The photoluminescence (PL) of barite is a noncharacteristic property and cannot be used for the investigation of its structure.
After thermal treatment of barite at 600°C several luminescent centers were observed, providing information about different
was determined from the vibrational structure and the long decay time of the luminescence band. Two different types of uranyl
were detected, thin films of uranyl mineral (most probably, reserfordin) and a solid solution of uranyl ion in barite crystal.
Characteristic green luminescence of UO
may be used as indicative feature for the prospecting of uranium deposits and for the sorting of barite ores with the aim
of cleaning from harmful U impurities. Eu2+ was determined from the spectral position, the half-width and the characteristic decay time of the luminescence band.
Mn2+ and Ag+ were determined by comparing luminescence bands spectral parameters to those of synthesized BaSO4−Mn and BaSO4−Ag. Fe3+ or Mn4+ were determined from the spectral-kinetic parameters of the luminescence bands.
Authors:Péter Bajcsi, Tamás Bozsó, Róbert Bozsó, Gábor Molnár, Viktor Tábor, Imre Czinkota, Tivadar M. Tóth, Balázs Kovács, Félix Schubert, Gábor Bozsó, and János Szanyi
Nasr-El-Din , H.A. , S.H. Al-Mutairi , H.H. Al-Hajji
2004 : Evaluation of a New Barite Dissolver: Lab Studies . — SPE International Symposium and Exhibition on Formation Damage Control, Lafayette , 11 p
The radiochemical method has been used for investigation of the adsorption of radium on eighteen inorganic ion exchangers. The distribution coefficient of radium obtained are as follows: barite 2955, celestite 2420, BaSO4 4350, BaCrO4 5245, Ba3(PO4)2 5775, MnO2·nH2O 1681, La2O3·nH2O 4150, Zerolit S/F 2920, etc.
Authors:Z. Řanda, J. Ulrych, K. Turek, M. Mihaljevič, J. Adamovič, and J. Mizera
A specific, radium bearing type of barites has been known from the Ohře (Eger) Rift, a region of Cenozoic volcanic activity
in northwestern Bohemia, Czech Republic, since 1904. Barites from Karlovy Vary, Teplice and Děčín areas have been studied
to elucidate geochemical history of these specific samples. Low background radiometric method using high-resolution gamma-ray
spectrometry has shown that radioactivity of these barites (up to 8 Bq g−1) is carried by 226Ra, which is not in equilibrium with the parent 238U. In all samples, uranium activity was below 0.005 Bq g−1––the detection limit achieved by instrumental neutron activation analysis. The alpha track method on a crystal plate has
shown that 226Ra is accumulated in surface layers or crystal cracks, therefore, the crystal rims must be relatively young, not older than
10–15 thousand years. In a lead fraction isolated from the barites, concentration and isotopic composition of lead were determined
by photon activation analysis and ICP MS, respectively.
A study of the immobilization for226Ra waste has been carried out. Cement-based concrete was used as a matrix for the solidification of radium waste. The experimental results show that the cement mixture with water/cement between 0.46–0.54 has higher strengh (above 20 MPa), and the compressive strength was not reduced by addition of 1% barite or the radium waste (RaSO4) into the concrete solid.
The influence of thermal treatments on photoluminescence spectra of several minerals has been investigated. By applying step-wise
heating, new luminescence centres were detected which had been not previously recognized in the corresponding minerals. Luminsecence
centres appearing as result of valence changing during oxidizing heating include:
(UO2)2+ as a result of nonluminescent U6+ transformation in zircon, barite, francolite and chert;
Eu2+ as a result of nonluminescent Eu+ transformation in barite.
Luminescence centres which were most stable under thermal treatment were Fe3+ in zircon and Mn2+ in barite. Luminescence centres with similar spectral-kinetic properties but with different thermal stability which allowed
them to be separated and properly identified were different metaloxygen complexes (MeOn)m− in zircon.
A radiotracer method was used for investigation of the adsorption and desorption of radium on stream sediments under conditions similar to those prevailing in waste and surface waters. The effects of pH, ionic strength and Ca2+ or SO
ions were studied. The results were compared with analogous data characterizing radium interaction with model solids representing components of the sediments. It has been found that the adsorption affinity of the sediments for radium cannot be easily derived from their composition or other properties. No simple correlation with specific surface area, organic matter, oxidic coatings or other components of the sediments was observed. However, an exceptional role of barite (barium sulfate) in the sediments was noted. In the presence of sulfate ions (60 mg/l) this component was responsible for the uptake of predominant or at least significant part of radium, depending on the barite content of sediments. In the absence of added sulfate ions, the adsorption of radium at ph 5–9 on sediments containing barite was lower than on similar sediments without this component, indicating that other components may be more efficient in radium adsorption.
Authors:Cs. Németh, J. Somlai, Á. Nényei, M. Skrinyár, B. Kanyár, P. Németh, and K. Hoffer
Slags, derived from coal mined in the neighbourhood of the town Tatabánya in Hungary, have been used as filling and insulating material for buildings of houses, block of flats, schools and kindergartens. The slag samples come from here have elevated concentrations of 226Ra, (range of 850–2400 Bq·kg–1). Therefore, the external gamma dose rates at 1 m height were about four times higher than the world average. It has been found, based on the modelling, that the dose rate could be decreased with 70–80% using an appropriate thickness of concrete or barite-concrete layers.
Authors:Y. Yoshida, T. Nakazawa, H. Yoshikawa, and T. Nakanishi
A partition coefficient (λ) for Ra in gypsum was determined from coprecipitation experiment using oversaturation method. The λ-value derived for Ra was: λRa = 0.32±0.15. Saturation state was estimated with the initial concentration of Ca and SO42− in an experiment of the present study. Saturation index was calculated to be (0.49±0.02). This value was similar to those
corresponds to analogous case where slow precipitation rate was kept in coprecipitation experiment for Sr in gypsum. Therefore,
derived λ-value is thought to describe partition of Ra and Ca in solid phase and solution under an equilibrium condition without the
effect of kinetic of precipitation. Determined λ-value was compared with those of other alkaline elements in sulfate minerals. The derived λ-value is smaller than that of Ra in barite and is similar to those of Sr in gypsum. This trend agrees with mechanical understanding
for the size effect against partition coefficient.