Uranium recoverable

An improved solvent extraction process, PUREX, utilizes an organic mixture of tributyl phosphate solvent dissolved in a hydrocarbon diluent, typically dodecane. This was used at Savannah River, Georgia, ca 1955 and Hanford, Washington, ca 1956. Waste volumes were reduced by using recoverable nitric acid as the salting agent. A hybrid REDOX/PUREX process was developed in Idaho Falls, Idaho, ca 1956 to reprocess high bum-up, fuUy enriched (97% u) uranium fuel from naval reactors. Other separations processes have been developed. The desirable features are compared in Table 1. 

Besides the conventional uranium resources, there are also the so-called unconventional uranium resources , which are defined as deposits with very low uranium content, from which uranium is typically only recoverable as a minor by-product. These unconventional uranium resources are obtained from the extraction of phosphates, non-ferrous ores and carbonatites, as well as black schist and lignite. It has to be noted that the distinction between conventional and unconventional resources is not entirely clear cut, but is, instead, somewhat transitional. 

The third fact is that spent nuclear fuel is not waste. Spent nuclear fuel contains 2% to 3% waste, but is about 97% recoverable uranium and plutonium. Each bundle has the potential electric energy equivalent of more than 10 million barrels of oil. High-level nuclear wastes consist of fission products and actinides that are extracted from spent fuel, but not saved for commercial use or research. Spent fuel may be temporarily stored until it is reprocessed to separate the waste from the valuable plutonium and uranium. The remaining glassified waste will then be permanently entombed. 

J. D. Parent. A Survey of the United States and Total World Production, Proves Reserves, and Remaining Recoverable Resources of Fossil Fuels and Uranium as of December 31,1977, Institute of Gas Technology, Chicago, March (1979). 

The uranium reserves are estimated as a function of the market value. This 5 million ton figure is based on a market value of 130/pound. If the market value is 60/pound, the profitably recoverable reserve is only 2 million tons. The absolute total uranium reserves are about 15 million tons. 

Current known, recoverable world resources of uranium are approximately 3.1 million tons, estimated to be sufficient for about 50 years at current levels of consumption. A doubling of price from present levels is projected to create a 10-fold increase in these resources. Moving from current nuclear power technology to breeder reactors is estimated to increase uranium utilization another 60-fold (World Nuclear Association, 2002). Breeder reactors, however, would aggravate some of the issues now associated with the nuclear industry, including those surrounding safety and nuclear proliferation, while possibly reducing the waste disposal problem. 

Water and wastes Acid digestion filtration (dissolved) acid digestion (total recoverable) ICP-MS (total uranium) 0.1 pg/L 105-110% Long and Martin 1991 (EPA Method 200.8)... 

The ICP-MS method was developed for measuring total uranium in water and wastes. The sample preparation is minimal—filtration for dissolved uranium, acid digestion for total recoverable uranium. Recovery is quantitative (near 100%) for a variety of aqueous and solid matrices and detection limits are low, 0.1 pg/L for aqueous samples and 0.05 mg/kg for solid samples (Long and Martin 1991). 

Some of the important but expensive rare metals are usually extracted as by-products of other metal separation processes. Selenium and tellurium are recoverable from copper refinery slime by pressure leaching (M40), scandium from uranium plant iron sludge (R15), uranium from gold cyanida-tion residues (G3), silver from aqueous chlorination process for the treatment of slimes, and gravity concentrates from gold ores (V2). A host of other processes are in use. 

According to the latest estimates of Skinner [18], elements potentially recoverable from seawater are sodium, potassium, magnesium, calcium, strontium, chlorine, bromine, boron, and phosphorus because of their practically unlimited presence in the ocean. After improving respective technologies, recovery of the following elements is expected to become profitable as well lithium, rubidium, uranium, vanadium, and molybdenum. Additional profit can be gained since desalinated water will probably be obtained as a by-product. This could be important for countries with a very limited number of freshwater sources (e.g., Israel, Saudi Arabia). 

Swedish shales contain 300,000 MT of recoverable uranium, together with organic matter from which fuel can be made and pyrites that can be converted to sulfuric acid. The combined value of these products makes the operation economic. 

Table 12.4 The EU share of the world s recoverable uranium resources (RAR+inferred) by extraction cost...

Uranium deposits occur in many countries, but as shown in Table 12.4 the economically recoverable reserves, like oil and gas reserves, are primarily located outside of Europe. The OECD Nuclear Energy Agency and the International Atomic Energy Agency (IAEA, 2008) expects that it will be possible to double the global uranium extraction at cost below US 80/ kgU to approximately 120,000 tU per year in 2016. At a constant rate of extraction these resources would allow for uranium extraction well into the 2040s. 

The process of rare earth recovery is based on rare-earth double-salt precipitation. However, yttrium and the heavy rare earths go with thorium. The rare earths are recoverable from the thorium fraction during the solvent extraction step used for the purification of uranium and thorium. Solvent extraction with TBP (tribulyl phosphate ), from an aqueous 8 N nitric acid solution of thorium and mixed rare earths, enables the recovery of thorium, uranium, cerium and cerium free rare earths (Gupta and Krishnamurthy 2005). Other significant processes involve precipitation of thorium pyrophosphate, or precipitation as basic salts from the leach fiquor. After that comes recovery of the rare earths from solution as double sulphates, fluorides, or hydroxides, and also selective solubilisation of thorium itself in the ore treatment stage. The sulphuric acid route does yield impure products, but it is not used anymore (Gupta and Krishnamurthy 2005). 

The polymeric imide could then be reacted with primary amines or ammonia to form ammonium salts for a subsequent reactions with a carboxylic acid in the presence of a coupling reagent. It could then be converted to amides or functionalized as a uranium salt for use as polymer-supported peptide coupling. In addition, the anhydride was also reacted with di(2-pyrldyl)methylamine and formed a recoverable palladium catalyst for cross-coupling reactions that could take place in water. 

The yield of uranium metal powder is about 93 per cent of the uranium content of the original oxide. The loss is entirely into the leaching solution, from which it is recoverable. 

This relation assumes an average load factor of 70% for the entire system of nuclear generating stations. The a is the ratio of parasitic capture to fission for the initial and bred fuel, appropriately averaged CR is the average conversion ratio and MJM2S is, again, the ratio of total uranium to recoverable In this case, however, allowance must be made for U discarded at the end of the fuel cycle, if the final enrichment is such that the is not economically recoverable. 

Significance of developing fast reactors (FRs) (OECD/NEA, IAEA 2007 OECD/NEA 2009). The reserve-to-productlon ratios of petroleum, natural gas, and coal were evaluated by dividing the ascertained recoverable reserves by the amount of production in 2008. The ratios of uranium were evaluated by dividing the reserves by the annuai demand in 2006 because uranium is easy to reserve and therefore the amounts of production and demand are not correiative. If the price level rises suddeniy because of huge demand, recoverabie reserves may increase (This is said to be more iikeiy for naturai gas]... 

The most important advantage of these gas core concepts, however, may lie in the fact that they can be designed as breeders but with minimal initial fissile feed requirements. This point is significant for two reasons (a) the rate at which these gas core reactors could be brought on line would not be dependent oh the rate of fuel being discharged from LWRs as would be the case fpr LMFBRs and b) the estimated easily recoverable U.S. uranium resources will probably be sufficient to fuel 500 to 1000 LWRs of 1000 MW(e) each, while this same amount of uranium could be used to fuel approximately... 

Measured resources of uranium, the amount known to be economically recoverable from ore bodies, are naturally relative to costs and prices. They are also dependent on the intensity of past exploration effort and are basically a statement about what is known rather than what is present in the earth s crust. 

The average uranium content of carbonatite is about 57 ppm, thorium is about 649 ppm and the Th/U ratio is 11.4. The spread of values is large for both U (0.05-400 ppm) and Th (0.1-2500 ppm), however, as was shown by Nishimori and Powell. It is estimated that carbonatites contain at least 150000 ton recoverable UsOb, most of it in the reasonably assured 50/lb category. 

At one stage mining took place in the Narke province for the extraction of oil (content 4%), sulphur, lime, ammonia, etc. Elements associated with uranium are V (same content as U), W, Mo, Ni, Zn and Ca—but pyrite and melnikovite are the most abundant (6-7% S). The total amount of resources reported was 1000 0001 U, but only 300 0001 U is considered as potentially recoverable. 

Full trans-uranic multi-recycle is employed to extract the full energy content from the uranium ore, and to consign only fission products (and trace recycle/refabrication losses) to waste. A millennium of global energy supply can be supported by the currently known plus speculative uranium resource base recoverable at <130 /kg. 

Uranium is a widely distributed element in the oxide form, but there are relatively few areas where it occurs in economically recoverable concentrations. Among the major potential sources are Australia, Canada, South Africa, and the Western United States. Recent estimates of the main... 

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