Minerals apatite

Despite its relatively late discovery, phosphorus is the eleventh most abundant element in Earth s crustal rock. It has been estimated that world reserves of phosphate rock are sufficient to last for several hundred years. Virtually all phosphorus deposits contain apatite, whose general formula is Caj (P04)3 X, where X — OH, or Cl. Fluoroapatite is the least soluble, hence most abundant, of the three apatite minerals. Phosphorus Is found in aqueous systems as HPOq and H2 PO4 ions. In biological organisms, phosphorus is a component of nucleic acids and energy-shuttling molecules such as ATP. 

Apatite, a natural calcium fluoride phosphate, can adsorb low to moderate levels of dissolved metals from soils, groundwater, and waste streams. Metals naturally chemically bind to the apatite, forming extremely stable phosphate phases of metal-substituted apatite minerals. This natural process is used by UFA Ventures, Inc., and is called phosphate-induced metals stabilization (PIMS). The PIMS material can by used in a packed bed, mixed with the contaminated media, or used as a permeable barrier. The material may be left in place, disposed of, or reused. It requires no further treatment or stabilization. Research is currently being conducted on using apatite to remediate soil and groundwater contaminated with heavy metals, and the technology may also be applicable to radionuclides. The technology is not yet commercially available. 

The apatite family of minerals is a common feature to many of the minerals shown in Table 3. In nature, the apatite mineral structure conforms to the 6/m class of minerals with hexagonal crystal structure and the generic formula Me5(X04)3Z where Me is Ca, Sr, Ba, Cd, and Pb (typically), X = P, As, V, Mn, and Cr and Z = OH, F, Cl, and Br. In addition to caibon-ate apatite, chloroapatite, chloropyromorphite, fluoroaptite, fluoropyromorphite, hydroxyapatite, and hydroxypyromorphite, the family includes abukumalite ((Ca,Th,Ce)5(P04, Si04)3(0H,F)),... 

Wright, J. V., Peurrung, L. M., Moody, T. E., Conca, J. L., Chen, X., Didzerekis, P. P. Wyse, E. 1995. In situ Immobilization of Heavy Metals in Apatite Mineral Formulations. Technical... 

Phosphoric acid is the starting material for most of the phosphates that are produced industrially. It is obtained from the reaction of the apatite mineral with sulfuric acid... 

The tri-calcium, barium, and strontium phosphates are members of an isostructural series M3(P04)2, where M = Ca, Ba, Sr, etc. The minerals formed by Ca are very important in bioceramics, and because Ba and Sr are fission products (i.e., formed as by-products in nuclear reactions), apatite minerals play a major role in their stabilization for disposal (see Chapter 17). Within these common structures, however, calcium phosphate goes through several phase changes at different temperatures. These phases are labeled as (3, a, a, etc. The reader is referred to Refs. [1,2] for details. 

J. Wright, L. Peurrung, T. Moody, J. Conca, X. Chen, P. Didzerekis, and E. Wyse, In situ immobilization of heavy metals in apatite mineral formation. Tech. Report to the Strategic Environmental Research and Development Program, Department of Defense, Pacific Northwest Laboratory, Richland, WA, 1995. 

Apatite minerals Extraction with 3-phenyl-4-benzoyl-s-isoxazolone ICP-AES 0.02 mg/L No data Fujino et al. 1994... 

Eujino O, Umetani S, Matsui M. 1994. Determination of uranium in apatite minerals by inductively coupled plasma atomic emission spectrometry after solvent extraction and separation with 3-phenyl-4-benzoyl-5-isoxazolone into diisobutyl ketone. Analytica Chimica Acta 296 63-68. 

The primary marine sedimentary apatite mineral is CFA (or francolite McClellan, 1980 Kolodny, 1981 Nathan, 1984 McClellan and Van Kauwenbergh, 1990 Follmi, 1996). CFA is... 

Lfntil recently, most experimental work on the thermodynamic and kinetic properties of apatite minerals focused on synthetic fluorapatite and hydroxyapatite, the compositional analogues for dental and skeletal apatite (Budz and Nancollas, 1988 Chin and Nancollas, 1991 Chin era/., 1993, Christoffersen et al., 1998). Recent research,... 

Lowenstam, H.A., 1967. Lepidocrocite, an apatite mineral and magnetite in teeth of chitons (Polyplacophora). Science, 156 1373—1375. 

Fig. 7 Proton-decoupled NMR spectra (119 MHz) of apatite minerals acquired with MAS...

Phosphorus is prepared from the apatites, mineral forms of calcium phosphate, Ca3(P04)2. The rocks are heated in an electric furnace with carbon and sand. The phosphorus vapor formed condenses as white phosphorus, a soft, white, poisonous molecular solid consisting of tetrahedral P4 molecules. It bursts into flame upon exposure to air and is normally stored under water. 

Phosphogypsum is the major byproduct of wet-process phosphoric acid production. Phosphate rock, which is composed of apatite minerals (4], (calcium phosphates containing varying amounts of carbonate and fluoride), is digested with sulfuric acid and water to produce phosphoric acid, phosphogypsum, and minor quantities of hydrofluoric acid. 

As was briefly mentioned earlier in this chapter, the inorganic matter of bone and teeth in many ways resembles apatite minerals (Ca5(0H)(P04)3). Table 3.5 summarizes inorganic solid components of other biominerals. A detailed... 

Cockbain AG, Smith GV (1967) Alkaline-earth - rare-earth silicate and germanate apatites. Mineral Mag 36 411-421... 

LeGeros RZ (1965) Effect of carbonate on the lattice parameters of apatite. Nature 206 403-404 Liu Y, Comodi P (1993) Some aspects of the crystal chemistry of apatites. Mineral Mag 57 709-719 Mackie PE, Elliott JC, Young RA (1972) Monoclinic stracture of synthetic Ca5(P04)3Cl chlorapatite. Acta Cry stallogr A28 1840-1848... 

Apatite minerals, the dominate weathering source of P, vary widely in chemistry and... 

P in soils is 600 years (Fig. 1). As noted above, the only significant weathering source for phosphorus in soils is apatite minerals. These minerals can be congruently weathered as a result of reaction with dissolved carbon dioxide ... 

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