The influence of the environment and bacterial cultures on the degree of gold leaching from Au-containing raw materials of different compositions, origins, and with different contents of gold, selected in the Ural Federal District (Russia), was determined. The leaching degree was determined according to the change of the gold concentration in the ore by means of mass-spectrometry with inductively-coupled plasma. It was demonstrated that the degree of Au bioleaching from carbonaceous-argillaceous slates, containing 2.17 g/t of gold, and from pyritic technogenic raw materials, containing 1.15 g/t, when holding them in peptone water and Leten medium reached 92.17% and 87.83%, respectively.
In this paper, we study the possibility of obtaining iron and titanium-vanadium concentrates with highest contents of iron and titanium, respectively, through hydrometallurgical processing of the titanomagnetite ores of the Chineisk deposit. We varied two key parameters to determine the efficiency of the process: (a) concentration of leaching solution (ammonium fluoride); and (b) acidity of solution. Ammonium fluoride concentration was varied from 0.08 mol/L to 4.2 mol/L with the other fixed parameters. It was shown that optimum ammonium fluoride concentration for leaching the ore is 0.42 mol/L; at these concentrations iron and titanium contents are about 62.8 wt % and 3.5 wt % in solid phase, respectively. The acidity of solution was changed by adding of hydrofluoric acid with varied concentration (from 0.86 mol/L to 4.07 mol/L) to ammonium fluoride solution with fixed concentration of 0.42 mol/L. The best results (degree of titanium extraction = 63.7%) were obtained when using a solution of hydrofluoric acid with concentration 4.07 mol/L. In this case, the addition of acid makes it possible to increase the Fe/Ti ratio by 3.4 times in comparison with the original ore. Thus, we conclude that acidity and the concentration of ammonium fluoride solution significantly influences the selectivity of the hydrometallurgical process.
In this paper we synthesized high entropy oxide system (Sc0.2Ce0.2Pr0.2Gd0.2Ho0.2)2O3±δ by precipitation of hydroxides from REE nitrates aqueous solutions and annealing the mixture at 800 °C. It is possible to obtain the various forms of simple and complex composition based on the rare earth oxides, including oxides in the form of nanosized powders. The main idea of obtaining HEOS comes from the field of high-entropy alloys. The interconnection between configurational entropy and mixing enthalpy is a key factor for determining phase transformations. The phase composition, structure, and surface morphology of the obtained powders were investigated by scanning electron microscopy and X-ray phase analysis methods.
In this paper, a method for determining the doping efficiency of dispersed semiconductor metal oxide materials is proposed proposing to use the dependences of the free charge carrier concentration, normalized to the concentration of the doping impurity (Ne spec.), on the content of this impurity. The possibilities of this method are demonstrated by the example of studying the effect of technological factors on the efficiency of doping of indium oxide with tin and doping of tin oxide with antimony. It is shown that it is impossible to achieve the concentration of free charge carriers in the ITO material, higher than that in ATO materials, due to the lower solubility of tin in the In2O3 lattice, as compared with the solubility of antimony in the SnO2 lattice.
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