Slag Removal Research Articles

Pilot-Scale Application of Red Mud-Based Slag Pellets in Steelmaking: Process Optimization, Mechanism, and Life Cycle Assessment.

The resource utilization of red mud (RM) is crucial for the aluminum industry and for addressing environmental concerns. In this study, RM-based slag pellets were prepared through a cold pressing process and used for converter steelmaking. In the pellet preparation experiment, the effects of binder starch and carboxymethyl cellulose sodium (CMC) dosage, moisture content, drying temperature, particle size, and forming pressure on the strength of RM-based pellets were studied. The formation mechanism of RM particles was determined by analyzing the changes in the crystal structure, functional groups, elemental valence state information, and density functional theory calculations. Finally, the environmental benefits of the pellet production process were analyzed. Under the optimal reaction conditions, the compressive strength of RM pellets prepared based on starch and CMC can reach 1162.06 and 1345.6 N/P, which can meet the production needs of the converter. Mechanism analysis shows that organic adhesives adsorb and solidify particles through chemical or hydrogen bonding, resulting in a denser particle structure. RM particles have an excellent slag and phosphorus removal performance. The results of the life cycle assessment clarify the potential contributions of each stage of particle production. The raw materials and transportation distance have significant impacts on the particle production system. The experimental results provide theoretical guidance and a sustainable evaluation for the production of RM slag aggregates.

Nuclear Fusion Rethought: Obeying the Quantum Regime is the Key to Permanent Plasma Confinement

A paradigm shift in the field of fusion energy production is heralded by the integration of quantum mechanics into the fusion technology landscape. The "Looperator" provides a reliable energy source by fusing the ionized nuclei of deuterium and tritium into helium in a timeless chain reaction within a magnetically confined plasma volume. This integration combines the continuous supply of fuel with the efficient removal of slag, ensuring sustained energy output.

Synergistic mechanisms of magnesium slag coupled with dust removal ash for CO2 sequestration via direct aqueous carbonation: High mineralization efficiency and optimization of reaction parameters

Synergistic mechanisms of magnesium slag coupled with dust removal ash for CO2 sequestration via direct aqueous carbonation: High mineralization efficiency and optimization of reaction parameters

Experimental Analysis of Weld Slag Separation in Pipelines

Abstract In order to effectively eliminate welding slag from pipelines, ensure equipment operates normally, and reduce production costs, experiments were conducted based on field construction operations, with a focus on the intensity and frequency of tapping. The study findings indicate that a tapping force of 341.8 N leads to a stabilization in the rate of welding slag removal. Following manual tapping of the pipelines, the welding slag removal rate is approximately 60 %, and it stabilizes gradually after four tapping instances. To provide guidance for on-site operations, an empirical expression capturing the pattern of welding slag removal was derived from experiments by establishing the correlation between tapping frequency, tapping force, and welding slag removal rate.

Continuous Slag Discharge Construction Technology for Shield Tunneling in Narrow Space Environment

The shield tunneling method is the main construction method in subway tunnel construction, which has the characteristics of safety, efficiency, mechanization, and high degree of automation. However, the shield tunneling equipment is huge, the supporting facilities are numerous, and the site requirements are high. In response to the problems of slow slag removal speed and low construction efficiency in shield tunneling under the construction conditions of small wellhead shield tunneling sections in urban subways, taking the shield tunneling section of Guangzhou Metro Line 13 Phase II as the background,This article introduces the main components, working principles, installation and transportation processes, fault handling, and benefit analysis of the continuous belt conveyor slag removal system,This article elaborates on the method of using a continuous belt conveyor in the tunnel combined with a vertical lifting system at the wellhead to achieve continuous slag removal during underground shield tunneling construction in a narrow wellhead construction site. This not only improves excavation efficiency but also reduces construction costs, solves construction problems, and provides reference for similar projects in the future.

Velocimetry of coarse particles in pipeline flow based on GMM model and flow direction constraints

Velocimetry of coarse particles in pipeline flow based on GMM model and flow direction constraints

Effect of coal suspension concentration and gas-air medium temperature on liquid droplets collisions

Relevance. Understanding the mechanisms of liquid droplets interaction with each other is important for many industrial and technical applications related to solving a range of problems like slag removal in a high-temperature environment, obtaining components of the desired fraction in the food industry, etc. Aim. Establishment of the main patterns of suspension droplets interaction in a gas-air environment with temperature variation. Methods. Using shadow high-speed video recording, the main patterns of the binary collision of suspensions droplets were determined. The paper introduces the results of experimental studies of the characteristics of collisions of droplets of coal-water suspensions in a gas-air environment with a temperature of 90–120°C. Parameters of the generated droplets: radius 1.0–2.2 mm, velocity 0.5–2.0 m/s. Results and conclusions. The authors have determined the modes of collision of droplets of suspensions (coagulation and separation) and the main characteristics of secondary fragments and constructed the maps of the modes of interaction of drops of suspensions with each other when varying the concentration of solid particles in the suspension, the temperature of the gas-air environment and the time the target drop spent in a gas-air environment with an elevated temperature. The conditions were established for the coagulation of droplets, as well as their intensive secondary grinding to intensify their drying, ignition and combustion in boiler furnaces. It was established that an increase in the temperature of the gas-air environment leads to a significant change in the size and properties of droplets, as well as to the occurrence of oscillatory phenomena in the system. It is substantiated that collision of droplets of suspensions in a gas-air environment with elevated temperature is complex and multi-parametric. Its characteristics depend on a combination of factors (surface tension and liquid viscosity, size and shape of droplets, speed of their movement, density and viscosity of gas-air environment). The authors obtained mathematical expressions to describe the boundaries of the modes of the studied processes and schemes for using the results obtained in order to increase the efficiency of the corresponding technological processes.

Comprehensive recovery of valuable elements from vanadium precipitation liquor using selective impurity removal-reduction precipitation process

Comprehensive recovery of valuable elements from vanadium precipitation liquor using selective impurity removal-reduction precipitation process

ЭФФЕКТИВНОСТЬ СУПЕРПЛАСТИФИКАТОРОВ В МЕЛКОЗЕРНИСТОМ БЕТОНЕ С ЗОЛОШЛАКОВОЙ СМЕСЬЮ

One of the determining factors in the development of modern concrete science is the development of new resource-saving technologies for the production of cement concrete and products made from them using various industrial wastes, in particular ash and slag mixtures (ASM) formed at thermal power plants during the joint hydraulic or pneumatic removal of ash and slag into a dump during the process. burning coal in a dusty state. The problem of waste disposal is especially relevant for territories with limited free land, high population density and lack of mineral resources. Such regions include the Transnistrian Moldavian Republic, in which one of the largest in Eastern Europe, the Moldavian State District Power Plant (MSDPP), operates, providing electricity to Transnistria and neighboring countries (Moldova, Romania, Bulgaria). During the operation of MSDPP, a zone of ash and slag mixtures with a volume of more than 10 million tons was formed on coal, the use of which in cement concrete technology can be based on the regulatory and technical documentation of the Russian Federation. The paper presents the results of studies of the structure and physicochemical properties (chemical and particle size composition, hydrosilicate and silica modules, quality factor) of the ASM MSDPP. An assessment of the effectiveness of naphthalene-formaldehyde and polycarboxylate superplasticizers was carried out according to the criterion of changing the strength of fine-grained concrete from the ASM MSDPP.

Scientific bases and peculiarities of conversion of CHPP anthracite boilers to sub-bituminous coal combustion

Scientific bases and peculiarities of conversion of CHPP anthracite boilers to sub-bituminous coal combustion Print EmailUser Rating: / 0 PoorBest Category: Content №1 2024 Last Updated on 29 February 2024 Published on 30 November -0001 Hits: 1 SocButtons v1.4 Authors: M.V.Chernyavskyy*, orcid.org/0000-0003-4225-4984, Thermal Energy Technology Institute of National Academy of Sciences of Ukraine, Kyiv, Ukraine, e-mail: mchernyavski@gmail.com O.Yu.Provalov, orcid.org/0000-0002-5191-2259, Thermal Energy Technology Institute of National Academy of Sciences of Ukraine, Kyiv, Ukraine, e-mail: eproval@ukr.net Ye.S.Miroshnychenko, orcid.org/0000-0003-2487-6886, Thermal Energy Technology Institute of National Academy of Sciences of Ukraine, Kyiv, Ukraine, e-mail: yevhenmi@gmail.com O.V.Kosyachkov, orcid.org/0000-0002-9445-8738, Thermal Energy Technology Institute of National Academy of Sciences of Ukraine, Kyiv, Ukraine, e-mail: alexkosoy@ukr.net * Corresponding author e-mail: mchernyavski@gmail.com повний текст / full article Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu. 2024, (1): 041 - 049 https://doi.org/10.33271/nvngu/2024-1/041 Abstract: Purpose. Development of scientific foundations and generalization of experience in development and implementation of technical solutions for conversion of CHPP anthracite boilers with steam productivity up to 250 t/h for combusting sub-bituminous coal with maximum use of existing equipment. Methodology. Consumption and heat calculations of pulverizing systems, aerodynamic calculations of pulverized coal pipes and burners, thermal calculations of boilers and combustion chambers. Calculation justification of technical solutions to eliminate the risk of coal ignition in pulverizing systems and in the burners. Industrial tests on CHPP boiler units. Findings. Different types of pulverizing systems of anthracite CHPP boilers with ball-drum mills, an intermediate pulverized coal hopper and with hot air as a drying agent were considered, and a classification of pulverizing systems by the method of pulverized coal transport to the burners (with drying agent or hot air), and boilers – by the type and location of the burners and the geometry of the furnace, was performed. The problems were analyzed, the calculations of pulverizing systems, pipes, burners, and boilers were performed according to the applied technical solutions, and the experience was summarized of conversion from anthracite to sub-bituminous coal in the boilers of Myronivska, Darnytska CHPP and of the first line of Slovianska TPP. Recommendations are given on methods of conversion of anthracite boilers with a steam capacity of up to 250 t/h with different types of pulverizing systems for burning sub-bituminous coal with maximum use of existing equipment. Originality. For pulverizing systems with ball-drum mills and an intermediate hopper for pulverized coal with hot air as a drying agent classification was made for the first time by the type of transporting agent, and it was shown that when converting from anthracite to sub-bituminous coal with the air transport of pulverized coal to the burners, it is necessary to use the selection of slightly heated air from the first stage of the air heater. It is substantiated that maintaining the temperature conditions of molten slag removal while reducing the share of hot air consumption to the furnace requires the preferential operation of pulverizing systems in a single-mill mode, which is possible due to the greater grindability of sub-bituminous coal. Practical value. Based on the experience of approving technical solutions at Myronivska, Darnytska CHPPs, and at the first line of Slovianska TPP, recommendations are given on how to transfer anthracite boilers with a steam capacity of up to 250 t/h with different types of pulverizing systems for burning sub-bituminous coal with maximum use of existing equipment.

Investigating the Corrosive Influence of Chloride Ions on Slag Recovery Machine Inner Guide Wheel in Power Plants.

An important method that coal-fired power plants use to realise low-cost zero discharge of desulfurisation wastewater (FGD wastewater) is to utilise wet slag removal systems. However, the high Cl- content of FGD wastewater in wet slag removal systems causes environmental damage. In this study, the corrosion behaviour of the inner guide wheel material, 20CrMnTi, was studied using dynamic weight loss and electrochemical methods. X-ray diffraction, scanning electron microscopy, and energy spectroscopy were used to analyse the organisational and phase changes on the surfaces and cross sections of the samples at different Cl- concentrations. The corrosion rate increased with the Cl- concentration up to 20 g/L, but it decreased slightly when the Cl- concentration exceeded 20 g/L. In all the cases, the corrosion rate exceeded 0.8 mm/a. The corrosion product film density initially increased and then decreased as the Cl- concentration increased. The corrosion products comprised mainly α-FeOOH, γ-FeOOH, β-FeOOH, Fe3O4, and γ-Fe2O3.

Sealing method and experimental study of large-diameter reverse circulation hole hammer

A reliable sealing structure is the key to achieving reverse circulation drilling technology for large- diameter reverse circulation down the hole hammers, and it is also a difficult point in the design of large- diameter reverse circulation down the hole hammers. The existing large-diameter reverse circulation down the hole hammers are designed based on the sealing structure of the bottom drilling tool body. This article proposes a joint sealing method for hole bottom and hole opening. Based on this sealing method, a bundle type reverse circulation down the hole hammer and hole opening sealing device with a diameter of 710/311mm were developed for hole expansion, and field tests were conducted with a double wall drilling tool with a diameter of 127/70mm. The method achieved good continuous reverse circulation slag removal effect, with an average mechanical drilling speed of 2.1m/h, which is 2.6 times higher than the conventional roller bit hole expansion method. The experimental results indicate that the joint sealing method between the bottom and the mouth of the hole is feasible and worthy of further promotion and application.

Research and practice of high-speed spiral composite drilling technology in complex and weak coal seams

In response to the difficult slag discharge and low hole formation rate encountered in the Wangpo Coal Mine, a study was conducted on high-speed spiral composite drilling technology. This study was integrated with the performance characteristics of the ZDY6000LR-type high-speed pit rig, resulting in the design of drill bits in three different specifications: Φ110/63.5 mm, Φ95/60.3 mm, and Φ88/50 mm. Additionally, the study optimized the three-wing drill pipe's feed speed, rotation speed, and airflow volume. The industrial field test, conducted on the 3206 working face of the Wangpo Coal Mine, resulted in the design of three drill bit combinations that exhibited high strength and stiffness. This design improvement led to enhanced hole integrity, elevated slag removal efficiency, and extended service life for both the drill pipe and bit. The high-speed spiral composite drilling technology, alongside the supporting equipment, effectively addresses the challenges of slag discharge and nozzle top drilling encountered during operations. It significantly improves the deep hole drilling rate, achieving a drilling depth of over 100 m with a success rate exceeding 70%. This technology provides vital support for the extraction of gas from coal seams within the mine. Notably, the Φ95/60.3 mm screw pipe and its corresponding drill bit demonstrated the optimal holeforming effect, with an average hole depth of 111.2 m and a hole formation rate of 90.9%. These findings offer valuable insights for drilling operations under similar conditions of complex and weak coal seams.

A review of application, modification, and prospect of melamine foam

Abstract Melamine foam (MF), a promising development in light materials, finds application in construction, agriculture, aviation, transportation, electronic message, and other fields due to its excellent thermal insulation performance, sound absorption and noise reduction capabilities, safety and health benefits, as well as easy processing. However, its own shortcomings such as hardness, poor toughness, fragility, and slag removal greatly limit its application scope. In this review, a survey of the literature from two aspects of toughening of melamine resin and regulation of MF pore structure are reviewed to explore the research progress of toughening modification of MF. The principle, merit, and demerit of different modification methods are analyzed. In addition, owing to the extensive literature available, this article also summarizes the representative achievements of the nanotechnology modification of MF derivatives (carbon foam and carbon aerogel). Eventually, based on an assessment of current application status for both MF and its derivatives while considering existing challenges in their modification processes using nanotechnology approaches, we discuss future prospects for their application.

CONVERSION OF ANTHRACITE BOILER UNITS OF CHP PLANTS FOR COMBUSTION OF SUB-BITUMINOUS COAL IN THE WAR CONDITIONS

The work describes the task of urgently converting the boilers of anthracite-burning combined heat and power plants to sub-bituminous coal, which arose in the conditions of Russian aggression in connection with the complete cessation of supplies of project fuel. The developed methods of solving it in a short time with the maximum use of available equipment are given, using the example of boilers with a steam capacity of 220 t/h of CHPP «EURO-RECONSTRUKTSIA» LLC (Darnytska CHPP, Kyiv). On the basis of calculation justification it is shown, and the tests and operation have confirmed, the safety and effectiveness of the technical solution with preservation of coal drying by hot air while limiting the temperature at the exit of the mill and with pulverized coal transport to the burners by half-heated air taken after the first stage of the air heater, while reducing the diameter of the pulverized coal pipes. Measures are proposed and implemented to equalize the distribution of pulverized coal and air among the burners, to operate the mills in alternating mode with the aim to increase the use of hot air, correspondingly to increase the coal jet temperature, to improve the conditions of molten slag removal and to reduce the temperature of flue gases, etc. Uninterrupted operation of the Darnytska CHPP became an important factor in ensuring the functioning of the critical infrastructure of heat and energy supply of Kyiv in conditions of enemy shelling. Bibl. 18, Fig. 5, Tab. 4.

The Kuznetsk Lean Coal Combustion Scheme Optimization Using Straight-Flow Burners and Nozzles with Solid Slag Removal

The Kuznetsk Lean Coal Combustion Scheme Optimization Using Straight-Flow Burners and Nozzles with Solid Slag Removal

Strength and deformation characteristics of slag crushed stone of coal thermal power plants

Mechanical properties of the slag crushed stone (coarse-grained ASM), formed in the course of coal combustion at Kansk-Achinsk, Kuznetsk coal deposits (in boilers equipped with liquid and dry slag removal facilities) and the application of the slag crushed stone in roadbuilding are considered. In the course of the research, the crushability and the deformation modulus of particular fractions of slag crushed stone samples taken from the dumps of Novosibirsk TPP-3 (that consumes the coal of the Kansk-Achinsk coal mining field) and from Novosibirsk TPP-2 and Seversk TPP (that consume the coal of the Kuznetsk coal mining field) were identified. To assess the factors influencing the mechanical strength of the slag crushed stone, ignition losses, the content of flaky and acicular particles, dust and clay particles and clay lumps was made. The difference in the mechanical strength of samples having different genesis was identified. The graphs obtained in the course of testing were assessed and deformability characteristics were calculated (for materials having different fineness values). The factors influencing the mechanical strength of slag crushed stone were determined. Dependencies between deformation parameters and crushability of the slag crushed stone were obtained. Some mechanical and physical parameters of the slag crushed stone were identified; they were applied to outline potential areas of the slag crushed stone application in road building. The mathematical relationship needed to project the deformation modulus of the slag crushed stone was identified. This relationship will be used to design structures to be made of this material.

Model development and probabilistic risks of cadmium transport in slag-soil-groundwater systems with heterogeneous conditions

Model development and probabilistic risks of cadmium transport in slag-soil-groundwater systems with heterogeneous conditions

Utilization of Steel Slag as a Soil Amendment and Mineral Fertilizer in Agriculture: A Review

The gradual increase in industrial wastes allowed the utilization of these wastes in different areas. Steel slag, one of the industrial wastes, is formed during the reduction of molten crude iron to molten crude steel in basic oxygen furnaces (BOF) or scrap to molten crude steel in electric arc furnaces (EAF) and induction furnaces (IF). Removal, storage, or disposal of steel slag is an important environmental and economic problem. Steel slag offers opportunities to be used as an alternative material in various areas and contributes to the national economies through recycling. This research provides information about the studies and application examples on the use of steel slag as a soil amendment and mineral fertilizer in the world. This usage allows reducing the consumption of natural resources and providing great agricultural, environmental, and economic gain by minimizing the negative environmental effects of steel slag.

Copper technology at the Early Iron Age fortified settlements near Lakes Itkul and Irtyash, middle Trans-Urals

Copper technology at the Early Iron Age fortified settlements near Lakes Itkul and Irtyash, middle Trans-Urals