Vol 60, No 1 (2017)
View or download the full issue
PDF (Russian)
RESOURCE SAVING IN FERROUS METALLURGY
5-12 934
Abstract
The problem of using dump slag in steelmaking production as an industrial source of metallurgical raw materials still has no practical decision and it demands new approaches and ideas. Disposal of slag can be organized so that the result is not only building materials, but metal, suitable for further processing and use in recent years are shown. The purpose of the current work is theoretical study of opportunity and feasibility of steel-melting slag recovery processing to receive metal and oxide phases, which can be used in metallurgy and construction industry. The object of the experimental study was the slag from slag dumps of Zlatoust metallurgical plant (Russian Federation). The programming complex “FactSage” (version 6.4) was used for thermodynamic modeling of the recovery processes of slag dumps. Slag recovery of three diff erent compositions with diff erent content of FeO (15, 10 and 5 wt.%) was modeled. Modeling was performed for the temperature range of 750–1650 °C in step of 5 °C at the pressure gas phase, equal to 0.1 MPa. Excessive amounts of carbon were introduced into the system as a reducing agent in the modeling. The main results of the calculations carried-out for convenience of the analysis are shown in the form of dependences of various characte ristics on temperature. The modeling results show in particular that at temperatures above 1340 °C the iron is recovered and goes into the composition of the melt almost completely. Nickel and copper behave similarly. Total recovery of manganese in the composition of the molten metal during the recovery with carbon will not happen. An app reciable amount of manganese remains in the slag composition and gas even at maximum extraction of manganese in the metal. Assessment of the volumes of gaseous substances formed in the process of recovery at diff erent temperatures was carried out. The modeling results indicate that carbon monoxide will dominate the gas phase composition in all the temperature range. Information about the enthalpy change of the system depending on temperature was obtained and allows to assess the costs of thermal energy required to bring the system to the state in which recovery processes become possible.
METALLURGICAL TECHNOLOGIES
13-18 708
Abstract
Ray tracing is used in radiative heat transfer calculations for utilizing presence ray obstructions and for view factors calculation. Ray tracing with finite-element mesh supposes determination of traversed cells and intersected faces along the ray. In standard ray tracing next cell is determined by searching cell’s intersected face among several cell faces. A new accelerated method of ray tracing is proposed. The method is based on assumption that track of each current ray is close to track of previous ray and current ray may intersect the same faces and cells as previous ray does. For current ray and current cell the face is firstly checked for intersection which was intersected by previous ray. If ray intersects that face, other faces are not checked. If ray doesn’t intersect checked face, remain faces are checked like with standard method. Proposed method was tested for view factors calculation with model of sectional furnace with hexahedral mesh. Both deterministic and Monte-Carlo methods were used for choosing ray directions. Various numbers of rays were tested to emit from each mesh face that involves in radiative heat transfer (furnace bounds, surface of billets and roll). The method gives acceleration if ray directions are chosen deterministically, and the acceleration increases as number of rays increases. It is shown that in many cases (from 19.6 % to 71.4 %) it is enough to check intersection with only one of five faces, and first checked face is intersected by checked ray. The method doesn’t aff ect the accuracy and gives up to 30 % of acceleration.
19-23 656
Abstract
The problem of gas movement and temperature distribution in the blast furnace is considered. Due to signifi cant nonlinearity differential equations of gas mechanics and the heat transfer (described in the Part 1) the problem was solved under the assumption of axisymmetric fl ow in the variable “vorticity – stream function”. The boundary conditions of the problem involve the calculations of vorticity and temperature on the oven walls at the level of the grist and hearth. The dependences of the coolant thermal properties on the pressure and temperature are taken into account in the calculations. The gas flow parameters (blast and gas tuyere hearth) for laminar fl ow and turbulent regime are described. Constitutive equations of reformulated mathematical model were solved numerically using of the method of successive over relaxation (PVR). Also, the problem of determining the thermal gas parameters in the hearth of a blast furnace was solved with the use of mathematical model previously developed at the chair.
24-29 636
Abstract
A mathematical model for finding the nature of the liquid metal motion in the section mold and its speed near the solidifying crust was made on the basis of the theory of free and limited submerged jet. The authors have selected the mathematical model to determine the heat fl ux when moving superheated liquid steel at a predetermined speed along the two-phase boundary. Therefore, the mathematical model was proposed to find the changes in the thickness of the ingot crust along the height of profiled square mold on diff erent surfaces and in its output around its perimeter with a horizontal displacement of the axis of the jet of the metal fed into the mold. Computer modeling of the asymmetry of crust growth along the perimeter and the height of the shell of the section mold with square section of 150×150 was made at the displacement of axis of the open metal jet. It was established that the horizontal displacement of the axis of the metal open jet of 40 mm may lead to a local change in thickness of the crust at the outlet of the mold on the left side up to 2 mm.
INNOVATIONS IN METALLURGICAL INDUSTRIAL AND LABORATORY EQUIPMENT, TECHNOLOGIES AND MATERIALS
30-35 950
Abstract
A theoretical method is proposed to predict the service life of metallurgical machinery parts according to the safety criterion of materials without the use of experimental data. It is based on the method of setting and solving the boundary value problems of the physical theory of mechanical systems element reliability rate. The main task of the research was to describe the process of formation of an element failure represented as a system of basic equations of the theory of parametric reliability of technical objects with the kinetic equation of its degradation (aging or defectiveness) in the process of future operation. The following equations are formed for the selected state parameter of the studied object as the basic equations of the theory of reliability: the equation of its evolution, the transition equation in limit state and the equation for calculation of design service life. The type of degradation equation is determined by the given conditions of loading of the product and the conjecturable criterion of its destruction. V.V. Fedorov’s fundamental equation of the thermodynamic theory of strength is used as degradation equation for the machinery parts in which static or cyclic loading conditions require their external probability of failure on the criteria of volume destruction. The universal dependence to calculate the average speed of damage to the structure of the most loaded volume of the test element in stationary loading conditions is proposed on its basis. The coeffi cient was calculated to take into account the resistance of the material structure according to Le Chatelier’s principle for the entire period of loading process until the destruction is detected. Energy-dependent basic mechanical concept of friction units is used as the degradation equation for details of machines operating under boundary friction. It is derived on the basis of the joint solution of the equations of energy and structural-molecular-mechanical theory of friction and allows us to evaluate the wear rate of frictional elements in steady-state conditions of friction engagement without experimental studies. The proposed method of analytical assessment of the predicted life (project life) of machinery parts is used in practice to increase the wearing quality of a number of metallurgical units as a method of formulating and solving boundary value problems of the physical theory of reliability on criteria for strength and total operation time of materials.
36-42 1794
Abstract
An original manufacturing technology of diamind drill bits with up to 212 mm at pressures up to 1.5 GPa and temperatures up to 1250 °C was developed. The bits were produced by sintering in a heat insulating jacket, an electrical insulating casing with electri cal heaters in a steel high pressure cell for 120 min. In the manufacture of drill bits by sintering under high pressure in steel HPC it was found that the sintering process is productive and apparatus for it can be used repeatedly. It can be used steel casing for pressing the diamond matrix material on it. The whole body can be made of diamond powder or holes for fi xing of diamonds by the subsequent soldering or by mechanical method. The authors have developed and manufactured a piston-cylinder type of HPC with a working diameter up to 280 mm by a high-pressure chamber. Also they have made a bit of model cutting elements such as polycrystalline carbonado diamonds and have tested their performance properties. When drilling of marble unit at load of 50 kN and the revolutions number of 355 rev/min the mechanical speed was reached up to 20 m/h. It was found that the developed technology allows to keep cutting properties such as carbonado diamonds have, which are analogues of PCD for thermal stability. Strength bit performance allows its operation under the most intense power drilling modes; metal-ceramic matrix provides a reliable fastening of the cutting elements. Carbonado is wear resistant and has high strength. This technology is energy effi cient, environmentally friendly and productive, as the technology can be used for the manufacture of metalceramic wear-resistant, corrosion-resistant casing bit and then fi xing it in the diamond cutting elements by soldering, or mechanical fastening, using a diamond composite materials of PCD types with diff erent thermal stability.
INFORMATION TECHNOLOGIES AND AUTOMATIC CONTROL IN FERROUS METALLURGY
PHYSICO-CHEMICAL BASICS OF METALLURGICAL PROCESSES
43-47 584
Abstract
Behavior of AISI 1020 steel at dry sliding against AISI 1045 steel under electric current of high density was studied. The plastic deformation of surface layer, its temperature increasing, appearance of new phases and structure defects occur in these conditions. It leads to formation of friction induced structures layer. Contact current density is the main deterioration factor of external action on surface layer. It is shown that average contact temperature and thickness of friction induced structure layer increase at current density increasing. The character of change of wear intensity and electric conductance at changing of contact temperature is represented. It is established that wear intensity linearly depends on the contact temperature at normal wear regime. It is noted that regime of catastrophic wear is revealed as sharp increasing of wear intensity and synchronous decreasing of electric contact conductance at contact temperature of 500–600 °C. The thickness of friction induced structure layer achieved the value of 50 μm in these conditions.
48-53 721
Abstract
Density and surface tension of ferronickel and oxidized Nickel ore melts are measured. Interfacial tension at this phases border at the 0 – 100 mas. % of nickel content in the metal phase and temperature range 1550 – 1750 °С is measured as well. Experimental results are generalized in the form of functional dependencies relating density, surface and interfacial tension with temperature and composition. The obtained data may be used for metallic phase formation processes analysis at the barbotage treatment of oxidized Nickel ore by carbon monoxide. Density and surface tension of the molten ferronickel (0 – 100 % Ni), and oxidized nickel ore melts (mas. %: 14.8 Fetotal , 7.1 FeO, 13.2 Fe2 O3 , 1.4 CaO, 16.2 MgO, 54.5 SiO2 , 4.8 Al2 O3 , 1.5 NiO, 1.2 Cr2 O3 ) are measured by the of sessile drop method as well as the interfacial tension at the interface boundary in the 1550 – 1750 °C temperature interval. This alloys density varies from 7700 to 6900 kg/m3 , oxide melt density – from 2250 to 1750 kg/m2 , surface tension – from 310 to 290 mJ/m2 . Obtained results agree well with the literature data. Functional temperature and concentration dependencies of density, surface and interfacial tension of the melts are presented. Temperature and concentration dependencies of the alloys meet fi rst order equations. Similar form has temperature dependence of surface and interfacial tension, while concentration dependence on nickel corresponds to the second order equation. The density and surface tension of the oxide melt meet linearly temperature dependence. The obtained results are supposed to use for description of metal phase formation in barbotage process of oxide melt by carbon monoxide.
54-59 885
Abstract
High phosphorus content in chromium steels causes reducing of the service characteristics and increasing of steel liability to brittle fracture. It is known that the process of dephosphoration in reducing conditions by treating the metal with calcium or REM depends on the possibility of retention of these elements in the melt, where the loss of chromium by this process do not exist. This work presents results of the study of dephosphorization of chromium steel (13 % Cr) by slag mixtures containing rare earth metals. The proposed thermodynamic model confi rmed the possibility of dephosphoration of high-alloyed steels with low contents of carbon, when other ways to get it are not possible. The experiments were performed in a resistance furnace with a graphite heater, argon was used as a protective atmosphere at a temperature of 1600 °C. After melting of the metal the mixture of the slag was added for 5 minutes. Moreover, the main infl uence on this process has an oxidation potential of the system “metal – slag”, which in turn is determined by the aluminum content in the steel. The volume of removed phosphorus increases with increasing content of rare earth metals oxides in the slag mixture. When this content reaches 40 % of rare earth metals oxides in the slag mixture (slag ratio 0.03) the volume of removed phosphorus amounts to 0.007 %, which corresponds to the dephosphoration degree of 20 %. When slag-metal ratio is 0.1 and 20 % of rare earth oxides in the slag, the phosphorus concentration is reduced to 0.014 %, i.e. by 36 %. The experimental data on dephosphoration on chromium-containing metal are consistent with the calculated data under the assumption of phosphorus transfer into the slag in the form of cerium phosphide. After the replacement of rare earth oxides (REO) to CaO the reduction ratio (% REO)/(% CaO) the degree of dephosphoration in the beginning is not changed, then, since (% REO)/(% CaO) = 0,67 it is rapidly declining, despite the fact that the concentration of aluminum in the metal does not change. It was noticed, that increasing of the REO content in the slag higher than 25 % is not economically attractive, as the degree of dephosphorization is constant.
SUPERDUTY STEEL
60-66 1108
Abstract
The article off ers a short review of iron and steel production history. The new metallurgy – metallurgy under [gas] pressure (MP) comes into existence at the end of 20th century and in authors’ opinion even at this early stage of its development MP is already showing many advantages to both conventional metallurgy (CM) and vacuum metallurgy (VM) such as: increase of the yield strength in four times with the rest of the uniquely retained steel properties; decrease or complete elimination of some expensive alloying elements (Ni, Mo, Co, W, etc.); possibility of using unconventional alloying elements (Ca, Zn, Pb, etc.); being highly ecological; its stable development, etc. Because of that it is to be expected that the development of MP will lead to a breakthrough in the areas of quality and special metallurgy. Out of all known to date MP methods, big steelmaking bath (BSB) process is considered to be the most promising of all.
ECONOMIC EFFICIENCY OF METALLURGICAL PRODUCTION
67-73 921
Abstract
The article defi nes and characterizes the factors and the degree of infl uence of foreign direct investment (FDI) in the ferrous metallurgy. To do this, the authors consistently have solved the following tasks: identifi cation of FDI factors that aff ect the performance of the steel industry; building an econometric regression model for the main companies of ferrous metallurgy of the Russian Federation on the basis of publicly available information and interpretation of the results of economic and statistical models. When writing the work the authors have used the methods of comparative analysis and synthesis of information received from various sources. Content analysis of analytical materials of leading domestic and foreign media has recently been carried out. Also, statistical data analysis was conducted on the basis of which (panel data) regression model was compiled, evaluated the method of least squares, which explains (dependent) variable advocated total revenue of metallurgical enterprises and explanatory (independent) – the amount of FDI, capital and materials in the enterprise. The study concludes that foreign direct investment is an important component of economic development and ferrous metallurgy. The positive eff ect of foreign direct investment is for large metallurgical enterprises, which have a larger share of foreign capital. The presented provisions and the conclusions of the work can be applied to the management of metallurgical holdings for the purpose of theoretical foundation of corporate development programs, as well as to the regional authority of executive power to identify ways of increasing the investment attractiveness of the region.
74-79 712
Abstract
The significance of the metallurgical industry for the economy of Russia is noted in the vector of new industrialization. At the same time the structural changes of the consumer market of metal products are clarified taking into account the conservation of the energy sector as part of prospective customers. The relevance of spatial integration of branch markets is described according to the problem of new industrialization of the national economy. Model-based evaluation of the integration of the domestic consumer market, proposed by K.P. Glushchenko, conducted an analysis of interregional integration of submarkets of metal production of varied quality, focused on the construction and energy sectors as an example of branch markets. The criteria for assessing the metallurgical products market integration is the law of one price, involving the establishment of a single price for identical goods in the territory of different segments of spatially-separated market in the absence of obstacles to the movement of goods between them. Autoregression (AR) model was constructed and it allowed to estimate the rate of prices convergence for each federal district to the national average, as well as to other districts. This approach allowed us to compare the branch markets of high-tech, qualitative and traditional metal by the spatial integration level. The results showed fairly low integration level of the regions in all three submarkets. In this case, for each of them is observed a different structure of integration interactions. According to the results of the study, a map of the spatial integration was compiled for the high-tech metal product market focused on the oil and gas sector, which refl ects the convergence of territories by the price level convergence in the time series model. It was found that there is no infl uence of geographical remoteness of the market segments in the speed of convergence of prices between regions. It was concluded that there is the possibility of considering indicators of spatial integration of industrial markets for assessing the external environment uncertainties in the implementation of the new industrialization of Russia’s economic strategy. The development of integration ties helps to reduce market risks and to create positive multiplicative and synergistic effects.
BASED ON THE MATERIALS OF THE 7TH EUROPEAN SINTERING & IRONMAKING CONGRESS
80-85 625
Abstract
At the European congress held on September 12-14, 2016 in Linz major attention was given to the prospects of iron metallurgy development. The fl ow “blast furnace – basic oxygen furnace” is expected to remain the main steelmaking process giving way to steelmaking in electrical furnaces starting from 1960s. Development of hydrogen metal lurgy and occurrence of industrial microbial fermentation of metallurgical gases with subsequent production of ethanol and other chemical products from them are forecast.
ISSN 0368-0797 (Print)
ISSN 2410-2091 (Online)
ISSN 2410-2091 (Online)