Never found free in nature, it is widely distributed in combination with minerals. Phosphate rock, which contains the mineral apatite, an impure tri-calcium phosphate, is an important source of the element. Large deposits are found in Russia, in Morocco, and in Florida, Tennessee, Utah, Idaho, and elsewhere.  [c.36]

Calcium is a metallic element, fifth in abundance in the earth s crust, of which if forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium.  [c.47]

Manne Marine algae Marine apatites Marine applications Marine coatings Marine equipment Marine oil (menhaden)  [c.595]

Direct Application Rock. Finely ground phosphate rock has had limited use as a direct-appHcation fertilizer for many years. There have been widely varying results. Direct appHcation of phosphate rock worldwide amounts to about 8% of total fertilizer phosphate used, primarily in the former Soviet Union, France, Brazil, Sri Lanka, Malaysia, and Indonesia. The agronomic effectiveness of an apatitic rock depends not only on the fineness of the grind but also strongly on the innate reactivity of the rock and the acidity of the sod performance is better on more acid sods. Probably more than half of the potentially productive tropical sods are acidic, some with pH as low as 3.5—4.5. Certain phosphate rocks may thus become increasingly important as fertilizer in those areas. The International Fertilizer Development Center at Muscle Shoals, Alabama is active in researching this field (30).  [c.223]

Igneous apatite Marine phosphorite Igneous apatite Marine phosphorite  [c.244]

Sodium monofluorophosphate is used ia most dentifrices at a concentration of 0.76 wt % which produces the desired fluoride level of 1000 ppm although one extra strength dentifrice has 1.14 wt % and 1500 ppm F. Although the mechanism of its efficacy ia reducing dental decay is not completely understood (75), it almost certainly reacts with the apatite of the tooth converting it to fluoroapatite which is less soluble ia mouth acids (see Dentifrices).  [c.226]

On the Mohs scale of scratch hardness, glass Hes between apatite, 5, and quartz, 7. Some common materials hard enough to scratch glass include agate, sand, siUcon carbide, hard steel, and emery. Glasses are harder than mica, mild steel, copper, aluminum, and marble. A typical glass-ceramic exhibits diamond penetration hardness ca 40% greater than borosiUcate glass.  [c.299]

Phospha.tes. Many phosphates cl aim unique material advantages over siUcates that make them worth the higher material costs for certain apphcations. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibiUty and, in some cases even bioactivity (the abiUty to bond with bone) (25). Recent combinations of fluorapatite with phlogopite mica provide bioactivity as well as machinability and show promise as surgical implants (26).  [c.325]

Other iron ore deposits of lesser importance in the United States are located in Missouri, Utah, Alabama, Wyoming, Texas, California, Nevada, Pennsylvania, New York, New Jersey, and Wisconsin. Of these deposits, only Missouri and Utah have mines operating. The Missouri deposit is located southwest of St. Louis near Sullivan and is a steeply dipping igneous intmsion in surrounding rock. The ore is composed principally of magnetite with some hematite, and minor amounts of quartz, apatite, and pyrite. The cmde ore is mined by underground methods and is upgraded from 56 to 70% iron by magnetic separation. The upgraded ore is used for specialty iron oxide appHcations such as pigments, ceramics (qv), and powdered metals.  [c.413]

Zaire, Norway, and the United States (14). It also occurs with calcite, dolomite, apatite, magnetite, and some siUcates. The density of pyrochlore is ca 4.0—4.4 g/cm. The tantalum content usually is low, ca 0.1—0.3% on a metal basis.  [c.22]

Phosphorite Deposits. Sedimentary phosphorites contain low concentrations of uranium in fine-grained apatite. Uranium of this type is considered an unconventional resource. Significant examples of these uranium ore types include the U.S. deposits in Elorida, where uranium is recovered as a by-product, and the large deposits in North African and Middle Eastern countries (16).  [c.184]

Because of the nutritive value, phosphates have been impHcated in promoting the growth of algae in lakes. Problems apparendy caused by sewage-home phosphates are mosdy localized to areas that have traditionally employed lakes as receiving waters for sewage efduents. It is beheved that much of the phosphate is precipitated in an insoluble form and trapped in sediments where it is ultimately converted to an apatite. Considerable controversy has centered on the contribution of phosphate-built detergents to excessive algae growth and subsequent eutrophication of natural receiving water. Legislation against the use of phosphates in detergents has resulted in a patchwork of restrictions woddwide. Home laundry detergents have been the most regulated. Societal pressure has resulted in the voluntary reduction or elimination of phosphates in many cleaning products by the manufacturers. It is open to question, however, as to whether a banning of phosphate detergents and cleaners can indeed sufficiendy reduce phosphoms input to the low levels needed to control algal growth, when, in fact, natural wastes and fertilizers provide most of the phosphoms input to receiving waters. A more logical but also more cosdy approach is phosphoms removal during sewage treatment. Excellent reviews of this area are available (36,37).  [c.345]

Dairy wheys containing complex mixtures of proteins, salts, and microorganisms rapidly foul membranes. Heat treatment and pH adjustment accelerate the aggregation of P-lactoglobulin with other whey components (33,34). Otherwise, they would interact within the polarization layer (35,36), forming sheet-like fouling gels. These methods also reduce microbial fouling and the formation of apatite gels. Other whey pretreatment methods include demineralization, clarification, and centrifugation (37,38).  [c.298]

Phosphate rock, mined widely throughout the world for its fertilizer value (see Fertilizers), in certain regions contains a few percent of lanthanides. For example, the apatite deposits in the Kola peninsula on the Russian/Finnish border. The Ln content is recoverable from the various processing residues, and because other Ln-containing minerals, such as loparite [12173-83-0], are also found there, the location suppHes a significant part of the demand in Eastern Europe.  [c.365]

The various clay minerals are the most common detrital mineral (see Clays) however, other common ones include quartz, feldspar, garnet, apatite, zircon, muscovite, epidote, biotite, augite, kyanite, mtile, stauroHte, topaz, and tourmaline. The secondary minerals are generally kaolinite, calcite, and pyrite. Analyses have shown the presence of almost all elements in at least trace quantities in the mineral matter (39). Certain elements, ie, germanium, beryUium, boron, and antimony, are found primarily with the organic matter in coal, whereas zinc, cadmium, manganese, arsenic, molybdenum, and iron are found with the inorganic material. The primary elemental constituents of mineral matter in coal are aluminum, siUcon, iron, calcium, magnesium, sodium, and sulfur. The relative concentrations depend primarily on the geographical location of the coal seam, and vary from place to place within a given field. In the eastern United States the most abundant mineral elements are siUcon, aluminum, and iron and there are much lower amounts of alkaU and alkaline-earth elements. West of the Mississippi River the relative amounts of siUcon, aluminum, and iron are much less and the alkaline-earth and alkaU elements are much greater.  [c.219]

Another desirable property for a ceramic color is a high refractive index. For example, valuable pigments are based on spinels [1302-67-6] ( 2jj = 1.8) and on zircon ( 2j = 1.9), but no valuable pigments are based on apatite ( 2j = 1.6), even though the lattice of apatite is as versatile for making ionic substitutions as that of spinel.  [c.426]

Phosphate rock, apatite 3.2 200  [c.163]

Low molecular weight polyacrylamide derivatives with mineral specific functionaHties have been developed as highly selective depressants. The depressants have certain ecological advantages over natural depressants such as starches and guar gums. The depressants provide efficient mineral recovery without flocculation. Partially hydrolyzed polyacrylamides with molecular weights of 7,000 to 85,000 can be used in sylvanite (KCl) recovery (115). Polymers having the functionaHty —CONHCN2OH are efficient modifiers in hematite—siHca separations (116). Polymers containing the —CONHCH(OH)COOH functionahty provide excellent selectivity in separation of apatite from siHceous gangue in phosphate benefication. Valuable sulfide minerals containing copper and nickel can be separated effectively from gangue sulfide minerals such as pyrite in froth flotation processes when acrylamide—allylthiourea copolymers are added to depress the pyrite (117).  [c.143]

Essentially all fertilizer phosphate is derived from mineral phosphates. Deposits of mineral phosphate are abundant and widely dispersed throughout the world. Nearly all of the mineable deposits are minerals of the apatite group represented by the general formula Ca (E,Cl,OH,0.5CO2)(PO 2- mined, essentially all the ores require beneficiation to reduce the content of clay, siUca, or other extraneous material. Beneficiation methods commonly used are washing (gravity separation) and/or flotation (qv) using various flotation agents. Beneficiated ores, as suppHed to fertilizer producers, range in 2 5 content from 28 to 38%. World average 2 5 content has been about 32%, but is decreasing as high grade ores become exhausted. The phosphoms content of ores and concentrates is, in the trade, usually expressed as bone phosphate of lime (% BPL), which is tricalcium phosphate, Ca2(P0 2-Concentrate of 32% P2 5 content has a grade of 69.9% BPL.  [c.222]

Resources for Phosphate Fertilizers. Natural mineral deposits are the source of phosphoms for essentially all manufactured phosphate fertilizer (see PHOSPHORUS PHOSPHORUS COMPOUNDS). Phosphate deposits are numerous throughout the world but size and quaHty vary widely. Those minerals that contain enough phosphoms to be potential sources for industrial use are called phosphate rock and, sometimes, phosphate ore. Phosphoms makes up about 1.22% of the earth s cmst. About 150 known minerals contain at least 1% P2O5. Nearly all mineable deposits of phosphate are of the apatite group represented by the general formula Ca (F,Cl,OH,0.5CO2)(PO 2- 7 small percentage comes from secondary aluminum deposits derived from apatite by weathering.  [c.243]

The foUowing definitions of terms are used widely by the phosphate rock industry (105). Phosphate rock designates either (/) an apatite-bearing rock containing enough P2O5 to be processed into fertilizer or phosphoms, or (2) a beneficiated apatite concentrate. Phosphorite is a sedimentary rock in which a phosphate mineral is a principal constituent. This category includes phosphatic sandstones and limestones. Ore, or matrix, is material that can be mined at a profit. Grade of ore is expressed in terms of phosphate content, either as % P2O5 or percent bone phosphate of lime Ca2(P0 2 (%BPL). Reserve is rock known to be mineable at a profit. Resource is rock which, for reasons such as low grade or inaccessibiHty, is not mineable at a profit as of this writing.  [c.243]

In the geochemistry of fluorine, the close match in the ionic radii of fluoride (0.136 nm), hydroxide (0.140 nm), and oxide ion (0.140 nm) allows a sequential replacement of oxygen by fluorine in a wide variety of minerals. This accounts for the wide dissemination of the element in nature. The ready formation of volatile silicon tetrafluoride, the pyrohydrolysis of fluorides to hydrogen fluoride, and the low solubility of calcium fluoride and of calcium fluorophosphates, have provided a geochemical cycle in which fluorine may be stripped from solution by limestone and by apatite to form the deposits of fluorspar and of phosphate rock (fluoroapatite [1306-01 -0]) approximately CaF2 3Ca2(P0 2 which ate the world s main resources of fluorine (1).  [c.171]

Apatite and other phosphorites constitute a substantial resource of rare earths. The REO content is highly variable and ranges from trace amounts to over 1%. Apatite- [1306-05-4] rich tailings of the iron ore at Mineville, New York, have been considered a potential source of yttrium and lanthanides. Rare-earth-rich apatites are found at the Kola Peninsula, Russia, and the Phalaborwa complex in South Africa. In spite of low REO content apatites could become an important source of rare earths because these are processed in large quantities for the manufacturing of fertilisers (qv).  [c.543]

Electrostatic Separation. Electrostatic separators exploit the differences in electrical conductivities, triboelectric effects, and polarizabiHties between minerals (2,6,10,13,37). These have a limited number of appHcations in minerals processing. They are used extensively in dust removal from gas streams, and are quite successfiil where appHed. They are frequently used in combination with gravity and magnetic separation. Whereas early usage was in the separation of high conductivity gold and metallic sulfides from low conductivity siHceous gangue and separation of sphalerite from galena, principal use in the 1990s is in processing beach sands and alluvial deposits containing titanium minerals (mtile and ilmenite are separated from zircon and monazite) (2). Other concentration methods have been less successfiil in these latter systems because of the similarities ia surface properties and specific gravities of the minerals to be separated. Other uses include beneficiation of cassiterite, columbite, and ilmenite iron ores separating haHte and sylvite shape separation of vermicuHte and gangue minerals and industrial waste recovery, eg, plastics from scrap. Minerals pinned on a rotor in an electric field are apatite, barite, calcite, comndum, garnet, gypsum, kyanite, monazite, quartz, scheelite, sillimonite, spinel, tourmaline, and zircon. Those thrown from the rotor are cassiterite, chromite, diamond, fluorspar, galena, gold, hematite, ilmenite, limonite, magnetite, pyrite, mtile, sphalerite, stibnite, tantaHte, and wolframite (2).  [c.410]

Phosphorites and Glauconite. Phosphorites, or marine apatites, Ca (F,Cl, OH,l/2C02)(P0 2 commonly, though not predominantiy,  [c.286]

Phosphorites. Phosphorites are of special significance. These constitute an already estabUshed and somewhat complex industry and a variety of technologies proposed for offshore mining. The deposits are most commonly bedded marine rocks of carbonate fluorapatite in the form of laminae, nodules, ooHtes, pellets, and skeletal or shell fragments. The commercial term phosphate rock includes phosphati2ed limestones, sandstones, shales, and igneous rocks containing apatite. Marine phosphorites, widely distributed in continental margins, vary in character depending on their genesis. They are found consohdated as cmsts and indurated sands, sands in shallow basins, submerged plateaux, on the slopes of islands, and in tropical lagoons. Extensive bedded deposits are indicated offshore of the eastern United States. Marine phosphorites commonly contain minor quantities of uranium—thorium, platinum, cadrnium, and rare earths (35,36).  [c.287]

Calcium Phosphates. The alkaline-earth phosphates are generally much less soluble than those of the alkaH metals. Calcium phosphates include the most abundant natural form of phosphoms, ie, apatites, Ca2Q(P0 3X2, where X = OH, F, Cl, etc. Apatite ores are the predominant basic raw material for the production of phosphoms and its derivatives. Calcium phosphates are the main component of bones and teeth. After sodium phosphates, the calcium salts are the next largest volume technical- and food-grade phosphates. Many commercial appHcations of the calcium phosphates depend on thek low solubiHties.  [c.333]

Commercial tricalcium phosphate is an effective flow conditioner for food products such as sugar and salt. The product is also used as a whitening agent in the manufacture of ceramics, as a mordant in dyeing, and as a polishing agent. Considerable research on apatites has been sparked in the 1980s and 1990s by the desire for biocompatible bone and tooth enamel replacements (see Prosthetic and biomedical devices).  [c.334]

See pages that mention the term Apatite : [c.40]    [c.212]    [c.308]    [c.308]    [c.416]    [c.208]    [c.66]    [c.66]    [c.66]    [c.9]    [c.42]    [c.48]    [c.50]    [c.540]    [c.291]    [c.334]    [c.334]    [c.419]    [c.140]    [c.426]    [c.408]    [c.1793]   
Modern inorganic chemistry (1975) -- [ c.208 ]