Uranium pitchblende

Marie Curie (1867-1934) and Pierre Curie (1859-1906) Nobel Prize for physics 1903. Only 0.1 g of radium chloride was isolated from about 500 kg or uranium pitchblende (1 5 million). 

Otto Hahn (1879-1968 Nobel Prize for chemistry 1944) and Lise PMeitner (1878-1968) as well as Frederik Soddy (1877-1956 Nobel Prize for chemistry 1921) discovered a further isotope in uranium pitchblende. 

Martin Heinrich Klaproth (1743-1817) discovered the new I.TJB metal in uranium pitchblende. 

Plan We have to find the mass of uranium in a known mass of pitchblende, given the mass of uranium in a different mass of pitchblende. The mass ratio of uranium/pitchblende is the same for any sample of pitchblende. Therefore, as shown by Equation 2.1, we multiply the mass (in kg) of pitchblende by the ratio of uranium to pitchblende that we construct from the mass analysis. This gives the mass (in kg) of uranium, and we just convert kilograms to grams. 

She found that all uranium salts were active, but so was aesc/i ife, which contained no uranium. Pitchblende produced emanations of greater intensity than could be attributed to its uranium content. 

Gr. technetos, artificial) Element 43 was predicted on the basis of the periodic table, and was erroneously reported as having been discovered in 1925, at which time it was named masurium. The element was actually discovered by Perrier and Segre in Italy in 1937. It was found in a sample of molybdenum, which was bombarded by deuterons in the Berkeley cyclotron, and which E. Eawrence sent to these investigators. Technetium was the first element to be produced artificially. Since its discovery, searches for the element in terrestrial material have been made. Finally in 1962, technetium-99 was isolated and identified in African pitchblende (a uranium rich ore) in extremely minute quantities as a spontaneous fission product of uranium-238 by B.T. Kenna and P.K. Kuroda. If it does exist, the concentration must be very small. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars. 

Originally, radium was obtained from the rich pitchblende ore found in Joachimsthal, Bohemia. The carnotite sands of Colorado furnish some radium, but richer ores are found in the Republic of Zaire and the Great Lake region of Canada. Radium is present in all uranium minerals, and could be extracted, if desired, from the extensive wastes of uranium processing. Large uranium deposits are located in Ontario, New Mexico, Utah, Australia, and elsewhere. 

Planet Uranus) Yellow-colored glass, containing more than 1% uranium oxide and dating back to 79 A.D., has been found near Naples, Italy. Klaproth recognized an unknown element in pitchblende and attempted to isolate the metal in 1789. 

Uranium, not as rare as once thought, is now considered to be more plentiful than mercury, antimony, silver, or cadmium, and is about as abundant as molybdenum or arsenic. It occurs in numerous minerals such as pitchblende, uraninite, carnotite, autunite, uranophane, and tobernite. It is also found in phosphate rock, lignite, monazite sands, and can be recovered commercially from these sources. 

Vein Deposits. The vein deposits of uranium are those in which uranium minerals fill cavities such as cracks, fissures, pore spaces, breccias, and stockworks. The dimensions of the openings have a wide range, from the narrow pitchblende-fiHed cracks, faults, and fissures in some of the ore bodies in Europe, Canada, and AustraHa to the massive veins of pitchblende at Jachymov, Czech RepubHc (15). 

Uranium [7440-61-17 is a naturally occurring radioactive element with atomic number 92 and atomic mass 238.03. Uranium was discovered in a pitchblende [1317-75-5] specimen ia 1789 by M. H. Klaproth (1) who named the element uranit after the planet Uranus, which had been recendy discovered. For 50 years the material discovered by Klaproth was thought to be metallic uranium. Pnligot showed that the uranit discovered by Klaproth was really uranium dioxide [1344-57-6] UO2, and obtained the tme elemental uranium as a black powder in 1841 by reduction of UCl [10026-10-5] with potassium (2). 

Uranium dioxide [1344-57-6], UO2, is found ki nature as the mineral pitchblende and as a component ki uraninite. The crystalline soHd melts at 2878°C and is paramagnetic with a room temperature magnetic moment of 3.2 )Xg. The density has been found to range from 10.79 to 10.95 g/cm, lower values are... 

In 1789 M. H. Klaproth examined pitchblende, thought at the time to be a mixed oxide ore of zinc, iron and tungsten, and showed that it contained a new element which he named uranium after the recendy discovered planet, Uranus. Then in 1828 J. J. Berzelius obtained an oxide, from a Norwegian ore now known as thorite he named this thoria after the Scandinavian god of war and, by reduction of its tetrachloride with potassium, isolated the metal thorium. The same method was subsequendy used in 1841 by B. Peligot to effect the first preparation of metallic uranium. 

Thorium is widely but rather sparsely distributed and its only commercial sources are monazite sands (see p. 1229) and the mineral conglomerates of Ontario. The former are found in India, South Africa, Brazil, Australia and Malaysia, and in exceptional cases may contain up to 20% Th02 but more usually contain less than 10%. In the Canadian ores the thorium is present as uranothorite, a mixed Th,U silicate, which is accompanied by pitchblende. Even though present as only 0.4% Th02, the recovery of Th, as a co-product of the recovery of uranium, is viable. 

Uranium, too, is widely distributed and, since it probably crystallized late in the formation of igneous rocks, tends to be scattered in the faults of older rocks. Some concentration by leaching and subsequent re-precipitation has produced a large number of oxide minerals of which the most important are pitchblende or uraninite, U3O8, and camotite, K2(U02)2(V04)2.3H20. However, even these are usually dispersed so that typical ores contain only about 0.1% U, and many of the more readily exploited deposits are nearing exhaustion. The principal sources are Canada, Africa and countries of the former USSR. 

Urano-hydroxyd, n. uranous hydroxide, ura-nium(IV) hydroxide, -reihe, /. uranous series, -salz, n. uranous salt, -uranat, n. uranous uranate, uranium(IV,VI) oxide, UaOa. -verbindung, /. uranous compound, Uran-oxyd, n. uranium oxide, specif, uranic oxide, uranium(VI) oxide, UOa. -ozydhydrat, n. uranium hydroxide, -oxydoxydul, n. = Uranoxyduloxyd. -oxydrot, n. uranium oxide red- -oxydul, n. uranous oxide, ura-nium(IV) oxide, UO2. -oxyduloxyd, n. uranoso-uranic oxide, uranium (I V,VT) oxide, UaOa. -oxydulsalz, n. uranous salt, uranium-(IV) salt, -pechblende, /., -pecherz, n. pitchblende, -phosphat, n, uranium phosphate. -rot, n. uranium red. -salz, n. uranium salt. 

Uranium is a metal that is found naturally as a constituent of chemical compounds m minerals such as pitchblende. Uranium ore is mined much like coal Open pits are used to mine shallow deposits, deeper deposits require shaft mining. Commercial ores yield 3 to 5 lb of nranitim compounds per ton of ore. A material called yellow-cake is produced that is... 

Radium is radioactive and extremely rare. It occurs in trace amounts (one part in 1012) in uranium ores such as pitchblende (mainly U308). 

For example, consider the chemical composition of a very old crystal of pitchblende, U308. We may presume that this crystal was formed at a time when chemical conditions for its formation were favorable. For example, it may have precipitated from molten rock during cooling. The resulting crystals tend to exclude impurities. Yet, careful analysis shows that every deposit of pitchblende contains a small amount of lead. This lead has accumulated in the crystal, beginning at the moment the pure crystal was formed, due to the radioactive decay of the uranium. 

Uranium is the fuel of nuclear reactors. The most important of its minerals is pitchblende, U02 (Fig. 17.28), much of which is obtained from strip mines in New Mexico and Wyoming. Uranium is refined to reduce the ore to the metal and to enrich it that is, to increase the abundance of a specific isotope—in this case, uranium-235. The natural abundance of uranium-235 is about 0.7% for use in a nuclear reactor, this fraction must be increased to about 3%. 

Radon is a naturally occurring, chemically inert, radioactive gas. It is colorless, odorless, and tasteless. It is part of the uranium-238 decay series, the direct decay product of radium-226. Radon moves to the earth s surface through tiny openings and cracks in soil and rocks. High concentrations of radon can be found in soils derived from uranium-bearing rocks, such as pitchblende and some... 

In every piece of uranium ore, such as pitchblende, there are 0.1-0.3 ppm of protactinium as an intermediate in the decay series. The isolation is not... 

Occurrence. Radium is found naturally in uranium ores such as pitchblende (mostly U02). One tonne of pitchblende might yield about 0.15 g of radium. 

Thorium is widely but rather sparsely distributed its only commercial sources are monazite (together with the rare earths) and uranothorite (a mixed Th, U silicate). Uranium is surprisingly common and more abundant than mercury, silver or cadmium in the earth s crust. It is widely distributed and it is found scattered in the faults of old igneous rocks. Concentration by leaching followed by re-precipitation has produced a number of oxide minerals of which the most important are uranite (also called pitchblende) U308 and carnotite, K UC HVO -SF O. 

Marie (NLP 1903, NLC 1911 ) and Pierre (NLP 1903 ) Curie took up further study of Becquerel s discovery. In their studies, they made use of instrumental apparatus, designed by Pierre Curie and his brother, to measure the uranium emanations based on the fact that these emanations turn air into a conductor of electricity. In 1898, they tested an ore named pitchblende from which the element uranium was extracted and found that the electric current produced by the pitchblende in their measuring instrument was much stronger than that produced by pure uranium. They then undertook the herculean task of isolating demonstrable amounts of two new radioactive elements, polonium and radium, from the pitchblende. In their publications, they first introduced the term radio-activity to describe the phenomenon originally discovered by Becquerel. After P. Curie s early death, M. Curie did recognize that radioactive decay (radioactivity) is an atomic property. Further understanding of radioactivity awaited the contributions of E. Rutherford. 

High-grade pitchblende ores are leached with nitric acid to recover uranium. Extraction of uranium from nitrate solutions is usually performed with TBP. TBP-based solvents are used in several areas of the nuclear industry, especially for reprocessing of spent nuclear fuels and for refining the uranium product of the Amex and Dapex processes. Extraction of uranium by TBP solvents is described in sections 12.3.4 and 12.5. 

Radium is the 85th most abundant element found in the Earths crust. Radium is found in the uranium ores pitchblende and chalcolite, which are both very radioactive. Radium metal exists to the extent of only one part to every three million parts of the uranium ore (pitchblende). Only about one gram of radium is found in every seven or eight tons of uranium ore. This scarcity seems to be the reason that only about five pounds of uranium are produced each year in the entire world. Uranium ores are found in the states of Utah, New Mexico, and Colorado in the United States and in Canada, the Czech Republic, Slovakia, Russia, Zaire, and France. 

Polonium is found only in trace amounts in the Earths crust. In nature it is found in pitchblende (uranium ore) as a decay product of uranium. Because it is so scarce, it is usually artificially produced by bombarding bismuth-209 with neutrons in a nuclear (atomic) reactor, resulting in bismuth-210, which has a half-hfe of five days. Bi-210 subsequently decays into Po-210 through beta decay The reaction for this process is Bi( ) Bi — °Po + (3-. Only small commercial milligram amounts are produced by this procedure. 

Marie Sklodowska Curie (1867—1934) and Pierre Curie (1859—1906) are credited with discovering polonium as they sought the source of radiation in pitchblende after they removed the uranium from its ore. Their discovery in 1898 led to the modern concepts of the nucleus of the atom, its structure, and how it reacts. 

They knew there must be another radioactive element in the pitchblende after the uranium was removed. Marie Curie painstakingly processed a ton of pitchblende to recover only a small amount of uranium. Even so, there was still something radioactive in all that processed pitchblende. As it turned out, there were two radioactive elements that she was able to isolate. One was radium, and the other polonium. They were identified by using piezoelectricity, discovered by her husband Pierre Curie, which could measure the strength of radiation given off by the radioactive elements with which Marie Curie was working. 

Actinium is a rare element that is found in very small amounts in uranium ore (pitchblende), making it difficult and expensive to extract even a small quantity. It is less expensive and easier to produce small amounts by bombarding the element radium with neutrons in a nuclear reactor. Actinium has few commercial uses. 

Protactinium is a relatively heavy, silvery-white metal that, when freshly cut, slowly oxidizes in air. AH the isotopes of protactinium and its compounds are extremely radioactive and poisonous. Proctatinium-231, the isotope with the longest half-life, is one of the scarcest and most expensive elements known. It is found in very small quantities as a decay product of uranium mixed with pitchblende, the ore of uranium. Protactiniums odd atomic number (gjPa) supports the observation that elements having odd atomic numbers are scarcer than those with even atomic numbers. 

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