|
Uranium Tailings
Uranium tailings are a waste byproduct (tailings) of uranium mining. In mining, raw uranium ore is brought to the surface and crushed into a fine sand. The valuable uranium-bearing minerals are then removed via heap leaching with the use of acids or bases, and the remaining radioactive sludge, called "uranium tailings", is stored in huge impoundments. A short ton (907 kg) of ore yields one to five pounds (0.45 to 2.3 kg) of uranium depending on the uranium content of the mineral. Uranium tailings can retain up to 85% of the ore's original radioactivity. If uranium tailings are stored aboveground and allowed to dry out, the radioactive sand can be carried great distances by the wind, entering the food chain and bodies of water. The danger posed by such sand dispersal is uncertain at best given the dilution effect of dispersal. The majority of tailing mass will be inert rock, just as it was in the raw ore before the extraction of the uranium, but physically altered, ground ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tailings
In mining, tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different to overburden, which is the waste rock or other material that overlies an ore or mineral body and is displaced during mining without being processed. The extraction of minerals from ore can be done two ways: placer mining, which uses water and gravity to concentrate the valuable minerals, or hard rock mining, which pulverizes the rock containing the ore and then relies on chemical reactions to concentrate the sought-after material. In the latter, the extraction of minerals from ore requires comminution, i.e., grinding the ore into fine particles to facilitate extraction of the target element(s). Because of this comminution, tailings consist of a slurry of fine particles, ranging from the size of a grain of sand to a few micrometres. Mine tailings are usually produced from the mill in slurry form, which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Thorium
Thorium (90Th) has seven naturally occurring isotopes but none are stable. One isotope, 232Th, is ''relatively'' stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe. This isotope makes up nearly all natural thorium, so thorium was considered to be mononuclidic. However, in 2013, IUPAC reclassified thorium as binuclidic, due to large amounts of 230Th in deep seawater. Thorium has a characteristic terrestrial isotopic composition and thus a standard atomic weight can be given. Thirty-one radioisotopes have been characterized, with the most stable being 232Th, 230Th with a half-life of 75,380 years, 229Th with a half-life of 7,917 years, and 228Th with a half-life of 1.92 years. All of the remaining radioactive isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes. One isotope, 229Th, has a nucl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium Mill Tailings Radiation Control Act
The Uranium Mill Tailings Radiation Control Act (1978) is a United States environmental law that amended the Atomic Energy Act of 1954 and authorized the Environmental Protection Agency to establish health and environmental standards for the stabilization, restoration, and disposal of uranium mill waste. Title 1 of the Act required the EPA to set environmental protection standards consistent with the Resource Conservation and Recovery Act, including groundwater protection limits; the Department of Energy to implement EPA standards and provide perpetual care for some sites; and the Nuclear Regulatory Commission to review cleanups and license sites to states or the DOE for perpetual care. Title 1 established a uranium mill remedial action program jointly funded by the federal government and the state. Title 1 of the Act also designated 22 inactive uranium mill sites for remediation, resulting in the containment of 40 million cubic yards of low-level radioactive material in UMTRCA Tit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Uranium Mines
Uranium production is carried out in about 13 countries around the world, in 2017 producing a cumulative total of 59,462 tonnes of uranium (tU). The international producers were Kazakhstan (39%), Canada (22%), Australia (10%), Namibia (7.1%), Niger (5.8%), Russian Federation (4.9%), Uzbekistan (4.0%), China (3.2%), United States (1.6%), Ukraine (0.9%), India (0.7%), South Africa (0.5%) and Pakistan (0.1%). Since 2009 the in-situ leach (ISL) operations of Kazakhstan have been producing the largest share of world uranium. The largest conventional uranium mines are Cigar Lake and McArthur River (Canada); Ranger and Olympic Dam (Australia); Krasnokamensk (Russia) and Rossing (Namibia). The largest uranium producers are Cameco, Rio Tinto, Areva, KazAtomProm and ARMZ-TVEL. The production methods employed are conventional underground and open cast (50%) and in-situ leaching (50%). About 50 uranium production centers are operational. Viable projects Potentially viable projects N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naturally Occurring Radioactive Material
Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium and any of their decay products, such as radium and radon. Produced water discharges and spills are a good example of entering NORMs into the surrounding environment. Natural radioactive elements are present in very low concentrations in Earth's crust, and are brought to the surface through human activities such as oil and gas exploration or mining, and through natural processes like leakage of radon gas to the atmosphere or through dissolution in ground water. Another example of TENORM is coal ash produced from coal burning in power plants. If radioactivity is much higher than background level, handling TENORM may cause problems in many industries and transportation. NORM in oil and gas exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Polonium
Polonium (84Po) has 42 isotopes, all of which are radioactive, with between 186 and 227 nucleons. 210Po with a half-life of 138.376 days has the longest half-life of naturally occurring polonium. 209Po, with a half-life of 125.2 years, has the longest half-life of all isotopes of polonium. 209Po and 208Po (half-life 2.9 years) can be made through proton bombardment of bismuth in a cyclotron. List of isotopes , - , 186Po , , style="text-align:right" , 84 , style="text-align:right" , 102 , 186.0044(18) , 34(12) μs , α , 182Pb , 0+ , , - , 187Po , , style="text-align:right" , 84 , style="text-align:right" , 103 , 187.00304(30) , 1.40(0.25) ms , α , 183Pb , (1/2-), (5/2-) , , - , style="text-indent:1em" , 187mPo , , colspan="3" style="text-indent:2em" , 4(27) keV , 0.5 ms , , , 13/2+# , , - , 188Po , , style="text-align:right" , 84 , style="text-align:right" , 104 , 187.999422(21) , 430(180) μs .40(+20−15)&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Radon
There are 37 known isotopes of radon (86Rn), from 195Rn to 231Rn; all are radioactive. The most stable isotope is 222Rn with a half-life of 3.823 days, which decays into . Five isotopes of radon, 217, 218, 219, 220, 222Rn occur in trace quantities in nature as decay products of, respectively, 217At, 218At, 223Ra, 224Ra, and 226Ra. 217Rn is produced in a rare branch in the decay chain of trace quantities of 237Np; 218Rn and 222Rn are intermediate steps in the decay chain for 238U; 219Rn is an intermediate step in the decay chain for 235U; and 220Rn occurs in the decay chain for 232Th. List of isotopes , - , 195Rn , , style="text-align:right" , 86 , style="text-align:right" , 109 , 195.00544(5) , 6 ms , , , 3/2−# , , - , style="text-indent:1em" , 195mRn , , colspan="3" style="text-indent:2em" , 50(50) keV , 6 ms , , , 13/2+# , , - , rowspan=2, 196Rn , rowspan=2, , rowspan=2 style="text-align:right" , 86 , rowspan=2 style="text-ali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Radium
Radium (88Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is 226Ra with a half-life of . 226Ra occurs in the decay chain of 238U (often referred to as the radium series). Radium has 33 known isotopes from 202Ra to 234Ra. In 2013 it was discovered that the nucleus of radium-224 is pear-shaped. This was the first discovery of an asymmetric nucleus. List of isotopes , - , 202Ra , , style="text-align:right" , 88 , style="text-align:right" , 114 , 202.00989(7) , 2.6(21) ms .7(+33−3) ms, , , 0+ , , - , rowspan=2, 203Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 115 , rowspan=2, 203.00927(9) , rowspan=2, 4(3) ms , α , 199Rn , rowspan=2, (3/2−) , rowspan=2, , - , β+ (rare) , 203Fr , - , rowspan=2 style="text-indent:1em" , 203mRa , rowspan=2, , rowspan=2 colspan="3" style="text-i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Chain
A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria). A food chain also shows how organisms are related to each other by the food they eat. Each level of a food chain represents a different trophic level. A food chain differs from a food web because the complex network of different animals' feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time. Natural interconnections between food chains make it a food web. Food chains were first introduced by the Arab scientist and philosopher Al-Jahiz in the 10th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept. A common metric used to quant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium Mining
Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account for 68% of world production. Other countries producing more than 1,000 tons per year included Namibia, Niger, Russia, Uzbekistan, the United States, and China. Nearly all of the world's mined uranium is used to power nuclear power plants. Historically uranium was also used in applications such as uranium glass or ferrouranium but those applications have declined due to the radioactivity of uranium and are nowadays mostly supplied with a plentiful cheap supply of depleted uranium which is also used in uranium ammunition. In addition to being cheaper, depleted uranium is also less radioactive due to a lower content of short-lived and than natural uranium. Uranium is mined by in-situ leaching (57% of world production) or by conventional und ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha decay ( ), beta decay ( ), and gamma decay ( ), all of which involve emitting one or more particles. The weak force is the mechanism that is responsible for beta decay, while the other two are governed by the electromagnetism and nuclear force. A fourth type of common decay is electron capture, in which an unstable nucleus captures an inner electron from one of the electron shells. The loss of that electron from the shell results in a cascade of electrons dropping down to that lower shell resulting in emission of discrete X-rays from the transitions. A common example is iodine-125 commonly used in medical settings. Radioactive decay is a stochastic (i.e. random) process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base (chemistry)
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their applica .... A base was therefore a metal hydroxide such as Sodium hydroxide, NaOH or Calcium hydroxide, Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
