Pitchblende uranium from

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. 

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. 

At the end of the eighteenth century, scientists thought that pitchblende was a mixture of iron and zinc compounds. In 1789 Martin Heinrich Klaproth (1743—1817) discovered a new metallic element in a sample of pitchblende, which he named uranus after the recently discovered planet. Although what he actually discovered was the compound uranous oxide (UOj), it was adequate to establish him as the discoverer of uranium. For almost a century, scientists believed that the compound uranous oxide (UO ) was the elemental metal uranium. In 1841 Eugene-Melchoir Pefigot (1811—1890) finally isolated the metal uranium from its compound. Even so, no one knew that both the compounds and metal of uranium were radioactive until 1896, when Henri Becquerel (1852—1908) mistakenly placed apiece of potassium... 

In studying the radioactivity of certain uranium minerals, P. and S. Curie found that the pitchblende residues from St, Joachimsthal, Bohemia, were more than three times as radioactive as uranium itself. This fact suggested the presence of a powerfully radioactive substance, and led to a thorough examination of the residues. 

Protactinium as 231Pa occurs in pitchblende, but even the-richest-ores contain only about 1 part of Pa in 107. The isolation of protactinium from residues in the extraction of uranium from its minerals is difficult, as indeed is the study of protactinium chemistry generally, owing to the" extreme tendency of the compounds to hydrolyze. In aqueous solution, polymeric ionic species and colloidal particles are formed, and these are carried on precipitates and adsorbed on vessels in solutions other than those containing appreciable amounts of mineral acids or complexing agents or ions such as F , the difficulties are almost insuperable. 

Marie Curie, Nobei prize discoverer of the eiements radium and poionium, carried out iaborious recrystaiiization experiments in order to eventually isolate very small amounts of a radium compound from the uranium ore pitchblende, obtained from Bohemian mines. The work was carried out in an old shed and took years of effort - the ore had to be cmshed and stirred with various solvents to remove the... 

Radium was discovered by Marie Curie and her husband Pierre in 1898 while removing uranium from pitchblende. They noticed that the remaining material was still radioactive. It wasn t until 1910 when it was isolated as a pure metal Marie Curie and Andre-Louis Debieme achieved this by electrolysis. 

Two of the most well-known applications of the sodium carbonate leaching of ores are the extraction of uranium from pitchblende in Canada and extraction of both uranium and vanadium from camotite, which is mined in numerous localities of the Colorado Plateau area of the United States. The latter deposits were originally worked for their vanadium content but since the 1939-45 war the emphasis has been on uranium, with vanadium a subsidiary product. 

Mass (kg) of uranium = 102 kg pitchblende x Converting the mass of uranium from kg to g ... 

If iron has been created in big stars outside our planetary system where does the iron in Kirunavaara s big magnetite ore deposit in northern Scandinavia come from. If no heavier elements than iron can be created in sidereal furnaces anywhere, where does the uranium in pitchblende come from. ... 

There is convincing evidence that some uranium ores have in past geological epochs sustained natural chain reactions. Some samples of pitchblende, UjOg, from the Oklo Mine in Gabon, Africa, have a U content distinctly lower than... 

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. 

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 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. 

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... 

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). 

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. 

As mentioned, protactinium is one of the rarest elements in existence. Although protactinium was isolated, studied, and identified in 1934, little is known about its chemical and physical properties since only a small amount of the metal was produced. Its major source is the fission by-product of uranium found in the ore pitchblende, and only about 350 milligrams can be extracted from each ton of high-grade uranium ore. Protactinium can also be produced by the submission of samples of throrium-230 (g Th) to radiation in nuclear reactors or particle accelerators, where one proton and one or more neutrons are added to each thorium atom, thus changing element 90 to element 91. 

The most common isotope of protactinium is Pa (tj/2 = 3.3 x 10 years), which occurs in pitchblende in the amount of 300 mg/ton, about the same as radium. The heroic efforts of British researchers resulted in the isolation of some hundred grams of Pa from the sludge left over from uranium processing without this supply, little or nothing would... 

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