Method Of X-ray Fluorescence Analysis Research Articles

X-ray Fluorescence Analysis of the Elemental Composition of Tungsten, Nickel and Copper

The purpose of this work was to conduct an X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using an Olympus Delta portable spectrometer.Methods. To determine the chemical composition of raw materials, samples of metal waste in the form of copper rods, tungsten rods of various diameters and scraps of nickel plates intended for recycling were examined. To determine the elemental composition of metal waste, the method of X-ray fluorescence analysis (XFA) was chosen. The X-ray fluorescence method is based on the ratio of the intensity of X-ray fluorescence to the concentration of elements in the sample. Samples irradiated with powerful X-ray tube radiation, in response, emit characteristic fluorescent radiation of atoms proportional to their concentration in the sample. This method allows us to qualitatively assess the elemental composition of complex samples without violating their physico-chemical properties with minimal time costs. The Olympus Delta spectrometer was used as an express analyzer of metals and alloys, with the help of which experimental data on the composition of metal waste of tungsten, nickel and copper were obtained.Results. Based on the conducted studies aimed at X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using the Olympus Delta portable spectrometer, it was found that the samples of the studied metal waste correspond to the following grades of alloys: tungsten rod made of tungsten grade VA; nickel plate made of nickel grade PNK-0T1; copper rod made of copper grade M3r.Conclusion. The results obtained will allow further research on their processing by the method of electroerosive dispersion and reuse in the production of heavy tungsten alloys. Renovation of metal waste, including tungsten, nickel and copper metal waste, will contribute to resource conservation, import substitution and ensuring the technological sovereignty of the Russian Federation.

Assessment of the possibility of X-ray fluorescence analysis before conducting the experimental work

The article proposes an approach to the development of a method for X-ray fluorescence analysis of an object using crystal-diffraction spectrometers prior to the experimental work. In case when the X-ray fluorescence analysis method is intended as a substitute for an existing method, then for the object being analyzed the statistical characteristics of the material for which the X-ray fluorescence analysis method is being developed, i.e. the average content of the elements to be determined, the dispersion and the range of the elements content, the requirements for the accuracy of determination, and some others, are calculated on the basis of archival data of the analytical laboratory (or an array of selected calibration samples). In case when a new method is developed, technical requirements for the product allowing estimating these characteristics are sufficient. Analytical characteristics, such as basic instrumental error, sensitivity, spectral resolution, contrast, must be measured and calculated over the entire operating range of the measured analytical lines for the spectrometer used. Metrological characteristics of the method for determining the elements, i.e. detection limit, differential sensitivity, instrumental reproducibility of content measurement at the selected exposure time, are evaluated on the basis of these data. At this stage the question concerning the necessity of diluting the samples with a heavy or light diluent for obtaining satisfactory differential sensitivity may be resolved. The regimes for recording the analytical signal for the elements to be analyzed, i.e. analytical lines, analyzer crystals, X-ray tube operating modes, are determined, the probability of overlapping spectral lines is estimated, and the background measurement points are selected. Calculation of theoretical and simulation of experimental intensities for selected calibration and test samples and calculation of theoretical coefficients of influence are carried out. The expected error of the analysis is estimated on the basis of the statistical characteristics of the material and the theoretical coefficients of influence, and the need to take into account the relationship between the interfering elements in the equations is determined for achieving the required accuracy of determining the elements. Selection of regression or theoretical coupling equations, which provide the required accuracy of determining the elements, is carried out on the basis of the simulated experimental intensities of the analytical lines of the elements. Such approach allows a priory estimate the possibility of developing an X-ray fluorescence analysis technique for an object selected, and can significantly reduce time for performing the experimental work. Keywords: X-ray fluorescence analysis, method of analysis, analyzed object, X-ray spectrometer, analysis characteristics, forecast of experimental intensities, estimation of expected error, modes of registration of the analytical signal, coupling equations.

Investigation of the Elemental Composition of Components of the Cutters of a Cold Miller by the Method of X-Ray Fluorescence Analysis

Purpose. Establishment of the elemental and quantitative composition of alloys - components of road milling cutters, which are used as working bodies for milling the road surface, by X-ray fluorescence analysis.Methods. To establish the chemical composition of alloys - components of cutters of a road milling cutter, WIRTGENW6/20X cutters and their domestic counterpart KZTS A6/20 were studied. The X-ray fluorescence method was chosen to study the elemental composition of the components of the road milling cutters. This method, based on the interaction of X-ray radiation with the analyzed substance, is the most effective and efficient method of analysis, which allows obtaining complete and reliable information about the elemental composition of complex samples in a minimum period of time without destroying them, while maintaining all the physicochemical properties, as well as without using a reference sample. The method is based on the correlation between the X-ray fluorescence intensity and the element concentration in the sample. As a result of irradiating the sample with an X-ray flux, a characteristic emission of atoms is created, which is proportional to their concentration in the sample. With the help of an express analyzer of metals and alloys - the Niton GOLDD spectrometer, experimental data were obtained on the composition of alloys - components of cutters of a road milling machine.Results. During the study, it was revealed that the components of the cutters are made from the following alloys:1. Cutter WIRTGEN W6/20X:- tip made of hard sintered alloy VK8;- housing made of structural alloyed steel 32G2;- spring sleeve of the cutter made of structural carbon steel 08ps;- washer made of structural quality carbon steel 60.2. Cutter KZTS A6/20:- tip made of hard sintered alloy VK8;- housing made of structural alloyed steel 38XV;- spring sleeve made of structural quality carbon steel 40;- washer made of structural alloyed steel 45G.Conclusion. The obtained research results can be used for subsequent processes of hardening or restoration of cutters of road milling machines.

Synthesis of Ti-Ni and Zr-Ni Core–Shell Particles Using Galvanic Replacement

This article focuses on the galvanic replacement synthesis of Ti-Ni and Zr-Ni metal systems with a “core-shell” structure, which are potential precursors for intermetallics. The authors defined effective synthesis parameters and formation features of polymetallic systems characterized by granulometric, phase, and elemental composition. X-ray fluorescence and X-ray phase analysis methods showed that the deposition of nickel on dispersed titanium and zirconium leads to the production of test samples with phase composition representing a mechanical mixture of Ni and Ti, and Ni and Zr. The method of X-ray fluorescence analysis showed that the presence of hydrofluoric acid with a 0.5-1.5 M concentration results in the formation of fixed quantitative ratios of elements in the precipitate, which allows the quantitative composition of dispersed systems “titanium-nickel” and “zirconium-nickel” to be regulated within a relatively wide range. Scanning electron microscopy proved that all synthesized systems are characterized by a highly porous structure that follows the titanium and zirconium particle surface contour and the presence of spherical nanoscale subunits on the formed particle surface.

USE OF UREA FOR CLEANING USED SEMI-SYNTHETIC MOTOR OILS

During the operation of motor vehicles with gasoline or diesel internal combustion engines, motor oil is exposed to high temperatures, is constantly in contact with metals, its hydrocarbon part undergoes chemical transformations, is contaminated by wear products of metal surfaces, decomposition of additives, and residues of incomplete combustion of fuel. As a result, motor oil undergoes irreversible changes in its high-quality chemical composition and loss of operational properties. The paper describes the results of the study of the process of cleaning exhausted semi-synthetic motor oils in the presence of crystalline urea. Castrol 10W-40 oil, widely used in truck diesel engines, and ELF Evolution 700 STI oil, used in passenger car gasoline engines, were chosen as used semi-synthetic motor oils. The influence of the main factors of process control (the amount of urea, duration, and temperature) on the change in the functional properties of refined motor oils was studied. It was established that the lowest values of defective indicators (acid number, water content, ash content, content of mechanical impurities) were obtained at 140 ºС, duration of 80 min., and 5 mass. % of crystalline urea. In addition, there is a slight increase in the values of kinematic viscosity and viscosity index. The method of X-ray fluorescence analysis confirmed that the content of metals decreased in urea-treated oils compared to used ones. IR spectroscopic research demonstrated that under the established optimal conditions of the purification process with crystalline urea, the content of oxygen-containing "aging" products (aldehydes, ketones, alcohols, ethers, esters, organic acids) in purified semi-synthetic motor oils significantly decreased. It is proposed to use the process of cleaning used semi-synthetic motor oils in the presence of crystalline urea as an intermediate stage of the combined technological cycle of regeneration of used motor oils.

Thermal Behavior of Biodegradable Compositions of Polylactide and Poly(3-hydroxybutyrate) with Chitosan and the Effect of UV Radiation on Their Structure

The negative influence of water pollution by heavy metals ions on human health represents a serious ecological problem which requires effective methods in the search for its solution. The creation of eco-friendly biodegradable polymer materials capable of performing the sorption of the water media of heavy metals followed by decomposition into harmless substances after the end of their service life presents an actual task. To this aim, binary compositions synthesized from natural raw polyesters polylactide (PLA) and poly(3-hydroxybutyrate) (PHB) with polysaccharide chitosan, corresponding to these requirements, were obtained in the liquid phase. The polyesters have mechanical characteristics close to the characteristics of synthetic polymers, while the chitosan containing the amino groups is capable of performing the sorption of heavy metals. The use of compositions on their base allows one to create the new inexpensive biodegradable sorbents stable in aqueous media as well as apply them as packing materials. The sorption capacity of PLA–chitosan and PHB–chitosan compositions in relation to iron ions from aqueous solutions was explored by a method of X-ray fluorescence analysis and it was established that the sorption of Fe3+ ions by PHB–chitosan composition is more than twice as high as that by the PLA–chitosan composition (2.30 and 0.66 wt. %, correspondingly, after sorption from 0.008 mol/L FeCl3 solution during 24 h). A comparative study of thermophysical parameters and the degree of crystallinity of PLA and PHB, as well as in their initial compositions and compositions, containing sorbed iron ions, was carried out by DSC method. The DSC analysis of the PLA–chitosan and PHB–chitosan compositions, containing sorbed iron ions, showed a slight decrease in the values of Tg, Tcc, and Tm as well as an increase in the enthalpy of cold crystallization and a reduction in the degree of crystallinity of these polyesters. At the same time, an increasing of the thermal stability of polyester compositions in the presence of iron ions was established. The influence of UV irradiation on the structure of PLA and PHB for 2, 5, 24, and 144 h was analyzed by FTIR spectroscopy and significant changes in the spectrum were observed. Based on the analysis of the IR spectra of PHB and PLA, it was concluded that, under the action of UV radiation, the destruction of ester bonds takes place, which is expressed in the appearance of intense bands characterizing the formation of new structural units, resulting in the decrease in the molecular weight of polyesters.

Algorithm for applying regression analysis to determine the concentration of the main component in mineral raw materials by X-ray fluorescence method

X-ray fluorescence analysis (XRF) is currently in high demand in such branches of science and technology as metallurgy and geology. Today, it is important to create such methods of X-ray fluorescence analysis that would provide high accuracy of the results obtained along with a short execution time. The basic work is a technique, the essence of which is the use of regression analysis to determine the content of gold, as the main component in jewelry alloys. The technique uses a training sample that contains correlated radiation intensities of sample components with their gold content, determined by the assay method of analysis. In this paper, it is proposed to apply a similar approach to the analysis of mineral raw materials. Raw materials from the same deposit may have a similar composition, which allows you to collect enough statistical data to apply regression analysis. The paper proposes an enlarged algorithm for the development of such methods of X-ray fluorescence analysis. Such methods are of limited use, since they depend on the representativeness of the training sample and therefore can only be used to analyze materials of the same type, but their strengths are high accuracy and low time costs.

The reaction of the urban soil-plant complex on abnormal weather conditions

This research is devoted to the study of geochemical features in the soil-plant complex of green spaces in Saint-Petersburg and their changes in abnormal weather conditions, which was the first experience of such work in this region. It included the research of such aspects as accumulation of heavy metals by plants from the soil, photosynthetic pigment apparatus of plants and the content of organic carbon in the soil. The X-ray fluorescence analysis method was used to determine the content of heavy metals, the determination of organic carbon in the soil was carried out in accordance with the Tyurin method, the content of chlorophyll and carotenoids was determined by photometrical method. The study showed that in stressful conditions (abnormal hot weather) there are changes happening in the pigments system of the leaf and in the barrier function in relation to heavy metals.

Determining changes in the mineral composition of concrete due to chemical corrosion in a sulfate environment

The object of this study was the concrete structures of a chemical enterprise for the production of titanium dioxide. In this case, the ore is decomposed with sulfate acid according to the sulfate production technology. In an aggressive environment, chemical corrosion of concrete occurs, prolonged over time. Using X-ray diffraction and X-ray fluorescence analysis methods, the mineral composition of two prototypes of concrete was determined. It was found that the sample obtained from the workshop for processing ore with sulfate acid showed an increased content of sulfur oxide (SO2) on the surface, by 33 %, with a reduced content of carbonates (CaCO3) on the surface, by 52.9 %, at a depth of 2 cm – by 53.65, compared to another (control) sample. At the same time, iron oxide (Fe2O3) was found on the surface in a sample of concrete from the ore storage room (control), the content of which decreased by 10.4 % at a depth of 2 cm, and by 12.4 % at a depth of 4 cm. The results of electron microscopy show sulfur crystals on the surface of a concrete sample. It was also found that the microstructure of concrete was changed under the influence of sulfate corrosion, depending on the intensity of the exposure to a depth of 2 to 4 cm. By the method of thermoprogrammed mass spectrometry, it was established that when a sample of concrete exposed to sulfate acid is heated to a temperature of 400 °C, sulfur dioxide SO2 is released mainly from the surface. From the surface of the control sample, which contains a significant amount of CaCO3, which is easily destroyed by sulfate acid, there is probably a smaller amount of the product of thermal destruction of calcium carbonate carbon dioxide (CO2). The results of the experiment can be used to study the mechanism of development of sulfate corrosion of concrete prolonged over time.

Investigation of Antibacterial Properties of Corrosion-Resistant 316L Steel Alloyed with 0.2 wt.% and 0.5 wt.% Ag.

The article is devoted to the study of melted ingots, plates rolled from them, and the resulting spherical powder made of corrosion-resistant 316L steel with the addition of 0.2 wt.% and 0.5 wt.% Ag. The study of antibacterial properties, microstructure, and distribution of silver concentrations, as well as qualitative analysis of silver content was carried out. The optimal mode of homogenization annealing of the ingot was 1050 °C for 9 h, which leads to the formation of an austenitic structure. It is shown that the addition of a small amount of silver does not affect the formation of the austenitic structure and silver is distributed evenly throughout the volume of the ingot. The austenitic structure also prevails in the plates after rolling. Silver is distributed evenly throughout the entire volume of the plate. It is noted that the addition of 0.2 wt.% Ag does not affect the strength, elongation, and microhardness of steel, and the addition of 0.5 wt.% Ag does not significantly reduce the strength of steel, however, all samples meet the mechanical characteristics according to the ASTM A240 standard. The qualitative chemical composition of samples made of corrosion-resistant steels was confirmed by X-ray fluorescence analysis methods. By the method of energy-dispersion analysis, the presence of a uniform distribution of silver over the entire volume of the powder particle was determined. The particles have a spherical shape with a minimum number of defects. The study of the antibacterial activity of plates and powder shows the presence of a clear antibacterial effect (bacteria of the genus Xanthomonas campestris, Erwinia carotovora, Pseudomonas marginalis, Clavibacter michiganensis) in samples No. 2 and No. 3 with the addition of 0.2 wt.% and 0.5 wt.% Ag.

X-RAY FLUORESCENT DETERMINATION OF TITANIUM, ZIRCONIUM, AND CHROMIUM IN TITANIUM-ZIRCONIUM SANDS OF THE BESHPAGIRSKOE DEPOSIT

Gaining current information about the chemical composition of samples from different areas of the deposit during geological exploration necessitates the use of methods of rapid analysis, most often X-ray fluorescence analysis in combination with a method of external standard and its modifications. The existing certified methods assume the construction of calibration characteristics using reference standards. We propose to use a rapid method of X-ray fluorescence analysis (XRF) in aversion of the method of fundamental parameters to determine non-ferrous metals in the samples of titanium-zirconium sands of the Beshpagirskoye deposit and specified conditions of analysis. It is shown that when using the method of fundamental parameters, the accuracy indicators are highly competitive with the indicators obtained by the certified method.

X-ray fluorescence for lithium metal anode quality inspection

A novel X-ray fluorescence (XRF) method is proposed in this study for quality inspection of thin Li metal anodes. The method can be used to determine Li coating thickness and to calculate Li mass absorption coefficient. The high correlation between the calculated Li mass absorption coefficient (263.9 cm2/g and 259.7 cm2/g at 930 eV) and the reported values in literature (NIST 260.0 cm2/g and CRXO 279.2 cm2/g) indicates this method can be a promising quality inspection tool. The suggested XRF method can also potentially be used to detect internal and surface defects in Li coatings, as well as to identify chemical impurities. The XRF analysis method is non-destructive, non-contact, covers large areas, provides compositional data and is amenable to online production. This study shows the potential of incorporating XRF analysis system as a quality inspection tool for the commercialization and large-scale manufacturing of Li metal anodes and next generation EV batteries.

ELEMTNTAL COMPOSITION OF SEEDS OF APIACEAE

The aim of the research is to study the quantitative content of macro- and micronutrients in the seeds of the Celery family. In the work using the method of X-ray fluorescence analysis, the elemental composition of the seeds of celery crops - carrots, parsley, celery, coriander and parsnip was studied. Individual profiles were compiled (series on the accumulation of macro- and microelements) and their similarity was noted for most elements, which indicates a common metabolic process in plants of related species. Of the macrocells in the seeds of the studied species, Ca and K, as well as P, Mg, S, accumulate in the maximum amount, and of the trace elements Fe, Zn, Mn. Differences in the accumulation of elements in different cultures depended on the type of macro- or microelement. The types of accumulation of Ca, P, K, Zn, Pb, Ni, Zr are relatively weak in types, and the concentrations of Si, Na, Al, Br, Ti Sr, and Fe are most variable in cultures. Significant accumulation of Si in parsnip seeds was noted which is not typical for other studied species. In general, parsnip seeds have the richest set of macro- and microelements in comparison with other celery crops. The seed samples analyzed had a wide variety in the mineral composition. Numerous variations among species belonging to the same family are probably due to individual genetic structure, as well as different growing conditions.

Биоэлементный статус организма у лиц с избыточной массой тела

The aim of the work is to assess changes in the bioelement status of overweight persons using the method of X-ray fluorescence analysis and to identify its correlations with nutritional features. It has been found that in a group of men with body mass index 25-30, the Ca/K ratio > 5 in 64 % of the surveyed, and the Zn/Cu ratio > 8 in 72 % of persons. Thus, it can be seen that in a group of men with increased body weight, the activity of calcium-regulating hormones is increased in 64%. In a group of women with body mass index 25-30, the Ca/K ratio > 5 in 92 % of the surveyed patients, and the Zn/Cu ratio > 8 in 56 %. It has been shown that with increased body weight, the activity of calcium-regulating hormones is increased in 92 % of the surveyed women. To construct the multiple regression equation, a matrix of paired correlation coefficients of factor levels is calculated and analyzed. The value of the Ca/K ratio in men is determined by the intake of potassium, calcium, iron, molybdenum, lead, and cadmium with food. The Ca/K ratio in women is determined by the intake of calcium, manganese, and sulfur with food. To normalize the work of calcium-regulating mechanisms, it is necessary to control the intake of these elements into the body.

Identification of white jewelry alloy based on silver and platinum for testing purposes

The procedure for the identification of white jewelry alloys based on precious metals, in particular, silver, platinum and platinum group metals with different contents of alloying components, by testing on an assay stone and by the method of X-ray fluorescence analysis has been considered. The methodology for assessing the compliance of silver and platinum fineness in white jewelry alloys of different component composition with the requirements of regulatory documents and the procedure for their identification has been improved. It has been established that the silver fineness in precious alloys of the AgCu, AgZnCu system, determined using the potassium dichromate reagent on the test stone, depends on the manifestation of the contrast of the qualitative reaction from the standard sample (assay needle). It has been proven that for testing silver alloys containing palladium, the "Acid reagent for gold 750" is effective, which works to determine the qualitative and approximate content of silver in alloys. It was determined that the reagent "Ferrous-cyanide potassium" is very sensitive to changes in the alloy composition of silver alloys and makes it possible to establish the silver content with an accuracy of 5 %. The presence in silver alloys of such impurities as zinc, cadmium, nickel, gold, palladium and others increases the error in determining the fineness of silver and forms a different color and shade. It has been proven that testing of silver alloys on an assay stone with silver nitrate is effective only for the СрМ system. The presence of zinc in 925 sterling silver alloys visually increases the color intensity of the sediment, which indicates a higher overestimated fineness. It has been found that the identification of the content of precious alloys based on platinum for the presence of ligature components is carried out with a potassium iodide reagent at t=120 °C by the color and shade of the sediment. The procedure for using potassium iodide during testing of precious platinum-based alloys has been optimized

X-ray fluorescence equipment and method, nutrient content analysis in solid NPK compound fertilizer

The paper presented two X-ray fluorescence analysis methods applicable to element content analysis in mixed fertilizers. The applied addition method determined the content of each ingredient in the fertilizer. The fundamental parameter method was applied for quick analysis, and at the same time, the content of ingredients on the fertilizer production line. X-ray fluorescence analysis methods and equipment have been researched and developed by the Institute of Materials Science - Vietnam Academy of Science and Technology and put into the gold and silver field for more than 30 years. The machines fabricated after 2014 applied TCVN 7055:2014, the 2nd edition "gold and gold alloys – Determination of gold content by X-ray fluorescence method". The national gold standard sample set, managed by the Vietnam Metrology Institute, was used to calibrate the machine, which has standard association with NIST (USA) and Krastsvetmet (Russia). Up to now, there are nearly 100 machines operating in more than twenty provinces and cities across the country, used to check the content of alloying components in gold jewelry processing, production and trading. The aim of new research and development in the field of fertilizers, in the coming time, is to transfer equipment and analysis methods to fertilizer production and trading enterprises.

Применение модифицированных гидролизных лигнинов в качестве компонентов буровых растворов на водной основе

The results of an experimental study of the effect of additives of the original and chemical by modified hydrolysis lignin on the rheological characteristics of water-based clay polymer drilling fluids are presented. The content of lignin in solutions varied from 0 to 5 wt. %. It was established by the method of X-ray fluorescence analysis, that the concentrations of toxic elements in the studied components of drilling fluids are at the level of background values and the highest static exchange capacity is observed for lignin samples converted into the sodium form during the modification process. It is shown that the introduction of modified hydrolysis lignin additives into clay based drilling fluids has a significant diluting effect. Therefore, the use of modified hydrolysis lignins as components of drilling fluids is a promising way of utilizing large-tonnage waste from biochemical plants.

ELIMINATION OF ANTIBIOTICS BY PHOTOCATALYTIC METHODS

Antibiotics have been found in water bodies of different origin around the world, including natural waters. The presence of antibiotics in natural waters is already an important environmental problem, as they pose a potential threat to the environment. Analysis of the literature shows that photocatalytic methods are considered to be more promising than biological methods and adsorption processes for the treatment of water bodies contaminated with antibiotics and other pharmaceuticals. The aim of this study was to determine the efficiency of antibiotics removal (ciprofloxacin, sulfamethoxazole and trimethoprim) by photocatalytic methods over TiO2 photocatalyst modified with yttrium oxide. For this purpose, a commercial sample of TiO2 P25 (Evonik) was modified, which was further characterized by X-ray diffraction and X-ray fluorescence analysis methods. The obtained data indicate the presence of yttrium in commercial P25 sample after modification. Studies on the removal of antibiotics from aqueous solutions by photocatalytic methods were carried out in three ways: employing modified photocatalyst; combination of photocatalyst and hydrogen peroxide, and the combination of photocatalyst with hydrogen peroxide and ozone. The results of research demonstrate high efficiency of photocatalytic methods in the oxidation of antibiotics in aqueous solutions, among which the greatest oxidation is achieved using the combination of heterogeneous photocatalyst, hydrogen peroxide and ozone.

Study of the composition and properties of the copper ore processing tailings of PJSC Gaysky Mining and Processing Plant

The article provides the results of studies to establish the environmental impact of the copper ore processing tailings storage facilities of PJSC Gaysky Mining and Processing Plant on the natural waters, as well as to estimate the value of the tailings if used as a technogenic raw material. The work was carried out using the results of the grainsize analysis and qualitative and quantitative assays of the copper ore processing tailings from the TSF of the concentrator, as well as the results of surface and ground water sampling in the area of the TSF. The grain-size analysis was carried out by the sieve method and used to classify the processing tailings into four size classes. The X-ray fluorescence analysis method was used to establish the composition of the tailings; the predominance of oxides of silicon, iron, sulfur, and aluminum was observed. Using an inductively coupled plasma emission spectrometer and an atomic absorption spectrometer, the total contents of heavy metals and toxic elements were measured, as well as the gold and silver grades. The results obtained indicate that operation of the copper ore processing tailings storage facilities is associated with the washout of both valuable and hazardous chemical components with the infiltration waters into the groundwater. All chemical studies and assays were carried out at the Scientific and Educational Center for Shared Use of the St. Petersburg Mining University and the laboratory of the Process Research Department of JSC Mekhanobr Engineering.

ИССЛЕДОВАНИЕ ДЕГИДРАТАЦИИ КОЛЕМАНИТА В НЕИЗОТЕРМИЧЕСКИХ УСЛОВИЯХ

The regularities of colemanite dehydration under non-isothermal conditions are investigated. It is established that colemanite, supplied to the Russian Federation from Turkey, has calcite in its composition. The chemical composition of colemanite is determined using the X-ray fluorescence analysis method. It is shown that the processes of dehydration of colemanite under non-isothermal conditions at a heating rate of 10 °С / min are accompanied by two endothermic effects at 660,7 K and 675,7 K with a total mass loss of 17,3 %. The rate of mass loss of colemanite from the temperature at heating up to 773 K, at which colemanite dehydrates and passes into the amorphous phase, is also studied. The regularities of changes in the rate of dehydration of colemanite are established. It is shown that the maximum values of the dehydration rate of colemanite are observed in the temperature range of 653–678 K. The activation energy of colemanite dehydration is determined to be 86,000 J/mol. Based on the experimentally obtained data, the rate constant of the colemanite dehydration process is calculated. The process of dehydration of colemanite is adequately described by the formal equation of kinetics. Most of the kinetic curve is adequately described by the resulting kinetic equation. It is proposed to describe the mechanism of dehydration of colemanite by a two-stage process, accompanied at the first stage by the removal of crystallization water, and at the second stage-by the removal of hydroxyl groups