Vol 50 Iss. 3

The general principles of selecting selectively acting solvents, conducting tests, and interpreting their results for the techno-economic assessment of mineral leaching processes have long been known and are described in detail in many hydrometallurgy courses. As regards the specific problems of selective dissolution in phase chemical analysis, these issues are also covered quite fully ...

The kinetics of oximation of substituted 1-phenyl-1,2-propanediones of the general formula CH₃COCOC₆H₄R, where R = H, p-CH₃, p-OCH₃, p-Cl, p-Br, m-Cl, m-CH₃, were studied at 278, 288, and 298 K and pH = 6.5.

Hydrochloric and nitric acids, commonly used to separate oxidized and sulfide bismuth compounds, do not permit quantitative separation of oxidized and sulfide bismuth minerals. ...

A fountain layer can serve as one of the intensive methods of contacting a solid material with a liquid. While a significant number of works have been devoted to its hydrodynamic regularities in the G‑S system, there is practically no work on the hydrodynamics and mass transfer of the fountain layer in the L‑S system. The lack of a complete analogy in the behavior of these two heterogeneous systems, caused by a significant difference in the viscosity and density of the light phases L and G, urgently requires independent hydrodynamic studies of the fountain layer in the L‑S system...

The method of mercury porometry is widely used to determine the geometric structure of solid porous bodies. The porous structure of granular materials with a granule size of at least 1–2 mm is usually determined. However, in a number of fields (flotation beneficiation processes, powder metallurgy), the objects of study are powders in which the minimum particle size decreases to several tens of microns. The method of mercury porometry is of interest for studying the structure of powders. ...

Studies on the autoclave oxidation of nickel sulfides mainly consider the behavior of fused nickel sulfide, close in composition to heazlewoodite Ni₃S₂. Only a few have highlighted the kinetics of dissolution of nickel monosulfide NiS, one of the main components of various intermediate products of nickel production: anode slimes, nickel sulfide concentrate obtained by precipitation with hydrogen sulfide, and the intermediate phase of autoclave dissolution of nickel concentrate from flotation of copper nickel matte...

When determining the specific surface area of solids by the gas chromatographic method of thermal desorption, the areas of desorption calibration peaks are compared. The catharometer is usually calibrated by introducing the adsorbate gas into the main stream. Another gas, such as air, can also be used for this purpose. ..

The dependences linking the degree of decomposition of a solid substance with the initial amount and concentration of a solvent through an equilibrium constant are described more simply if the equation of the chemical dissolution reaction, accompanied by the formation of complex or sparingly soluble products, is referred to one mole of solvent. The proposed mathematical formulation, using equilibrium constants, establishes the dependence of the degree of decomposition of a solid on the relative amount of solvent.

The labour‑intensiveness of calculating the porosity characteristics prevents the widespread use of the mercury porometry method in factory and research laboratories. It is possible to reduce the calculation time by standardizing measurements on a high‑pressure porosimeter, using pre‑prepared tables, simplifying the calculation scheme, and reducing the number of measurements. Simplification is permissible, however, only for materials that are finely porous and have a highly developed porosity...

The kinetics of dissolution and methods of phase analysis of antimony compounds have been studied repeatedly. To study the kinetics of Sb₂S₃ and Sb₂O₃ dissolution in KOH solutions, polydisperse samples of these antimony compounds (analytical grade) were taken with a view to using them for phase analysis. Using the low temperature inert gas adsorption method, the specific surface area was determined for Sb₂S₃ and Sb₂O₃. The kinetics of the interaction of Sb₂O₃ with solutions follows the laws of first order reactions under the conditions of the diffusion regime of the dissolution process. The dissolution of Sb₂O₃ and Sb₂S₃ in solutions cannot be used for selective dissolution in phase analysis. ...

Hydroxamic acids have been used as effective flotation reagents and are promising in the extractive recovery of metals. The analysis of hydroxamic acids was studied by K. E. Istomina and L. A. Ionina. The quantitative determination of small concentrations of heptylhydroxamic acid in aqueous solutions was carried out as follows...

Studies on the kinetics of apatite dissolution in sulfuric acid have shown that the formation of insoluble compound films on the surface of the solid phase hinders solvent access to it and leads to a slowdown and even complete cessation of the dissolution process. In the concentration range of 16–25 N H₂SO₄, the dissolution reaction is sharply retarded. At concentrations above 25 N, apatite dissolves rapidly. This is attributed to the different physical structure of the calcium sulfate film, which depends on the concentration of the solvent. ...

Very small amounts of sulfides must be determined in natural waters, wastewater from concentrating plants and other enterprises. Evaporation of such solutions often changes their chemical composition and requires considerable time. ...

One of the ways to extract tin from tinplate waste is to dissolve tin in alkaline solutions containing metanitrobenzoic acid, followed by electrolysis. The process solution is a complex multicomponent system. In addition to free alkali and metanitrobenzoic acid, it may contain tin stannates and stannites, as well as various reduction products of nitrobenzoic acid (azoxy-, azo-, hydrazo- and other compounds). The formation of carbonates is inevitable due to the absorption of carbon dioxide from the air. ...

During extraction of non-ferrous metals from dilute solutions with naphthenic acids, salts are formed that are soluble in the organic phase and sparingly soluble in water. The solubility of naphthenates in the organic phase is determined both by the nature of the solvent and by the composition of the extracted compound, which usually contains a certain amount of water of hydration. ...

The effect of temperature on the distribution of substances in extraction processes has been repeatedly considered. The distribution of coordination‑solvated compounds is usually regarded as more dependent on temperature than the distribution of hydrate‑solvates...

Methods of phase chemical analysis of iron ores have not been sufficiently developed. Methods for the separate determination of iron oxides, hydroxides, and silicates have been particularly poorly studied. In their study, it is possible to apply sample treatment with gaseous hydrogen chloride. Unlike chlorine, a common and well‑studied chlorinating agent, hydrogen chloride is not an oxidizing agent and does not change the valence of iron in the initial compounds when they are converted to chlorides ...

Due to the success of vacuum metallurgy in the post war years, an assessment of the applicability of this method to non ferrous metal sulfides is of undoubted interest. The kinetics of distillation of lead and zinc sulfides in vacuum at 10⁻² – 10⁻³ mm Hg were studied in the apparatus and according to the procedure described earlier [4]. Experiments have shown that under isothermal conditions, the distillation of lead and zinc sulfides proceeds at constant rates...

Extensive experimental material on the kinetics of the pyrrhotite roasting process has made it possible to establish the influence of temperature, oxygen concentration, and particle size on the rate of the oxidation process. Oxidative roasting of pyrrhotites is a complex physicochemical heterogeneous process accompanied by the formation of gaseous and solid reaction products, which leads to additional resistance to mass transfer caused by the diffusion of oxygen through a porous layer of solid oxides...

In sulfatizing roasting of copper zinc concentrates and intermediate products, it is most difficult to achieve a high degree of zinc sulfatization. When studying the causes of this phenomenon, the main attention should be paid to the kinetics of the zinc sulfate formation reaction. ...

The possibility of successfully using naphthenic acids for the extractive recovery of non ferrous and rare metals has been established by numerous studies. The widespread industrial use of this extractant in non ferrous metallurgy is hindered by the unavoidable presence of ferric ions in the initial solutions. To remove these ions, it is proposed to use other extractants (for example, fatty acids) or hydrolytic precipitation, which undoubtedly complicates the technological process....

The distribution of the extracted substance between the aqueous and organic phases depends on the nature of the diluent used. If kerosene or individual alkanes are used as a diluent, i.e. compounds that are low‑polar and do not have the ability to form donor‑acceptor bonds, then their interaction with tributyl phosphate (TBP) and the solvate is apparently limited to the occurrence of dispersion forces without the formation of molecular compounds with the dissolved substances. In such systems, limited solubility of solvates of the extracted compounds is very often observed. ...

Molybdenum and tungsten can be extracted with alkylamines from acidic solutions obtained during the chemical upgrading of scheelite concentrate at the Tyrnyauz Processing Plant. These solutions contain 5‑8 g/l of molybdenum and tungsten. Each is present in both oxidized and reduced forms. The solution also contains significant amounts of phosphorus and silicon. Apparently, molybdenum and tungsten are found in these solutions in the form of phosphoric and silicic heteropoly acids, since these metals are excellently extracted by solutions of amines in nonpolar diluents. To determine the state of molybdenum and tungsten in these solutions, the behavior of the metals during extraction with amines from hydrochloric acid solutions in the presence of phosphorus and silicon over a wide range of hydrochloric acid concentrations was studied. ...

Magnesium ions, along with other unavoidable impurities, are usually contained in solutions obtained during the hydrometallurgical processing of ore raw materials and in the aqueous part of the flotation pulp. It is of interest to clarify the composition and properties of compounds formed by magnesium ions with naphthenic acid, the possibility of using naphthenic acid for extraction of non ferrous metals from solutions and flotation of some non sulphide minerals has been established by many studies. ...

The flotability of a mineral is influenced by the electrical characteristic of the boundary layer in the mineral solution system. Therefore, it is important to correctly determine the point of zero charge, which characterizes the absence of a double electric layer. It can be found by measuring the capacitance of this layer. ...

Currently, methods of precipitation of dissolved substances by various precipitators are most widely used for wastewater treatment of mining and metallurgical enterprises, with the concomitant extraction of metals contained in them. However, bulky equipment for settling, filtration, or centrifugation limits the use of these methods associated with a large expenditure of time. The use of ion exchange resins, given the solid phase in wastewater, is also not always economically justified. The method of liquid extraction from very dilute solutions is associated with significant losses of extractant per unit of extracted metal caused by the solubility of the extractant in the aqueous phase. ...

The harmful effect of fine slimes on the flotation of mineral grains is due to the absorption of part of the reagents, slime coatings on the surfaces of minerals and air bubbles, changes in the viscosity of the pulp, increased foam stability, etc.

In copper‑nickel ores, some of the nickel isomorphically bound to some silicates floats very poorly. At the same time, the easy decomposability of nickel silicate by acids indicates the possibility of using the V. Ya. Mostovich method for certain difficult‑to‑beneficiate intermediate concentrates or off‑grade concentrates with a high content of silicate nickel. In order to judge the possibility of practical and economically advantageous application of the proposed combined method of processing intermediate nickel products, it was necessary to establish the conditions for flotation of cement nickel, ensuring high results in this operation. ...

Top purging of metallurgical melts with gaseous agents is currently being successfully used in ferrous metallurgy and is beginning to gain recognition in non‑ferrous metallurgy, where an arrangement of nozzles inclined to the surface of the bath is most promising for such units...