Phosphorite

Industrially. phosphoric(V) acid is manufactured by two processes. In one process phosphorus is burned in air and the phos-phorus(V) oxide produced is dissolved in water. It is also manufactured by the action of dilute sulphuric acid on bone-ash or phosphorite, i.e. calcium tetraoxophosphate(V). Ca3(P04)2 the insoluble calcium sulphate is filtered off and the remaining solution concentrated. In this reaction, the calcium phosphate may be treated to convert it to the more soluble dihydrogenphosphatc. CafHjPOjj. When mixed with the calcium sulphate this is used as a fertiliser under the name "superphosphate . 

Igneous apatite Marine phosphorite Igneous apatite Marine phosphorite... 

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). 

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). 

Domestic. Estimates of U.S. uranium resources for reasonably assured resources, estimated additional resources, and speculative resources at costs of 80, 130, and 260/kg of uranium are given in Table 1 (18). These estimates include only conventional uranium resources, which principally include sandstone deposits of the Colorado Plateaus, the Wyoming basins, and the Gulf Coastal Plain of Texas. Marine phosphorite deposits in central Elorida, the western United States, and other areas contain low grade uranium having 30—150 ppm U that can be recovered as a by-product from wet-process phosphoric acid. Because of relatively low uranium prices, on the order of 20.67/kg U (19), in situ leach and by-product plants accounted for 76% of total uranium production in 1992 (20). 

The ocean is host to a variety and quantity of inorganic raw materials equal to or surpassiag the resources of these materials available on land. Inorganic raw materials are defined here as any mineral deposit found ia the marine environment. The mineral resources are classified generally as iadustrial minerals, mineral sands, phosphorites, metalliferous oxides, metalliferous sulfides, and dissolved minerals and iaclude geothermal resources, precious corals, and some algae. The resources are mosdy unconsoHdated, consoHdated, or fluid materials which are chemically enriched ia certain elements and are found ia or upon the seabeds of the continental shelves and ocean basias. These may be classified according to the environment and form ia which they occur (Table 1) and with few exceptions are similar to traditional mineral deposits on land. 

Fig. 1. Global distribution of seabed mineral deposits, where x represents chromite + barite titanium, zirconium, hafnium, and thorium tin I gold, platinum, and silver 3 sand and gravel shell, calcium carbonate gems marine polymetaUic sulfides phosphorites Cl cobalt cmsts S sulfur and B...

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

Continental Shelf. Most consohdated mineral deposits found on the continental shelf are identical to those found on land and are only fortuitously submerged. Exceptions include those laid down in shallow marine seas or basins in earlier geochemical environments such as bedded ironstones, limestones, potash, and phosphorites. 

Owing to the stability of the uranyl carbonate complex, uranium is universally present in seawater at an average concentration of ca. 3.2/rgL with a daughter/parent activity ratio U) of 1.14. " In particulate matter and bottom sediments that are roughly 1 x 10 " years old, the ratio should approach unity (secular equilibrium). The principal source of dissolved uranium to the ocean is from physicochemical weathering on the continents and subsequent transport by rivers. Potentially significant oceanic U sinks include anoxic basins, organic rich sediments, phosphorites and oceanic basalts, metalliferous sediments, carbonate sediments, and saltwater marshes. " ... 

Phosphorus is the eleventh element in order of abundance in crustal rocks of the earth and it occurs there to the extent of 1120 ppm (cf. H 1520 ppm, Mn 1060 ppm). All its known terrestrial minerals are orthophosphates though the reduced phosphide mineral schrieber-site (Fe,Ni)3P occurs in most iron meteorites. Some 200 crystalline phosphate minerals have been described, but by far the major amount of P occurs in a single mineral family, the apatites, and these are the only ones of industrial importance, the others being rare curiosities. Apatites (p. 523) have the idealized general formula 3Ca3(P04)2.CaX2, that is Caio(P04)6X2, and common members are fluorapatite Ca5(P04)3p, chloroapatite Ca5(P04)3Cl, and hydroxyapatite Ca5(P04)3(0H). In addition, there are vast deposits of amorphous phosphate rock, phosphorite, which approximates in composition to fluoroapatite. " These deposits are widely... 

Chemogenic Volcanogenic Polygenic <10 >50 <10 Iron-manganese nodules, glauconite, phosphorite, nodules, phUlipsite, palagonite, celestobarite, and evaporites Pyroclastic material 38 Red clay... 

Schuffert, J. D., Jahnke, R. A., Kastner, M., Leather, J., Sturtz, A., and Wing, M. R. (1994). Rates of formation of modem phosphorites off western Mexico. Geochim. Cosmochim. Acta 58, 5001-5010. 

Longinelli, A. and Nuti, S. 1968 Oxygen isotopic composition of phosphorites from marine formations. Earth andPlanetary Science Letters 5 13-16. 

T. K. Rakhmamllin, F. A. Agzamov, V. V. Ivanov, N. Kh. Karimov, M. A. Tankibaev, and N. V. Trenkenshu. Clinker-less binder composition—contains mixture of slag from melting of oxidised nickel ores and tails from enrichment of phosphorite ores. Patent SU 1777617-A, 1992. 

Kolodny Y, Kaplan IR (1970) Uranium isotopes in sea-floor phosphorites. Geochim Cosmochim Acta 34 3-24... 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Phosphorite Deposits in Florida, USA, and the large deposits in North African and Middle-eastern countries. Uranium is recovered as a by-product from Florida deposits. 

Spectrophotometric analysis following extraction with Aliquot 336 has been used to determine uranium in seawater [108]. Kim and Burnett [109] used X-ray spectrometry to determine the uranium series nucleides including 238uranium, 226radium and 210lead in marine phosphorites. 

Phosphorite deposits, 17 688, 691 Phosphorite uranium deposits, 17 520 Phosphorochloridate synthesis, 19 28 Phosphorodithioate DNA, 17 630 Phosphorodithioates, 17 630 Phosphorothioates, 17 629-630 synthesis of, 17 630 Phosphorous acid, 19 52 Phosphorous donor ligands, thorium and, 24 768 Phosphors... 

Other resolubilized trace metals precipitate as replacement ions in existing solids such as fecal pellets and bone. Examples of these fiassilized materials include barite, phosphorite, and glauconite. These precipitates contain small amounts of a variety of trace metals as well as other elements. As a result, their chemical composition is variable and their structure is usually amorphous, making it difficult to assign them an empirical formifia. 

Each of these solid phases can be described in terms of their mineralogy. This classification scheme is based on crystal structure and chemical composition. The most common minerals found in marine sediments are listed in Table 13.2. Most are silicates in which Si and O form a repeating tetrahedral base unit. Other minerals common to marine sediments are carbonates, sulfates, and oxyhydroxides. Less common are the hydrogenous minerals as they form only in restricted settings. These include the evap-orite minerals (halides, borates, and sulfates), hydrothermal minerals (sulfides, oxides, and native elements, such as gold), and phosphorites. 

Table 18.1 Average Compositions of the Earth s Upper Continental Crust, Shale, Iron-Manganese Oxides, Phosphorite, and Various Types of Marine Sediments (All in Units of ppm. Unless Noted otherwise), along with Seawater and a Hydrothermal Vent Solution from the East Pacific Rise (both in Units of 10 g L ). 

Element Z (atomic ) Upper Crust Shale Pelagic Clay Phosphorite Fe-Mn Nodule Fe-Mn Crust MOR Basal Sediment MOR Ridge Sediment Seawater Hydro- thermal Fluid... 

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