INTERNATIONAL SYMPOSIUM ON ADVANCED SUSTAINABLE IRON AND STEEL MAKING

In this paper the multiphase transient multi-dimensional mathematical model of the blast furnace is applied to analyze small coke based compact blast furnace process operating with hydrogen injection into a second level of tuyeres. The hydrogen injection into the shaft of the furnace drastically modify in furnace conditions and only comprehensive models can accurately estimate the effective inner conditions and stability of the process. The model is based on transport equations of momentum, energy and chemical species describing a five phase system coupled with additional relations for interphase momentum, heat and chemical reactions rates. The set of differential equations are iteratively solved based on the finite volume method discretization procedure for a general coordinate system. Four cases of stable all pellets operations are studied: I) Base case with small coke and 100 kg/t of PCI; Ii) 10% of the reducing gas replaced by H2 at the second level of raceway; Iii) 20 % of the reducing gas replaced by H2 and iv) 30% of the reducing gas replaced by H2. Under the above simulation conditions, it was found out that is possible to enhance the furnace performance and decrease the specific emissions of CO/CO2. The results indicated that high amount of reducing gas replacement by H2 is possible if fine adjustments of the blast conditions is carried out. In this investigation was found that up to 50% of the replacement is feasible with smooth operation, in contrast, higher amount presented unstable operation mainly due to deterioration of the inner gas thermo physical properties which strongly affects the rates of heat and chemical reactions in the shaft region

This paper aims to propose to present a theoretical and experimental analysis of the optimizing procedures of the electric arc furnaces in the case of valorization by recirculation of the secondary powder materials, resulted from steel industry in primary technological fluxes. Based on this analysis we proposed a new technology for efficient valorization of the secondary materials resources by realizing cold auto reducing briquettes chargeable in the electric arc furnaces. Based on the tests that we used for these briquettes it was established that these powder materials can fulfill the function of replacing scrap iron as well as the ecological – economic function if the ration between the new and normal technology is under unit.

Nitrogen pickup in steel melt can take place in different stages of steel making and this is important in respect of grades which have stringent standards in respect of Nitrogen content. In this work, Nitrogen pickup between tapping from Oxygen converter to steel delivery to secondary steelmaking stations has been analyzed on the basis of data from Arcelor Mittal-Tubarão steel plant situated in Vitoria , Brazil. A model for the entry of Nitrogen through the plume eye in the ladle during injection of Argon used for rinsing has been applied using data from the plant. Nitrogen pickup seems to be influenced by the steel grade, like steel for appliances, IF steels, API steels etc. Additions, especially aluminium used for deoxidation, have a strong influence on the absorption of Nitrogen particularly in the in the case of API steels . There is also Nitrogen pickup , due to Argon gas injection in the ladle, through the plume eye . Ladle slag plays an important role acting as thermal and chemical insulator in this process. The results of the model based on incorporation of Nitrogen through plume eye together with the pickup from other sources have been analyzed and compared with the industrial data.

The solidification and cooling of a continuously cast slab and the simultaneous heating of the mold is a very complicated problem of three-dimensional (3D) transient heat and mass transfer. The solving of such a problem is impossible without numerical models of the temperature field of the concasting itself while it is being processed through the concasting machine. Experimental research and measurements have to take place simultaneously with numerical computation, not only to be confronted with the numerical model but also to make it more accurate throughout the process. An important area of the caster is the so-called secondary cooling zone, which is subdivided into thirteen sections, where the first section uses water jets from all sides of the concasting and the remaining twelve sections engage air-water cooling jets positioned only on the upper and lower sides of the concasting. In the secondary-cooling zone, where the slab is beginning to straighten out the breakout of the steel can occur in points of increased local chemical and temperature heterogeneity of the steel, from increased tension as a result of the bending of the slab and also from a high local concentration of non-metal, slag inclusions. Especially dangerous are the changes in the chemical composition of the steel during the actual concasting. In the case of two melts one immediately after the other, this could lead to immediate interruption in the concasting and a breakout. The material, physical, chemical and technological parameters, which both melts differed in were determined. If the dimensionless analysis is applied for assessing and reducing the number of these parameters, then it is possible to express the level of risk of breakout as a function of five dimensionless criteria.

Lateral movement of a strip is typical problem in rolling mill process which results in quality deterioration of products and in worst case, a fatal accident that may harm workers. It is a cause of instability of rolling process and as a result, trouble related with decrease of productivity is more likely happen. In this paper, according to the linear mathematical model of lateral movement, a feedback law considering stability and disturbance tolerance of the closed loop system with actuator saturation is proposed. For a linear system, one of the suitable measurements of disturbance rejection is using L2 gain, the ratio of the L2 norm between disturbance and system output. However, sufficiently large disturbance may cause the state and output of the system unbounded. In this paper, degree of disturbance is represented as the bounded energy concept. The first step of the proposed control method is getting maximum disturbance energy such that the state will be bounded for. The second step is getting disturbance rejection capability which is measured by the restricted L2 gain over a given bounded disturbance energy. These approaches are based on constrained optimization problems with two nested ellipsoid. Optimization problem which makes state trajectories starting from the point inside of an ellipsoid to stay in the outer ellipsoid with bounded disturbance energy is formulated to the LMI optimization problem. Solving LMI problem where the feedback gain is free parameter, feedback gain of the lateral movement system with actuator saturation is presented. Numerical examples are shown to confirm the efficiency of proposed control algorithm in lateral movement problem.

We have applied high current density and short duration electric current pulses to deformed carbon steels at room temperature, and obtained significant refined microstructures and improved mechanical properties. This presentation will demonstrate the experimental results at various processing conditions and the theoretical understanding of the observed phenomena.

Brazil is the largest producer of charcoal pig iron in the world, also called "green pig iron ". With an installed capacity of approximately 15 millions tons/year, two major types of Brazilian companies, the "integrated steelmakers" and the "independent ironmaking producers", perform efficiently the iron ore reduction in charcoal blast furnaces, with capacities ranging from 25000 to 300000 ton/year of hot metal. The first Brazilian charcoal blast furnace was installed in 1888 and the integrated steelmaking charcoal plant (Belgo Mineira Company), in 1937. Considering the last ten years, the share for the average production of 10 millions tons/year was 15% for the former and 85% for the independent producers. This work intends to present the Brazilian scenario regarding the pig iron production during the last years, and also to describe some characteristics of the charcoal blast furnace technology. Additionally, considerations will be made concerning two case studies regarding the mini blast furnace.

Replacing or producing part of the traditional coke ironmaking by renewable energy source can avoid using around 0.45 t of carbon from fossil source which represents 1,65t of CO2 emission after total combustion. Brazil, unlike in almost other ironmaking producing countries, already contributes and presents a potential for higher contribution in charcoal ironmaking. This is due to the large extension of native forests, the availability of land suitable for forest plantations, excellent sun energy and water, which have allowed charcoal production at low cost. Presently, in Brazil, 30% of the total 35Mt/year of pig iron production comes from charcoal based native technology. Many “Mini Blast Furnace� each one with capacity from 20,000 up to 300,000 t/year of pig iron produces them. Many developments, based on technology adopted in coke Blast Furnaces, have been lead to better performance of these Mini Blast Furnaces. On the other hand, the productivity evolution on planted forest of eucalyptus has been increased, over last 30 years, from 20 to 41 m3/ha. Year, and it is expecting to achieve 60 m3/ha. Year up to year 2020. Presently the main constraints, in Brazil, are on charcoal making technology, which is mostly based on ancient ones and the capital cost for 6 to 7 years growing plantations A mandatory regulatory new policy should consider the similar mechanism like carbon credit for charcoal production development and as a source for capital.

In the present paper, the technologies to control inclusions are reviewed in particular focusing on the recent progress. In stainless steels, spinel inclusions are recognized to be harmful not only for practices, sometimes causing nozzle clogging at a continuous caster, but also for product in which defects occasionally appear. The ways how spinel inclusions can be prevented are shown from the view points of thermodynamics and kinetics. Higher cleanliness is required for some electronic devices. Effects of inclusion state on some properties necessary for these alloys are explained showing the examples of Fe-42%Ni alloy for lead frames and Fe-80%Ni-5%Mo alloy for soft magnetic materials. Further, it is demonstrated that corrosion is sometimes initiated around inclusions on strip surface. In addition, positive application of inclusions to improve mechanical property of some steels is shown. Lastly, difficulties in evaluation of cleanliness are mentioned due to achievement of higher cleanliness brought by the recent progress in refining technologies.

Questions of the mathematical exposition of gas dynamics, heat exchange, mass exchange and the reduction phenomena in the dense bed, occuring at blast furnace smelting in their interrelations, and applications of the mathematical exposition for studying the processes determining reduction of metals from iron ores are considered. The condition of non-uniform two-dimensional movement is taken into account at the formulation of a problem of movement of gas. The account of the phenomena gas dynamics in addition to the phenomena heat and mass transfer and reduction of metals from oxides has allowed to use the module of velocity of gas at the analysis of the last. The integral transfer coefficient depending on coefficient of interior diffusion is injected into combined equations of mass transfer and reduction. Influence of magnitude of an integral transfer coefficient on character of two-dimensional fields - degrees of reduction of iron and concentration potentials of gas in shaft of a blast furnace is investigated. Processes of reduction define economy of blast furnace smelting. Examples of practical use of models are resulted.

Within the non-ferrous metal processing industry, stainless steel can be considered for parts that require a material with good chemical and mechanical properties at high temperature. One example is the lance inserted in the molten slag bath of an Isasmelt furnace to inject air, or oxygen-enriched air, into the slag. The use of stainless steel as lance material relies for a large part on the resistance of the material against the, often corrosive, slag. Within this framework, the interaction between PbO-CaO-SiO2 based slag and stainless steel grades with 18 to 26 wt. % Cr and 0 to 19 wt. % Ni is experimentally investigated. The PbO/SiO2 and CaO/SiO2 ratios of the slag are varied from 2.9 to 12.9 and from 0.03 to 0.2, respectively. Stainless steel samples are immersed in the slag at 1200°C during 3 hours. Thereafter they are analyzed with Scanning Electron Microscopy. In contact with pure PbO-CaO-SiO2 slag, both oxidation and liquid metal corrosion of the stainless steel through the reduction of PbO to Pb are identified as degradation phenomena. An increase in Cr content of the steel from 18 to 26 wt. % for low Ni content enables the formation and presence of a Cr2O3 layer that prevents contact between the liquid Pb and the steel. For similar Cr content but with increasing Ni content, the Cr2O3 layer loses its protective character. The steel is subject to degradation through liquid metal corrosion due to the high solubility of Ni in liquid Pb. The highest degradation rates are observed for the highest PbO/SiO2 ratio. The CaO/SiO2 ratio appears to have less influence. The addition of S to PbO-CaO-SiO2 slag influences the degradation behavior of the steel grades with low Ni content through the formation of chromium containing sulfides. This consumption of Cr decreases the tendency of the steel grade to form a protective Cr2O3 layer. Once the steel is subject to liquid metal corrosion, the sulfides form preferential penetration paths for the liquid Pb. The formation of a liquid (Ni, Pb) matte phase is considered to be responsible for the fast degradation of the steel grades with the highest Ni contents.

The lateral movement of the strip is defined by the distance between the centers of the strip and the roll. It caused by off-center rolling, entry side wedge, temperature difference along the strip width direction and an initial off-center. When asymmetric conditions such as temperature, roll gap, the friction coefficient occur, speed difference is generated. It causes lateral movement. It is also called snake motion because its motion appears to zigzag. Strip steering is important problem because it leads to strip tearing in extreme case and it reduces productivity. Control methods for lateral movement have been studied to reduce this problem. State feedback control, PID control, sliding mode control and fuzzy control have been studied. Recently, Choi et al. Proposed mathematical model for lateral movement of strip and used the PID sliding mode control to reduce lateral movement and to improve performance. However, this solution did not consider time delay when the output is measured. In various systems, time-delays frequently make system unstable. The lateral movement of strip is also measured with time-delay in strip rolling process. In this paper, time-delay is considered to make the steering system stable. Mathematical model for the lateral movement of strip is solved as linear system with input delay. State derivative feedback is applied to the input time-delay system. Based on Lyapunov-Krasovskii theory, bilinear matrix inequalities are constructed to guarantee the asymptotic stability. State and state derivative feedback gain are solved iteratively not only depending on constant delay information but also satisfying H infinity performance. The results demonstrate that the proposed approach is suitable to control strip steering when the output measure has time-delay.

FLSmidth is under taking developing a process to direct treatment of magnetite ore. After magnetic ore separation, two pyrometallurgical options are evaluated to reduce Iron and decrease the phosphorous content in the final product. Magnetic separation, iron water vapor reduction with enriched hydrogen is tested. A thermodynamic and experimental investigation to develop a new process to extract Iron from their ores is then carried out. Iron sample with 40-48% Fe and levels of 0.3-0.9% of P are tested to obtain a metallic iron product of > 90% and less than 0.05% of P. The kinetics of the reaction are determined by measuring the weight change of a sample with time in water vapor at temperatures between 1000-1350oC.

The paper begins with a classification of the functional and constructive variants for the EAF’s charge preheating plants. The classification’s most important criteria is the proceeding’s technical-economical efficiency. The original optimisation mathematical model of the electric arc furnace’s charge preheating process mainly takes into considers 2 thermo-technological aspects: The heat transfer between fluids and particles and the heat transfer between the fizz layer and an exchange surface. On the basis of the energetically balance at the gaseous environment level, the conductive transfer model is also analysed through the finished elements method. The mathematical model’s results are presented as the analysis and quantification of the thermo gradients obtained during the charge preheating process. These thermo gradients are determined for various temporal moments and for different capacities of the electric arc furnace.

The iron ore sintering technology is a well established process in use at the integrated steel plant. The process is complex involving various physical and chemical phenomena. The raw materials used can vary to a wide extent, from iron ore to dust and solid residues from the steel plant. The process takes place in a moving strand where a mixture of iron ore (sinter feed), fine coke, limestone and water is continuously charged to form a thick bed of approximately 80cm. Along the first meters of the strand the charge is ignited by gas burners. The hot gas, generated by the combustion of natural gas with air, is then sucked in through the packed bed from the wind boxes placed below the grate. The combustion of coke breeze or alternative fuels begins at the top of the layers, and as it moves, a relative narrow band of ignition zone moves down through the bed. Several chemical reactions and phase transformations take place within the bed, part of the materials melt when the local temperature reaches the melting temperature and as it moves, the solidification process is completed. The partial melting and diffusion within the materials promotes the particle agglomeration forming a porous sinter cake. Recently, it has been proposed to reuse the outlet gas with a preconditioning system which use a gas fuel like coke oven or natural gas which furnish preheating gas and heat input to the sintering zone. The physicochemical and thermal phenomena involved are complex and numerous. Special mention is made to the phenomena of gas flow through the porous bed, gas-solid heat transfer, drying and several chemical reactions and phase transformations1-3). When recycling solid waste a special concern is due to the chlorides presents into the solid wastes which decomposes into the bed and can be precursor of PCDD/F3-5). In this analysis 5 tests of raw materials are considered: I) base case of actual operation; Ii) 5 t/h of solid waste with 1.5% of chlorites with conventional operation practice; Iii) 5 t/h of solid waste in the mix of raw materials with 3% of chlorites; Iv) 5 t/h of solid waste with 3% of chlorites and precondioned gas at 600 oC and 5% of CO2 and 2%of CH4; V) 5 t/h of solid waste with 3% of chlorites and preconditioned gas at 600 oC and 5% of CO2 and 5% of CH4. The above cases were tested in a multiphase mathematical model which takes into account coupled phenomena of momentum, energy and chemical reactions. The model predictions indicated that in all cases wider sintering zones are obtained and the formation of calcium ferrite are increased. The productivity of the sinter strand could be increased and the proposed amount of waste solid recycling would not strongly affect the total amount of PCDD/F generation. In the cases of gas recycling the total amount of PCDD/F decreased

Inclusions in specimens taken from continuously cast slabs of 304 stainless steels were observed to evaluate their maximum size in a unit area. Two different types of slab specimens were sampled to understand the effect of deoxidizer; One was Si/Mn killed and another was Al killed. Statistics of extreme values in a square root of area were applied to comprehensively express the distribution of inclusions. As a result, the distribution of the extreme value of the Si/Mn killed has been found to be larger. The largest size of inclusion detected in 1 mm2 as a unit area ranged between 3 and 17 µm for the Si/Mn killed steel while it ranged between 2 and 5 µm for the Al killed. Thereby, inclusion with maximum size existing in arbitrary area is able to be predicted. Regarding the compositions, inclusions were identified as silicate type for the Si/Mn killed, while those composed of CaO, MgO and Al2O3 were identified for the Al killed. The difference in inclusion compositions is therefore considered to bring the difference in size distributions.

The Fe2O3 particles (150-224 μm diameter) obtained by sintering and crushing were reduced with CO in a laboratory fluidized bed in this study. On account of thermal effect of stepwise reduction reactions from Fe2O3 to Fe, the interesting variation of powder layer temperature was verified through the evolution of ex-endothermal peaks by means of DTA. The sticking time based on the pressure drop was defined to describe the sticking behavior. The results indicated that the sticking occurred during the precipitation stage of metallic iron and XRD analysis found metallic iron in the new sticking particles, therefore, the sticking behaviors was associated with the precipitated iron. The similar sticking phenomenon also appeared during refluidization of the reduced particles with N2, which further proved the above mentioned conclusion. For the same materials, the sticking time decreased with increase of the metallization ratio at the same temperature, due to the larger probability of iron-iron contact with the increase of metallization ratio. However, the influence of the metallization ratio on the sticking time strongly depended on the fluidization temperature. Apart form the precipitation kinetics, the temperature determined the thermal characteristic of the newly precipitated iron, such as its surface tension or viscosity. Maybe the thermodynamic factors were more important when judging the sticking behaviors.

The aim of this research work is to study the effect of thermomechanical process on microstructure and properties of structural microalloyed steels, as well as to study of precipitation of carbonitrides because is an important phenomenon influencing the microstructure of microalloyed steels and their corresponding mechanical properties. This is very important for the thermomechanical treatment to be applied to achieved the desired mechanical strength. Processing parameters are considered such as finishing rolling temperature, rolling reduction, cooling rate and their effect on microstructure and mechanical properties of experimental microalloyed steels has been studied by tensile and charpy impact test and optical microscopy. Microalloyed steel with was produced by casting in an electrical induction oven of 25 Kg. Capacity. Carbon content in steel was less than 0.1 %. Steel was processed thermomechanically; reheated to 1250 °C and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 950ºC and a thickness reduction of 80%. It has been found that tensile and impact properties of microalloyed steels are improved by controlled rolling. The cause of such improvement in mechanical properties of steel is correlated with changes in microstructure, i. E. Ferrite grain refinement. Furthermore low carbon content in steel cause improvement in toughness and weldability. This work shows what precipitates are present in steel, the type of precipitates and their morphology. Particles of precipitates of NbC were found by transmission electron microscopy.

Due to the depletion of high grade iron ore and environmental issues, it is required to understand the development and behavior of mineral phases such as the calcium ferrites formed in sintering process for producing high quality sinter ore with low energy consumption. In the present study, the effects of basicity (CaO/SiO2 ratio) and Al2O3 content on the reduction and melting behaviors of main phases (calcium ferrites) in sinter ore were investigated by employing thermogravimetric method (TGA) and confocal scanning laser microscope (CSLM). Constitutional and phase analyses were carried out by using EPMA and XRD measurements. It was found that the reduction and melting behaviors of calcium ferrite phases were significantly affected by the content of gangue materials in sinter as well as the mineralogical characteristics.

Several lab and pilot researches have been conducted during 2006 – 2008 in order to establish the adequate technology for the recycling of electrofilter dust from the electric-arc furnaces. The purpose of this research is to eliminate local air and soil pollution in the electric-arc furnace plants. The objective of this paper work is the design of a dust recycling technology under the current conditions of an existent plant in Romania, which produces approx. 500 tones of dust per year and has inherited an impressive stock of waste dump. This is an original procedure and it is based on specific experimental results and taking into consideration the real case of an electric-furnace steel plant – TMK CS Reşiţa. The pelletizing process for a self-reductant mixture (C ~ 15%), as well as the process of iron and zinc oxides reduction were under study. The dezincation and metallization coating of the mini-pellets obtained from the electriofilter dust enables the iron complete saving and recycling during the steel production process. Additionally, the granulated zinc concentrate, with a concentration of 50-70% ZnO and approx. 10-12% Pb is produced, which is recirculating in the non-ferrous industry. From the Fe concentration (~ 50%) and the metallization coating degree (70%) point of view, as well as the structure of the sterile resulting from the EAF slag, the quality of the metallized iron pellets is compatible to the process of steel production. The recycling costs do not exceed the value of the recovered iron and sterile, while the commercialisation of zinc concentrate (~ 200 kg/tone metallezed pellets) generates a significant profit. The recovery of reductant gas thermal and chemical energy additionally grows the efficiency of the recycling process. -------------------------------------------In the Steel Industry of Romania, near each production 's unit are accumulated istorical dusty waste dumps, powered by about 4,000 tons per month of EAF dust from current steel production. A recycling flux for this waste is not funded yet. A series of laboratory and pilot experimental research proved that recycling of this waste in the Iron metalized pellets form is a efficient funding. Our team designed the technological flow for EAF dust, where as a secondary product results is a marketable concentrate, contained 70 % of zinc oxide and 10 % of metallic lead.

Due to the existing fine copper concentrate particles in the thickener overflow which can’t be reused, the water and copper resources have been wasted for a long time. In this study, the combination of coagulant (PAC and PAFC) with flocculant (N83376) were used to enhance the process of sedimentation of copper concentrate pulp, and the results of the above were compared with those when coagulant and flocculant was used alone. It is suggested that PAC and PAFC were both effective with the combination of N83376, however, excess of PAFC resulted in dispersion of particles. Therefore it was feasible to select PAC and N83376 as final combined reagent. The effectiveness of the coagulant and flocculant were evaluated based on the turbidity and the removal rate of suspended solids (SS) of the supernatant. It can achieve 17.03NTU of turbidity and 94.82% of SS removal rate with 750g/t PAC and 1.25g/t N83376, at pH 9~11. The results of filtration test indicate that the performance of copper concentrate pulp after coagulation-flocculation was improved. The filter rate was 0.45 ml/s faster than without reagent, and the water content of filter cake also decreased 1.84%.

The fabrication and application of a new style cast copper cooling elements for blast furnaces are introduced in this paper. The cooling channel is formed by submerged copper pipes and the dovetail groove on the surface is formed in casting in one step. The liquid copper partially melts submerged copper pipe, forming an integrated block with very high contacting ratio at the interface between the pipe and cast copper. The cooling elements are featured by high thermal conductivity for cooling, high working pressure with no leakage risk and low water flow resistance. The shape of the cooling elements is flexible and is easy to fit the furnace configuration, thus used as not only the flat furnace walls but also complicated components in difficult areas. The cooling elements were installed and in operation in many blast furnaces which had volume from 2000 cubic meter to 5800 cubic meter. With its high quality, SXSG copper cooling elements guarantees the furnaces safe and reliable performance .

Iranian steel production rate reached 11 million tons in 2009. BOF and EAF share in this production were 19.3 and 81.7%, respectively. Iron bearing charging materials of steelmaking units includes sponge iron (65.1%), hot metal (20.2%) and scrap (13.7%) in steelmaking furnaces. Due to limitation of scrap supply, Iranian EAFs work with 90% DRI and 10% scrap rate. In 2009, all sponge iron (8.2 million tons) charged in EAF as cold DRI. In this year, three DRI production units were commissioned in Iran. Each of them has 0.8 million tons capacity per year. According to the latest technology of DRI charging in Iranian EAFs, it’s possible to adopt hot DRI charging in Iranian EAFs. Nowadays, electric energy consumption in Iranian EAFs for charging rate of 90% DRI and 10% scrap is about 630 Kwh/t. L. S. By using HDRI charging process in Iranian EAFs, electrical energy can be saved with a rate of 140 Kwh/t. L. S. For the existing DRI-EAF facilities, usage of insulated containers and pneumatic transportation is recommended. For the forgoing and future projects, it’s recommended to use hot conveyors and direct gravity HDRI charging, respectively. From HSE view, this could reduce CO2 emissions by 10% per ton liquid steel . With adaptation of HDRI charging method in Iranian EAFs, economical saving for existing facilities will be at least 200 million US $ per year.

In metallic materials, even in single crystals, the microstructure is influenced by heterogeneities as inclusions, micro-cracks, grain boundaries and dislocations. The theoretical treatment of such homogeneities in materials deal to a new concept of the driving forces (configurational forces, material forces), developed on the virtual displacements or velocities of the defects. M. E. Gurtin show that the balance of configurational forces is an autonomous law of nature, in contrast to the original worksof Eshelby which say that the constitutive assumptions of the bulk material yields tothe expression of the configurational forces. We deduce the tractional forces developedon the crack tip and we indicate a manner of calculation of configurational forces.

The influence of casting speed variation on non-metallic inclusions in surface layers of IF steel slabs during continuous casting was investigated with OPA (Original Position Statistic Distribution Analysis) method. It was found that, when the casting speed was evenly decreased from 1.4m/min to 0.6m/min, increases of the nonmetallic inclusions owing to the increase of the mold powder entrapment were observed only on those slabs which were cast at the start of casting speed change. While, in experiment of increasing casting speed evenly from 0.6m/min to 1.4m/min, increases of nonmetallic inclusions were observed only on slabs which are cast at the time when the casting speed was stopped to increase after it had been increased to 1.4m/min. For slabs which were cast during the casting speed evenly increasing or decreasing period and at the time when increasing or decreasing the casting speed at low casting speed level (0.6m/min), the influence of casting speed change was very small. In addition, it was found that, at higher casting speed level (1.4m/min), even a little change of casting speed could result in remarkable increase of the non-metallic inclusions. Thus, at high casting speed, changing casting speed should be avoided or using slower speed changing rate. In the study, mathematic simulation was made to the flow in the mold, which also indicated that the flow of the liquid steel was much more largely influenced at the time when the casting speed started to decrease or casting speed increasing is stopped at higher casting speed level.

Supply chain of iron-units for integrated steel plants still follows same historical pattern: Iron-ore from mines to plant site. As plant sites became farther apart from mines, massive long distance and overseas transportation of iron-ore became necessary. Larger bulk carriers, sea ports and railroads became the rule. New challenges to cope with ever increasing cost and environmental constraints, call for a re-design of the supply chain. New technology products as iron granules, from emerging new processes, as Tecnored and others, bring the opportunity to a new pattern: Iron-ore to metallic granules at mine sites or at the iron-ore export ports, shipped to remote steel plants as metalized charge for Blast-furnaces and steel-shops. Use of Primary Energy Melting furnaces, to progressively replace aging remote BFs, shall further enhance coke replacement benefits and power savings in steel plants. This paper puts together an appraisal of these new proposed production models, its economical and environmental positive impacts, plus the new business opportunities, for iron-units marketing and supply, thus associated.

Chemical heterogeneity of elements is predominant cause of imperfections and defects of cast and formed steel products. During crystallisation and solidification of metals and alloys chemical non-homogeneities occur, i. E. Chemical heterogeneities of individual elements, since the elements, both constitutive and tramp elements and admixtures, segregate [1, 2]. Crystallisation occurs in real castings and ingot in comparatively broad zone, in which solid phase separates out in the form of lattices from axes or arms, which form frames of dendrites. Lattice frames of dendrites do not interrupt continuity of the liquid phase, so diffusion can be running in it. This diffusion is, however, much smaller in comparison with diffusion in free melt, since arms of dendrites prevent convection. Under these conditions it is possible to consider the diffusion exchange of admixtures between more distant areas of crystallisation zone as limited or possibly negligible. As a result of incomplete diffusion of admixture in solid phase concentrations of admixtures in solid crystals are not getting balanced and admixtures remain segregated in spaces between arms of dendrites and cause thus dendritic segregation. Due to the fact that mechanism of dendritic segregation is controlled by diffusion processes at the phase boundary liquidus-solidus, its magnitude depends significantly on kinetics of crystallisation. Parameter of back diffusion (the mass Fourier number) occurs in majority of the used micro-segregation models. It characterises diffusion of elements in solid phase in respect to the secondary dendrite arms spacing and to the local time of solidification. The presented paper calculates parameters of back diffusion of determined elements (C, Si, Mn, P a S) in selected areas of cross-section of continuously cast steel billet. Calculations were made with use of our own experimental data, tabulated data and also outputs from the original nonstationary heat model simulating temperature field of billet at solidification and cooling. On the basis of these results it is possible to formulate a hypothesis about influence of cooling rate on back diffusion of investigated elements at solidification of steel billet.

The physical and chemical processes that are developing in the combustion zone of the blast furnace depend on many physical and metallurgical parameters, such as: Blast air flow, oxygen content in blast air, humidity, pressure and blast air flow temperature. The presented mathematical model establishes the correlation between blow parameters mentioned before and a performance function that is sect to reflect precisely the development of the physical and chemical processes in the combustion zone of the blast furnace in case of using various auxiliary combustibles. This performance function is the theoretical temperature of the oxidant zone. The establishment of the model equations was made starting from the functional real data of 1000 m3 blast furnaces.

The blast furnace industry is one of two productions under the base methods of manufacture of steel “the blast furnace - the converter�. Now in the world it is fabricated about 950 million tons of pig-iron per annum, for its production it is spent about 400 million tons of unprofitable and expensive coke per year. Specific coke consumption in the blast furnace smelting and productivity of the blast furnace are substantially defined by processes of heat and mass transfer. Therefore use of mathematical models in study blast furnace smelting, at system engineering monitoring and control of a blast-furnace smelting operation is great importance. The role of mathematical models will increase at a shortage of the information on the phenomena happening in the furnace such as temperatures of material and gas, pressure and composition of gas, a degree of reduction of iron in volume of the furnace. In this paper the modern conceptions about heat and mass transfer in the blast furnaces are given. The two-dimensional mathematical model of heat interchange founded on an original mathematical model of the gas dynamics is presented. In the paper the solution of some problems of the blast furnace smelting having theoretical and practical significance are considered.

The iron ore raw materials and coke quality is the basic reserve of improvement of the blast furnace technology. Some of the quality indicators of iron ore raw materials and coke and their influence on the main parameters of the blast furnace smelting are considered in the paper. The questions of forecasting the technical and economic indicators of the blast furnace smelting are of great importance for development the iron ore raw-material base. The industrial tests are connected with the big material and financial difficulties. Therefore we widely use the following approach: Experimental measuring of the quality indicators of iron ore materials (the reducibility and durability) and coke (the reactivity), calculation of the indicators of the blast furnace smelting (the coke consumption and productivity) by means of the mathematical models. The technique of definition the minimum coke consumption in blast furnace smelting developed by us allows to calculate the reserve of coke economy.

The melting rate of Direct Reduced Iron (DRI) is simulated with the aid of a CFD computational code. Due to the complex nature of DRI it is represented by metallic particles in the simulations. The computational domain includes a realistic geometry as well as multiphase flow conditions. Some of the problems with multiphase flow are indicated in this work. A more fundamental knowledge on the melting rate of metallic particles in a slag-liquid steel system has been obtained with this investigation. The effect of processing variables such as arc length and particle properties such as density, temperature and particle size on the melting rate have been investigated. The results of this work report the melting time of metallic particles as a function of the previous variables.

High-phosphorous-content oolitic hematite ore is one of typical intractable iron ores in China, and conventional beneficiation methods are found impracticable to remove phosphor from the ore effectively. In this study, it can get a better beneficiation index(P content decrease from 0.82% in raw ore to 0.06% in iron concentrate, and total iron grade increases from 43.65% to 90.23%, the recovery of iron can be reached 87%)by reduction roasting with addition of sodium salt followed by two stages of grinding and magnetic separation. Mechanisms of phosphor removal in the beneficiation of high-phosphorous-content oolitic hematite ore by reduction roasting with sodium salt as dephosphorization agent were studied using XRD, SEM, EMPA, and TG-DSC. It is shown that about 20% of the apatite in raw ore is transferred into phosphor and volatilized with the gas in the process of reduction roasting. The rest of apatite is not involved in the reaction of generation of phosphor, and remains in the roasted sample, which is removed to tailings by grinding and magnetic separation. A small amount of phosphor as the phase of apatite exists in wustite of iron concentrate. The oolitic texture of raw ore is partly changed by the reaction between the sodium salt, quartz and kaolinite, which generated sodium aluminosilicate during roasting, and then the apatite and iron produced in reduction roasting can be separated by the process of grinding and magnetic separation.

Quality, warranty and reliability of shipping depends onsustainability and quality of construction of ships. Welding isbasis of any constructive element type withlarge production method in this field of interest. Despite the achievements in the field of technical design and productionmarine resources, yet much remains to be done, since the changesaffected by the use of more constructive elements in our casewelded structures, causing unpredictable damage. In the study we bring through metallographic analysis the evolution ofWelded structures (tegeteve) for Fleet vessels navalForums. On these tests provided the properties of welded connections and condition of the fleet in these important moments for the stateForums.

It was attempted to quantitatively elucidate the effect of FetO content on MgO solubilities in lime-based slags using the measured data of MgO solubility in the slags. The magnesia capacities of the lime-based liquid slags were nicely correlated with the optical basicities in case the ideal solution was assumed for the magnesiowustite saturation phase which is actually in equilibrium with the slags. The substitution of MgO for CaO in lime-based slags increased the activity coefficient of FetO for the constant activity of FetO, resulting in decreasing FetO content in the slags. It is believed that the FetO activities in metallurgical slags containing iron oxide play the decisive role in determining the MgO solubilities into the slags.

Five slag film samples including their slag rims of a single mould flux and its associated mould flux were collected after service during tail out. These slag films were obtained after casting of three different alumina killed steel grades. They were located up to 100 mm down the mould from the meniscus. For all samples distinguishable layers could be observed: In contact with the mould a mainly glassy phase, with little crystallisation, a well crystallised layer and a solidified layer, which had been liquid during casting. Like most of all fluorine containing, silica based mould slags cuspidine is the prevailing crystal phase in the crystalline layer. With increasing Al2O3 contents, due to the contact with alumina alloyed steel grades, nepheline was formed beside cuspidine. Here the change of the cuspidine crystal shape is remarkable. Contrary to the slag films the slag rims consist partly of crystallised slag as well as sintered powder. It was found that the casting temperature is the determining factor for the generated slag rim size that will generate. In addition quench tests of the original mould powders as well as investigations with the hot stage microscope were carried out. DTA and viscometer of the original mould powder and the slag films were performed to reconstruct the microstructure under service conditions and to define a crystallisation sequence. All methods revealed the impact of the Al2O3 pick-up on the crystallisation temperature and the viscosity as well as on the phase composition of the slag films and the crystal shape. Comparing the results of the original slag under laboratory conditions with the results from casting, laboratory tests will give a hint on the slag film structure that will be formed during casting. Chemistry modifications, temperature gradient within the mould and temperature fluctuation during casting have an impact on deviations.

Solidification and cooling of a continuously cast steel and the heating of the mould is a very complicated problem of transient heat and mass transfer. This paper brings new findings in the field of heat and mass transfer during solidification (crystallization) and cooling. Following the thermo physical phenomena and parameters are simulated: Development of latent heat of phase or structural changes, prediction of the character of primary crystallization, speed of casting and its optimization, cooling of the mould, mould oscillation, intensity of cooling in the secondary zone by means of water or water-air nozzles, prediction of the position of the latest solidification. This original 3D numerical model is capable of simulating the temperature field of a caster. The numerical computation has to take place simultaneously with the data acquisition—not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. The utilisation of the numerical model of solidification and cooling plays an indispensable role in practice. This is ensured by the correct process procedure: Real process > input data > numerical analysis > optimisation > correction of process. The presented model is a valuable computational tool and accurate simulator for investigating transient phenomena in caster operations, and for developing control methods, the choice of an optimum cooling strategy to meet all quality requirements, and an assessment of the heat-energy content required for direct rolling.

Phase diagrams (PD) computer models with kinematical and minimal surfaces are the effective devices for the different applied and fundamental tasks in the field of materials science and industrial practice [1]. Mathematical description of surfaces is based on the thermodynamic calculation of one-phase regions borders. Contour of the surface is used to imitate the soap film with the minimal area. T-x-y diagram construction begins with the spacious scheme of monovariant reactions. On this stage the F. Rhines’ comparing of liquidus with the shorthand writing of PD is to be enhanced by the analysis of subsolidus regions. When the surfaces of ruled type, as the borders of 3-phase regions (with the additive directive lines), are built, then the contours of 2-phase regions borders are constructed. As all geometrical elements of PD (points, curves, surfaces, regions) have been coded with the meaningful designation, it is convenient to decipher the experimental graphics and to enquire the errors. Vertical (for the given centre of masses) and horizontal (for the isopleth’s isotherm) material balances help to confirm the results of the microstructures design. A. Prince idea to visualize the 2-phase region with the iron allotropies by the plasticene is improved. In the transparent prism the set of one-phase, two-phase and three-phase regions of different colors, made on the software-ruled machine-bench, demonstrate the structure of PD.

This paper deals with a thermo-chemical model of BOF based on detailed physico-chemical analysis. The model is also to predict the required amount of raw materials to be input for the target carbon content and temperature. The model incorporates empirical relations obtained from plant data to improve accuracy of prediction. The variables such as Whm, Wslag, WCaO, WMgO, WCO2, WO2, WScrap are solved simultaneously with the help of mass and heat balance equations. The results obtained are then plotted for variation of FeO content of the slag with percentage carbon. It is found that for low carbon heats, FeO content is independent of carbon content but it depends on carbon content for high heats. The model also shows the variation of scrap content vs iron ore content required for obtaining the desired heat. This helps to reduce the consumption of scrap vis a vis iron ore. An attempt was made to develop software based on this model. However, when several parameters are changed at the same time, it fails due to non linear process.

The concentration of low grade iron ores is performed by gravity methods for coarser fractions, magnetic separation for the intermediate size range and froth flotation for particles smaller than 150 µm. The depletion of the higher grade deposits is a challenge for the minerals processors, for the liberation between iron oxides and quartz particles requires fine grinding forcing the increased use of flotation. The cationic reverse flotation of iron ores produces two kinds of reject products: Slimes and flotation tailings. Traditionally both products are thickened and disposed into tailings ponds, resulting in significant losses of the valuable minerals. The costs of constructing and maintaining tailings damns is also high. Last but not least, the environmental impact of impounding huge amounts of material must not be disregarded. The use of wet high intensity magnetic separation and reverse cationic flotation, individually or combined, for the production of pellet feed fines from the desliming hydrocyclones overflow and the flotation tailings is addressed. Results from laboratory and pilot plant scale experiments are presented, showing the feasibility of successfully concentrating both reject products.

The iron and steel industry sector has made remarkable progress in the last 40 years to reduce its energy consumption and corresponding greenhouse gas emissions (GHGs). To sustain this progress, unconventional ironmaking routes have been reconsidered in the last 10 years. Indeed, in the context of energy supply constraints, climate change, and GHG emissions mitigation, post-carbon societies are expected to rely on carbon-free electricity, a form of energy not currently associated with iron extraction. Among the possible electrometallurgical technologies is electrolysis, itself a well established production method making tonnage quantities of metals such as aluminium and magnesium. Indeed, in the last ten years both in Europe through ULCOS and in North America under the auspices of the CO2 Breakthrough Program, electrolytic approaches to ironmaking have been the subject of investigation. Following a recitation of the key performance requirements of a disruptive technology capable of tonnage iron production, this presentation describes the special challenges taking a high-temperature electrolytic process from the laboratory bench to industrial scale. Recent advances in the field will be presented, and the remaining scientific questions and technological obstacles to commercialization will be enumerated.

The environment surrounding the iron and steel industry has changed greatly. This paper describes the technology adopted by the Japanese iron and steel industry to cope with changes in global demand, changes in the availability of coal and iron ore resources, correspondence to the extension of plant life, and energy conservation. In addition, efforts to reduce the amount of exhausted CO2 due to environmental concerns are discussed. ・Recent Production Conditions and Changes in Production StructureThe Japanese production of crude steel and pig iron and the transition of the number and the inner volume of the blast furnaces are introduced. ・Changes in the Availability of Coal and Iron Ore Resources and Progress of Pretreatment TechnologiesChanges in circumstances of iron ore resources and the process of iron ore pretreatment technologies are presented. ・Correspondence to the extension of plant lifeThe technology for extension of blast furnace life and extension of coke oven life are described. ・More Efficient Operation and Operational StabilityDevelopment of hybrid bonded lump ore, CO2 reduction in the sintering process, start up of SCOPE21 type new coke oven battery, improvement of productive efficiency of blast furnace, and NG injection to blast furnace are introduced. ・Conservation of Energy and CO2 Reduction TechnologyInnovative iron-making process and COURSE 50 is described.

Manganes is one of the important alloying elements in high grade steels. In Japan, the total amount of Mn in steelmaking slag is close to the imported amount. Therefore, the steelmaking slag is considered to be a resource of Mn. Although ferro-manganese alloy can be produced by a reduction of steelmaking slag, P content in the alloy is too high and Mn content is too low for the use of steelmaking process as an alloying material. The authors have proposed a new Mn recycling process. In the proposed process, at first steelmaking slag is sulfurized, making it possible to separate the P from the manganese by creating a liquid sulfide phase(matte). After that, high purity ferro-manganese alloys can be made by the desulfurization of the matte, which emininates P. Fundamental knowledge about the distribution of Fe, Mn and P in both the matte and the steelmaking slag is required to clarify the feasibility of this process. In this study, the equilibrium distribution of P, Mn and Fe between FeS-MnS matte and FeO-MnO- SiO2-MgO-P2O5 slag was determined under the controlled partial pressure of oxygen and sulfur. It was revealed that P was not distributed to the matte and that a complete separation of P from Mn was achieved. The distribution ratio of Mn in the matte increased as the partial pressure of sulfur increased.

In the present investigation, the reduction and swelling behaviours ( in low grade coal ) of fired iron ore pellets, prepared by blending hematite iron ore fines of –100, –18+25 and –10+16 mesh sizes in different proportions, have been studied in the temperature range of 850 – 10000C with an objective to promote massive utilization of fines in sponge ironmaking. An increase in temperature up to the range studied ( 850 – 10000C ) substantially enhanced the reduction rate and the rate was found to be highest in the first 15 – 30 min at all these temperatures. All the fired pellets, made by mixing iron ore particles of ±100 mesh size, have shown approximately the same reduction rates and slightly higher swelling indices than those made from fines of –100 mesh size only. In all the fired pellets reduced at temperatures of 850 and 9000C, the results indicated an increase in the extent of swelling with reduction time. Maximum swelling was obtained in the fired pellets at a reduction temperature of 9000C, followed by a decrease thereafter. Reduction of fired pellets at temperatures of 950 and 10000C exhibited shrinkage in their reduced products, and the extent of this shrinkage increased with increase in exposure time.

Reaction kinetics of electric arc furnace dust (EAFD) from stainless steel plant with different ratios of graphite addition by microwave (MW) irradiation was studied. The reduction experiments were conducted in a microwave muffler furnace at 2.45GHz and microwave power of 1200W. At normal pressure, the specimen was reacted in the furnace chamber with no protective atmosphere and normal pressure. The results showed that the reduction fraction of dust was enhanced at the higher temperature and using more content of graphite. Compared with the conventional heating methods, it can reduce the temperature and the amount of reducing agent by microwave heating. The results also showed that the solid/solid interface or local chemical reaction is the limitation step of carbothermic reduction of stainless steel plant dust in a microwave field. According to the calculation results with Arrhenius equation, the apparent activation energy of the solid/solid interface or local chemical reaction is between 20.87 ~ 30.73 kJ/mol. Moreover, the pre-exponential factors of reduction reaction decrease with the carbon content and activation energy.

This work is aimed at the effect of titanium bearing materials on thermal state in the hearth of blast furnace. With the purpose of the carbo-nitrides production, the raw materials with titanium content, which protect the lining of the blast furnace hearth against wear and in that way prolonging its working life, are added into the blast furnace. The campaign life of a blast furnace depends greatly on the lifetime of hearth refractory lining. Hearth refractories are represented mainly by carbon bricks or carbon ramming mixes. In the blast furnace No.1 in U. S. Steel Košice is refractory wear monitored by four levels of termocouples. Once the critical value of temperature is crossed, necessary precautions must by done e. G. Charging of titanium-bearing materials in order to create a protection layer of titanium carbonitrides.

Taking into consideration the complexity of the traditional iron and steel elaborating methods that demand the existence of ore preparation plants, cookery, etc. Moreover the deficit of coking coals and iron scrap it is necessary to search new possibilities of modifying the existent technologies or replacing them by new methods. One option regarding this way represents the use of sponge iron obtained by direct reduction of iron ores or prepared into the iron and steel elaborating process. Considering the high materials and energy consumption and environment pollution in the traditional iron and steel elaborating methods our paper’s aim is to analyze the opportunity and the possibilities of obtaining the iron and steel by non-conventional technologies. Our paper presents the results obtained from direct reducing of iron ores and our conclusions resulted from statistic analysis of obtained data by correlating the initial characteristics of the ores and qualitative characteristics of the pre-reduced product.

This presentation will first develop an overall understanding of the role of grain size in oxidation of Fe-Cr microcrystalline alloys. Based on this understanding for nanocrystalline grain size, the mechanistic role of nanocrystalline alloy grain size in oxidation resistance of Fe-Cr alloys will be discussed. An elaborate description of the author’s own hypothesis that nanocrystalline structure can impart extraordinary oxidation resistance and the validation of this hypothesis will be presented. The data to be presented will include the results establishing that an Fe-Cr nanocrystalline alloy with only 10wt% Cr can provide as much oxidation resistance as an Fe-20Cr alloy, suggesting possibility of Fe-Cr alloys with the necessary corrosion resistance at much lower Cr contents.

The last decade has witnessed a great surge in the materials science and engineering research on the development of nanocrystalline and sub-microcrystalline materials. A great deal of these studies has focused on the fundamental characterisation of the structures and their bearing on the physical and mechanical properties of nano-size and ultrafine grain materials. However, oxidation and aqueous corrosion behaviour of nanocrystalline materials has received very limited research attention. Rather simplistic approach to understanding the role of nanostructure in corrosion as compared to the microcrystalline material of same composition may suggest an increase in corrosion rate of the nanostructured material due to large fraction of grain boundaries (i. E., high energy areas). However, the nature of influence of nanostructure per se on corrosion does not seem to be similar in all cases. In fact, the nature of such influence can be contradictory, depending on the type of corrosion and environment-material system. For example, nanocrystalline structure is reported to improve the resistance of an iron aluminide system in a corrosive gas, whereas the dissolution rate of a nanocrystalline copper is reported to be greater than the conventional polycrystalline copper. This presentation will first develop an overall understanding of the role of grain size in oxidation of Fe-Cr microcrystalline alloys. Then the paper will examine the validity of the mechanistic role of such nanocrystalline grain size oxidation. Examples of authors own work on both micro- and nanocrystalline materials will be presents. In particular, it will show results to establish that an Fe-Cr nanocrystalline alloy with only much less Cr can provide as much oxidation resistance as an Fe-20Cr alloy, suggesting possibility of Fe-Cr alloys with the necessary corrosion resistance at much lower Cr contents. The presentation will also report the role of additives such as zirconium in improving both processing and oxidation resiatnce.

Reactions taking part at metal–slag interface depend on both factors: Chemical compositions of phases staying in contact and intensity of reactants transport across the metal-slag interface. The first factor depends on alloy added during process of steel refining to metal bath and materials affecting chemical composition of slag. The second factor mainly depends on intensity of metal bath mixing by inert gas injection. In papers authors present hybrid model of steel refining process in ladle furnace. The research was focused on influence mixing conditions on time needed to achieve equilibrium state in the system. The hybrid model pays special attention to chemical reactions taking part at metal-slag interface which have been simulated based on thermodynamic calculation. On the basis of verified model of steel refining process the series of virtual experiments were done. The goal of those experiments was to find out the model sensitivity on main factors connected with process steering. The model’s results were compared with industrial data collected during testing heats on ladle furnace. The structure of proposed model make it possible to consider time and duration of materials added to ladle during process which gives the possibility to model precisely the real process in ladle furnace. In summary of research authors contain conclusions concerning the area of model application and possibilities of future development of hybrid model to steel refining processes which proceed at very low pressure.

In spite of the various benefit of fluorspar use in BOF operation such as increasing refining capacity of slag and powerful fluxing ability, environmental problem of fluorine has enforced steelmaking companies to develop its substituting materials. In the present study, it is proposed to utilize slag from ferroalloy production as fluorspar substituting material and results of plant trial are introduced. Significant quantities of slag from ferroalloy production are generated and so far they are considered as waste material though they usually contain considerable quantities of valuable metals and materials. The physical and chemical characteristics of several kinds of slag from ferro-manganese production are investigated. Considering all aspects when being used as substitutes of fluorspar, FeMn refining slag which is generated from the production of low or medium carbon grade ferro-manganese was chosen as a fluorspar substituting material. It has a low melting point less than 1250℃, high MnO content up to 35% and low P and S content. It is applied to converter operation so that 3 to 7 kg FeMn refining slag per ton of liquid steel was added into 100 ton capacity of converter several times during blowing. From the result of plant trial, more than 70% of fluorspar consumption was decreased and additionally 0.03~0.08% of manganese content in molten steel increased.

The components and quantities of atmospheric dusts fallout has been reported to be the pollution indicator of large urban areas. The multiplicity and complexity of sources of atmospheric dusts in urban regions (e. G. Industrial complexes composed of a variety of industrial processes, automobiles, construction activities etc.) has put forward the need of source apportionment of these sources indicating their contribution to specific environmental receptor. The study presented here is focused on investigation of source contribution estimates of mercury in dusts fallout at an urban-acadamic area, Raipur, India. Six sampling sites have been identified on the basis of land use for development plan of anthropogenic activities and factors related to the transportation and dispersion pattern of atmospheric dusts. 12 samples of dusts fallout has been collected from each site (one in each month) and subjected to chemical analysis of selected chemical constituents known as markers of selected major dust emitting sources(Steel making average, Road traffic-borne dusts, construction activities, municipal waste burning, and soils). Chemical profiles alongwith SPECIATE of USEPA has been used for the preparation of source profiles. Source apportionment has been done using Chemical Mass Balance (CMB 8). Good fit parameters and relative source contribution has been analyzed and documented. Variations in source contribution estimates of selected indicator species has been occurred and justify the significant contribution of local area and line sources of dusts emission in various parts of the study region. Local sources along with Coal-fired steel making industries have shown dominating contribution compared to other sources.

From the material flow of various elements, many of them are consumed as alloying elements for steel. It is well known that the excellent characteristics of steel are generated by the precise addition of alloying elements. Although steel is recycled as steel scrap, in the steel scrap, the values of the added alloying elements are not considered and the scraps are reused in low grade steel. In these sense, steel is a place where the elements play active parts but also the place for the elements as graveyard. On the other hand, steelmaking slag contains many valuable elements. To extract these elements, separation of harmful element, i. E. P and S is imperative. In this paper, the relation of element circulation and steel scrap recycling was discussed and it was clarified that the contribution of the steel scrap recycling on the element circulation is not effective except the austenitic stainless steel. In addition, the possibility to extract the valuable elements from scrap and steelmaking slag was discussed by the thermodynamic consideration. The result indicates that the formation of slag by oxidation is an effective method to enrich these elements, although the oxidation of P also occurs. As most of the phosphorous in slag forms the solid solution and the P content in the other phase is low, some technologies have been proposed to remove P from other oxide, using the difference of density, magnetic property and water solubility between these phases. On the contrary, by the sulfurization, Mn would be enriched in sulfide phase without containing P. For the recovery of valuable elements from steel scrap and slag, the sulfurization process combined with oxidation is undergoing.

Direct reduction of iron (DRI) is a constantly developing direction towards the reduction of energy consumption at production of iron. Application of the iron-carbon composites is the promising option aimed at wider use of coals and/or biofuels for ironmaking. Most of the coal-based DRI processes operate int a temperature range favourable for the formation of liquid FeO-rich slag inside of the iron-carbon composite. Interaction of this slag with the rest of a gangue as well as with the newly formed iron sponge determines efficiency of the reduction processes as well as further saturation of iron with carbon and sulphur. In the current research the interaction phenomena on the slag-metal interface for the slags representing liquid FeO-SiO2-CaO-Al2O3 system were studied. A comparison of slag interaction with Armco-Fe and with DRI material was done.

The sulfide capacity of the CaO–SiO2–MnO–Al2O3–MgO slags was measured through a wide composition range at 1873 K using a gas–slag equilibration method. The effects of basicity and the activity coefficient of sulfide on the sulfide capacity of molten slag were investigated. Furthermore, the relationship between sulfide capacity and the optical basicity of MnO–containing slags was evaluated in the context of industrial applications. The sulfide capacity of slag increased with increasing content of MnO at a fixed Vee ratio (=CaO/SiO2). The capacity and the modified Vee ratio (=(CaO+MnO+MgO)/(SiO2+Al2O3) showed a good linear relationship. Assuming that the basicity and the stability of the sulfide ions in the slag are proportional to the activity of MnO (aMnO) and the activity coefficient of MnS (rMnS), the composition dependency of sulfide capacity is well described by changes in the aMnO to rMnS ratio. We also constructed the iso–sulfide capacity of the CaO–SiO2–MnO and the CaO–SiO2–MnO–20wt%Al2O3–5wt%MgO slags at 1873 K, respectively. The capacity contours seemed to rotate clock–wisely from the CaO–SiO2 binary side to the MnO–corner in ternary system, whereas the capacity contours seemed to be parallel to the monoxide (Mn, Ca)O saturating line in 5 component system. The sulfide capacity dominantly decreased with increasing silica content in the latter system. The sulfide capacity generally increased with increasing MnO content regardless of changes in the contents of other constituents in multicomponent MnO–containing slags.

Electric arc furnace (EAF) dust from stainless steel plant has been considered as a toxic solid waste due to its significant levels of toxic substances, such as Cr(VI). In this paper, X-ray photoelectron spectroscopy (XPS) was employed to determine the elemental distribution profiles of Cr (VI) species. The XPS elemental survey showed that the elements that exist on the surface of the Electric arc furnace (EAF) dust from stainless steel plant are C, O, F, Si, Fe, Zn, Cr, Ca and Cl. The F concentration in the surface layers is higher than its bulk composition of the dust, while Cr content is lower in the surface than that in the bulk. The detailed scanning results showed that major compounds detected by XPS are SiO2，ZnO，Fe2O3，CaO，FeCl3，FeF3，Cr2O3，CrO3 or CrCl3. In addition, the Cr(VI) species exist in the form of CrO42- and Cr2O72-. After sputtering about 305s with Ar+ ions, the Cr(VI) species on the surface of the EAF dust disappears. This possibly indicates that the Cr(VI) mainly exist on the surface of dust, and therefore demonstrates that the Cr(VI) species could not form in the furnace but mainly form in the off-gas duct.

Fully sustainable iron production will require the industry to reach the level of “zero waste�, which will ensure that any plausible future environmental regulations will be met. The basis of zero waste is that all of the inputs to ironmaking should be minimized by conservation and re-use within the process. Further, any material leaving the process should ultimately become marketable products of one sort or another. This will require attention in three areas: (1) Air emissions; (2) Water effluents; And (3) Solid wastes. For air emissions, a concern is the release of airborne particulates (dust) when pellets are produced and handled during stockpiling and loading/unloading operations. Airborne particulates finer than 2.5 micrometers are a particular health hazard due to their ability to embed in lung tissue. Effective dust suppressants not only prevent dust emissions, but also ensure that more material remains in the marketable product. For water effluents, most of the water requirement is in the iron ore concentration processes. With extensive use of water recirculation, the amount of water that must be returned to the environment can be minimized. The ideal situation will be complete recirculation of all water, eliminating effluents completely. Regarding solids wastes, the conventional routes for making iron and steel require that the ore be upgraded through a series of physical separation processes in sequence. The unit operations involved include crushing, grinding, separation, dewatering, pelletization, blast furnace processing, and basic oxygen furnace processing. This complex sequence is not only restricted to ores that are coarse-grained enough to be processed, but also generates large volumes of unmarketable mineral tailings. Exploitation of these iron minerals can be carried out using a more direct smelting process , with fewer process steps than are required for conventional ironmaking. This also has the potential for producing additional marketable slag by-products rather than waste tailings.

The sticking of hematite and iron powder during fluidization process was investigated using a visual fluidized bed reactor. In addition, the fluidizing performance of some other typical crystalline materials was tested. The results showed that most of the materials defluidize in reducing atmosphere. The High-temperature defluidization occurred only when Fe2O3 particles were covered with iron precipitated above a certain temperature, at which the fluidizing performance of particles undergone abrupt changes. The higher fluidization temperature, the less iron was needed to stick. This suggested that the reduced products covered with iron transformed into cohesive particles (Geldart group C), which formed self-agglomeration above minimum sintering temperature. Due to iron surface generation, the inter-particle force arising from sintering of iron-iron contact should be taken into consideration. Especially, iron surfaces with nano/micro structures favored the formation of agglomeration of particles, because of their lower melting point. By comparison, the sticking temperature of hematite was always lower than that of iron powder in the same sizes. The interface reaction, which changed the surface structure and improved the surface diffusion of atoms, had a promotive effect on agglomeration and subsequent defluidization. Experimental certified the sticking was also associated with the type of crystal structure of materials. The order of sticking temperature was metallic >ionic > atomic crystal from high to low. For metals, one with lower melting point had a lower sticking temperature. Especially, for Fe, Cu and Ni, the ratio between sticking temperature and melting point was almost constant at 0.5~0.55.

Almost all the palletizing plants in the world which process iron ores containing hematite now add carbon (anthracite, coke breeze or petroleum coke) to the green pellet mixture. The carbon in this solid fuel reduces the hematite to magnetite. When the magnetite produced is re-oxidised in the pelletising process it produces heat inside each pellet. This form of heat transfer inside the pellet is much more efficient than the transfer from hot process gases heated by external burners. This results in higher production rates with lower total energy consumption and with higher effective capacity of the process fans. This technology works particularly well together with the deep pelletising bed practice that is being introduced into MSCo. The benefits from carbon addition is summarised as fallow:1) Increase in production rate of indurations machine (typically 20 % without modification or increase of grate area or process fan capacity.2) Reduced overall energy consumption (natural gas and electricity) of at least 20%3) More uniform firing with less quality difference between pellet at the top and bottom of the bed on the grate.4) Lower temperature in the grate bars, pellet cars and wind boxes (about 90-110 oC). This gives increased life of expensive equipment, lower maintenance cost and less stoppage time for pallet car changes. For Mobarakeh the addition of carbon (less than 0.65 %) to the green pellets has allowed the new required production levels to be more easily achieved and sustained with an overall decrease in operating cost and with more consistent pellet quality. Usage of solid carbon inside the green pellet also has showed increase the production of a further 0.9 Mtpa of pellet for internal use or sale.

AHMSA raw materials to Hot metal production, coal and coke mainly, have high values ofsulfur (0.9 - 1%). As a consequence, the value of sulfur in hot metal is one of the highestworldwide (0.15 – 0.18%). This generates that we have to use large volumes ofsulphurising agents to meet sulfur requirements by the steel works which range from 30-150 PPM. And promotes a high rate of slagEfforts have been directed to seek alternatives to improve the physical and chemicalconditions of the slag generated during the desulphurisation process, seeking to have morefluid slag, easy extraction for skimming operations and drained from the torpedo cars inorder to increase hot metal yield and maintain clean and high transport capacity. This paper describes the benefits achieved with the use of slag aditive during thedesusphurization process, regarding the increase in the yield of pig iron delivered to theBOF shop and the behavior of the tonnage of pig iron transported by the fleet of torpedocars.

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