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Date submitted2024-05-06
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Date accepted2024-06-14
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Date published2024-07-04
Natural carbon matrices based on brown coal, humic acids and humine extracted from it for purification of aqueous solutions from low molecular weight organic impurities
Heterogeneous systems including natural carbon matrices in the solid phase and aqueous solutions of low molecular weight organic compounds with positive and negative variations from ideality in the liquid phase are considered. The technical characterization of the considered supramolecular ensembles on the basis of brown coal of the Kara-Keche deposit (Kyrgyzstan), humic acids and humine extracted from it is given. Functional analysis of the samples was carried out using FTIR spectroscopy. The morphology of the surface of the considered carbon matrices has been investigated, in different points of which the local microelement composition has been established. An X-ray phase analysis of Kara-Keche brown coal and humic acids and humine extracted from it was carried out. The isothermal adsorption of bipolar molecules of glycine and urea, neutral D-glucose from aqueous solutions on solid carbon sorbents has been studied. An assumption has been made about the adsorption of low molecular weight organic compounds from aqueous solutions on humine and Kara-Keche coal in irregularities and pores of the carbon matrix of sorbents, for humic acids – on surface reaction centers. Due to its developed pore structure and resistance to acids and alkalis, humine from Kara-Keche coal is recommended for the purification of industrial wastewater from low molecular weight organic ecotoxicants.
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Date submitted2022-04-14
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Date accepted2022-07-21
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Date published2022-11-03
In-situ leaching of molybdenum and uranium by percarbonate and chloride-hypochlorite solutions
In-situ leaching of molybdenum and uranium is becoming an increasingly common process. The features of the material composition of ores, leading to a decrease in their filtration properties, were considered. Activation leaching with leaching solutions that have undergone electrophotochemical activation before contact with the ore mass were studied. Activation preparation of leaching solutions promotes the synthesis of clustered water molecules with collectivized protons and hydroxyl ions, as well as active forms of oxygen and hydrogen. Cell leaching of molybdenum from mature tailings of the Shakhtaminsk deposit was studied experimentally. After pre-oxidation with an active carbonate solution, a model borehole leaching was carried out with a chloride-hypochlorite solution. Molybdenum extraction on resin a was 85 % in 30 days. Experiments on the percolation leaching of uranium from the ores of the Uchkuduk and Sugraly deposits confirmed the potential possibility of a significant increase in the extraction of uranium by electrophotoactivated percarbonate solutions relative to aqueous solutions of sodium and ammonium carbonate. When leaching with carbonate solutions without an additional oxidizing agent, the extraction of uranium from the Sugraly deposit ore sample was 52 and 59 % (sodium carbonate and ammonium carbonate). The use of hydrogen peroxide as an oxidizing agent made it possible to achieve 87-88 % extraction into pregnant solutions in 21 days without pre-oxidation. The performed studies confirm the processing capability of extracting uranium and molybdenum by percolation leaching in columns and borehole leaching.
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Date submitted2021-06-22
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Date accepted2021-11-30
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Date published2021-12-27
Increasing the efficiency of rare earth metal recovery from technological solutions during processing of apatite raw materials
The issues of complex processing of mineral resources are relevant due to the depletion of available raw materials. So, it is necessary to involve technological waste, generated during the processing of raw materials, to obtain valuable components. In the process flow of apatite concentrate treatment using the sulfuric acid method, a large amount of phosphogypsum is produced with an average content of light rare earth metals (REMs) reaching 0.032-0.45 %. When phosphogypsum is treated with sulfuric acid solutions, a part of REMs is transferred to the sulfate solution, from which it can be extracted by means of ion exchange method. The study focuses on sorption recovery of light REMs (praseodymium, neodymium and samarium) in the form of anionic sulfate complexes of the composition [ln(SO 4 ) 2 ] – on polystyrene anion exchanger AN-31. The experiments were performed under static conditions at a liquid-to-solid ratio of 1:1, pH value of 2, temperature of 298 K and initial REM concentration in the solutions ranging from 0.83 to 226.31 mmol/kg. Thermodynamic description of sorption isotherms was carried out by the method based on linearization of the mass action equation, modified for the ion exchange reaction. As a result of performed calculations, the authors obtained the constants of ion exchange equilibrium for Pr, Nd and Sm, as well as the values of the change in the Gibbs energy for the ion exchange of REM sulfate complexes on the AN-31 anion exchanger and the values of total capacity of the anion exchanger. Calculated separation factors indicated low selectivity of AN-31 anionite exchanger for light REMs; however, the anion exchanger is suitable for effective recovery of a sum of light REMs. Based on the average value of ion exchange equilibrium constant for light REMs, parameters of a sorption unit with a fluidized bed of anion exchanger were estimated.
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Date submitted2018-12-28
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Date accepted2019-03-24
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Date published2019-06-25
Modern physicochemical equilibrium description in Na2O–Al2O3–H2O system and its analogues
Equilibrium and non-equilibrium states of systems Na 2 O–Al 2 O 3 –H 2 O and K 2 O–Al 2 O 3 –H 2 O are crucial for establishing key technological parameters in alumina production and their optimization. Due to a noticeable discrepancy between experimental results and thermodynamic calculations based on materials of individual researchers the necessity of systematization and statistical processing of equilibrium data in these systems to create a reliable base of their physicochemical state, analysis and mathematical modeling of phase equilibria is substantiated. The tendency to a decrease of the hydration degree of solid sodium aluminates with increasing temperature and the transition of systems from the steady state of gibbsite to equilibrium with boehmite is revealed. The paper contains approximating functions that provide high-precision description of equilibrium isotherms in technologically significant area of Na 2 O–Al 2 O 3 –H 2 O and K 2 O–Al 2 O 3 –H 2 O concentrations. Approximating function can be simplified by dividing the isotherm into two sections with the intervals of alkaline content 0-0.25 and 0.25-0.4 mole/100 g of solution. The differences in solubility isotherms for Na 2 O–Al 2 O 3 –H 2 O and K 2 O–Al 2 O 3 –H 2 O systems provide are associated with changes in the ionic composition solutions that depends on concentration and temperature, as well as differences connecting with alkali cation hydration, which is crucially important for thermodynamic modeling of equilibria under consideration.
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Date submitted2018-01-15
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Date accepted2018-02-28
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Date published2018-06-22
About the role of hydrafed calcium carboaluminates in improving the technology of complex processing of nephelines
- Authors:
- V. M. Sizyakov
- V. N. Brichkin
The scientific justification and development of the method for industrial synthesis of complex aluminates of alkaline earth metals is an innovative solution that determined several directions in the development of technology for complex processing of nepheline raw materials. It ensures the production of high-quality metallurgical alumina, the effective utilization of nepheline sludge and production of new types of multipurpose by-products. The modern development of these technical solutions is associated with ensuring the energy efficiency of the synthesis of hydrafed calcium carboaluminates (HCCA) and increasing the level of purification of aluminate solutions. The conditions for synthesizing HCCA with the use of calcareous materials of natural and technogenic origin have been experimentally determined, which makes it possible to isolate the average particle diameter as one of the determining factors of this process. The effect of the turnover of the hydrogarnet sludge on the removal of kinetic limitations in the process of deep desalination of aluminous solutions is theoretically justified. The conditions of a two-stage dosage of HCCA are experimentally determined. It is shown that the optimum ratio of the amount of the reagent supplied in the first and second stages is about 3: 2. At the same time, the maximum degree of precipitation of silica provides the production of aluminate solutions with a silicon module at the level of 95,000, which is achieved by using a HCCA synthesized based on chemically precipitated calcium carbonate in the processing of wastes from the production of mineral fertilizers.
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Date submitted2015-07-25
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Date accepted2015-09-01
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Date published2016-02-24
The phenomenon of isothermal transition of metastable aluminate solutions into the labile area and prospects of its industrial use
- Authors:
- V. N. Brichkin
- A. Kraslawski
The paper presents theoretically based requirements for the activation of synthetic gibbsite for maximum solubility of the activated product. The article describes the methodological foundations of gibbsite thermal activation and its effectiveness evaluation in terms of aluminate solutions decomposition. It is shown that to obtain high-saturation aluminate solutions, activation should provide generation of the reagent with highly-developed surface area, which is not identical to the structure of the deposited gibbsite. As a result of high-gradient thermal activation of synthetic gibbsite, it has been found that the targeted product develops predominantly an amorphous structure with a specific surface area up to 256 m2/ g, preserving its primary particle size. Activation products were investigated using modern methods of physical and chemical analysis. The experimental results confirmed the possibility of the activated product dissolution in the aluminate solution with a metastable compound and their spontaneous decomposition with aluminum hydroxide formation, characterized by high dispersion ability. It is shown, that a significant difference in kinetics and decomposition rates of solutions is connected with the use of a seed material with different particle size composition, which leads to the development of competing mechanisms, resulting in seed recrystallization, homogeneous and heterogeneous nucleation.
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Date submitted2015-07-07
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Date accepted2015-09-16
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Date published2016-02-24
Activation of heap leaching of low-sulfide ores the invisible gold
- Authors:
- A. G. Sekisov
- Yu. I. Rubtsov
- A. Yu. Lavrov
This article deals with a physical-chemical model of heap leaching processes justifying new technological approaches to recovering dispersed forms of gold from ores, placer sands and deute-rogene mineral raw materials. The key process of this model includes lattice diffusion of high-energy hydrion minerals and hydroxyl-radicals formed as a result of photochemical and electro-chemical processing of initial reagent aqueous solutions. Active components of gas-water emulsions obtained while processing initial reagent solutions provide a structural and material trans-formation of a mineral lattice which concentrates clusters of dispersed gold creating conditions for its interacting with complexing compounds of process solutions. The article also considers the technological processes of activation heap leaching of dispersed gold from the Pogromnoe ore field and the results of the experiments conducted in percolators with their charge ranged from 3 to 100 kg. The results have proved the efficiency of using gas-water suspensions prepared in the pho-toelectrochemical reactor with active ion-radical oxidizing agents.
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Date submitted2010-07-13
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Date accepted2010-09-25
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Date published2011-03-21
Hydrogeological typisation of the north part of the Mid-Atlantic ridge
- Authors:
- M. V. Krivitskaya
The deep basite-hyperbasite rocks wich are special features for the north part of the Mid-Atlantic Ridge (MAR) are observed. The hydrogeological structures of the MAR are distinguished.
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Date submitted2010-07-20
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Date accepted2010-09-04
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Date published2011-03-21
Forming of the composition of hydrotermal solutions in hydrogeological massifs of ultrabasic rockes of the Mid-Atlantic ridge
- Authors:
- S. M. Sudarikov
- M. V. Krivitskaya
Difference in structural position and influence of ores from different types of sediments on the geochemical characteristic of ores are observed. Results of end member composition correlation analysis show negative link of H 2 S with CH 4 и Н 2 .
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Date submitted2009-09-21
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Date accepted2009-11-10
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Date published2010-06-25
Simultaneous doping of silicon carbide with aluminum and nitrogen
- Authors:
- I. I. Parfenova
Three atomic shell cluster of SiC is treated as a set of chemical bonds with tetrahedral coordination. Chemical bonds energies are determined in tight binding approximation taking into account second neighbors interaction and relaxation of atomic positions. Correlations in behavior of Al and N atoms in Si-C-Al-N system determine the quasibinary character (SiC) 1-x (AlN) x alloys. Inhomogeneous regions in (SiC) 1-x (AlN) x system were evaluated using the condition of mixing free energy minimum. We assumed that doping does not change the vibration spectra of the crystal.
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Date submitted2009-08-10
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Date accepted2009-10-21
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Date published2010-02-01
Precipitation of alumina liquor inclusive potassium
- Authors:
- V. V. Radko
The materials of experimental research on alumina liquor precipitation kinetics in system Na 2 O – K 2 O – Al 2 O 3 – H 2 O using carbonated alumina hydroxide as a seed are presented. Particle size distribution (PSD) analyses of settling products are given. Correlation link of alumina liquor decomposition degree and average median diameter of received aluminum hydroxide are shown.
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Date submitted2009-07-05
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Date accepted2009-09-25
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Date published2010-04-22
Active methods for control of geomechanical state of rock mass in coal deposit mining under complicated geological-and-mining conditions
- Authors:
- F. N. Voskoboev
- Yu. A. Semenov
- V. A. Zvezdkin
The paper presents the main technologies, characteristics, schematic diagrams and parameters of active methods for control of geomechanical state of technogenic rock mass, domain and technical-and-economical efficiency of their industrial application.
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Date submitted2008-10-13
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Date accepted2008-12-28
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Date published2009-12-11
Ore-forming hydrothermal solutions and gas hydrate formation in the ocean
- Authors:
- S. M. Sudarikov
- S. S. Filatova
Geological and tectonic settings and thermobaric characteristics of hydrothermal activity are confronted with those of gas hydrate formation. Hydrocarbon concentrations and isotopic composition in hydrothermal fluids of mid-ocean ridges with different thickness of sediment cover and marginal oceanic basins are compared. The possible influence of rising thermal fluids on gas hydrate accumulations was analyzed and examples of hydrate formation linked with hydrothermal process are given.