Peat uranium

Sur cia.1 Deposits. Uraniferous surficial deposits maybe broadly defined as uraniferous sediments, usually of Tertiary to recent age which have not been subjected to deep burial and may or may not have been calcified to some degree. The uranium deposits associated with calcrete, which occur in Australia, Namibia, and Somaha in semiarid areas where water movement is chiefly subterranean, are included in this type. Additional environments for uranium deposition include peat and bog, karst caverns, as well as pedogenic and stmctural fills (15). 

Sheppard MI, Vandergraaf TT, Thibault DH, et al. 1983. Technetium and uranium Sorption by and plant uptake from peat and sand. Health Phys 44 635-644. 

Titayeva, N.A., 1967. Association of radium and uranium with peat. Geochem. Intemat., 4 1168-1174 (translated from Geokhimiya, 12 1493-1499). 

Gentry et al. (1976) have recently shown, on the basis of isotopic analyses, that uranium introduction may have occurred far more recently than was previously supposed. However, they find also that, in some instances, the uranium was introduced before coalification was complete since the haloes have been compressed with the coal as it increased in rank. These results are consistent with laboratory and field work by Szalay (1964) who showed that the insoluble humic acids in peat are capable of concentrating uranium from very dilute solutions in natural waters. Sorption occurs as uranyl humate , the process following the normal kinetics of the Langmuir adsorption equation. (Where uraninite occurs in association with peat or other carbonaceous matter, the uranium may thus have been initially sorbed as a uranyl compound which was later reduced to uraninite.)... 

This kind of enrichment of uranium is most pronounced where peat bogs or peaty soils lie in the path of surface water draining rocks from which uranium is being leached. Armands (1967) described a situation where water entering bogs in Northern Sweden averaged 0.1 pg U g . He found that peat in the bogs contained up to 3% uranium on a dry basis. Szalay (1958) has shown that peat, fully saturated with uranyl ion, can contain nearly 10% uranium on a dry basis. 

Horvath, E., 1960. Uranium adsorption on peat in natural waters containing uranium traces. Atomki Kozl., 2 177—183 (in Hungarian). 

In most minerals uranium is in the tetravalent state. The most important one is uraninite 0.25), in which the uranium concentration is 50 - 90% it is foimd in Western Europe, Central Africa (e.g. Katanga, Gabon) and Canada (e.g. Cigar Lake) and Australia (e.g. Koongara). In the USA and Russia camotite (a K + U vanadate) is the most important mineral and contains 54% uranium. In the high grade ores the mineral is mixed with other minerals so the average uranium concentration in the crushed ore is much less e.g. 0.5 % on the Colorado Plateau. Uranium is often found in lower concentration, of the order of 0.01 - 0.03%, in association with other valuable minerals such as apatite, shale, peat, etc. 

Uranium ores at surface level are usually identified from the p etrating y-ray emissions of die daughter products. However, it has been observed that some peat, which absorb uranium from local drainage, contain very little of the daughter products because they have been formed so recoitly that radioactive equilibrium has not been established. 

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