[en] The present work shows the results obtained from chemical and mineralogical researches performed to a granular phosphorite sample from Meseta Roja deposit, in Guines Pipian region

[en] The experience gained in applying the spectrometric gamma-logging technique to the survey of concretionary phosphorites of the Chilisajsk deposit (the Aktyubinsk phosphorite-bearing basin) is described. The possibilities of using the gamma-logging spectrometry are studied to solve the following problems: to isolate the phosphorite-bearing horizons, to determine the depth of their occurrence, their thickness and internal structure, to test phosphorite-bearing horizons in wells with-out sampling

[en] The Senonian phosphorites which form the Palmyrides deposits in Syria (Khneifiss and Charquieh) were studies in order to determine the relationships of uranium and apatite in these deposits. A very good U-P₂ O₅ correlation is evident in all the deposits, though it is slightly better developed at Charquieh than at Khneifiss. The fission track method makes it possible to seen that uranium is essentially concentrated within the phosphatic grains. The distribution of uranium in the grains is not random; a closer association between uranium and organic matter is apparent. In the discussion concerning this distribution and the behaviour of uranium during the reworking and weathering of the phosphorites, it is proposed that uranium is not only in the lattice of apatite, but is also absorbed on the surface of crystallites and is trapped at a very early stage in the formation of the grains. (author). 44 refs., 3 tabs., 13 figs

No abstract available

[en] The nucleophilic substitution reactions of bis(2,6-dimethylphenyl) chlorophosphate with substituted anilines (XC₆H₄NH₂) and deuterated anilines (XC₆H₄ND₂) are investigated kinetically in dimethyl sulfoxide at 55.0 .deg. C. The anilinolysis rate of 4 is much slower than bisphenyl chlorophosphate due to the steric hindrance of four ortho-methyl substituents in 4. The magnitudes of secondary inverse deuterium kinetic isotope effects (k_H/k_D < 1) invariably increase as the nucleophiles change from the strongly basic to weakly basic anilines contrary to 1. A stepwise mechanism with a rate-limiting leaving group expulsion from the intermediate involving a backside nucleophilic attack towards the leaving group Cl is proposed on the basis of the variation trends of the k_H/k_D values with substituent X in the nucleophiles. Continuing the kinetic studies of the anilinolyses of diphenyl chlorophosphate derivatives, Y-aryl phenyl [1: (C₆H₅O)(YC₆H₄O)P(=O)Cl],1 Y-aryl 4-chlorophenyl [2: (4-ClC₆H₄O)(YC₆H₄O)P(=O)Cl], and bis(aryl) chlorophos-phates [3: (YC₆H₄O)₂P(=O)Cl], the nucleophilic substitution reactions of bis(2,6-dimethylphenyl) chlorophosphate {4: [2,6-(CH₃)₂-C₆H₃O]₂P(=O)Cl} with substituted anilines (XC₆H₄NH₂) and deuterated anilines (XC₆H₄ND₂) are investigated kinetically in dimethyl sulfoxide (DMSO) at 55.0 ± 0.1 .deg. C to gain further information into the substituent effects, steric effects, and deuterium kinetic isotope effects (DKIEs) on the reactivity and anilinolysis mechanism. The numbering of the substrates of follows the sequence of the size of the two ligands, R₁O and R₂O

[en] Phosphate rocks(PR) which have high reactivity may be effective as a direct application of fertilizer especially in highly weathered acid soils. The agronomic effectiveness of such PR, Minjingu rock phosphate (MRP)was compared with that of highly soluble phosphate,triple superphosphate (TSP), in pot studies with seed bean (P. vulgaris L.) in a green house at the field station of faculty of Agriculture,University of Nairobi, Kenya. MRP final y ground with 30 Grade % P and TSP with 99.0 Grade % P fertiliser at rates 0, 30, 45 and 60 mg P per pot were applied on 2kg soil per pot. The soil used in the study was an acid humic andosol from fields with moribund tea bushes,tea bushes planted in 1958 and 1979 and newly cleared forest in Kagaa, Kenya. Shoot and root dry matter yields,dry seed yield responses and their responses estimates were determined and showed positive significance in most cases when TSP fertiliser was applied on the soils except that from moribund tea field. The relative agronomic effectiveness (efficiency) of MRP on biomass and also seed yield of beans was found to be significantly inferior to TSP in most of the soils except that from moribund tea field where both sources were found to be effective. This study confirms that in spite of its high reactivity, MRP is still agronomically ineffective as nutrient source of P for growing P. vulgaris in acid Soils

[en] El-Sibaiya phosphorites represent a part of the Middle East to North Africa phosphogenic province. They encountered in the Gabal (G.) Duwi Formation of Late Cretaceous to Paleogene age. The studied samples have been collected from the eastern and western sides of the Nile River. Major elemental analysis of the collected samples declared positive correlations between P₂ O₅ an d CaO and F. These correlations indicate that these elements are contained in the apatite phase. On the other hand, P₂O₅ shows negative correlations with other major elements such as Al₂O₃ , SiO₂, Fe₂O₃ and MgO. Some trace elements such Cr, Sr and V s how positive correlation with P₂O₅ . The average of the total rare earth elements (∑REEs) in the studied phosphorites is 262 ppm. Chondrite-normalized patterns of ∑REEs of the studied phosphorites show a good coherence with the world average of shale suggesting that ∑REEs in the studied phosphorites were derived from the associated clastic debris through the diagenetic remobilization. The week negative Ce and Eu anomaly of the studied samples and the marked enrichment in LREEs emphasize that the studied phosphorites subjected to a later post-depositional modification. Laser ablation analysis showed that apatite mineral of the studied phosphorites is enriched in some elements such as Ca, F, Cr, Sr, V, Zn, Ba and REEs. This explains the major role of substitution processes of these elements within apatite lattice. The uranium average in El-Sibaiya East phosphorites is 81.6 ppm, while in El-Sibaiya West is 51.1 ppm. Apatite minerals play an important role in the accumulation of U within the studied phosphorites

[en] Published in summary form only

[en] The objective of this work is to analyze and to define fundamental aspects of the contents of natural radionuclides in the phosphoric fertilizations and its primary material. The results of experimental measurements show that in phosphoric fertilizers produced by Gomel chemical factory there is null quantity of Ra 226 and exists slightly increased content of Th 232. In addition, the amount of Th 232 in fertilizers depends on technological particularities of primary products reprocessing. It is almost impossible to reveal any regularities in quantitative amount of natural radionuclides in mineral fertilizers because of lack of measurements; it's possible only to speak of approximate contents. Taking in consideration the well-known fact that in Belarus maximal contents of natural radionuclides in natural objects does not exceed 40 Bq/kg, their activity in samples of mineral fertilizers can be classified as anomalous. Experimental measurement of natural radionuclide contents in phosphoric fertilizers shows good agreement with other authors. (authors)

No abstract available