Granulometric Composition Research Articles

Influence of fines less than 0.125 mm on abrasion resistance of concrete

Abrasion resistance is very important in concrete intended for making roads, canals, floors or pavements and it can be defined as the ability of a surface to resist wear due to rubbing. It is tested by grinding the specimen according to the standard procedure and the measurements are done through volumetric loss of the specimen. Abrasion resistance is influenced by many factors such as the type of aggregate, placement, concrete composition, etc. It is desirable that the concrete contains less cement matrix and that this cement matrix achieves as much strength as possible. Cement matrix achieves the highest strength if it consists of a binder without or with small amount of very fine aggregate particles. The purpose of this paper is to examine the influence of these particles on abrasion resistance and compressive strength of concrete. Six concrete mixes were made, which differ in the granulometric composition of the aggregates and the origin of the aggregates. Same type and quantity of the cement and superplasticizer were used in all mixtures with the same water/cement ratio. The workability of the concrete was tested using the slump method. The ultrasound pulse velocity (UPV), density, dynamic modulus of elasticity, compressive strength and abrasion resistance were tested after 28 days of specimens curing. The measured UPV are within the limits of 3989.36 to 4128.44 m/s, which indicates a good quality of concrete. Compressive strengths ranging from 61.6 to 95.6 MPa were achieved. Abrasion resistance was determined by the loss of volume of the specimen in cm3 in an area of 50 cm2, and values from 21.6 to 27.3 cm3/50 cm2 were measured. According to the test results, no harmful effect of very fine aggregate particles on the abrasion resistance of concrete was observed in this investigation. Also, the positive effect of quartz sand on abrasion resistance was confirmed.

Field test of compactability of soaked subsidence soil using heavy tamper

Dynamic compaction, including heavy compaction, is a widespread method throughout the world for improving the physical and mechanical characteristics of subsidence and low-density soils. The results of theoretical and experimental studies have established that the depth of compaction and the density of compacted soils depend on the weight, shape of the bottom, the height of the tamper and humidity, the type of structural connection, and the granulometric composition of the compacted soil. This article discusses the results of compaction with a heavy tamper when soaking loess-like subsidence soil, widespread in the city of Darkhan, Mongolia, to optimal moisture.

Enrichment of manufactured waste at the AMMC copper processing factory in Uzbekistan

This article is devoted to the additional extraction of valuable components from the waste tailings of the AMMC copper processing plant. The mineral composition of the waste tailings of the CCP is mainly represented by quartz, feldspars, sericites and, in a subordinate amount, mafic and secondary minerals. Pyrite is the most widespread ore mineral in the waste tailings of the CCP. Chalcopyrite, sphalerite, galena, molybdenite, and iron oxides are also noted. The copper content in the selected spot samples from tailings after chemical analysis averaged 0.139%. A sieve analysis was carried out to determine the granulometric composition of waste tailings, the distribution of valuable components by size classes. On the basis of the obtained results on the study of the material composition, flotation of tailings of the CCP AMMC was carried out with recleaning of the main flotation concentrate. During tailings flotation with one recleaning of the main flotation concentrate, the extraction of copper and molybdenum into the total concentrate is 56.8% and 63.8%, respectively.

Formation of saline soils in the dry steppe landscapes of the Western Manych Valley on different forms of microrelief

The results of studying the physical and chemical characteristics of dry-steppe saline soils of the Western Manych valley, confined to different forms of microrelief, are presented. The soil cover of the studied territory is characterized by pronounced complexity due to the interrelation of natural and anthropogenic factors. It was revealed that chestnut saline soils and chestnut saline soils are mainly formed on micro-slopes and micro-elevations, and typical hydromorphic salt marshes are formed in saucer-shaped depressions. The soil profile has both common features (the presence of a saline horizon, a heavy loamy granulometric composition, etc.) and differences (the depth of formation of a saline horizon, the degree and chemistry of salinity, the boundaries of boiling of carbonates, the occurrence of gypsum and iron oxide forms, etc.). All saline horizons have increased density values (1.43-1.64 g /cm3), reduced humus content (no more than 2.0%) compared to the upper horizons. Geobotanical studies have shown that specific vegetation, represented by xerophilous and halophilic species, is formed on micro-slopes and micro-elevations during the development of the saline process. Various meadow and halophyte communities are formed in micro-depressions.

Formation, morphology and mechanical composition of meadow-alluvial soils in the Jizzakh desert

This paper explores the origins, formation processes, properties, and characteristics of meadow-alluvial soils found in the Jizzakh desert, as well as their morphological structure. The article delves into the role of soil-forming factors, the conditions of their formation, and the significance of parent rocks and deposits in shaping the mechanical structure of the soil. The granulometric composition of meadow-alluvial soils, including the quantity of dust and clay particles and the total amount of microaggregates, is examined. The mechanical composition of arable and sub-arable soils is described, along with the lithological structure and structural composition of the salt profile.

Study and assessment of mineralogical, chemical and granulometric composition of volatile soil-sand aerosols from the dried-out part of the Aral Sea

Study and assessment of mineralogical, chemical and granulometric composition of volatile soil-sand aerosols from the dried-out part of the Aral Sea

Influence of biological fertilizers on the carrots cultivation and yield

Providing the country’s population with high-quality vegetables remains one of the priority areas for agricultural development. The task of agricultural science in solving this problem is to improve agrotechnological techniques and individual operations of soil cultivation, sowing and harvesting, as well as measures to protect against infections and pests. The purpose of this study was to determine the effectiveness of using biofertilizers when cultivating carrots on gray forest soils of medium loamy granulometric composition. Small-plot experiments to improve the technology for cultivating carrots of the Losinoostrovskaya variety were carried out on the basis of the experimental collection site of the Chuvash State Agrarian University during 2022–2023. To stimulate the processes of growth and accumulation of plant biomass, three-time root and leaf feeding of vegetative plants with biological preparations Microbionic and Gumat EM was used. In the course of monitoring the growth processes of carrots, the accumulation of tops and root crops biomass, the authors recorded positive changes in the reduction of the duration of phenophases and a positive trend in increasing carrot yields. The timing of the onset of bunching and trimming ripeness in carrots in plots using root and leaf fertilizing with biological products was shifted by 2–5 days, the total biomass of aboveground mass and root crops was increased to 36%, the yield and marketability of finished products was up to 43% compared with a control group.

Improvement of environmental sustainability of milk processing enterprises

Sewage from milk processing enterprises remains a factor of environmental pollution. This is caused by a high concentration of organic pollutants contained in a dispersed and dissolved state, among which protein predominates. An effective way to increase the environmental friendliness of dairy enterprises is to minimize emissions of pollutants. In particular, this applies to dairies, the main products of which are protein products - cheese and casein, and the main pollutant - whey. This could be achieved through complete processing of whey. The article considers the possibility of reducing the polluting effect of wastewater from milk processing enterprises by separating dispersed protein from milk whey. The results of the study of the content and granulometric composition of dispersed whey protein are presented. The design of the filter with a self-cleaning filter element developed by the authors is presented, which allows for a continuous process of serum purification with a consistently high degree of separation.

Corrigendum to: Investigation of the complex granulometric composition of suspended particles in seawater

Corrigendum to: Investigation of the complex granulometric composition of suspended particles in seawater

Минералого-геохимические особенности золотосодержащих руд месторождения Пакрут (Центральный Таджикистан) как основа гравитационного обогащения

The mining sector, in particular gold mining, plays an important role in the economy of Tajikistan. Today, the issue of optimizing gold mining mechanisms, increasing its efficiency and expanding the resource base is of topical importance. The depletion of easily accessible gold deposits is stimulating the development of methods for extracting gold from refractory and low-grade ores. One of the promising methods of pre-treatment of such ores is gravity enrichment. The aim of the study is to characterize the Pakrut gold deposit, to determine its mineralogical and chemical composition, and to develop an optimal gravity enrichment scheme for gold recovery. Research objectives are as follows: to study the mineralogical composition and geochemical characteristics of gold-bearing ores, and then to develop a technique for their gravitational enrichment. The object of the study is the gold-bearing ores of the Pakrut deposit (Central Tajikistan). Materials and methods of research: analytical work and enrichment in laboratory conditions were carried out in the chemical laboratory of the Pakrut Joint Venture, the ore enrichment laboratory of the V. I. Nikitin Institute of Chemistry of NANT, the Central Committee of the Main Geological Directorate under the Government of the Republic of Tajikistan. It is found that gold in the Pakrut ores is mainly represented by native gold and electrum. The main gold-bearing minerals are pyrite, arsenopyrite, sphalerite, galena, jamesonite and some vein minerals. The gold content in the ore is about 6 g/t. The granulometric composition of gold is extremely uneven. Most of the gold particles are less than 10 μm in size and are coated with gold-bearing minerals, which hindered their release during grinding. In accordance with the characteristics of the gold deposit, gravity enrichment method has been used to extract the liberated coarse gold. Studies have shown that the gravity separation process is used for the primary processing of ore to recover coarse gold particles. The gold content and recovery in the gravity separation concentrates are 46.58 g/t and 44.59 %, respectively.

Growing food potatoes from small fraction minitubers obtained under conditions of water-air culture

Currently, due to the shortage of their own seed material Russian producers of original seed potatoes are interested in using highly efficient cultural practices based on the use of aerohydroponic cultivation technologies. The results of studies conducted in the period of 2019-2021 in order to determine the effectiveness of growing food potatoes from mini-tubers obtained using aerohydroponic systems with a compound nutrient scheme are presented in the work. The field test was launched according to the available procedures on the territory of the Korenevo (Kraskovo) experimental station in the Moscow region on sod-podzolic medium-cultivated, granulometric composition sandy loam soil. Sprouted small fraction mini-tubers of 10-15 mm in size and 3-5 g in weight of the following varieties were planted: Gulliver (early ripening (ER)), Amethyst and Grand (medium early ripening (MER)), Sineglazka and Fritella (midseason variety (MSV)). The research years – 2019, 2020 and 2021 – were characterized, respectively, as humid, very humid and slightly arid. The average yield for all varieties was 16.4 t/ha, including commercial tubers in size – 96.5-98.6%, or 38-89% of the possible potential yield, depending on the variety. The starch content in tubers was within the range of potentially possible values, namely, in Grand (16.5-18.3%), in Sineglazka (16.0- 19.8%) and in Fritella (16.3-17.6%). The nitrate content in potato tubers of all varieties did not exceed MPC – 250 mg/kg. Tubers of all varieties turned out to be quite tasty – 5.5-8.0 points, Gulliver tubers (7.5 points) being found the most delicious, despite the low starch content. Potatoes were sold at a price of 17 rubles/ kg, the income from potato cultivation amounted to 17.2-79.9 thousand rubles/ ha, and profitability was 15.5- 24.5%. The economic feasibility of producing food potatoes grown in the field from mini-tubers of small fractions obtained using aerohydroponic devices with a compound nutrition system has been shown.

ВКЛАД НГМС РК В СЕЛЕВУЮ БЕЗОПАСНОСТЬ СТРАНЫ

In this paper, the scientific activities of the National Hydrometeorological Service of Kazakhstan to study the origin, development and degradation of debris flows, carried out with the aim of reducing the damage caused by debris flows, are presented over a long period. The features of precipitation, emptying of surface and intraglacial reservoirs, mineralogical and granulometric compositions of debris rocks, geomorphological conditions of debris flow formation, recurrence and characteristics of debris flows were studied. Methods for computation of the viscosity and plasticity of debris-flow mass, used in mathematical modeling of debris flow formation have been developed. A method for ultra-short-term forecasting of catastrophic debris flows caused by rainfall, based on data on preliminary soil moisture, the position of the zero isotherm and seasonal snow line, and current actual meteorological information has been developed. The feasibility of this method is tens of times greater than the feasibility of the method for short-term forecasting of debris flows caused by rainfall, which was used previously. The computation of the characteristics of debris flows is based on the discovery of an ambiguous dependence between the density of debris-flow mass and the slope of way of debris flow. A debris-flow hazard map for the territory of the Republic of Kazakhstan has been developed. A concept for protection against debris flows of Almaty city under climate changing has been proposed. A geological and geomorphological method has been developed for determining the genesis of fan, which allows optimizing the work on assessing the risk of urbanization of territories located in the mountain and foothill zones.

Investigation of physical, chemical, and technological properties of titanium powder obtained by thermal dehydrogenation in vacuum

In recent times, there has been significant interest in powder metallurgy, driven primarily by the active development of additive manufacturing. Consequently, a pressing task is the development of methods for producing initial metal powders that are cost-effective while meeting high consumer standards. This research is a continuation of studies on titanium powders obtained through SHS hydrogenation and thermal dehydrogenation. The titanium hydride powders, previously obtained using SHS technology, were sieved, resulting in fractions that matched the granulometric composition of titanium powders of PTK, PTS, PTM, and PTOM grades. Subsequently, the titanium hydride powder samples underwent dehydrogenation through vacuum annealing in an electric resistance furnace. Throughout the dehydrogenation process, the kinetics of hydrogen release from the titanium powder were examined as a function of particle size. The macro- and microstructure, chemical composition, and technological properties of the dehydrogenated powders were thoroughly analyzed. It was determined that the titanium powder maintained its original polygonal fragmented shape after dehydrogenation. The average particle size decreased by 5–20 %, and “satellites” were observed on larger particles. Chemical analysis revealed that larger samples contained a higher level of residual hydrogen and gas impurities (Σ 0.77 wt. %) compared to finer powders (Σ 0.26 wt. %). Regarding the study of technological properties, the resulting powders exhibited the necessary characteristics for use in titanium powder metallurgy, with the exception of low flowability due to the particle shape and microstructural heterogeneity). In conclusion, this research has demonstrated the potential of the SHS hydrogenation and thermal dehydrogenation method in producing high-quality titanium powders.

The investigation of the frost resistance of the aggregate-sand mixes

Problem. Recently there is a steady trend to the increase of the intensity of traffic and of the loads from the wheels of the rolling stock on the whole structure of the road pavement, therefore during the building of the road pavement layers the most important thing is a rational choice of the materials for the base layers and for the top layers which will provide the performance of the entire structure during the designed service life under the working conditions which are getting worse all the time. Nowadays the most widespread material for the road base layers is aggregate mix strengthened by cement. One of the ways of the base layers materials improving is the increase of their frost resistance. One of the ways to solve this problem can be the different additive and fibers usage as a reinforcing component of the aggregate mix. But until today the influence of the internal factors such as size of mineral grains, granulometric composition and binder content on the indexes of frost resistance is still not investigated.
 Goal. The aim of the research is the investigation of the maximum grain size and content and also mineral binder concentration influence on the indexes of frost resistance of the aggregate mixes strengthened by cement. Methodology. To achieve this goal in the laboratory of the Department of Highway Building and Maintenance named after O. Birulia the samples of sand, fine-grained, medium-grained and coarse-grained aggregate mixes with cement content from 2 to 10 % were prepared. Results. For the frost resistance indexes determination of the aggregate mixes of different compositions strengthened by cement according to the maximum grain size the cement concentration influence on the grade strength indexes was found. The research results have shown that: with the increase of cement content the compressive strength indexes in the fine, medium and coarse-grained mixes are increasing; the increase of the maximum grain size of the same cement concentration shows that compressive strength and tensile strength indexes are increasing. The repeated freezing and thawing is one of the main aggressive factors of the external environment influence which reduces strength and durability of the materials, therefore the influence of this factor on the compressive strength and tensile strength was evaluated. In Ukraine according to the current standard the frost resistance of the aggregate mixes is evaluated only in terms of compressive strength index of samples which were subjected to certain number of freeze-thaw cycles. It is determined that the aggregate mixes with the same cement content with larger mineral grains in its composition have higher indexes of the frost resistance coefficient. Also it was found that the influence of the freeze-thaw cycles is more informatively shown at the samples testing according to the split tensile test. Conclusions: 1. The increase of the binder content in the composition of strengthened aggregate mixes leads to the decrease of the freeze-thaw cycles influence on the compressive strength and splitting strength for all studied compositions of aggregate mixes. 2. The aggregate mixes strengthened by the same cement amount with the larger size of mineral grains in its composition have higher values of frost resistance coefficients in comparison with strengthened aggregate mixes with smaller maximum size of mineral grains in its composition. 3. The influence of the freeze-thaw cycles is showed more informatively by the split tensile scheme.

Sorption of humus and its distribution in the profile of chernozems depending on the granulometric composition

Particle-size composition is a fundamental characteristic that has a significant impact on many properties and regimes of soils, including sorption and fixation of humus by elementary soil particles (ESP). The main role in increasing the humus content of soils belongs to ESP with sizes <0.01 mm. We examined the structural features of humus profiles of leached chernozems formed on soil-forming rocks of different granulometric compositions. For this purpose, a large sample of data on the quantitative content of humus in chernozems of different granulometric compositions was analysed. The goal of the research was to identify the dependence of humus sorption on the granulometric composition of chernozems, and also to reveal the features of the profile distribution of humus in them. Objectives: conduct field research of chernozems of different granulometric composition; select soil samples and conduct a series of laboratory studies of these samples for the identification of the sorption properties of ESP in relation to humus; identify the features of humus distribution in soils of different granulometric compositions. It has been shown that with an increase in the granulometric composition of the content of ESP related to physical clay (<0.01 mm), the sorption capacity of the soil for humus increased. Thus, from sandy loam (ESP <0.01 mm=14-20%) to clayey varieties (ESP <0.01 mm = 61-64%) of chernozems, the humus content increased, respectively, from 3.88 to 7.09%. The thickness of the humus layer increased in the same direction from 22 to 100 cm. Therefore, soils of different granulometric compositions have their own structural features of the organoprofile, consisting in the nature of the humus distribution.

Using the zirconium­containing binders for obtaining refractory concretes

Now the creation of new heat­resistance and refractory binding materials contributing towards reliable and durable service of high­temperature plants is paid great attention. To develop the physical and chemical principles of such materials technology first of all it is necessary to study the high­melting oxide systems and as a consequence, to obtain refractory products in terms of ones. Taking into consideration all mentioned above, the multicomponent zirconium­oxide systems are of potential interest.
 As a result of our investigations new compositions of high­strength, heat­resistance, and refractory zirconium­containing binders on the basis of different sections of the quaternary system CaO—Al2O3—ZrO2—SiO2 are obtained. Refractory concretes in terms of zirconium­containing cement and various aggregates, both natural (corundum, baddeleyite) and artificial (calcium zirconate), have been elaborated. It is revealed that the kind and granulometric composition of aggregates, molding methods, as well as cement­aggregate relation influence the physical and mechanical properties of concrete developed. Concretes obtained are characterized by high strength (50—60 MPa) and service property stability: refractoriness — more than 1700 °C thermal shock resistance — more than 30 cycles; thermal linear expansion coefficient — 4.8×10–6 ÷ 5.6×10–6 deg.–1, initial strain point under load of 0.2 MPa — 1400—1500 °C Materials developed comply with requirements to refractory materials and can be applied for monolithic linings of heat density parts of high­temperature plants.

Mineral Magnetic Modification of Fine Iron Ore Tailings and Their Beneficiation in Alternating Magnetic Fields

In this paper, the properties, mineral magnetic modification, and beneficiation of tailings from the central mining and processing plant in Kryvyi Rih, Ukraine, have been studied. Samples were investigated by X-ray diffraction, X-ray fluorescence, microscopy, and magnetization measurements. The beneficiation was conducted using magnetizing roasting with carbon monoxide followed by dry low-intensity magnetic separation. The effects of chemical, mineral, and granulometric composition on the processing of fine tailings of different sizes sampled at different points of the tailings pond were investigated. Additionally, we proposed a new approach for magnetic separation of fine magnetically modified tailings based on the combination of permanent and alternating magnetic fields. Magnetizing roasting resulted in an enhancement in mass magnetization to 11–62 Am2/kg in comparison with initial values of 0.3–1.5 Am2/kg. After magnetic separation, the magnetic concentrates consisted almost completely of magnetite (with the magnetization of 75–88 Am2/kg) and non-magnetic residues contained major quartz. The content of iron in magnetic concentrates reached 68.5–70.2 wt.% and iron recovery 77–96 wt.%, depending on size fraction. We could conclude that the tailings are represented by fine-grained liberated material that can be effectively upgraded using magnetizing roasting and magnetic separation into two valuable products, such as iron concentrate and quartz powder.

Повышение качества и расширение ассортимента продуктов на основе технического монокальцийфосфата

Production of a low-grade phosphate raw materials-based line of products using economically and environmentally appropriate hydrochloric-phosphorus acid technology is a promising area. A double superphosphate (P2O5 = 46 wt. %) was obtained by isothermal re-crystallization due to removing iron(III) from impurities of the technical monocalcium phosphate (P2O5 = 35 wt. %). The obtained product is represented exclusively by a mobile (water-soluble) phosphorus form. The development of greenhouses and requirements for closed soils impose strict restrictions on the impurities composition in the mineral fertilizers. The current State standards regulate such physico-chemical and physico-mechanical parameters of phosphorus-containing fertilizers as nutrients’ concentration, moisture content, pH of 10% solution, granulometric composition, granules’ strength, friability, heavy metals’ concentration. But they ignore a number of impurities, for example, iron(III), that can lead to phosphorus retrogradation. The simple enough technology makes it possible to obtain cheap effective product –monocalcium phosphate (MCP) – from low-grade ores (phosphorites). This explains the high demand for it among farmers. MCP can also be used in animal husbandry, provided that the sanitary regulations and norms requirements on MPC of controlled impurities are met. The development of the “Green Chemistry” involves the use of water-soluble fertilizers and eliminates the toxic elements content that can accumulate in the soil. The iron(III) extracted from impurity minerals binds to phosphorus and forms FePO4 with the citrate-soluble form of P2O5, thereby reducing its mobile form (P2O5 wat.) in the product. A more concentrated product corresponding to the double superphosphate in the main component (P2O5 wat.) content was produced by isothermal re-crystallization of MCP with ballast impurity. In addition, the final product was purified from iron compounds to trace amounts. Thus, purification of technical MCP by isothermal recrystallization method due to the removal of iron impurities to trace amounts expands the field of its application.

Переработка отходов металлургической промышленности для стабилизации и укрепления проблемных грунтов

Purpose: To examine existing methods of processing and recycling waste from the metallurgical industry, to elucidate their classification. To touch upon the negative impact of the metallurgical industry, in particular, of the waste generated from its activities on geosystems. To present technological solutions for addressing the issue of weak soils through their initial stabilization and subsequent reinforcement, specifically for urban infrastructure objects in the Russian Federation. Methods: Various technologies for the complex processing of solid waste from metallurgy have been developed, some of them have been implemented on an industrial scale abroad. We develop such technologies at the level of research and semi-industrial tests. Results: A distinctive feature of soils reinforced with solid wastes of metallurgy is that structure formation and strength development occur both in air-dry and in humid environments. These wastes effectively strengthen soils of different granulometric and chemical-mineralogical composition. As shown by laboratory studies and supporting construction, soils reinforced with this complex waste are suitable for constructing pavement structural layers. When strengthening sandy soils, a purely mechanical penetration and enveloping of soil particles (due to the small amount of clay particles) occurs without the formation of a strong spatial structure. Practical significance: The possibility of using waste from metallurgical production to strengthen weak soils is shown, and these new methods can be recommended for practical use.

Study of the soybean varieties quantitative traits variability in the Central Non-Chernozem Earth Region conditions

In the experiments, the formation of the yield of new early-ripening soybean varieties Georgiy, Slavyanka and Snezhana under the conditions of the Central Non-Chernozem Region was studied and an assessment was made of the influence of hydrothermal conditions on the variability and conjugation of soybean agronomic traits. Field experiments were carried out in 2020-2022. at the Institute of Seed Production and Agrotechnologies, a branch of the FGBNU FNAC VIM (Ryazan region), located in the forest-steppe agro-climatic zone of the Non-Chernozem zone of the Russian Federation. The soil is dark gray forest, heavy loamy in granulometric composition, of medium fertility (humus content - 4.54%), with an average content of exchangeable potassium and mobile phosphorus. Through correlation analysis, a significant positive relationship was established between the duration of the growing season and the HTC (r = 0.916 + 0.09), with the average daily temperature in August (r = 0.896 + 0.04). The height of plants and the height of attachment of the lower bean in the varietal section changed to an average degree (V = 7.96-21.38%). The greatest variability over the years was noted for the number of beans (V=31.92%) and the weight of seeds per plant (V=38.03%). The weight of 1000 seeds changed the least during the years of the study (V = 8.54-13.38%). The yield of the studied varieties is directly related to the number of beans and seeds per plant, and has no significant relationship with the height of the plant. The results of the research were used in the development of varietal technologies for the cultivation of soybeans in the conditions of the Ryazan region.