Search

The paper analyzes promising industrial processes for obtaining electrolytic hafnium powder. It is shown that extraction and iodide refining are the main processes used to purify hafnium from impurities, achieving both reactor-grade and high purity. The conducted studies have demonstrated the possibility of creating an alternative, more economical, and environmentally safe technology for hafnium recovery, compared to the current magnesium-thermal method. Production of reactor hafnium by electrolysis from molten electrolyte K2HfF6-KCl-KF is possible due to obtaining hafnium oxynitrate salt of nuclear purity and the creation of a hermetic electrolyzer. It is shown that the process of electrolysis leads to the accumulation of potassium fluoride in the electrolyte and requires its periodic draining with deterioration of technological indicators associated with increased recycling of the electrolyte. It was found that along with hafnium, metallic potassium is released on the cathode, which additionally worsens the technical and economic indicators of production. Sealing the electrolyzer makes it possible to create an overpressure of anode gas and determine its quantitative and chemical composition. Processing hafnium cathode sludge with potassium carbonate solution preserves the potassium cycle in the system and eliminates the effluents generated by ammonium carbonate. [ABSTRACT FROM AUTHOR]

The interaction of ions with water was considered using the example of alkali metal cations with a common hydroxyl anion. Structural and energetic changes in the ion-dipole system of water were analyzed. A significant influence of the size of the cations on the change in the interaction energy and the polarizability (dielectric permeability) of water around the ion was shown. In this case, at the boundary with the lithium ion, the dielectric constant was close to 1, and at the boundary with the cesium ion, it increased to 1.67. The dielectric constant at the boundary of the first hydrate shell for lithium and cesium ions increased to 2.1 and 2.25, respectively, corresponding to the experimentally obtained value given in the literature. An analysis of energetic and steric factors affecting the amount of ions hydration was carried out. Lithium was shown to have two shells consisting of 4 and 8 dipoles of water, corresponding to primary (positive) hydration. A significant value of the ion-dipole bond energy made it possible to consider the hydrated ion as a quasisolid particle. The effect of hydrated ions on the water viscosity was calculated using Einstein formula. Two opposite factors were shown to affect the viscosity during hydration: the presence of quasi-solid particles increased the viscosity, and the existence of a secondary hydrated shell with broken bonds between water molecules decreased it. Satisfactory correspondence between theoretically calculated and experimentally determined viscosity values was obtained. [ABSTRACT FROM AUTHOR]

The paper describes an aggregate technology for extraction of uranium and related rare earth elements, scandium and phosphorus from uranium-phosphorite ores with the recycling of spent reagents for the production of nitrogen-phosphorus fertilizers. It is shown that increasing the fraction of nitric acid in the mixture with sulfuric acid (melange) for leaching uranium to 100% increases the extraction of all valuable elements up to 95-98%. Optimal parameters (hydro module, duration and acidity) of the raw material processing have been determined. Reducing the content of sulfuric acid in melange to 15% reduces the yield of gypsum with the content of radionuclides of natural origin, which must be buried. The isolation of uranium, thorium, rare earth elements, scandium and radioactive isotopes (Ra, Po, Ac, Pb) is carried out by chemical precipitation using iron in the form of cast iron chips. As a result of processing, a nitrate-phosphate solution purified from radioactive elements and impurities is formed, based on which a complex nitrogen-phosphorus fertilizer «Nitrofos» is fabricated. [ABSTRACT FROM AUTHOR]

The main factors limiting the possibility of organizing the cultivation of the hydrogen-oxidizing bacterium Alcaligenes eutropha Z-1 in combination with electrolysis were determined: accumulation of the oxidizing agents (hypochlorite, persulfate ions, hydrogen peroxide) in the process of electrolysis and deposition of microelements contained in the growth medium on the cathode. The limits for the susceptibility of the bacterium to the oxidizing agents were established. The rate of accumulation of the oxidizing agents and formation of the cathode deposit were found to depend on the current density, the pH and composition of a solution, and several other factors. The concentration of hypochlorite decreased if the content of chloride ions in the growth medium was reduced to approximately 10(-5) g/l; the concentrations of persulfate and hydrogen peroxide is decreased using a certain electrolysis regime and adding ferrous ions which reduce the oxidizing agents. The cathode deposit is dissolved by periodically reversing the current in the course of electrolysis.