Apatite phosphor

Emission Color of Sr-Apatite Phosphors Under 2527 X Excitation... 

Mn in an octahedrally coordinated site (Fig. 7). Such a change is observed in synthetic Sr and Ba apatite phosphors (Shionoya and Yen 1999). Sr preferentially occupies the Ca2 site (Rakovan and Hughes 2000), and it is probable that Pb and Ba also prefer the Ca2... 

Table 1. Fluorescent lamp synthetic apatite phosphors.

Robbins M (1983) The collectors book of fluorescent minerals. Van Nostrand Reinhold, New York Robbins M (1994) Fluorescence Gems and Minerals Under Ultraviolet Light. Geoscience Press, Phoenix Roeder PL, MacArthur D, Ma X-P, Palmer GR, Mariano AN (1987) Cathodoluminescence and microprobe study of rare-earth elements in apatite. Am Mineral 72 801-811 Ronsbo JG (1989) Coupled substitutions involving REEs and Na and Si in apatites in alkaline rocks from the Ilimaussaq intrusion, South Greenland, and the petrological implications. Am Mineral 74 896-901 Ropp RC (1971) The emission colors of the strontium apatite phosphor system. J Electrochem Soc 118 1510-1512... 

Since there are no volatile components this halophosphate phosphor is prepared with close to the stoichiometric amounts of SrHPO, SrCO, CaCO, BaCO, SrCl2, or NH Cl and EU2O2. The blend is fired under an atmosphere containing 1—2% hydrogen at 1100°C. A small excess of chloride provides some fluxing action and gives weU-formed crystals of apatite. The chlorapatites are dimorphous one modification is hexagonal and the other monoclinic. 

Hydroxyapatite, Ca2Q(PO (OH)2, may be regarded as the parent member of a whole series of stmcturaHy related calcium phosphates that can be represented by the formula M2q(ZO X2, where M is a metal or H O" Z is P, As, Si, Ga, S, or Cr and X is OH, F, Cl, Br, 1/2 CO, etc. The apatite compounds all exhibit the same type of hexagonal crystal stmcture. Included are a series of naturally occurring minerals, synthetic salts, and precipitated hydroxyapatites. Highly substituted apatites such as FrancoHte, Ca2Q(PO (C02) (F,0H)2, are the principal component of phosphate rock used for the production of both wet-process and furnace-process phosphoric acid. 

Almost all phosphoric acid is produced directly from apatite. The ore is partially purified, crashed, and then slurried with aqueous sulfuric acid ... 

C21-0054. Describe the reactions that convert apatite to phosphoric acid. Identify Brnsted acid-base reactions and redox reactions, if any. 

Dorr One of the two wet processes for making phosphoric acid by the acidulation of phosphate rock the other is the Haifa process. The Dorr process uses sulfuric acid. Phosphate rock is primarily apatite, Ca5(P04)3F. The calcium phosphate portion generates orthophos-phoric acid and calcium sulfate ... 

By reacting apatite with sulfuric acid, phosphoric acid and gypsum will result. Most phosphoric acid is produced in this way and is normally used as raw material (green acid) to produce fertilizers. A small amount, however, is further refined to phosphoric acid of food grade quality. 

Phosphorous occurs in nature in several forms, mostly as phosphates. The most common source is phosphate rock [Caj(PO )j] and a mineral called apatite. Phosphorus is found in all animal bones and teeth and in most living tissue. Phosphorous nodules are found on the ocean floor along with manganese nodules. 

Low-purity technical grade phosphoric acid for use in fertdizers is produced from phosphate rocks by digestion with concentrated sulfuric acid. The apatite types, primarily consisting of calcium phosphate phosphate rocks, are used ... 

Ninety five percent of the phosphorus on Earth belongs to the minerals of the apatite group. Apatites are inorganic constituents of bones and teeth of vertebrate and man, as well as a basis of many pathologic sohd formations. Minerals of the apatite group are the main raw materials in the production of phosphorus fertilizers, fodder and technical phosphates, elementary phosphorus, and phosphor-organic compounds. The mineral is sometimes substantially enriched in rare-earth elements (REE) making their extraction possible (Altshuller 1980). 

Relatively recently, AIS Sommer GmbH of Germany delivered a laser-induced fluorescence (LIP) analyzer for quality control in minerals and mineral processing (Broicher 2000). The LIP analyzer includes two light detector systems with three photomultipliers each, which evaluate three spectral bands in two time windows each. It was done in the Kiruna phosphorous iron ore mine, Sweden. The limitation of LIP analysis is that its accuracy depends on the complexity of the composition of the ore and the concentration and fluorescence properties of the critical minerals in relation to all the other minerals present. The phosphorous iron ore in Kiruna is ideal for LIP analyzes, because its iron minerals are practically non-luminescent, while magmatic apatite is strongly fluorescent with intensive emissions of Ce and Eu ". ... 

Tricalcium Phosphate. CarlPOjij. white solid, insoluble in water, reactive with silicon oxide and carbon ai eleciric furnace temperaiure yielding phosphorus vapor reactive with H1SO4 to form, according tn the proportions used, phosphoric acid, or dicalcium hydrogen phosphate, CaHPOa, white solid, insoluble or calcium dihydrogen phosphate, Cal 1L POrb- H O. white solid, soluble. pK,p = 28.70. See also Apatite. 

The solvent extraction of rare-earth nitrates into solutions of TBP has been used commercially for the production of high-purity oxides of yttrium, lanthanum, praseodymium and neodymium from various mineral concentrates,39 as well as for the recovery of mixed rare-earth oxides as a byproduct in the manufacture of phosphoric acid from apatite ores.272 273 In both instances, extraction is carried out from concentrated nitrate solutions, and the loaded organic phases are stripped with water. The rare-earth metals are precipitated from the strip liquors in the form of hydroxides or oxalates, both of which can be calcined to the oxides. Since the distribution coefficients (D) for adjacent rare earths are closely similar, mixer—settler assemblies with 50 or more stages operated under conditions of total reflux are necessary to yield products of adequate purity.39... 

Reaction Mechanism in Mixtures of Apatite and Additional Minerals with Phosphoric Acids at Heating... 

The world s major source of phosphorus is apatite, a class of phosphate minerals. Commercially, the most important is fluoroapatite, a calcium phosphate that contains fluorine. This fluorine must be removed for the manufacture of phosphoric acid, but it also can be used to produce hydrofluoric acid and fluorinated compounds. 

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... 

For products that require high purity, such as detergents and foodstuffs, phosphoric acid is produced from elemental phosphorus (at about four times the cost). An electric furnace operating at 1,400-1,500°C (2,552-2,732°F) is used to form a molten mass of apatite and silica that reacts with coke and reduces the phosphate mineral... 

Sources of Phosphates.—The most available and most exploited sources of phosphorus and its compounds at the present day are the phosphatic rocks, or phosphorites, which consist of tribasic calcium phosphate associated with calcium carbonate, alumina, magnesia, etc.1 Phosphates of alumina are also useful. The production of these secondary rocks from the older rocks has already been mentioned (p. 208). Although the apatites themselves, as pure minerals, contain a high proportion of phosphoric anhydride, they are difficult to decompose, and are admixed with other minerals of a still more refractory nature. 

Poorly crystalline or amorphous Phosphorite sediments made from the hard remains of marine organisms are the principal commercial source of phosphates, although Apatites are also mined. Treatment of phosphate minerals with sulfuric acid yields superphosphate fertilizer, a mixture of Ca(H2P04)2, H3PO4 and CaS04. Phosphoric acid treatment gives triple superphosphate , rich in Ca(H2P04)2. Other soluble fertilizers such as ammonium phosphates are obtained from these products. 

Accessory minerals commonly contain high concentrations of radioactive elements, and are a common target of radiogenic isotope measurements. Specific elements include uranium (zircon, apatite, titanite, monazite, xenotime, allanite) and thorium (monazite and allanite). Each accessory mineral is stabilized in a rock via a single element or suite of related elements, specifically phosphorous (apatite), REE (allanite, monazite, xenotime), zirconium (zircon), and titanium (titanite). Trace elements also occur in the major minerals (particularly phosphorous, zirconium, and titanium), so accessory minerals participate directly in major mineral reactions (Pyle and Spear, 1999, 2000, 2003 Ferry, 2000 Pyle et al, 2001 ... 

Phosphorus (0.11% of the lithosphere) is found mainly in minerals based on calcium phosphate, collophanite, the monohydrate, Ca3(P04)2.H20, and apatite, CagF(P04)3. About 90% of the phosphate rock mined is converted into fertilisers, the rest is used for making elementary phosphorus, phosphorus compounds and such alloys as phosphor bronze. For fertilisers rock phosphate is finely ground and treated with sufficient concentrated sulphuric acid to convert it to the soluble dihydrogen phosphate ... 

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