Uranium Extraction from Sea Water with Composite Adsorbents, (III)

Measurements were made of the extent of magnetization shown by composite hydrous titanium (IV)-iron (II) oxide adsorbents for use in uranium extraction from sea water. The possibility of removing the adsorbent by means of high-gradient magnetic separation was demonstrated by calculations based on a force balance model.

Removal experiments were also carried out, which demonstrated that the composite hydrous oxide can be trapped effectively: A composite hydrous oxide with 1:1 Ti-to-Fe mole ratio, of 400–625 mesh particle size, proved to be removed to 99.9% by a magnetic field of 2.5 kOe, with the slurry flowing at 20 cm/s through a filter matrix 50 cm long packed to 90% void with 100 μm diameter nickel wire stuffing.

Together with the evaluations made of the electric power consumed by the high-gradient magnetic separators, the experimental results indicated the possibility of economically extractng uranium from sea water using these separators in combination with magnetic adsorbents.     

Uranium Extraction from Sea Water with Composite Adsorbents, (IV)

Composite hydrous titanium(IV)-iron(II) oxides prepared by precipitation from homogeneous solutions were studied with a view to developing magnetic adsorbents for uranium extraction from sea water.

Higher uranium adsorption capacity was registered with homogeneous than with heterogeneous solution used for preparing the oxide. The adsorbents for uranium prepared from homogeneous solution moreover were found to require the copresence of urea and a suitable anion such as SO^2- ₄, in order to provide strongly active adsorption of uranium.

The value of saturated magnetization of the composite hydrous oxides decreased with increasing titanium mole fraction up to 0.75, increase of the titanium mole fraction had, on the other hand, the effect of enhancing uranium adsorption capacity, which however saturated beyond 0.75 titanium mole fraction.

The change of enthalpy brought by the uranium adsorption on the composite hydrous titanium (IV)-iron (II) oxides was 10 kcal/mol, and the amount of change independent of the conditions of precipitation.     

Basic Study on Uranium Extraction from Sea Water, (II)

The possibility was examined of extracting U (VI) from sea water by adsorption on gel particles containing various metal hydroxides, including Ti(OH)₄ and Zn(OH)₂, dispersed in Polyacrylamide gel particles. The hydroxide adsorbent thus prepared in gel form was packed in a column for processing the sea water (both sea water sampled from harbor and artificially prepared solution). The U(VI) collected in the column was eluted with 0.10 M Na₂CO₃ solution. Factors affecting the performance of the hydroxide adsorber were examined: The kind of metal hydroxide used, the degree of cross-linking of the Polyacrylamide, the content of hydroxide in the gel and the concentration of U (VI) in the original sea water. Of the five kinds of metal hydroxides tried, only titanium hydroxide was found to function usefully as adsorbent for the U(VI). The degree of Polyacrylamide crosslinking was found have no relation to adsorption performance, which, on the other hand, was significantly influenced by changes in titanium hydroxide in the gel: The amount of U (VI) adsorbed reached a maximum at 2 mg Ti/ml gel. Also, the adsorption improved consistently with decreasing concentration of U (VI) contained in the original sea water, down 10^?6 M.     

Extraction of Uranium from Sea Water by Method of Dispersion and Deposition

The extraction of uranium from sea water by the adsorption on the mixture of titanic acid and bentonite making the uranium rich deposit on the sea bottom is described. The purpose of this work is the minimization of energy required for contacting the vast volume of sea water with the adsorbent. Unique features of bentonite are applied to the coagulation of adsorbent forming the particles of suitable size in the sea water to make uranium rich deposit on the sea bottom close to the land. The concentration of uranium in the deposit is about 380 times that of sea water, and the loss of titanium is about 2% of the total amount of titanium which is used with the bentonite of ten times as much as it.

The depths of sea necessary to make uranium rich deposit for the various conditions were calculated and the result was obtained that 50 m was sufficient for this method. As a trial of the second stage of concentration of deposited uranium, the continuous RIP method was carried out in counter-current fluidized bed which was operated without reversal of flow.

The results reported in this paper are based on the laboratory scale experiments using the artificial sea water and on the calculations concerned with the rate of adsorption in agitated systems.     

Chloride Pyrometallurgy of Uranium Ore, (II)

Selective extraction of uranium from a phosphate ore was studied by using the mixed gas of Cl₂ and O₂. On heating the ore and carbon mixture in Cl₂, the volatilized chloride of uranium is accompanied by iron, aluminum, phosphorus and silicon chlorides. The addition of O₂ gas effectively lowered the volatilization ratios of aluminum, phosphorus and silicon. The ratio decreased with increasing oxygen flow rate up to 50ml/min at 1,223 K (Cl₂: 100ml/min, O₂+N₂: 400m//min). The volatilization ratio of uranium was almost unchanged at 90% up to 50 ml/min O₂ (carbon amount: 15wt%). The effect of the other parameters, i.e. Cl₂ flow rate, carbon amount, reaction temperature and time was examined.     

Extraction of Lithium from Sea Water with Metallic Aluminum

Extraction of lithium from sea water was investigated. It was found that a corrosion product of metallic aluminum immersed in sea water extracts lithium from it selectively. Effects of the temperature and the pH of sea water, and of the initial concentration of lithium in it were examined. On the basis of the analysis of the surface deposit on aluminum, which is a corrosion product of aluminum, the selectivity coefficients were calculated. For the extraction of lithium from natural sea water, the values of K ^Li _Na ^Li _MgK ^Li _Ca and ^Li _K were 9.9 × 10², 1.1×10, 4.5×10 and 4.4 × 10², respectively.     

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (II)

The precipitations of thorium and uranium(VI) sulfito complex ions with hexammine cobalt(III) chloride as the precipitant have been studied.

The orange-colored uranium(VI) precipitate obtained is [Co(NH₃)₆]₄[UO₂(SO₃)₃]₃22H₂O, which is in the form of square bipyramid, about 4 μm across in a cubic symmetry of the diamond type with a=10.40Å It decomposes to an oxide mixture of Co₃O₄ and U₃O₈ above 850°C in the air through a sulfate mixture of CoSo₄ and UO₂SO₄.

Composition of the thorium precipitate varies with the precipitation conditions. Therefore, it is considered that the thorium precipitate contains thorium hydroxide and basic thorium sulfite.     

Structural Material Anomaly Detection System Using Water Chemistry Data, (II)

A calculation model was developed to predict the dose rate, caused by ⁵⁸CO which is formed by the activation of ⁵⁸Ni, around the recirculation pipes m boiling water reactors (BWRs). The model is characterized by considering direct deposition of Ni ion on the nuclear fuel cladding surface and the geometrical contact probability for the ferrite formation reaction between deposited Ni(Co) and Fe₂O₃ on fuel cladding surface.

This model showed the important role of the amount of Fe crud on the surface to reduce ⁵⁸CO ion concentration in the reactor water. And the necessary Fe concentration in the feedwater for reducing the dose rate in the primary system was estimated as a function of the operating time. This model also enables the quantitative predictions of the effect of prefilming treatment of the feedwater heater tubes or another methods to reduce dose rate in an Fe crud suppressed BWR.     

N,N,N,,N,-四己基丁二酰胺萃取铀、钍及硝酸的机理

合成了 N,N,N?N?四己基丁二酰胺(THSA)。以正十二烷为稀释剂研究了THSA萃取硝酸的平衡,认为在低酸度下主要形成THSA·HNO3加合物,在高酸度下主要形成加合物THSA·HNO3和THSA·(HNO3)2;还研究了THSA从硝酸介质中萃取铀、钍的机理,通过考察 HNO3浓度、THSA浓度及温度对铀和钍分配比的影响,得出了萃合物的组成为UO2(NO3)2·THSA和Th(NO3)4·2THSA,并计算出萃取反应的表观平衡常数及热焓。实验结果表明THSA具有较强的对铀、钍萃取能力,并有望实现铀、钍分离。     

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (I)

The precipitation of uranium(VI) peroxo complex ion with both tris (ethylenediamine) cobalt (III) and tris(trimethylenediamine) cobalt(III) salts has been studied.

The precipitates obtained immediately are, respectively, [Co(en)₃]₄ [(UO₂)₂ (O₂)₄]₃nH₂O and [Co(tn) ₃]₄ [(UO₂)₂ (O₂)₃]₃nH₂O, which change to [CO(en) ₃]₄ [(UO₂)₂ (O₂)₂ (OH) ₄]₃nH₂O and [CO(tn) ₃]₄ [(UO₃)₂ (O₂)₂ (OH) ₄]₃nH₂O with time.

Carbonate ion affects the precipitation reactions by forming stable outer-sphere complex ion with cobalt (III) complex cation.     

Sorptive Removal of Cesium-137 and Strontium-90 from Water by Unconventional Sorbents. I. Usage of Bauxite Wastes (Red Muds)

Bauxite wastes of alumina manufacture, i.e., red muds, have been tested for radiocesium and strontium removal from water. The red muds were water-washed, acid-, and heat-treated before usage to produce hydrous oxide like sorbents. Surface treatment of the sorbent was benefical for ¹³⁷s uptake, while heat-treatment was detrimental to the -SOH surface sites responsible for high ⁹⁰Sr affinity. Fractionation of the sorbent with respect to apparent grain size did not produce significant differences in the sorption efficiency. The distribution coefficients vs. equilibrium activity in solution showed a maximum with Cs, and a gradual decrease trend with Sr. The solution activity vs. adsorption data were fitted to B.E. T. (essentially types IV-V) isotherms for Cs and B.E. T.-Langmuir isotherms for Sr. Desorption, temperature-, pH-, and ionic strength-dependence tests revealed that the primary mode of sorption for both cations is specific adsorption while the secondary mode is ion exchange. A rise in pH favours the ion- exchange sorption of Sr while the specific adsorption of Cs is negatively affected. Competitive adsorption of an inert electrolyte, i.e., NaCl, severely hinders Cs sorption, while Sr sorption on water-washed red mud is not significantly affected.     

Extraction of uranyl（VI）ion with N,N—dibutyloctadecanamide from nitric acid solution

The extraction of U(VI) with newly synthesized long chain alkyl amide,N,N-dibutyloctadecanamide(DBODA),has been studied.The dependence of the extraction on nitric acid concentration,DBODA concentration and temperature from nitric acid solution has been investigated and the extracted species has also been investigated using FT-IR spectrometry.The related thermodynamic functions were calculated.The separation factor between U(VI) and Th(IV) is higher and there is no third phase formation under the conditions studied.     

Experimental Study on Coolability of Particulate Core-metal Debris Bed with Oxidization, (II) Fragmentation and Enhanced Heat Transfer in Zircaloy Debris Bed

The oxidization and coolability characteristics of the particulate Zircaloy debris bed, which is deposited under the hard debris and through which first vapor penetrates and then water penetrates, are studied in the present paper. In the vapor penetration experiments, it is found that Zircaloy debris particles are effectively broken into small pieces after making thick oxidized layer with deep clacks by rapid oxidization under the condition that vapor with 20 cm/s penetrates for 30 to 70 min at an initial debris bed temperature of 1,030°C. It is also confirmed in the water penetration experiments that the oxidized particle debris bed has potentiality of high coolability when water penetrates through the fully oxidized particle bed because of a high capillary force originating from those particles with deep cracks on their surfaces.

Based on the present study, a new scenario for the appearance and disappearance of the hot spot in the TMI-2 accident is posssible. The particulate core-metal debris bed is first heated up by rapid oxidization with heat generation when vapor can penetrate through the debris bed with porosities. This corresponds to the appearance of the hot spot. The resultant oxidized particulate debris bed causes a high coolability due to its high capillary force when the water can touch the debris bed at wet condition. This corresponds to the disappearance of the hot spot.