Study of the acid bake-leach process has shown potential advantages for the treatment ofenargite (Cu3AsS4) concentrates. Among the most important advantages of theprocess is the transformation of enargite to water-soluble copper sulfate and highlysoluble arsenic trioxide (arsenolite). Because arsenic is retained in the condensed phaseduring the baking, the vapor pressure of arsenic trioxide should be estimated at typicalbaking temperatures (e.g. 473 K). To that end, the vapor pressure of As4O6 (g) was estimated under thebaking conditions based on published thermodynamic values. The vapor pressure ofarsenolite at 473 K was found to be approximately 9.03 × 10-4 atm. Based on thelinear regression analysis of the published vapor pressure values for arsenolite in thetemperature range 366−579 K,the equation for the best fit line was found to be as follows, with a correlationcoefficient of 0.9973:

logPArsenolite(atm) = (-5780.7)/(T (K))+9.16.

Available information on arsenic trioxide does not allow a definite conclusion regardingthe arsenolite/claudetite transformation temperature and their exact melting points.However, the transition temperature has been reported to be in the wide range of240−506 K in differentreferences. Furthermore, the thermodynamic information concerning arsenolite/claudetite issparse and at times not consistent. An effort has been made in this paper to compile themost reliable thermodynamic information for arsenic trioxide (arsenolite and claudetite).

This study aims at presenting a way to obtain nanostructured materials. Austeniticstainless steel (316L) nanopowders and ferritic/martensitic alloy steels (Fe14Cr) aresintered with the Spark Plasma Sintering (SPS) technique. This technique leads to a fullydense/nano-sized microstructure material after a short treatment. The optimal sinteringtemperature was found to be 850°C for both materials. The relationship between the Vickers Hardnessand scale of the microstructure is in good agreement with the Hall-Petch Law.

The influence of variable Manganese content (2.4−4.6 wt%), while keeping constant Silicon(1.5 wt%) and Chromium (0.3 wt%) levels, and variable oxidation potential of the annealingatmosphere on hot dip galvanizability was investigated. Surface oxides prior to hot dipgalvanizing were analyzed and coating quality assessed. The increasing oxidation potentialof the annealing atmosphere led to a transition from external to internal selectiveoxidation of Mn, Si and Cr; their enrichment at the surface could be reduced and themetallic iron at the surface was increased. Hot dip galvanizability could thus be obtainedup to 2.9%Mn. With increasing Mn content, the surface was covered by a rising amount ofMn-oxides. By exceeding a critical amount of Manganese, reactivity in the Zinc bath wasdeteriorated. This amount was found to be between 2.9 and 3.8 wt% for Si content of 1.5wt%.

Aluminium (Al) consumption growth exceeded those of all other major metals over the lastdecades. The main driver for this development is the broad range of applications for Aland Al-alloys. As the growth in consumption went along with an increase of anthropogenicstocks and flows of Al, information about material cycles became a crucial issue in termsof resource management. In this study a comprehensive material flow analysis (MFA) of theflows and stocks of Al in Austria for the year 2010 is conducted. The focus of thepresented Al balance is on data harmonization and plausibility checks, both based onextensive data and literature research. The stock of Al is derived from bottom-upcalculations indicating a total stock of about 260 kg Al per capita with an annual growthof 11 ± 3.1 kg/cap yr in 2010.Total old Al scrap generation is calculated to be 7 ± 1 kg/cap yr. For considering dataquality aspects of single input data an adopted method for uncertainty assessment has beenapplied to the different material flows. This allowed a consistent evaluation ofuncertainties within the material flow model. Due to the substantial uncertaintiesassociated with end-of-life Al flows and their significance for secondary Al production inAustria, a better data base is needed in order to evaluate and optimize national Al scraputilization in secondary production. Therefore, a dynamic MFA model will be built forAustrian Al flows and, in conjunction with the results from the static analyses, willprovide a reliable decision basis for future Al resource management.

Accretion on the lining of the blast furnace results in a harmful effect on burdendescent, which also has a negative effect on energy balance. This eventually leads toincreased CO2emission. We examined which blast furnace zones were significantly affected by thethickness of the accretion layer and how this affects the blast furnace gas streamrelations. Using a heat transfer model, the samples taken from the accretion andstatistical analysis of the typical operating parameters of the blast furnace, amathematical model was created in order to determine the thickness of blast furnace shaftaccretion and its effect on gas utilization.

In this work, direct potential measurements during cold rolling of zinc and X20Cr13stainless steel were carried out in the rolling slit to follow the tribologic and galvanicmechanisms of hydrogen formation and absorption on the surface of the working rolls madeof DHQ1 grade steel. An Ag/AgCl in 3.5 M KCl reference microelectrode was used to recordthe open circuit potential of the electrochemical system roller-product immersed intocommercially relevant electrolyte (rolling emulsion) with a pH value of 4.5 and anelectric conductivity 46 mS cm-1. The potential shift into either negative or positivedirection of the rolls-product system gives information on the processes taking place atthe surface in the course of the friction. A detailed discussion of the in-situpotentiometry experiments reveals a stationary situation established between thedestruction and repassivation of the surface structures during continuous cold rollingaccompanied with intensive hydrogen evolution. Galvanic coupling of the working rolls withthe product significantly intensifies the hydrogen embrittlement related problems of therolls. Atomic hydrogen is adsorbed on the surface and exhibits a pressure supportedabsorption into the rolls during their whole lifetime.

The goal of zero-waste is one of the main challenges of modern steel industry, which over the past 20 years has been committed to increase the recovery and the use of by-products generated during the ironmaking and steelmaking processes. Among the main by-products generated during iron and steel production, such as slags, dusts and sludges, slags constitute about 90% of the total. Slags are currently used in various fields (such as cement production, road construction, environmental recovery in landfill covers, as fertilizer and soil conditioner, etc.) according to their chemical features, which depend on production process origin. In Italy, in particular for example, BF (Blast Furnace) slag is used for cement production while BOF (Basic Oxygen Furnace) slag without iron (inert slag) is used as landfill cover, in compliance with Italian legislation. In Germany, BF and BOF slag use as fertlisers and liming materials has a long tradition. Although in recent years slag use has increased, the application for agriculture purposes needs to be further investigated. Slag can be used as a soil conditioner (high content of Ca and Mg), Si supply (improves the crops resistance to pests and diseases), P fertilizer production and micro-nutrients supply. Use of slags can affect human health and environment, because of heavy metal content, which can leache to groundwater or be transferred to surface water. The assessment of risk to the environment based on slag application requires further investigation. This represents an opportunity for both the steel and fertilizer industries to promote natural resources savings, CO2 emission reductions, landfill waste prevention as well as social awareness of sustainability of some industrial activities. The BOF slag has been shown to be useful as liming material for acidic soil amendment and it can replace commercial fertilizers. Different effects on crop yields and on soil parameters can be found, depending on soil characteristics and climate conditions. In Middle Europe, with humid climate, lime losses through leaching of up to 0.5 t CaO/ha have to be replaced with liming material to prevent acidification. Evaluation of long-term field trials with slag liming materials can give information about the impact of slag applications on crop management and the environment. In Mediterranean regions, such as in Italy, arable soils rarely show acidic characteristics. Alkaline soils from coastal areas are often rich in sodium content, due to seawater intrusion and irrigation with saline water. The aim of this research is also to investigate the application of BOF slag to these soils, in order to assess the effect of Ca contained in slag in balancing negative Na effects. This paper is based on the preliminary study and experiments carried out within an ongoing RFCS (Research Fund for Coal and Steel) project.

Many materials can only be recycled a limited number of times because of physicaldegradation (paper and board), chemical degradation (plastics), or impurities (severalmetals). Management of the quality of materials is a key to high long-term recycling ratesand, hence, to the sustainable future. This key includes several elements, such as:retaining the quality of materials in the production and use of products; retaining thequality of materials in the recycling processes; and using high-quality materials onlywhen it is required. Pinch analysis is a set of methods to optimize physical flows bytaking the quality into account. It was originally developed for minimizing the energydemand in process industries. It has been adapted for optimization also of water andsolvents flows. A Japanese research group applied part of the method on flows of steelwithin Japan and globally. We present a pilot study that illustrates how all the elementsof the basic pinch approach can be applied to global systems of material flows. Ourmaterial pinch analysis (MPA) distinguishes between three categories of steelapplications, each with its own requirements on the material quality: rolled steel,sections and re-bar. Copper in wiring etc. increases the copper content of steel recycledfrom machinery and eventually restricts the recyclability of the steel in a global systemwhere steel use does not increase. This is important because an MPA is mainly relevantwhen impurities or other quality aspects restrict the recycling rate. Our quantitativeresults should not be considered accurate reflections of the reality, because the pilotstudy is to a large extent based on assumptions and crude data. However, the model gives afirst indication that the maximum recycling rate of steel is approximately 80% in apotential future when steel use does not increase, unless technology is improved. A fullMPA with more thorough data collection would more accurately define the maximum long-termrecycling rate and the minimum quantity of ore-based material. In addition, a full MPAwould give information on for what applications ore-based material should be used, andwhat scrap flows should be discarded rather than recycled. Such information can beimportant for policy-making aiming at increased resource efficiency. If it is importantfor policy-making it is also likely to be important to industrial companies that can beaffected by policies.

Les boulets de broyage ou de concassage sont des éléments de broyeurs utilisés dans lescimenteries; ils exigent une résistance à l’usure élevée sous l’action de produitsabrasifs lors de la transformation de la roche en fines particules de taille inférieure aumillimètre. Les traitements thermiques constituent une étape essentielle pourl’élaboration du boulet. Ils permettent d’obtenir des duretés et une résistance à l’usureconvenables. Les analyses structurales et microstructurales par diffraction X etmicroscopie électronique à balayage permettent de comprendre leurs corrélations. Dans cetobjectif, nous avons étudié l’influence de quelques facteurs déterminants dans cestraitements. Les facteurs considérés dans le présent travail sont : la températured’austénitisation (950 °C et1050 °C), la sévérité dumilieu de trempe (refroidissement à l’air ventilé et à l’huile) et le diamètre des boulets(boulets de diamètre 50 et 70 mm). Les résultats obtenus ont révélé la présence decarbures de type Cr7C3 répartis dans une matrice martensitique ou ferritique etque le taux de l’austénite présent dans les boulets trempés à l’air ventilé est inférieurà celui des boulets trempés à l’huile. La température d’austénitisation et la taille desboulets influent sur la trempabilité. En effet, l’écart de dureté entre la surface et lecœur des boulets de diamètre 50 et 70 mm chauffés à 1050 °C, refroidis à l’air ventilé et à l’huile,est plus important que celui des boulets correspondants chauffés à 950 °C. Une augmentation de la taille desboulets conduit à la diminution de la trempabilité notamment les boulets de diamètre 70 mmchauffés à 1050 °C.

A comprehensive three-dimensional (3D) stochastic model for simulating the evolution ofdendritic crystals during the solidification of binary alloys was developed. Themulti-scale model takes into account all the length scales (e.g., macro, micro- andmeso-scales) required to accurately predict the evolution of dendritic morphologies duringsolidification of alloys. The model includes time-dependent computations for temperaturedistribution, solute redistribution in the liquid and solid phases, curvature, and growthanisotropy. Stochastic models previously developed for simulating dendritic grains in 2Dwere modified to control the nucleation and growth of dendrites in 3D. 3D mesoscopiccomputations at the dendrite tip length scale were performed to simulate the evolution ofcolumnar and equiaxed dendritic morphologies including segregation patterns and comparedthen with predictions based on 2D mesoscopic computations.

A model for predicting the austenite grain growth during a common heating process including continuous and isothermal heating processes in medium carbon alloy steel 42CrMo was developed. The isothermal austenite grain growth kinetics were studied with conditions involving soaking time and soaking temperature. The time exponent n in the model was obtained considering the influence of the initial grain size rather than simply utilizing Beck’s equation. The results showed that the value of the time exponent n is 3.55 ± 0.30 when the temperature is above 1000 °C, while the value is 8.33 when the temperature is below 1000 °C. When the temperature is below 1000 °C, the pinning effect of carbides contributes to the higher value of the time exponent. Based on the isothermal model and the rule of additivity, a model for predicting the grain growth occurring during continuous heating was proposed. A reasonable agreement between the calculations and experimental measurements of grain size was obtained. According to the model, the effect of the initial austenite grain size on the final austenite grain size during induction quenching was analyzed. The initial austenite grain size has a significant effect on the final austenite grain size. In order to obtain a refined quenched microstructure, it is necessary to refine the microstructure at room temperature.

Most theoretical work on solidification focuses on dilute binary alloys, while thosecommonly used in industry are multi-component with high solute concentrations. Inconcentrated alloys, the diffusion of one component will be inevitably influenced by theothers, which will further affect the rapid solidification kinetics. Assuming localnon-equilibrium at the solid/liquid (S/L) interface and in the bulk liquid, the kineticsof planar interface migration and dendrite growth in strongly non-equilibriumsolidification of Ni-Cu-Co alloys is comparatively studied. It is found that, for planarinterface kinetics, the thermodynamic interactions lead to a non-monotonic tendency of thepartition coefficient of Co with a slightly lowered interface temperature. Meanwhile, fordendrite growth (i.e. curved interface), the curvature effect and the thermodynamicinteractions together result in the non-monotonic variation of partition coefficients. Dueto the lowered dendrite tip temperature as a result of the thermodynamic interactions,larger undercooling is needed for interface migration and the dendrite growth is sloweddown.

Freckle defects were found in electro-slag remelting (ESR) ingots, which severely limitthe development of the larger-diameter ingots. The macrostructure and the composition ofthe freckles in a low-alloy structure steel ESR ingot were investigated to clarify thefreckle formation mechanism. The results shows that the freckles in the ingot were causedby the upward solute-rich liquid flow in the mushy zone, and the composition of thefreckles corresponds to that of the liquid, with a liquid fraction of 0.36 to 0.43. Therelative Rayleigh number (Ra), a freckle criterion considering the effect of atilted solidification front, was adopted to evaluate the freckle formation tendency in theindustrial-scale ESR ingots based on the results of the experiments, kinetic simulationand thermophysical property calculation. The calculated results of Ra are in good agreementwith the actual distribution of the freckles in the ingot.

In order to obtain the dynamic variation rule of the sulfur content of liquid steel inthe LF refining process, a complete mathematical model including a desulfurization kineticmodel and temperature model in the deep desulfurization process is presented, based on thepractical production and reaction mechanism of ultra-low-sulfur steel in a LF. The resultsshow that the calculated values of the sulfur content in liquid steel using the model fitthe experimental values well, and the relative error is less than 8%. The effects ofrefining slag on the desulfurization process are analyzed in this paper, which shows thatslag basicity is most important at the early and middle stages of the process, while slagweight is most important at the middle and late stages. The effect of the above factors onthe final sulfur content of liquid steel is further analyzed quantitatively. The simulatedresults provide a theoretical basis to segment control the refining process in order toachieve the maximum effect, improving efficiency, saving energy and reducingconsumption.

Steam ejector vacuum pumps (SVPs) are mainly used on larger melt sizes up to 350 t inintegrated steel plants because of the availability of steam. The use of dry operatingmechanical vacuum pumps (MVPs) for steel degassing has made a tremendous step forward inthe past 10 years but is still confined to melts below 150 t while its progress towardslarger melt sizes is not completed. Besides the consideration of investment and operatingcosts there is no restriction in using any type of modern vacuum pump system for allvacuum processes and plant designs. Both systems fulfil all metallurgical requirements.Considering the significant savings in operating cost offered by MVP systems it is worthreconsidering the efforts for reducing air leaks, the use of protective gases and pressurelosses between the pump set and the metallurgical reaction vessel. Both systems have madeprogress in energy optimising but the MVPs have a striking energy advantage. Only theoverall costs should be considered, including those necessary to meet emission constraintsand safety standards, and only the pressure prevailing at the reaction vessel is to beconsidered when comparing vacuum pump systems. Also, the means and use of dust abatementsystems should be reconsidered since they offer cost savings by reducing the frequency ofcleaning, less wear, little sludge handling and the significantly lower design suctioncapacity of SVP systems. The SVP mass flow need is to be corrected by a specialcoefficient before being applied to the volume conveying MVPs. Depending on theoperational pressure required for the pump design, MVP systems can reach the sameperformance at the reaction vessel with much less mass flow capacity than that needed by aSVP system.

Electric vehicles in Germany are expected to have an average lifetime of twelve years. During their long use-phase these vehicles rely on electricity from the power grid. A historic review shows that over the last twelve years the German electricity-mix has undergone a massive transition. Renewable energy sources are on the rise, while nuclear power is phased out. This trend is expected to continue. Since the environmental impacts of electric vehicles depend on the electricity-mix, this study performs a life cycle assessment that respects the transitions in the observed time-span. This study defines the new term “time-resolved LCA”, in contrast to conventional LCA- and dynamic LCA-methodology, as an LCA-approach which is based on statistical, time-resolved data. Time-resolved LCA aims at becoming a simple and feasible method to reduce model-uncertainty in LCA. The authors conclude that time-resolved LCA improves model-quality significantly. Most environmental impacts of electric vehicles decrease, when the more precise time-resolved approach is employed. Further implications of the new approach are outlined.

The paper reports the results of studies on the validation of a numerical model of theflow of liquid steel through the tundish used for continuous casting of steel. Thefacility under investigation is a single-nozzle tundish designed for casting concastslabs. For the description of the turbulence of steel flow through the tundish, thek-ε, RNG k-ε and Realizable k-ε turbulence model wereadopted. Computer simulations of liquid steel flow were performed using the commercialprogram Ansys-Fluent®.For the validation of the numerical model and verification of the hydrodynamic conditionsoccurring in the examined tundish furniture variants, obtained from the computersimulations, a physical model of the tundish was employed. During laboratory testssimulating the process of steel flowing through the tundish, E and F-type RTD (ResidenceTime Distribution) curves were recorded, which were then juxtaposed with results obtainedfrom computer simulations. In order to obtain a complete hydrodynamic picture in thetundish furniture variants tested, the computer simulations were performed for bothisothermal and non-isothermal conditions.

The future evolution of energy supply technologies strongly depends on (and affects) theeconomic and environmental systems, due to the high dependency of this sector on theavailability and cost of fossil fuels, especially on the small regional scale. This paperaims at presenting the modeling system and preliminary results of a research projectconducted on the scale of Luxembourg to assess the environmental impact of future energyscenarios for the country, integrating outputs from partial and computable generalequilibrium models within hybrid Life Cycle Assessment (LCA) frameworks. The generalequilibrium model for Luxembourg, LUXGEM, is used to evaluate the economic impacts ofpolicy decisions and other economic shocks over the time horizon 2006−2030. A techno-economic (partialequilibrium) model for Luxembourg, ETEM, is used instead to compute operation levels ofvarious technologies to meet the demand for energy services at the least cost along thesame timeline. The future energy demand and supply are made consistent by coupling ETEMwith LUXGEM so as to have the same macro-economic variables and energy shares driving bothmodels. The coupling results are then implemented within a set of Environmentally-ExtendedInput-Output (EE-IO) models in historical time series to test the feasibility of theintegrated framework and then to assess the environmental impacts of the country.Accordingly, a disaggregated energy sector was built with the different ETEM technologiesin the EE-IO to allow hybridization with Life Cycle Inventory (LCI) and enrich the processdetail. The results show that the environmental impact slightly decreased overall from2006 to 2009. Most of the impacts come from some imported commodities (natural gas, usedto produce electricity, and metalliferous ores and metal scrap). The main energyproduction technology is the combined-cycle gas turbine plant “Twinerg”, representingalmost 80% of the domestic electricity production in Luxembourg. In the hybrid EE-IOmodel, this technology contributes to around 7% of the total impact of the country’s netconsumption. The causes of divergence between ETEM and LUXGEM are also thoroughlyinvestigated to outline possible strategies of modeling improvements for future assessmentof environmental impacts using EE-IO. Further analyses focus first on the completion ofthe models’ coupling and its application to the defined scenarios. Once the coupling isconsistently accomplished, LUXGEM can compute the IO flows from 2010 to 2030, while theLCI processes in the hybrid system are harmonized with ETEM to represent the futuredomestic and imported energy technologies.

The Research Fund for Coal and Steel (RFCS) was established in 2002 to contribute to thecompetitiveness of the European Coal and Steel sectors by supporting collaborativeresearch, pilot and demonstration projects. A Monitoring and Assessment exercise of theRFCS programme covering the period 2003–2011 was carried out by an Expert Committeecomprising four coal and six steel experts appointed by the European Commission. Theassessment exercise involved the analysis of the 198 projects completed during thisperiod, with special emphasis on the benefits for beneficiaries, Sectors and Society.Based on actual fact and figures provided by the project partners, it was established that1 euro spent in the project budget delivered a benefit of about 2 euros for the projectpartners. Extrapolated at the level of the coal and steel sectors with very conservativeassumptions, the potential benefit of the projects was estimated at about 700 M€/year. Tocapture this potential benefit, additional efforts and budget must be spent at the companylevel for implementing the relevant technological solutions.

In this study, the effect of titanium addition on the microstructure and wear behavior ofHadfield steel was investigated. To do so, four groups of samples with different titaniumcontents of 0, 0.2, 0.4 and 0.6 wt% were prepared. After casting, the samples wereaustenitized at 1100 °C for 3h and quenched in water subsequently for solution treatment. Themicrostructure of the samples was investigated using an optical microscope (OM) andscanning electron microscope (SEM). For more studies the carbide composition was analyzedvia energy-dispersive spectroscopy (EDX). A wear test was performed via a pin-on-disk weartesting machine. The results show that after heat treatment the microstructure of thetitanium-free sample is fully austenitic, while the other samples show an austeniticstructure with non-continuous carbide precipitates. It was also revealed that titaniumaddition improves the hardness and wear resistance of the samples. The highest wearresistance was observed in the sample with 0.6 wt% titanium content. It was also shownthat the predominant wear mechanisms are adhesive and tribo-chemical. Beyond this, theeffect of cold working via a hammering treatment was studied on the samples and revealedthat austenite-to-martensite transformation improves the hardness and wear resistancesignificantly.