Determination of Uranium, Thorium, Niobium and Tantalum in Some Uraniferrous Minerals from the Araxa Area; DETERMINACAO DE URANIO, TORIO, NIBIO E TANTALO EM ALGUNS MINERIOS URANIFEROS DE ARAXA

Technical Report · Wed Aug 01 04:00:00 EDT 1962

OSTI ID:4765964

Abrao, A; Atalla, L T

Ores from the Araxa area, Minas Gerais, Brazil were analyzed. The samples analyzed could be considered as Mixtures of pyrochlores, phosphorite and apatite; they contained titanium, niobium, tantalum, phosphorus and calcium, with small quantities of iron, manganese, uranium. rare earths (cerium), and thorium. Analyses were made for the elements of greater importance: uranium, thorium, niobium, tantalum, titanium, and phosphorus. Previous experiments had shown that a digestion with perchloricnitric acid mixture, solubilizing the total uranium, was advantageous over aqua regia digestion or fusions. Uranium was extracted with tributylphosphate (TBP), diluted with carbon tetrachloride, and determined by polarographic technique. Some experiments were performed on solubilization of the ores with a perchloric--nitric--hydrofluoric acid mixtures and subsequent extraction of uranium with TBP, the interference of hydrofluoric acid being minimized by controlled addition of aluminium nitrate. Niobium and tantalum were first determined together by the tannic acid procedure of Schoeller applying some corrections for titanium after its determination in the total oxides (Nb-TaTi). The Schoeller procedure applied to those ores gave high results for Nb + Ta when compared with the tantalum results obtained by neutron radioactivation analysis and the niobium results from polarography. For the radioactivation analysis the oxides obtained by burning the tanninc acid precipitate were submitted to the neutron flux of the Sao Paulo IEA-R1 Reactor. Tantalum was determined by comparing the area of its photoelectric peak (Ta/sup 182/, half life 111 days, gamma energy of 0.08 and 1.22 Mev) with that of a tantalum standard irradiated simultaneously in the same geometry, using a single-channel gamma spectrometer. Niobium was determined by the polarographic technique using the cathodic reduction wave of the EDTANb complex at pH 2 to 3, after fusion of the oxides with KOH in a Pyrex glass tube with good results and without loss of niobium. Thorium was measured spectrophotometrically with thoron; it was coprecipitated with the calcium existing in the sample with oxalic acid, was then collected with iron hydroxide, followed by a coprecipitation with lanthanum oxalate, and finally separated from lanthanum by solvent extraction with mesityl oxide in the presence of nitric acid and aluminium nitrate. The whole analytical procedure was controlled by using Th/sup 234/ tracer, the final recovery of Th being about 95% (from solubilized ore until spectrophotometric readings). Seven tables are given with the results of various elements analyzed in eight different flotation fractions of the ores in which were found U/sub 3/O/sub 8/ varying from 0.01 to 0.04%, (Ta + Nb)/sub 2/O/sub 5/ from 0.01 to 0.5%, Ta/sub 2/O/sub 5/ fro m 0.003 to 0.07%, Nb/sub 2/O/sub 5/ from 0.01 to 0.4%, ThO/sub 2/ from 0.02 to 0.1%, and P from 2.1 to 13.8%. (auth)

• Research Organization: Brazil. Instituto de Energia Atomica, Sao Paulo
• NSA Number: NSA-17-001382
• OSTI ID: 4765964
• Report Number(s): IEA-53
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACIDITY
ACTIVATION ANALYSIS
ALUMINUM NITRATES
APATITES
BRAZIL
BUTYL PHOSPHATES
CALCIUM
CALCIUM PHOSPHATES
CARBON TETRACHLORIDE
CATHODES
CHEMICALS
CHEMISTRY
COMBUSTION
EDTA
FUSED SALTS
GAMMA SPECTROMETERS
HALF-LIFE
HYDROFLUORIC ACID
IRON HYDROXIDES
LANTHANUM COMPOUNDS
MESITYL RADICALS
MINERALS
NEUTRON FLUX
NIOBIUM
NIOBIUM COMPLEXES
NIOBIUM OXIDES
NITRIC ACID
ORGANIC ACIDS
OXALATES
OXALIC ACID
OXIDES
PERCHLORIC ACID
PHOSPHORITE
PHOSPHORUS
PHOTOELECTRIC EFFECT
PHOTOMETRY
POLAROGRAPHY
POTASSIUM HYDROXIDES
PRECIPITATION
PYROCHLORE
QUALITATIVE ANALYSIS
QUANTITATIVE ANALYSIS
RADON 220
RECOVERY
REDUCTION
SOLUBILITY