Enrichment blanket

Leach caps have a significantly lower amount of Cu than in enrichment blankets due to downward migration and precipitation of leached copper in the form of chalcopyrite (CuFeS2) chalcocite (CU2S) and cuprite (CuO). 

In the leach cap, the Cu isotopes are lighter than those in the enrichment blanket. Near the surface, the isotopes are extremely low, to about -14%o. Deeper in vertical profile at about 300 feet, the enrichment blanket contains a heavier isotope signature around 8%o. This pattern is observed throughout the drill core. The hypogene mineralization is near 0%o and therefore, there has been fractionation of copper isotopes in the chalcopyrite during dissolution. This fractionation is seen because the hypogene ores are distinctly different than leach cap and enrichment minerals. 

Samples included hematite (Fe203), goethite (FeO(OH)), and jarosite (KFe " 3(0H)6(S04)2) from the leach cap and chalcopyrite (CuFeS2), chalcocite (CU2S), and cuprite (CU2O) from the enrichment blanket. 

The A Cu values greater than 1 correlate with deposits that have well developed enrichment blankets, whereas deposits with lower values such as Butte,... 

Cu isotope compositions of chalcocite from enrichment blankets or Fe-oxides... 

Keywords Epithermal Gold, Porphyry Copper, Geostatlstic, Enrichment Blanket, Reserve... 

World mine production of copper is currently in the range of 13-14 Mt, about a third of which is from Chile. Other large producers are the United States, followed closely by Indonesia and Australia. The most important ore mineral is chalcopyrite [CuFeS2], and also significant are bornite [CusFeSJ and chalcocite [CU2S]. The first two are primary minerals, whereas chalcocite forms principally by their weathering and subsequent reprecipitation of the solubilized copper as enriched blankets of chalcocite ore beneath the oxidation zone. 

The 4000-liter Assembly 6A (core radius = 91.4 cm heig >s 1S2.4 cm) had a 30-cm-thlck depleted uranium (0.2% enrichment) blanket. Two of Uie ejq>erimental Objectives were (a) to establish the critical size of a single zone core and blanket system, and (b) to measure the activation distribution indicative of the overall spatial distiibutimis of the fluxes. The measured critical mass was 1798 1 kg of D. 

The only large-scale use of deuterium in industry is as a moderator, in the form of D2O, for nuclear reactors. Because of its favorable slowing-down properties and its small capture cross section for neutrons, deuterium moderation permits the use of uranium containing the natural abundance of uranium-235, thus avoiding an isotope enrichment step in the preparation of reactor fuel. Heavy water-moderated thermal neutron reactors fueled with uranium-233 and surrounded with a natural thorium blanket offer the prospect of successful fuel breeding, ie, production of greater amounts of (by neutron capture in thorium) than are consumed by nuclear fission in the operation of the reactor. The advantages of heavy water-moderated reactors are difficult to assess. 

Lepisto and Rintala [87] used four different types of thermophilic (55°C) anaerobic processes, namely an upflow anaerobic sludge blanket (UASB) digester, UASB enriched with sulfate, UASB with recirculation, and fixed-bed digester with recirculation for investigating the... 

The fast breeder reactor cycle in this cycle, the spent fuel is similarly reprocessed and the uranium and plutonium fabricated into new fuel elements. However, they are recycled to fast breeder reactors, in which there is a central core of uranium/plutonium fuel surrounded by a blanket of depleted uranium (uranium from which most of the uranium-235 atoms have been removed during the process of enrichment) or to burner reactors. This depleted uranium consists mostly of uranium-238 atoms, some of which are converted to plutonium during irradiation. By suitable operation, fast breeder reactors thus can produce slightly more fuel than they consume, hence the name breeder (see Fig. 7.1). 

In some types of thermonuclear power systems it is desirable to use a blanket of lithium enriched in Li to increase the volumetric rate of neutron capture to produce tritium. 

The active core consists of 181 fuel subassemblies with two enrichment zones, of which 85 with 21% Pu02 content are in the inner enrichment zone and 96 with 28% Pu02 content are in the outer enrichment zone. Each fuel subassembly consists of 217 helium bonded pins of 6.6 mm outside diameter. Each pin has 1000 mm column of MOX, 300 mm each of upper and lower depleted UO2 blanket columns and lower fission gas plenum (fig. 1). 

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