Multicomponent Charge Research Articles

Application of a Mechanoacoustic Method for Preparing a Multicomponent Charge for Producing Ceramics from Aluminosilicate Raw Materials

Application of a Mechanoacoustic Method for Preparing a Multicomponent Charge for Producing Ceramics from Aluminosilicate Raw Materials

COMPLEX MATHEMATICAL MODEL OF THE PROCESS OF LOADING A MULTICOMPONENT CHARGE INTO A BLAST FURNACE

The rational mode of loading the blast furnace is the most important condition for its highly efficient operation. The selection of rational values of the control parameters of the load mode is carried out on the basis of information obtained with the help of instrumental tools and mathematical models. Mathematical models of the process of blast furnace loading are necessary components of expert (intelligent) control systems for blast furnace melting. The presented complex mathematical model of the process of loading a multicomponent charge into a blast furnace differs from known developments taking into account the redistribution of components into the volume of loaded portions during movement along the path "charge feed - blast furnace", which provides the possibility of obtaining calculated characteristics of the distribution of each component of the charge and determining the composition of the formed mixtures of charge materials in any given zone of the furnace. The existence of such a model opens up new opportunities in the management of the blast furnace smelting process, as well as in conducting analytical studies of the conditions of slag formation and the distribution of properties of melts across the section of the blast furnace.

Hydrodynamics of plastic deformations in electronic crystals

We construct a new hydrodynamic framework describing plastic deformations in electronic crystals. The framework accounts for pinning, phase, and momentum relaxation effects due to translational disorder, diffusion due to the presence of interstitials and vacancies, and strain relaxation due to plasticity and dislocations. We obtain the hydrodynamic mode spectrum and correlation functions in various regimes in order to identify the signatures of plasticity in electronic crystal phases. In particular, we show that proliferation of dislocations de-pins the spatially resolved conductivity until the crystal melts, after which point a new phase of a pinned electronic liquid emerges. In addition, the mode spectrum exhibits a competition between pinning and plasticity effects, with the damping rate of some modes being controlled by pinning-induced phase relaxation and some by plasticity-induced strain relaxation. We find that the recently discovered damping-attenuation relation continues to hold for pinned-induced phase relaxation even in the presence of plasticity and dislocations. We also comment on various experimental setups that could probe the effects of plasticity. The framework developed here is applicable to a large class of physical systems including electronic Wigner crystals, multicomponent charge density waves, and ordinary crystals.

Determination of mechanical and tribotechnical properties of coatings during laser surfacing of tool steels

The paper considers the results of metallographic studies and tribotechnical tests of samples of 9CrSi tool steel and multicomponent coatings obtained by laser surfacing with the addition of ultrafine titanium carbide particles into the charge. As an additional parameter, transverse high-frequency oscillations of the beam along the normal to the velocity vector of the laser surfacing were used. Tribotechnical tests were carried out according to the scheme “the plane is the end of an annular 40Cr steel plate with volumetric hardening”. To determine the critical sliding speeds, the tests were performed at a constant pressure of 2.5 MPa. Industrial I20 oil was fed into the friction zone. The minimum values of the friction coefficients depending on the sliding speed were obtained when 7 vol% titanium carbide was introduced into the multicomponent charge. The sliding speed to the bully increases by 2, 2.7 and 3.5 times when surfacing with a multicomponent charge without carbides and with the introduction of 4 and 7 vol% titanium carbide, respectively. Coatings with a high content of the hardening phase had the greatest wear resistance. Laser surfacing technology can be applied to the restoration of worn surfaces of rolls of rolling mills, die-cutting dies and other parts of die tooling.

Effect of the composition of multicomponent powders on the mechanical and tribotechnical properties of coatings obtained by laser additive technologies

The paper presents the results of metallographic studies and tribotechnical tests of samples of medium-carbon steel 34KhNi3MoA and coatings obtained by laser surfacing of a powder multicomponent charge based on iron and cobalt in a ratio of 3:1 with additives of nano particles of tantalum carbide. The samples were processed with a circular defocused beam and with transverse beam oscillations normal to the scanning speed. Comparative tests for friction and wear were carried out in a pair with a hardened 40Kh steel counterplate. The load and sliding speed during the tests varied discretely. Turbine oil TP 22C was used as a lubricant. It is shown that the introduction of additives of nano-tantalum carbide into the charge reduces friction losses, increases the wear resistance of coatings compared to the charge without carbides and the base material. The wear resistance of coatings with an increase in the amount of the hardening phase increases compared to the original steel. It has been established that the technology of laser surfacing with multicomponent coatings with nano particles of tantalum carbide can be used to restore worn surfaces of shaft necks, turbine blades, thrust discs, shut-off valves and other parts operating at high temperatures and in corrosive environments.

Increasing the Energy Efficiency of Blast-Furnace Smelting by Choosing Rational Parameters for Loading a Multicomponent Charge

The purpose of this study was to develop a calculation tool for researchers and technologists - metallurgists, providing the ability to quickly assess the distribution of charge materials in a blast furnace when it is loaded with a multicomponent charge. The goal is achieved by analyzing and summarizing the multidimensional matrix of values for the content of the charge components in the annular zones of the blast furnace, obtained using a mathematical model of its loading under various modes, changing the content of pellets in the charge and the moment the pellets are unloaded onto the main conveyor. The most important results of the studies carried out are the substantiation of the possibility of obtaining and applying calculated dependencies to determine the characteristics of the distribution of charge components with an accuracy acceptable for technological practice, as well as the established relationship between the content of the component in the charge and the value of the set point for the start of unloading it onto the conveyor with the content of this component in the annular zones of the top. Estimated composition of mixtures of charge materials formed in different zones of a blast furnace makes it possible to predict the properties of melts formed from them and to correct them in order to achieve the required level of energy efficiency in melting a multicomponent charge by promptly choosing rational parameters of the loading mode.

Physicochemical regularities of complex reduction of iron chromite

Physicochemical patterns of complex reduction of multicomponent charge have been studied in the absence of liquid phases in order to obtain spongy ligatures. The charge contained both simple oxides and complex oxide compounds. The reduction was conducted being realized at the expense of carbon and gases (CO and H2) as well as with the participation of the carbide phase, which was formed during the reduction process. The dependence of the phase composition of the reduction products on the initial ratios O/(C+H) and C/H was determined. The possibility of the presence of Femet in the products was shown at increasing the C/H ratio and the formation of complex carbide based on (1/60 Fe3C+1/3 Cr3C2). The temperature limits of the appearance of metallic and carbide phases have been theoretically determined based on both thermodynamic modeling of the system Cr–Fe–C–O–H using the software HSC Chemistry 5.1 and the results of X-ray phase analysis of the reduction products. The equilibrium composition of the gas phase for the complex reduction of iron chromite under different conditions was calculated. To evaluate the kinetic features of the reduction of iron chromite, the rate of the complex reduction of Fe(CrO2)2 was determined under conditions of chemical-catalytic action. Salts of alkali metals (potassium and sodium) were used as catalytic additives. The influence of temperature, reducing agent composition and the nature and amount of catalytic additive on the process rate was investigated. Conclusions on the type and optimal proportion of additives have been made. The mechanism of influence of catalytic additives on the kinetic characteristics of the complex reduction of iron chromite was analyzed.

Розробка та випробування алгоритмічного забезпечення експертної системи вибору оптимального складу багатокомпонентної доменної шихти у конкретних умовах роботи доменних печей

The aim of the work is to develop and test for specific conditions of the blast furnace algorithmic means of the Expert system for selecting the optimal composition of the multicomponent charge, which provides the necessary technical and economic indicators of melting in variable raw material and energy conditions. The features of algorithmic means of the system for selecting the optimal composition of blast furnace charge, which are developed using methods of physicochemical and mathematical modeling of the processes of distribution and melting of iron ore materials in different zones of the furnace for the development of scientifically based recommendations for adjusting the composition of the charge, taking into account the available raw materials and energy resources. The system implements a set of physicochemical models and criteria for describing the processes of distribution of iron ore materials along the blast furnace radius, their phase transformations in high-temperature zones and directed formation of melts, which are regulated by a system of reasonable technological constraints. The information basis for the creation of predictive models for calculating the physical and chemical properties of metallurgical melts is the information accumulated in the databases "Iron ore materials", "Slag" and "Metal-slag" created in the Institute of Ferrous Metallurgy of the integrated Knowledge Base "Metallurgy". The solution of the optimization problem is carried out on the basis of expert evaluation of the forecasting of melting indicators and calculation of the optimal composition of the charge using vector optimization methods by finding a compromise between the accepted optimality criteria and technological constraints. The Expert system has been tested and recommendations on the component composition of blast charge for specific blast furnace operating conditions have been developed.

A Model to Control the Formation of Multi-Component Charge Portions on a Blast Furnace Conveyor

Introduction. Bell-less tops used in the charging area give significantly wider opportunities for regulating and distributing the charge material along the furnace top radius. Moreover, it becomes feasible to develop the methods for gas flow control and these methods shall differ from the conventional ones. One of such methods is introduction of multi-component portions of the charge with a technology based component ratio. Problem Statement. The bell-less top charging device is not designed for that type of portioning when the charge material mixing is accompanied with a simultaneous shift of one component with respect to other one for a certain set value, while charging. These portions can be formed with the use of computer-aided stock-conveying system, while discharging the material from weighing hoppers into the blast furnace conveyor. Purpose. This research aims at the development of the structure, the functioning algorithms and the mathematical model for the system to control the formation of multi-component mixed charge batches in order to increase the blast furnace productivity and to reduce the specific coke consumption. Materials and Methods. In this research, the methods of automatic control theory and artificial intellect for the synthesis of weight neuro-fuzzy controllers within the automatic control system of charge dosage have been used. The developed system designed to control multi-component charge portioning via PC has been tested by means of simulation modelling methods. Results. There has been developed an algorithm for operating the system for controlling the multi-component mixed charge preparation on the conveyor, given the arrangement of the specified components, their ratios in portions, total volumetric productivity of the conveyor, the variable geometry of the unloaded material, in the connection with the on-line information on the mixing process. The feasibility of the system has been verified by its simulation with the use of standard application tools. Conclusions. It has been established that the designed control system allows the formation of mixed portions of any composition defined by an operator at a given maximum output of the conveyor and prevents its overload in terms of mass or volume.

On the Importance of Silane Infusion Order on the Microscopic and Macroscopic Properties of Multifunctional Charge Gradients.

Four multicomponent charge gradients containing acidic and basic functionalities were prepared via sol–gel processes and the controlled-rate infusion (CRI) method to more clearly understand how preparation conditions influence macroscopic properties. CRI is used to form gradients by infusing reactive alkoxysilanes into a glass vial housing a vertically oriented modified silicon wafer. The concentration and time of infusion of the silane solutions were kept constant. Only the sequence of infusion of the silane solutions was changed. The first set of samples was prepared by initially infusing a solution containing 3-aminopropyltriethoxysilane (APTES) followed by a mercaptopropyltrimethoxysilane (MPTMS) solution. The individual gradients were formed either in an aligned or opposed fashion with respect to the initial gradient. The second set of samples was prepared by infusing the MPTMS solution first followed by the APTES solution, again in either an aligned or opposed fashion. To create charge gradients (NH3+, SO3–), the samples were immersed into H2O2. The extent of modification, the degree of protonation of the amine, and the thicknesses of the individual layers were examined by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. The wettability of the individual gradients was assessed via static contact angle measurements. The results demonstrate the importance of infusion order and how it influences the macroscopic and microscopic properties of gradient surfaces including the surface concentration, packing density, degree of protonation, and ultimately wettability. When the gradient materials are prepared via infusion of the APTES sol first, it results in increased deposition of both the amine and thiol groups as evidenced by XPS. Interestingly, the total thickness evaluated from ellipsometry was independent of the infusion order for the aligned gradients, indicative of significant differences in the film density. For the opposed gradients, however, the infusion of APTES first leads to a significantly thicker composite film. Furthermore, it also leads to a more pronounced gradient in the protonation of the amine, which introduces a very different surface wettability. The use of aminosilanes provides a viable approach to create gradient surfaces with different functional group distributions. These studies demonstrate that the controlled placement of functional groups on a surface can provide a new route to prepare gradient materials with improved performance.

A Model to Control the Formation of Multi-Component Charge Portions on a Blast Furnace Conveyor

Introduction. Bell-less tops used in the charging area give significantly wider opportunities for regulating and distributing the charge material along the furnace top radius. Moreover, it becomes feasible to develop the methods for gas flow control and these methods shall differ from the conventional ones. One of such methods is introduction of multi-component portions of the charge with a technology based component ratio. Problem Statement. The bell-less top charging device is not designed for that type of portioning when the charge material mixing is accompanied with a simultaneous shift of one component with respect to other one for a certain set value, while charging. These portions can be formed with the use of computer-aided stock-conveying system, while discharging the material from weighing hoppers into the blast furnace conveyor. Purpose. This research aims at the development of the structure, the functioning algorithms and the mathematical model for the system to control the formation of multi-component mixed charge batches in order to increase the blast furnace productivity and to reduce the specific coke consumption. Materials and Methods. In this research, the methods of automatic control theory and artificial intellect for the synthesis of weight neuro-fuzzy controllers within the automatic control system of charge dosage have been used. The developed system designed to control multi-component charge portioning via PC has been tested by means of simulation modelling methods. Results. There has been developed an algorithm for operating the system for controlling the multi-component mixed charge preparation on the conveyor, given the arrangement of the specified components, their ratios in portions, total volumetric productivity of the conveyor, the variable geometry of the unloaded material, in the connection with the on-line information on the mixing process. The feasibility of the system has been verified by its simulation with the use of standard application tools. Conclusions. It has been established that the designed control system allows the formation of mixed portions of any composition defined by an operator at a given maximum output of the conveyor and prevents its overload in terms of mass or volume.

A new level of blast furnace control in the developments of the IFM

Under today’s conditions, characterized by the instability of the composition and quality of charge materials, the composition of the combined blast, as well as the significant variability in the intensity of heat, the timely expert evaluation of the current heat parameters and reasons of their variations comparing with the setup parameters is rather actual. The expert evaluation can allow to issue recommendations to reach the setup technical and economic indices while minimizing the energy costs. The main features of the decision-making support intellectual system for blast furnace heat control, developed by the Institute of Ferrous Metallurgy, presented. The system based on the heat conditions diagnostic with application of evaluation criteria of heat conditions and BF heat gas-dynamic regime, effectiveness of axes coke funnel, evaluation of the form, location and thickness of the plastic zone in a blast furnace and other criteria, based on technological parameters of BF heat and control systems information. It was noted, that the elaborated system allows to evaluate adequately the processes of BF heat under conditions of multicomponent charge, which is stipulated generally by utilization of raw materials and fuel of lower quality within the BF charge to make it cheaper. A comprehensive mathematical model of multicomponent portions of charge materials forming, their charging into the bunker of the bell-less charging facility, discharging out of the bunker and distribution on the charge surface elaborated. The elaborated intellectual system tested under real conditions of “ArcelorMittal Krivoy Rog” No. 9 blast furnace operation. The system showed effectiveness of its algorithms functioning within a sequence of test periods.

Compaction of porous powder body consisting of the elastic­plastic medium

In the development of technological processes of producing cold-pressed sintered parts of low porosity, special attention is paid to the mechanism of density variation. In powder metallurgy, a multicomponent charge consisting of plastic metals, as well as poorly compressible inclusions and compounds, is often used. Such charge can equally be attributed to the charge consisting of iron powder, cast iron and glass. In this charge, the first component (base) is ductile iron, and the other two, cast iron and glass, are elastic components. It is of some interest what kind of compaction can be obtained in this case and what resulting equations can be used to estimate the mechanics of compaction of such a powder charge. The resulting equations of compaction of porous powder bodies of iron-cast iron-glass are proposed. The analysis of the isotropic, rigid-plastic hardening material such as iron-cast iron-glass is given. When compacting such a material, the rate of energy dissipation (pressing pressure) is determined by the rate of volume and form change of the body. It is shown that the difference between compressed (cast iron and glass) and plastic compacted (iron) materials forms special mechanical properties of the matrix. Consequently, hydrostatic pressure can affect the form change of the body, and shear stresses – volume change. The results of the mathematical approach to obtaining the resulting equations of compaction of the elastic-plastic medium showed the way to build a theory of plasticity of the compacted body, which eliminates the need to take into account the type of loading surface. When accounting the loading surface, it is impossible to obtain universal equations of compaction of the porous elastic-plastic medium. It is shown that to apply the classical formulation of the model of the elastic-plastic compacted body, it is necessary to assume that the loading surface is convex-closed

Mathematical Modeling of Determining the Composition of the Charge in the Cross Section of the Blast Furnace

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Complex Mathematical Model of the Distribution of Multicomponent Charge in a Blast Furnace

We present the results of development of a complex mathematical model of formation of multicomponent batches of charge materials, their charging into the hopper of a bell-less top system, discharging from the hopper, and distribution over the backfill surface and show the possibilities of its technological application. The results of mathematical modeling can be used to improve the applied modes of charging and correct these modes in the case of addition of new components into the charge, they allow us to analyze the influence of the applied program of distribution of charge materials on the distribution of individual components (both in the iron ore and fuel parts of the charge), which makes it possible to select and adjust the program according to the results of predictive calculations prior to entering it into the charging control system. It is shown that the application of the mathematical model gives a possibility of making substantiated choice of rational parameters of the modes of charging of multicomponent charge and decreases the level of hazard of making inefficient decisions.

ИССЛЕДОВАНИЕ ВЫСОКОТЕМПЕРАТУРНЫХ СВОЙСТВ ЖЕЛЕЗОРУДНЫХ МАТЕРИАЛОВ В ЛАБОРАТОРНЫХ УСЛОВИЯХ

The aim of the study is to simulate in laboratory conditions the behavior of iron ore materials in the zone of softening-melting DP and drip flow using an integrated method developed at the Institute of Ferrous Metallurgy. It is shown that the widespread idea of the formation in the blast furnace of primary slag melt based on FeO takes place mainly in the initial period of slag formation and is true for low basicity iron ore materials. For pellets, the nature of the formation of liquid phases differs significantly from the agglomerate. Experimentally established changes in the composition of the slag melt as heating. It is shown that under the conditions of temperature and heat treatment of raw materials, each temperature has its own composition of the liquid phase. When the pellets are melted, the primary melt is formed in the temperature range of 1330–13600C, in which the proportion of primary slag is 16–25%. Melt from high-silicon lumpy ore is formed at high temperatures of 1490-15200С. The mass of the primary slag with 42-48% FeO is 4-8% by weight of iron ore materials. The main part of the melt hangs on the coke nozzle on the coke layer at temperatures above 16000C. Melts formed from mixtures of iron-containing materials, as a rule, have averaged characteristics. The observed patterns make it possible to predict the behavior and properties of multicomponent charge mixtures in a blast furnace.

Cooperative Effects in Aligned and Opposed Multicomponent Charge Gradients Containing Strongly Acidic, Weakly Acidic, and Basic Functional Groups.

Bifunctionalized surface charge gradients in which the individual component gradients either align with or oppose each other have been prepared. The multicomponent gradients contain strongly acidic, weakly acidic, and basic functionalities that cooperatively interact to define surface wettability, nanoparticle binding, and surface charge. The two-step process for gradient formation begins by modifying a siloxane coated silicon wafer in a spatially dependent fashion first with an aminoalkoxysilane and then with a mercapto-functionalized alkoxysilane. Immersion in hydrogen peroxide leads to oxidation of the surface immobilized sulfhydryl groups and subsequent protonation of the surface immobilized amines. Very different surface chemistries were obtained from gradients that either align with or oppose each other. X-ray photoelectron spectroscopy (XPS) data show that the degree of amine group protonation depends on the local concentration of sulfonate groups, which form ion pairs with the resulting ammonium ions. Contact angle measurements show that these ion pairs greatly enhance the wettability of the gradient surface. Finally, studies of colloidal gold binding show that the presence of both amine and thiol moieties enhance colloid binding, which is also influenced by surface charge. Cooperativity is also revealed in the distribution of charges on uniform samples used as models of the gradient surfaces, as evaluated via zeta potential measurements. Most significantly, the net surface charge and how it changes with distance and solution pH strongly depend on whether the gradients in amine and thiol align or oppose each other. The aligned multicomponent gradients show the most interesting behavior in that there appears to be a point at pH ∼ 6.5 where surface charge remains constant with distance. Setting the pH above or below this transition point leads to changes in the direction of charge variation along the length of the substrate.

Features of Structurization During Sintering of Compacts from a Multicomponent Ti–Cr–Fe–Ni–Cu Charge

A heterophase alloy with hardness 103 HRB and a porosity of ~5% is produced by sintering compacts from a Ti–Cr–Fe–Ni–Cu multicomponent charge. It is demonstrated that after sintering a mixture of elemental powders, four phases with different types of lattice are formed: (i) two multicomponent phases with FCC-lattice, (ii) one Cr–Fe phase with BCC-lattice, and (iii) one phase with HCP-lattice with crystallographic constants based on titanium lattice. Well-defined peaks of Cr2Ti, Fe2Ti, and Ni3Ti intermetallides are seen in the X-ray photograph of the alloy.

Computational Fluid Dynamics Study on the High Temperature Proton Exchange Membrane Fuel Cell

A two-dimensional non-isothermal steady state numerical model for high temperature polymer exchange membrane fuel cell based on Nafion212/SiO2 composite membrane was developed. Finite element method was used to solve electrochemical kinetics coupled with multi-component transport, flow, charge balance and energy conservation. The model-predicted fuel cell polarization curve was compared with published experimental result and a good agreement was found. The distributions of species and temperature in the fuel cell were predicted and the effects of the operational pressure and the porosity of gas diffusion layer on the performance of high temperature polymer exchange membrane were evaluated. A temperature rise of 5.8K was deserved when the operational pressure was 2atm, cathode relative humidity 59% and current density 500mA cm-2. The increasing of the operational pressure and the porosity of gas diffusion layer were found to be beneficial to the fuel cell performance.

Comparing Charge Transport Predictions for a Ternary Electrolyte Using the Maxwell–Stefan and Nernst–Planck Equations

In this work, we investigate and compare the Maxwell–Stefan and Nernst–Planck equations for modeling multicomponent charge transport in liquid electrolytes. Specifically, we consider charge transport in the ternary electrolyte originally found in dye-sensitized solar cells. We employ molecular dynamics simulations to obtain the Maxwell–Stefan diffusivities for this electrolyte. These simulated diffusion coefficients are used in a multicomponent charge transport model based on the Maxwell–Stefan equations, and this is compared to a Nernst–Planck based model which employs binary diffusion coefficients sourced from the literature. We show that significant differences between the electrolyte concentrations at electrode interfaces, as predicted by the Maxwell–Stefan and Nernst–Planck models, can occur. We find that these differences are driven by a pressure term that appears in the Maxwell–Stefan equations. We also investigate what effects the Maxwell–Stefan diffusivities have on the simulated charge transport. By incorporating binary diffusivities found in the literature into the Maxwell–Stefan framework, we show that the simulated transient concentration profiles depend on the diffusivities; however, the simulated equilibrium profiles remain unaffected.