 3. Simulations calculated with the PHREEQC geochemical code (Parkhust Appelo 1999) (a) time-dependent diagram for the pH evolution of the Aspo ground water/bentonite interaction (b) time-dependent diagram for the pe evolution of the Aspo groundwater/bentonite interaction. Curves correspond to different initial partial oxygen pressures. Initial calcite and pyrite contents are 0.3 wt% and 0.01 wt% respectively, except for the curve of log/02 = —0.22 where calcite and pyrite contents are 1.4 wt% and 0.3 wt%, respectively, pe calculated stands for the cases where the oxygen fugacity is obtained from the groundwater redox potential (Bruno et at. 1999).

Cave deposits consist of minerat calcite fCaCOgj that precipitate from ground-water that enters a cavern and evaporates into the air. An abundance of caicite deposits form the rock travertine (a variety of limestone). 

Stuckless, J S., Z.E. Peterman, and D.R. Muhs U and Sr Isotopes in Ground Water and Calcite, Yucca Mountain, Nevada Evidence Against Upwelling Water, Science, 551 (October 25, 1991). 

Vacher H.L., Bengtsson T.O. and Plummer L.N. (1989) Hydrology of meteoric diagenesis - Ground-water residence times and aragonite-calcite stabilization rates in island fresh-water lenses. Geol. Soc. Amer. Bull, (in press). 

Coleman, R.D., Sutherland, J.P. and Capes, C.E., Reduction of the calcite content of ground shale by liquid-liquid particle transfer, J. Appl. Chem., 17 (1967) 89—90. 

Calcium carbonate (also known as chalk) is the most commonly used filler for PVC. This material is mined as calcite mineral and ground to a particular particle size range. It may also be precipitated from solution to give a fine particle size suitable for use in high performance areas. 

Composite cements may contain mineral additions other than, or as well as, ones with pozzolanic or latent hydraulic properties. Regourd (R34) reviewed the use of ground limestone, which is widely used in France in proportions of up to 27%. The limestones used consist substantially of calcite, with smaller proportions of quartz or amorphous silica and sometimes of dolomite. They must be low in clay minerals and organic matter because of the effects these have on water demand and setting, respectively. The XRD peaks of the calcite are somewhat broadened, indicating either small crystallite size or disorder or both IR spectra confirm the occurrence of disorder. 

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