[en] The effects of temperature, time and reagent-to-mineral ratio on the completeness of digestion of xenotime with 40 per cent sodium hydroxide were studied. The digestion at 180 degrees C with an alkaline-to-mineral ratio of 2 : 1 for a period of 3 hours gave a digestion yield of 90 per cent. The mixture of rare earth hydroxide was dissolved by concentrated hydrochloric acid and separated into groups by gradient pH precipitation. Yttrium was found to precipitate between pH 3.5 - 7.0. The compositions of the rare earth hydroxide were determined either by X-ray fluorescence or instrumental neutron activation

[en] Published in summary form only

[en] 89.76% Y element has been purified from local xenotim sand (partial impurity Gd 3,43% and Dy 6,9%), by this material ceramic superconductor YBa₂Cu₃0_7-x has been fabricated.The material was prepared by mixing 1,13 g Y₂0₃ (90% Y local),3,95 g BaC0₃(99,9%) and 2,39 gCuO (99,9%). Powders were mixed and pressed into disc shaped pellets and calcined at 950^oC, The resultant mixture was pulverized, pressed again into disc shaped pellets having 13 mm diameter and 3 mm height ,sintered at 950^oC for 12 h in 0,6 1/h flowing of oxygen and then furnace was cooled to room temperature. The sample were proved meissner effect in liquid nitrogen ,the measurement of meissner effect showed arise at liquid nitrogen temperature and have critical point -192^oC

[en] The formation constant of molybdophosphate complex and it's application in the product of xenotime sand, tooth and bone have been studied by spectrophotometric method. The molybdophosphate complex were formed from reaction between phosphate and molybdate on several of pH in the strong acid condition (pH = 0.45 - 0.71) and several of phosphate mole fraction (0.01 - 0.08). The several of complex formation reactions were determined by matrix disintegration technique. Molybdophosphate complex were founded three forms i.e. (P₂Mo₁₈O₆₂)^6- or 9 MPA, (PMo₁₁O₃₉)^7- or 11 MPA and (PMo₁₂O₄₀)^3- or 12 MPA. The formation constant of (PMo₁₂O₄₀)^3- complex was found β = 10^46.95 ± 10^3.7, while for (P₂Mo₁₈O₆₂)^6- and (PMo₁₁O₃₉)^7- were not detected. The application in samples were found the concentration of P in product of xenotime sand : 5.37±0.08 μg/ml, in canine-tooth: 10.40 - 19.49 % in cutting-tooth : 11.08 - 18.05 % and in bone 10.94 - 14.29 %. (author)

[en] Significant placer deposits were identified along coastal tract of Andhra Pradesh of various dimensions, grade, tonnage, nature and character due to the role played by climate, geomorphology, coastal processes and sea level changes. Andhra Pradesh ranks first in respect to heavy mineral resources of the country. Formation of heavy mineral deposits in any coast depends on the hinterland geology and the geomorphic processes operating along the coast. The geology of the east coast comprises of Eastern Ghat Mobile Belt (EGMB) group of rocks of Archean to Proterozoic age. They consist of khondalites, charnockites, calc - granulites, quartzites, crystalline limestones, anorthosites, migmatites of both charnockites and khondalites, intrusive granites, leptynites and pegmatites, Upper Gondwana sandstones and Rajamundry sandstones of Tertiary age. Some volcanic flows of Deccan traps are observed in Godavari basin. Quaternary formations include high level and low level laterites and beach and dune sands. Morphologically, there are wide variations along the coast and accordingly the Andhra Pradesh coast has been divided into three segments. The Northern segment (from Ichapuram in Srikakulam district to Tuni in Visakhapatnam district) is dominated by promontories and has narrow coastal width. These heavy minerals are medium to coarse grained in size. Heavy mineral deposits from this segment account for 45% of heavy minerals resource of the state. Srikurmam deposit occurs between Nagavali and Vamasadhara rivers contains highest content of garnet (7.9%). Srikurmam deposit is under exploitation. Due to the presence of a number of erosional features, this part of the coast is termed as erosional coast. Structural land forms as hogbacks and denudational

[en] Radioactive xenotime and monazite have been recorded for a considerable stretch in the placer sands and nala soils along Kandera nala and Baljora nala in Raigarh district, Madhya Pradesh. The observed radioactivity of the samples of sand and soil has been correlated with the mineral constituents of the placer sands and soils. It has been confirmed that the major activity is contributed by monazite and xenotime and the ratio (epsilon) of monazite/xenotime remains nearly constant as 2 in all the samples studied. Statistical analyses of the mineral constituents and the radioactivity bring out three ratios, Ω(opaque/zircon + epidote-zoisite + chlorite), γ(xenotime + opaque/monazite + epidote-zoisite + chlorite) and theta(Ω/γ) vary linearly with eU₃O₈,U₃O₈ and eU₃O₈/U₃O₈ values respectively with the correlation coefficients of 0.94, 0.90 and 0.95 respectively. It is suggested that the xenotime and monazite in the original host rock probably formed at the alkaline-acidic interface of the granitic melt. (author)

[en] The research of solution of rare earth hydroxide product of xenotime sand in HCl have been done. Yttrium hydroxide was the most content in the rare earth hydroxide product of xenotime sand The purpose of this research for determination of rate constant of solution reaction Yttrium hydroxide in HCl. The parameters was observed were temperature of reaction and concentration of Y (Y_0) in the rare earth hydroxide product of xenotime sand as feed. From the data reaction of reaction time and concentration of Y in HCl (Y) at the variation temperature and (Y_0) can be concluded that the rate constant of reaction was influenced by temperature of reaction and concentration of reactant. The all solution reaction of yttrium hydroxide in HCl was the second order reaction. The relation the second rate constant with temperature (1/T) as exponential function so the Arrhenius equation become k = 0,8954e"-"8"7"","7"6"5"8"/"R"T and can be expressed as linear function. - ln k = (1055.6/T) + 2.6088 with the linearity factor or correlation coefficient = 0.8954 From the calculation was obtained the value of activation energy 87.762584 kcal/mol."0K. The reaction of the second rate constant with (Y_0) as polynomial function k = -4.10"-"5(Y)"2 + 0.0032 (Y) - 0.0194 with correlation coefficient = A = 0.9807. (author)

[en] Rare earths consists a group of 15 element from La to Lu in the periodic table and it also includes Sc and Y since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. The unique physical-chemical properties of the REEs render them important in applications as varies as high strength magnets, lighting phosphors, policing compounds and ceramics. In particular, yttrium finds numerous applications in many areas including superconductors, lasers, phosphors, nuclear reactors, astronavigation, ceramics etc. Yttrium is chemically similar to heavy rare earths (HRE: terbium, dysprosium, erbium, holmium, ytterbium, thulium and lutecium). Yttrium behaves like HRE due to similarity in ionic radius and finds place between Ho and Er. The cross current profile in terms of the plot of concentration of yttrium in raffinate as a function of contact number indicated the complete recovery of rare earths from nitrate solution of xenotime wet cake

[en] The possibility of using phosphorescence technique in determining uranium in mineral samples and its comparison with that of fluorescence using high carbonate flux is presented. Samples used are tin-tailings mineral such as monazite, xenotime, ilmenite and zircon. The calibration graph obtained shows a linear relationship between the concentration range of 0-55 ppm U. From here, analysis of the standard showed that the result obtained and that of the certified value are consistent. HN0₃:H₂SO₄ (1:3) and phosphoric acid leaching methods are tried and the results show that phosphoric acid is the better method for phosphate mineral. Comparison of the results obtained from this technique and that of the direct and extraction methods of fluorimetry are also made. Phosphorescence is found to be a better method in determining uranium in this type of samples. (author)

[en] Purified yttria and zirconia are being used in many advanced materials applications. The paper discussed on the possibility of purifying these products from local mineral resources. Conventional method of purifying likes selective precipitation, fractional precipitation and leaching of contaminants were used to produce products with limited purity. Solvent extraction method enable to produce product of very high purity especially it it is incorporated with a counter-current mixer-settler equipment. 7 figs