Sulfur-containing Minerals Research Articles

Hydrochemical Characteristics and Evolution under the Influence of Multiple Anthropogenic Activities in Karst Aquifers, Northern China

The intensification of anthropogenic activities (agriculture, industry, and exploitation of water resources) during urbanization has posed significant challenges to the aquatic environment, particularly in karst regions. Karst aquifers are highly susceptible to surface contaminants and exhibit minimal natural remediation capabilities. Our understanding of the anthropogenic activities involved in these sensitive karst systems remains limited. To address this gap, we conducted a comprehensive study, collecting 285 groundwater samples in Feicheng, northern China, from 1996 to 2015. The overexploitation of karst groundwater has resulted in several concerns. The whole dataset was classified into four groups according to land use. Water quality assessments revealed a yearly decline, particularly in industrial and agricultural areas. The water chemistry transitioned from Ca-Mg-HCO3 to Ca-Mg-HCO3-SO4. Such evolution was attributed to natural hydrogeochemical processes, atmospheric precipitation, and anthropogenic inputs. Natural factors included water-rock interactions (the mineral dissolution) and ion exchange. Absolute principal component scores with multiple linear regression (APCS-MLR) were used to quantitatively estimate the sources of pollution. The results showed that hydrogeological settings (recharge, runoff, and discharge) were crucial in the hydrochemistry evolution of karst groundwater systems. In agricultural areas, it is recognized that much of the NO3− accumulation in aquifers came from upstream inputs in the groundwater system, not just irrigation and fertilization. Urban areas were affected by Cl− pollution, primarily due to domestic waste. Industrial regions of recharge zones were more susceptible to atmospheric precipitation and industrial waste, with pollutants infiltrating through rainfall and degrading water quality. Mining areas exhibit higher SO42− and lower pH due to the oxidation of sulfur-containing minerals. Therefore, the rapid response and low self-purification capacity of groundwater in karst regions necessitate caution in urban planning to mitigate impacts on these fragile systems.

The coupling of sulfide and Fe-Mn mineral promotes the migration of lead and zinc in the redox cycle of high pH floodplain soils

In this study, we investigated the impact of fluctuating water levels on the distribution of lead (Pb) and zinc (Zn) in soil and sediments at a historical Pb-Zn smelting site along the Xiangjiang River. Despite the high pH levels (7 to 11) in the study area, which generally inhibits heavy metal solubility, we found that regular changes in water levels still affect Pb-Zn movement. Soil analysis revealed distinct redox zones within the unconfined aquifer, as shown by the variable Fe/Mn and Ce/Ce* ratios. Advanced techniques such as Mn K-edge XAFS, Mössbauer spectroscopy, and TOF-SIMS indicated persistent Fe-Mn redox cycling and highlighted the presence of Pb and Zn-rich manganese oxides near sulfur-bearing minerals. These findings suggest that acidic microzones produced by the oxidation of sulfur-bearing minerals become "refuges" for microbial and heavy metal activity. Considering that sulfur-containing minerals are widespread waste types in nonferrous metal smelting sites, these findings are instructive for a better understanding of the transformation mechanisms of heavy metal ions in nonferrous metal smelting-polluted environments and for guiding pollution remediation strategies.

Assessment of rapid initiators and long-lasting nutrients for developing biological permeable reactive barriers to treat mine-contaminated groundwater

ABSTRACT The formation of mine-contaminated groundwater as a result of acidic mine drainage from the oxidation of sulfur-containing minerals entering the groundwater. Biological permeable reactive barrier (Bio-PRB) technology is excellent for the remediation of mine-contaminated groundwater. Usually, the organic substrates utilized in Bio-PRB are a combination of rapid initiators, which are readily bioavailable, and long-lasting nutrients, which are more difficult to degrade. Herein, we investigated the effectiveness of three rapid initiators and three long-lasting nutrients to remove sulfate from simulated mine-contaminated groundwater via simulated column experiments. The rapid initiators comprised crude glycerol, sodium acetate, and industrial syrup (IS), and the long-lasting nutrients included biodiesel emulsified oil, soybean oil emulsified oil, and high-carbon alcohol emulsified oil (HO). Microorganisms were stimulated using IS to create a sulfate reduction system owing to its high total organic carbon content (24.30 g L−1), achieving optimal sulfate removal rate (1.69 mmol dm−3 d−1). The fastest (2.93 mmol dm−3 d−1) and highest (88%) sulfate removal rates were achieved using HO, which is probably associated with the ability of HO to provide the most suitable C/N ratio (111.75) and induce the growth of sulfate-reducing bacteria (SRB) for substrate degradation. Conversely, a high concentration of sulfate reduction products inhibited SRB growth in the HO column. The addition of organic materials promoted SRB growth and various organic substrate–degrading bacteria. Furthermore, the competitive growth of methanogens (86.6%) may be responsible for the decrease in the relative abundance of SRB during the later stages of the experiment in the HO column.

High heterogeneity and aging state of mineral particles in a slowly-moving dust plume on the southwestern coast of Japan

Aerosol particles in two size ranges, namely 0.18–1.4 μm (fine) and larger than 1.4 μm (coarse), were collected in the pre-dust, in-dust, and post-dust air during the passage of a slowly-moving dust event at a coastal site in southwestern Japan. We identified the composition and size of individual particles using a scanning electron microscope to investigate the variations during dust passage. The particles could be classified as mineral-seasalt mixtures, non-mixture minerals, sulfur-containing minerals, and seasalt particles, and the number fractions of these type particles in the two size ranges exhibited significant variation across the three periods. In the coarse size range, mixture particles accounted for 17.6 %, 26.8 %, and 37.8 % of the particles in the pre-dust, in-dust, and post-dust air, respectively. Non-mixture particles made up 36.8 %, 29.2 %, and 24.3 % in the same respective periods. In the in-dust air, the average relative ratio of sulfur content in sulfur-containing mineral particles in the coarse range was 5.5 %, whereas in the fine range, it was 17.2 %. The aging state of sea salt components, described by the Cl loss and reflecting the changes in particles due to chemical reactions, exhibited significant differences in the two size ranges. In the fine range, the aging of >90 % particles was predominantly influenced by sulfate formation in the in-dust air. In contrast, nitrate likely played a certain role in both the pre-dust and post-dust air. In the coarse range, the aging was independent of sulfate formation. These results indicate the close dependence of the aging of dust particles on their size and the notable variations of the aged states, underscoring the essentiality to treat dust particles properly according to time and space for a better understanding on their roles in the marine atmosphere.

Modern technologies for cultivation of winter wheat on leached chernozems of the Republic North Ossetia-Alania

The purpose of the research was to study and use modern agrobiological principles of adaptive intensification of the technology for cultivating promising introduced varieties of winter wheat, their responsiveness to growth stimulants and winter hardiness of plants, as well as to identify inhibitory functionality in the destruction of weeds, reducing the incidence and number of pests on leached chernozems of the Republic North Ossetia–Alania. The processes of pre-vegetation were studied and it was found that the energy of seeds germination had a positive correlation with air temperature within the range of r=0,68–0,84. A slightly lower correlation coeffi cient (r=0,61–0,68) was noted when taking into account laboratory seeds germination. The maximum weight of 1000 seeds was observed in the varieties Aivina, Vassa and Kameya – 44,8–51,9 g, which was 1,2–8,3 g higher than in the control. High resistance to low temperatures was determined with normal autumn development of plants with sugar content in within 30 % or more. A recommended method for pre-sowing treatment of winter wheat seeds consists of soaking in a 0,1 % aqueous solution of sodium selenate (Na2SeO4) for 0,5–1 hour, enveloping with soil from the rhizosphere of Galega eorientalis Lam., thereby increasing the productivity and fertility of soils without additional costs for nitrogen fertilizers. The infl uence of seeding rates and predecessors such as clover and peas on the yield of Batko variety on leached chernozems of the foothill zone of the Republic of North Ossetia-Alania was revealed. The optimal germination rate was 89,5 %, when sowing after peas with a seeding rate of 4,5 million pcs/ha, the yield reached 3,7 and 3,8 c/ha after clover and peas, respectively, with a profitability level of 77,7 % for due to the lack of additional technological methods. It was revealed that the biological product Nikfan in mixed with sulfur-containing mineral water as a top dressing for crops during the spring regrowth period after various predecessors contributed to an increase in yield and quality indicators of grain, a profitability level of 51,9 % and a reduction in prime-cost to 5,77 rub./kg.

The mineral composition of sediments and the reasons for their formation in the heating and hot water supply systems of the towns of Apatity and Kirovsk (the Murmansk Region)

The development of the housing and communal complex is focused on ensuring guaranteed access of the Russian population to high-quality drinking water. Due to the deterioration of drinking water quality, the mineral composition of sediments in the heating and hot water supply systems of the towns of Apatity and Kirovsk (the Murmansk region) has been studied. It has been established that sediments in the heating system mainly consist of iron oxides and oxyhydroxides: magnetite, goethite and lepidocrocite. All these mineral phases are products of active oxidation (corrosion) of steel pipes and heating system equipment. No mineral phases of ferrous forms of iron have been found in the sediment, which indicates sharply oxidizing environment in the heating system. The presence of sulfur-containing mineral phases, namely, anhydrous calcium sulfate - anhydrite and elemental sulfur, has been recorded in the heating system of the Apatity combined heat and power plant. Indirectly, the presence of such sulfur-containing phases may indicate the possible presence of microflora (bacteria) in the heat-transfer agent, in the metabolic processes of which sulfur and sulfur-containing compounds are involved.

INFLUENCE OF SULFUR-CONTAINING FERTILIZERS ON PRODUCTIVITY AND FATTY ACID COMPOSITION OF OIL IN WINTER AND SPRING RAPESEED WHEN CULTIVATED ON SOD-PODZOLIC LOAMY SAND SOIL

The paper contained the results of the data on the impact of various forms of sulfur-containing mineral fertilizers on productivity of winter and spring rapeseed and fatty acid composition of oil. It has been etstablished that sulfur-containing fertilizers application resulted in the increase of oil yield and improvement of production quality (fatty acid composition).

Identification of Heavy Metal Compounds in Technogenically Transformed Soils Using Sequential Fractionation, XAFS Spectroscopy, and XRD Powder Diffraction

The transformation of technogenic Cu and Zn compounds in technogenically transformed soils (Spolic Technosols) with high and very high concentrations of metals formed at the site of a natural tailings pond in the floodplain of the Seversky Donets River, the main tributary of the Don River (Rostov oblast, Russia) has been studied. The Technosols are compared to an unpolluted meadow-chernozemic soil (Fluvisol) outside the impact zone. The state of Cu and Zn is assessed using three sequential extraction schemes—Miller’s, Tessier’s, and BCR, as well as synchrotron X-ray powder diffraction (XRD) and analysis of synchrotron X-ray absorption spectrometry (XAFS) spectra. It is shown that the distribution of metals in soil is largely related to their properties, such as electronegativity, hydrolyzability, and softness parameter. As is observed, Cu mainly concentrates in the residual fraction (to 42%) and in the fraction associated with organic matter (up to 27%). The mobility of Zn in the studied soils is higher than that of Cu. Its main part (up to 56%) is in the residual fraction and the fraction associated with Fe and Mn oxides (up to 48%), especially with Fe(III) crystalline compounds. The combination of a three-stage BCR scheme with XAFS and XRD techniques is used for the first time. Most of the peaks in diffraction patterns of soil samples after the first and second extraction stages correspond to the authigenic sulfur-containing minerals, namely, wurtzite (ZnS with a hexagonal structure), sphalerite (cubic ZnS), covellite (CuS), and bornite (Cu5FeS4). Wurtzite is present in the exchangeable and reducible fractions. These fractions also contain chalcocite (Cu2S). Sulfides are most abundant in soil sample after extraction of the oxidizable fraction, while phyllosilicates are prevalent in the sample after extraction of the reducible fraction. X-ray absorption spectroscopy demonstrates molecular structural changes in the Zn and Cu compounds in heavily polluted soils, suggesting the transformation of metals under different environmental conditions, which is important for assessment of the soil protective function.

Obtaining elemental sulfur for Martian sulfur concrete

A potential candidate material for the construction of Mars habitats is concrete made from the Martian regolith and sulfur extracted from the regolith itself. Sulfur concrete, which has excellent mechanical properties, can be prepared at a low temperature (<150 °) and without water (unlike Portland-cement concrete). The surface of Mars has a much higher concentration of sulfur than those of the Earth, the Moon, or the asteroids. Sulfur on Mars, however, exists not as elemental sulfur—which is needed in concrete production—but as sulfates (usually hydrated) and sulfides. This paper surveys thermochemical and electrochemical methods that might be used to produce elemental sulfur from its compounds contained in the minerals on Mars. Possible methods include chemical or electrochemical oxidation or decomposition of sulfides, which include sulfides that exist naturally on Mars as well as sulfides that are produced via chemical or electrochemical reduction of sulfates. Some of the methods to obtain elemental sulfur—such as chemical or electrochemical oxidation or decomposition of metal sulfides or hydrogen sulfide—have already been demonstrated. The methods of producing elemental sulfur from sulfur-containing minerals on Mars will have the added benefit of generating byproducts (e.g. water, hydrogen, oxygen, and metals) that are useful for explorations of the Red Planet. In the future, chemical processes for the production of elemental sulfur may also have important industrial applications on Earth.

Digestion behaviors of sulfur-containing minerals and desulfuration during alumina production process

The pyrite and sulfate digestion behaviors and sulfur removal of high sulfur bauxite during Bayer process were studied in this paper. The thermodynamic analysis shows that pyrite reacts with alkali solution to generate different valence sulfur (S2-, S2O32-, SO32-, SO42-), Fe2O3, and Fe3O4; the standard Gibbs free energy of these reactions is negative and decreases with the increasing of temperature in range from 473 K to 573 K; the generation order of different valence sulfur is easily determined: S2-﹥SO42-﹥SO32-﹥S2O32-; the gypsum reacts with sodium aluminate solution to generate SO42- and Ca(OH)2. The digestion experiment researches indicates that pyrite and sulfate enter solution mainly in the form of S2- and SO42- respectively, the Fe2O3 and Fe3O4 are also found in red mud, experiment results are consistent with our thermodynamic calculation results. Based on the digestion behaviors of pyrite and sulfate, we propose appropriate methods of S2- and SO42- removal. The S2- which is the main form of sulfur in digestion liquor A was removed completely by adding ZnO in digestion process, and the SO42- which is the main form of sulfur in digestion liquor B was removed completely by adding BaO·Al2O3. The results may throw a new light upon the sulfur removal of high-sulfur bauxite in alumina production.

In-situ detection of sulfur in the atmosphere via laser-induced breakdown spectroscopy and single particle aerosol mass spectrometry technology

The combustion of sulfur-containing minerals is one of the primary causes of various atmospheric and water pollution issues, including sulfuric acid rain. Considering that sulfur is particularly susceptible to oxidation in the air, the direct detection of sulfur via laser-induced breakdown spectroscopy (LIBS) has presented a major challenge. In this work, CS2 was used as a sample evaporated and atomized into the air. A new experimental device that combines the LIBS system with the single particle aerosol mass spectrometry (SPAMS) system was adopted for the direct detection of sulfur in the atmosphere. Under the optimal experimental conditions, the characteristic spectral lines of sulfur were observed and recorded in the LIBS spectra. Additionally, in the LIBS spectrum, CN molecular bands were observed, and the vibration and rotation temperature of the CN molecules in the experiment were obtained through software simulation. While the SPAMS system generates the real-time composition of a single CS2 aerosol particle, the isotope information of sulfur can also be distinguished simultaneously. Sulfur isotopes are widely used as tracers in chemistry, agricultural science, and environmental science research. Finally, the LIBS and SPAMS experiment systems can perform the direct in-situ detection of sulfur in the air and provide its isotope information.

Физиолого-биохимическая оценка эффективности нового пищевого ингредиента: источника фитоэкдистероидов и флавоноидов из зерна киноа

Abstract- One of the promising food sources of biologically active substances is quinoa grain, which is valued for its high content of protein, sulfur-containing amino acids, lysine, fiber, and minerals. In addition, quinoa grain can be a valuable food source of polyphenolic compounds and phytoecdysteroids. The method for production of a concentrate of flavonoids and 20-hydroxyecdysone from quinoa grains sorbed on coagulated egg protein has been developed. The in vivo evaluation of efficacy of the developed food ingredient was conducted using male Wistar rats under immobilization stress and after exhausting physical exertion. The consumption of the food ingredient prevented an increase in the level of the main stress markers, catecholamines, in animals subjected to immobilization stress. The opposite effect was observed in animals that received the food ingredient after exhausting physical exertion: their levels of catecholamines were significantly higher than in the rest comparison groups. Using the Elevated Plus Maze and Open Field tests, it was shown that the consumption of the developed concentrate neutralized the negative effect of immobilization stress and treadmill exercise on anxiety in Wistar rats. The results obtained require additional study under conditions of preventive introduction of the food ingredient into the diet of intact animals, as well as a toxicological safety assessment. Key words: quinoa, 20-hydroxyecdysone, flavonoids, stress, immobilization, exhaustive physical exercise, catecholamines, corticosterone This work was supported by the Russian Scientific Foundation, grant no. 19-16-00107.

ГИДРОТЕРМАЛЬНЫЙ НАНОКРЕМНЕЗЕМ КАК СТИМУЛЯТОР РОСТА И РАЗВИТИЯ РАСТЕНИЙ ОДНОЛЕТНИХ ВИДОВКЛЕВЕРА И АМАРАНТА

The article considers the results of application of scientific-research practical technique on new pre-treatment of seeds of plants of annual types of clover and amaranth of fodder with growth stimulator hydrothermal nanosilicon (GNA) in combination with sulfur-containing mineral water. Earlier, numerous tests showed the effectiveness of the use of GNA to increase the yield and growth rate of agricultural plants: amaranth, zucchini, onions, spring wheat, sugar beets, etc. Silica nanoparticles increase the growth rate of microorganisms, including pathogenic ones, which allows reducing the time for diagnosing antibiotic resistance of pathogen microbes. Hydrothermal nanosilicon has high biochemical activity, high penetration rate into plant seeds, high sorption capacity due to silica particle size and their surface area up to 500 cm2/g. There are no toxic substances in the prepared working solution of the plant growth stimulator, which makes the proposed pre-treatment more environmentally friendly and bioavailable for seeds, in particular, to endosperm and intensify the germination process. The essence of the studied procedure was that the seeds of clover and amaranth were soaked in a 0,005% solution of hydrothermal nanosilicon dissolved with sulfur-containing mineral water during exposure for 30-40 minutes before sowing, as a result of which the efficiency of the stimulator was increased, the possibilities of hydrothermal nanosilicon were expanded, which made it possible to reduce the costs of pre-treatment of seeds. The obtained data make it possible to conclude that nanosilicon of hydrothermal origin in combination with hydrogen sulfide mineral water is a stimulator of plant development at the germination stage and can be used to reduce labour intensity and costs for pre-treatment of seeds, increase efficiency and expand the field of application in the technology of production of biomass of clover and amaranth in field-agro-production of North Ossetia.

The usefulness of sulfur fertilizers for balanced nutrition of spring wheat on zonal soils of the south-western Forest steppe zone

The importance of sulfur for a balanced nutrition of grain crops is demonstrated. The content of mobile forms of sulfur in the main zonal soils of the Kursk region – black soil and gray forest soils is given. Gray wooded soils have a low content of mobile sulfur in most areas of the region. The availability of sulfur in black soil ranges from low to medium. Practical studies on the effectiveness of different types and forms of using sulfur-containing mineral fertilizers in the cultivation of spring wheat on zonal types of soils in the south-western forest steppe of the Central Black Earth Region have been performed. Research has found that the practicability of using sulfur-containing mineral fertilizers and their agronomic effectiveness is directly associated with the content of available forms of sulfur in the arable layer of the soil. It is most effective and reasonable to use sulfur-containing mineral fertilizers in the cultivation of spring wheat on gray wooded soils. The practical data obtained prove the urgency of the use of sulfur-containing fertilizers in technologies for the cultivation of grain crops on soils with inadequate content of available forms of sulfur.

Study on the factors affecting the deep reduction of coal gangue containing high contents of iron and sulfur

Although coal gangue (CG) contains various valuable metal elements, it has not been utilized efficiently. It is of great significance for the sustainable development of the coal industry to improve the added value of comprehensive CG utilization by adopting a deep reduction method. In this study, the effects of a reducing agent and desulfurizer on the properties of the CG reduction products were studied via deep reduction experiments. The results show that CG exhibits a self-reduction effect, which can reduce the amount of external reductant. In addition to the lignite coal (LC) reducing agent, the iron grade reaches its maximum when the other reducing agents are added at a ratio of 10%. Due to the high content of iron minerals in CG, the H2 produced by the individual pyrolysis of CG undergoes a reduction reaction with iron minerals. The addition of CaCO3 improves the reduction condition of iron minerals and promoted their direct reduction. However, an excessive amount of CaCO3 leads to the failure of iron particles to aggregate into large particles or iron-linked crystals, which reduces the recovery of iron. Prolonging the reduction time promotes the migration and diffusion of the iron phase, which is conducive to the aggregation and growth of iron particles. The finer the particle size of the raw material, the worse the permeability of the material layer which results in the incomplete reaction of the sulfur-containing minerals contained in the particles and lead to a higher the S content in the direct-reduction iron obtained after magnetic separation.

The chromophore fading and spectroscopy analysis of lazurite in annealing treatment.

Sulfur-containing minerals play a key role in the sulfur cycle of the Earth's crust. However, there are few experimental studies and extrapolations on the stable existence and its conditions of polysulfides in the Earth's crust. Addressed this question, a mineral with sodalite group containing S3-, lazurite, was selected to be the research subject. Lazurite is a tectosilicate mineral with an incommensurately 3D modulated (ITM) structure. In this paper, lazurite powder and bulk samples were subjected to short-time (8h), high-temperature (800℃) annealing experiments, and subsquently conducted the tests of FTIR, RAMAN, X-ray diffraction (XRD), and TG-differential scanning calorimetry (DSC). The identity of both the initial and annealed lazurite demonstrated that the silicate framework has a structural memory at certain temperatures. Also, the results indicated that the thermal behavior of lazurite with framework expansion, cell distortion, and reversion is about 550-650 ℃, 650-750 ℃, and below 450 ℃, respectively. With the increase in temperature, the framework expanded, and the cage clusters were reversibly distorted. Meanwhile, the chromophore S3- could be oxidized, and it faded following the framework shrinkage during the cooling process. Moreover, the reversible forced equilibrium of the ITM formation had a limit temperature indicating that the annealing treatment and spectroscopy analysis of lazurite blocks and samples might be used as a reference for temperature limitation markers in geological processes.

Environmental impacts of reclaimed asphalt pavement on leaching of metals into groundwater

To investigate the environmental impacts of reclaimed asphalt pavement (RAP) while it was freshly processed (i.e. hot mixed asphalt or HMA) and after being subjected to weathering, three RAP materials, namely north-RAP, central-RAP, south-RAP, from three plants and one fresh HMA loose mix sample (Fresh-HMA) throughout New Jersey, USA underwent four different weathering processes including: Ultraviolet (UV) and precipitation weathering on unbounded RAP, UV and precipitation weathering on compacted RAP, weathering by heat and moisture cycles, and groundwater flow-through leaching. Batch experiments were conducted to mimic releasing of trace elements in weak acidic leachate from landfills. North-RAP and central-RAP released levels of Pb greater than the United States Environmental Protection Agency (USEPA) primary drinking water maximum contaminant level (MCL) of 15 µg/L. Novel two-column experiments (a RAP column followed by a soil column) were conducted to investigate the release of trace elements from RAP and the attenuation effect of soil on potential pollutants. The results of these experiments showed that pollutants released from RAPs such as Mn and Ni were largely attenuated in the soil. The results suggest that RAP can be used as an unbound material in environments except those acidic (i.e., pH < 5 as in mines with sulfur-containing minerals and landfills with acidic environment).

Sulfur fixation characteristics of single coal briquette particle during the process of combustion in different atmospheres

Fixing sulfur in ash is an important way to reduce SO2 emission from coal combustion. The main purpose of the research is to investigate the transformations of sulfur-bearing minerals and the reaction processes of sulfur fixation in different atmospheres and temperature ranges so as to provide new data for research in sulfur fixation mechanism. As a part of this research, the radial distribution of sulfur fixation products in the combustion process of single coal briquette was studied. It is found that CaSO4 and CaS as sulfur fixation products were formed. CaSO4 distributed in outer layer of coal briquette ash ball, and CaS was in inner layer of ash ball. The results indicated that combustion atmosphere can considerably affect the formation of sulfur fixation products. Furthermore, the main sulfur-containing mineral pyrite (FeS2) in coal and CaO were selected to explain the mechanism of sulfur fixation in different atmospheres. The transformations and thermal behaviors of FeS2 and mixture of FeS2 and CaO in oxygen-containing atmosphere and inert atmosphere were studied by means of X-ray diffraction and thermogravimetric analysis. In oxygen-containing atmosphere, FeS2 was decomposed to F1-xS and S2(g) above 390.34 °C, F1-xS was further oxidized to Fe2O3 and SO2, and then SO2 reacted with CaO and O2 to form CaSO4. In oxygen-free atmosphere, FeS2 was decomposed to Fe1-xS and S2(g) above 408.75 °C, CaO reacted with Fe1-xS to form CaS above 847.48 °C. It can be concluded that atmosphere condition affected the sulfur fixation processes, the evolution of sulfur was FeS2→Fe1-xS→SO2→CaSO4 in oxygen atmosphere, FeS2→Fe1-xS→CaS in argon atmosphere in the processes of sulfur fixation.

The effect of the Megamix preparation and complex mineral fertilizers on germination and photosynthetic productivity of spring wheat

The method of presowing and foliar treatment of spring wheat crops with various growthregulating preparations should be referred to a number of promising techniques that provide increased productivity and quality of crop production. The conducted studies have shown that the highest values of germination energy and laboratory germination during presowing treatment of seeds with experimental preparations were found in the option Megamix-zinc. The use of various modifications of the Megamix preparation for presowing seed inoculation contributes to an increase in the field germination of the experimental crop according to all options, depending on the year of the study. On average, over the years of the research, the used modifications of the Megamix preparation and their combination with mineral fertilizers contribute to an increase in productivity by 0.51–3.23 kg/ha, the best result over control is ensured by the use of the Megamix-zinc modification compared to complex sulfur-containing mineral fertilizers, which is 11.83 %. Thus, the use of experimental preparations and their combinations with complex mineral fertilizers has a positive effect on production processes which ultimately contributes to an increase in the productivity of spring wheat.

ОЦЕНКА ВЗАИМОСВЯЗИ САМОВОЗГОРАНИЯ ПОРОД С ДЕФОРМАЦИОННЫМИ ПРОЦЕССАМИ ПРИ КОМБИНИРОВАННОЙ РАЗРАБОТКЕ МЕСТОРОЖДЕНИЙ КОЛЧЕДАННЫХ РУД

For decades and centuries, spontaneous combustion of minerals occurs, which leads to significant material, economic and environmental damage. Under anthropogenic impact on the subsoil, conditions are created for the active development and opening of cracks as a result of deformation of the rock mass, under the influence of its open and underground parttime work. as a result, the emergence of conditions for the active penetration of atmospheric oxygen from the mine ventilation system and the surface atmosphere along the cracks formed as a result of deformation to sulfur-containing minerals of ores and rocks, prone to oxidation and spontaneous combustion. The mechanism of spontaneous combustion of pyritic rocks in the rock mass during the development of deposits is analyzed. It is proved that in the combined development of pyrite ore deposits, exogenous physicochemical processes must be considered in conjunction with geomechanical processes due to the development of mining operations beyond the open pit contour, aerogasdynamic determined by the method, scheme and ventilation system of an underground mine, as well as thermo-physical processes occurring as a result of exothermic oxidation of sulfides...