CFD Modelling of matte droplets coalescence in Flash smelting settler

Computer simulations are popular due to difficulty in setup of conventional experimental methods at high temperature processes. Computational Fluid dynamics is an important tool to study settling mechanism in Outotec's flash smelting settler. Commercial Ansys Fluent model was used to study settling previously by researchers, but no study was done to model coalescence. The thesis aims in studying the suitability of the Ansys fluent built in code to model coalescence for flash smelting settler. The success of the model helps to understand copper loss mechanisms and find ways to increase copper recovery. Firstly, collision theory and coalescence mechanism is reviewed thoroughly. Secondly, Ansys fluent built in models for modeling coalescence are listed and compared to select best mathematical model. The primary criteria for selection was ability to model collisions, coalescence, particle tracking and better visualization capacities. The selected discrete phase model is parametrized to model coalescence during settling of matte droplets through slag phase. It is noted that DPM could be used to simulate settling and coalescence of matte droplets. DPM can be used to get the idea of the process/coalescence phenomenon in a short period. The simulation showed droplets change trajectory after collisions/coalescence. Simulation also revealed coalescence dramatically affects settling time. Settling time is not only affected by increase in droplet diameter but also due to change in droplet trajectory after coalescences. However, Parametrized DPM model uses parcels injection technique that makes it difficult to track droplets individually for accurate comparison. In future user defined function should be written to identify and track droplets individually for accurate analysis of individual droplets

Process Modeling in Pyrometallurgical Engineering

The Special Issue presents almost 40 papers on recent research in modeling of pyrometallurgical systems, including physical models, first-principles models, detailed CFD and DEM models as well as statistical models or models based on machine learning. The models cover the whole production chain from raw materials processing through the reduction and conversion unit processes to ladle treatment, casting, and rolling. The papers illustrate how models can be used for shedding light on complex and inaccessible processes characterized by high temperatures and hostile environment, in order to improve process performance, product quality, or yield and to reduce the requirements of virgin raw materials and to suppress harmful emissions

Metal droplet entrainment by solid particles in slags : a combined phase field-experimental approach

This doctoral work investigated metal droplet entrainment by solid particles in slags with a combination of two experimental set-ups and two phase field models. The binary model with limited complexity already clarified our view of the interaction between metal droplets and nonreacting solid particles to a great extent. For example, the fact that the movement of one phase with respect to the others influenced the apparent wetting regime is very interesting for the interpretation of experimentally obtained results. Moreover, the two different types of experiments confirmed that a chemical reaction might lay at the origin of the attachment, but that it requires nucleation sites in the form of metal droplets before it takes place. However, the first phase field model assumed nonreactive solid particles. Thus, a model concerning the growth of the solid phase in a realistic quaternary oxide system was also considered. Future work needs to consider the interaction of reacting metal droplets with reacting solid particles in a realistic liquid slag

Challenges and Prospects of Steelmaking Towards the Year 2050

The world steel industry is strongly based on coal/coke in ironmaking, resulting in huge carbon dioxide emissions corresponding to approximately 7% of the total anthropogenic CO2 emissions. As the world is experiencing a period of imminent threat owing to climate change, the steel industry is also facing a tremendous challenge in next decades. This themed issue makes a survey on the current situation of steel production, energy consumption, and CO2 emissions, as well as cross-sections of the potential methods to decrease CO2 emissions in current processes via improved energy and materials efficiency, increasing recycling, utilizing alternative energy sources, and adopting CO2 capture and storage. The current state, problems and plans in the two biggest steel producing countries, China and India are introduced. Generally contemplating, incremental improvements in current processes play a key role in rapid mitigation of specific emissions, but finally they are insufficient when striving for carbon neutral production in the long run. Then hydrogen and electrification are the apparent solutions also to iron and steel production. The book gives a holistic overview of the current situation and challenges, and an inclusive compilation of the potential technologies and solutions for the global CO2 emissions problem

Mathematical Programming of Peirce-Smith Converting

RÉSUMÉ : Le convertissage par méthode Pierce-Smith (PS) est l'étape clé de la production de cuivre et du nickel. Cette opération se poursuit par des étapes séquentielles et présentent un cas idéal pour la programmation mathématique. Ce travail démontre les complexités thermochimiques et les étapes du convertissage au moyen d'un programme linéaire (PL) en nombres entiers mixtes. Ceci est la première fois que le convertissage PS est abordé dans un cadre de programmation mathématique et représente un avancement majeur de l'application de la recherche opérationnelle aux étapes de production des fonderies de cuivre et de nickel. Les résultats démontrent que le cadre mathématique est fonctionnel, et peut être utilisé quotidiennement pour la gestion optimale des séquences d'opération de l'élaboration de cuivre et de nickel. Le cadre est flexible quant à la définition des contraintes du système et de la fonction objective. Cette flexibilité évoque la formulation de divers modes d'opération des fonderies. Le cadre pourra être exploité en forme de logiciel industriel que les fonderies pourraient utiliser pour coordonner la production journalière, et de varier leur mode d'opération selon les conditions de l'usine et du marché. Le cadre a été formulé suivant une méthodologie qui est typique de la programmation mathématique, mais qui n'avait jamais été adaptée au convertissage PS. Premièrement, le problème se pose en forme générale. En effet, Le problème de convertissage consiste de la coordination des convertisseurs PS avec d'autres opérations dans la fonderie afin de maximiser la production durant une période fixe, tout en respectant les contraintes chimiques, volumétriques et thermiques. Deuxièmement, les diverses composantes et dimensions du système sont représentées par des structures algébriques générales; c'est-à-dire, des ensembles, des paramètres et des variables. Troisièmement, ces composantes sont liées de telle manière à ce que la formulation puisse être supportée par des techniques de résolution. Les techniques de résolution par la programmation linéaire (PL) en nombres entiers mixtes sont bien établies. Par contre, il a été nécessaire d'introduire des simplifications pour pouvoir résoudre le problème des convertissages par l'adoption d'un cadre hypothétique de PL en nombres entiers mixtes. En considérant la vaste gamme de problèmes qui ont été déjà abordées dans ce type de cadre, il semblait raisonnable que le convertissage PS nécessiterait seulement des simplifications mineures. En fait, le nouveau cadre mathématique exige certaines simplifications. En particulier, il impose une rigidité artificielle sur deux températures variables : la température nominale d'effluent gazeux, et la température d'écrémage de la scorie. Ces simplifications peuvent être considérées mineures, puisqu'il existe des logiciels qui ne traitent même pas ces quantités comme variables. En outre, il semble maintenant plausible de formuler un cadre non linéaire qui fournirait un traitement plus robuste et réaliste qui tient compte de ces températures. Les résultats de cette étude ont un attrait considérable pour les industries de cuivre et de nickel, puisque l'opération efficace d'une fonderie dépend directement de la coordination quotidienne de la production. Suivant les succès du travail actuel, des efforts superficiels provoqueront des changements majeurs dans les opérations journalières des fonderies de cuivre et de nickel.----------ABSTRACT : Peirce-Smith (PS) converting is central to the production of copper and nickel, and is a lucrative, yet previously undeveloped, context for mathematical programming. The thermochemical complexities of PS converting have now been represented within a mixed-integer linear program (MILP). This is the first time that PS converting has been treated within a mathematical programming framework, hence a major advancement in the operations research of copper and nickel smelters. The MILP framework is now functional, and can be used to construct optimal daily production schedules. The framework offers flexibility in the definition of system constraints and objective functions. This flexibility can accommodate the formulation of alternative modes of operation for smelters. The MILP framework can now be marketed as industrial software, to produce optimal daily schedules, and allow smelters to change their mode of operation in accordance to plant and market conditions. The framework has been created using a methodology that is typical of mathematical programming, but which had never been adapted to Peirce-Smith converting. Firstly, the problem has been posed in appropriately general terms; indeed, the PS Converter Problem is to coordinate Peirce-Smith converters with other objects in the smelter, so as to maximize production within a fixed period of time, while respecting chemical, volumetric and thermal constraints. Secondly, the various components and dimensions of the system have been represented using general algebraic structures, such as sets, parameters and variables. Thirdly, these components have been related to each other in a manner that can be supported by solution techniques. The solution techniques for MILP are well established. However, it was initially unclear what degree of simplification would be required in order to fit the PS Converter Problem into a hypothetical MILP framework. Given the vast scope of problems that have already been treated using MILP, it seemed plausible that the PS Converter Problem would require only minor simplifications. The new MILP framework has indeed required some simplification. More precisely, the framework imposes an artificial rigidity on two classes of temperature variables: nominal offgas temperatures, and skimming temperatures. These simplifications can be considered minor, since there are existing software tools that do not even treat these quantities as variables. Moreover, it now seems plausible to extend the current formulation into a nonlinear framework that would provide a more intensive and realistic treatment of the offgas and skimming temperatures. The results of this study have a considerable appeal to the copper and nickel industries, since the efficient operation of a smelter is directly linked to its scheduling practice. Following the successes of the current work, superficial efforts will cause major changes in the daily operations of copper and nickel smelters

Modelling of freeze layer formation and refractory wear in direct smelting process

The work discussed in this thesis is aimed at examining the formation of freeze layers and refractory wear on water-cooling elements within direct smelting processes through the use of computational modelling techniques. The motivation of performing this work is to examine the cooling of regions of the Smelt Reduction Vessel of the HIsmelt process closer to the molten bath material. HIsmelt is a novel process for the production of pig iron which has been under development by Rio Tinto and is now being commercialised. The previous work performed in this are has been reviewed with particular focus on the refractory wear mechanisms as the solidification algorithms have been thoroughly implemented within the Computational Fluid Dynamics (CFD) framework PHYSCIA used within this work. The governing equations along with the Finite Volume discretisations of these equations are set out within this thesis. Some comment is made about the solution methods used, and how boundary conditions are implemented. The Free-surface flow and Solidification governing relationships are also described as these are important for investigating the formation of freeze layers. The implementation of the refractory wear mechanisms are discussed in some detail. The three mechanisms implemented are for the penetration of slag into the refractory, the corrosion of the refractory by this penetrated slag; and the erosion of the refractory by the bulk flow of slag within the furnace. To be able to reasonably predict refractory wear, it is necessary to make the properties of the materials within the system temperature dependent. During the pilot plant trials at the HIsmelt® Research and Development facility, located in Kwinana Western Australia, accretions formed on the end of the solids injection lances. These accretions have been termed Elephant's Trunks. With the imminent construction of the Development Plant which injects the iron bearing feeds at an elevated temperature rather than at ambient temperatures used on the pilot plant, the formation of these pipe-like accretions under both the cold and hot injection conditions have been examined. This work provides confidence that the freeze layers predicted from the model will reflect those formed within the furnace. To evaluate the effectiveness of the refractory wear mechanisms, data from experimental and the HIsmelt pilot plant have been modelled. Sections of refractory samples from an induction furnace test and a rotary slag test have been modelled. The results are in agreement with the profile and affected regions of the sectioned refractory test pieces. A part of the HIsmelt pilot plant Smelt Reduction Vessel (SRV) has been modelled for the period of campaign 8-1 & 8-2 (just over 20 days). The predicted wear is in agreement with the measurements taken after the vessel had been cooled. To bring together freeze layer formation with the refractory wear mechanisms, a water-cooled element was modelled for the sloping slag section. The results show the growth of a small freeze layer that is consistent with the small freeze layer seen on the upper cooling panels of the pilot plant SRV. This model is an ideal tool to evaluate different water-cooling strategies for HIsmelt and other similar direct smelting processes. This work has developed models that predict the formation of freeze layers and refractory wear within direct smelting processes. The models have focused on slag-refractory interactions and further work would be needed to extend the refractory wear models to account for metal-refractory interactions. To examine spalling, stress calculations could be performed to determine when this may occur

Reduction of scrap percentage of cast parts by optimizing the process parameters

Casting is a widely used manufacturing process in the automotive industry. Die casting is the most popular type of casting processes. But the fact observed in many industries is the scraps or wastages occurring after the process. Thus, this thesis is primarily based on understanding the die-casting process and the factors governing them. In this study, the part to be studied is a throttle body. The raw material used for the production is AlSi9Cu3. The main concern in this part is the occurrence of defects such as bad filling, heat bubbles, and porosity. Thus, it is important to perform process optimization. Techniques or methods such as Design of Experiments, ANOVA analysis, and numerical simulations are used. This thesis also focuses on the use of brainstorming as an industrial discussion tool and the use of quality tools for process optimization. Thus, these techniques are utilized in order to eliminate the defects. The scrap after using these techniques and methods is reduced to 9% from 14% initially found. This investigation has been performed as a continuous improvement project in Sonafi and as a master thesis for “Instituto Superior de Engenharia do Porto”.A fundição é um processo de fabrico amplamente utilizado na indústria automóvel. A fundição injetada é o tipo mais popular de processos de fundição. Mas, o facto observado em muitas indústrias é o aumento de sucatas ou desperdícios que ocorrem após o processo. Assim, esta tese é baseada principalmente na compreensão do processo de fundição e nos factores que a governa. Neste estudo, a parte a ser estudada é um corpo do acelerador. A matéria-prima usada para a produção é AlSi9Cu3. A principal preocupação nesta parte é a ocorrência de defeitos como mau preenchimento, bolhas de calor e porosidade. Assim, é importante realizar a otimização do processo. São utilizadas métodologias como o Desenho de Experiências, análise ANOVA e simulações numéricas. Esta tese também se concentra no uso do brainstorming como uma ferramenta de discussão industrial e uso de ferramentas de qualidade para otimização de processos. Assim, essas técnicas são utilizadas para eliminar problemas ocorridos na produção. Esta investigação foi realizada como um projeto de melhoria contínua na Sonafi e como uma tese de mestrado para o Instituto Superior de Engenharia do Porto

Archaeometric Investigation for Provenance Studies about Copper Metallurgy in the Phoenician and Punic Cultures

The doctoral thesis regards an innovative method based on an elaboration of chemical-physical data in terms of statistics and georeferencing of copper-based alloys artefacts in the Mediterranean and Atlantic regions which underwent the influence of Phoenician-Punic cultures. Fundamental aim of the research is the localization of areas where this influence is evidenced by the presence of artefacts which characteristics can be attributable to Phoenician and Punic presence. The chronological range considered is mostly between the Late Bronze Age (LBA) and the Early and Middle Iron Age (EIA- MIA), even if more ancient and more recent periods have been considered for coparison. The study of Phoenician-Punic archaeological sites, trade routes and the type of bronze processing have been considered broadly throughout the Mediterranean Basin and surrounding areas (but also atlantic and continental areas), leading to the production of databases containing information on archaeological settlements, mines and ore basins, and compositional data coming from literature or obtained from the analyses of bronze artefacts (SEM-EDS and EDXRF analyses), managed through an unprecedented application of Geographic Information System (GIS tool). So the GIS application includes data coming from archaeometric analytical sessions and from analogous researches published on specialised literature, carried out on samples of different typologies. The collected databases were elaborated on the basis of statistics-mathematic methods, in particular Principal Component Analysis (PCA), while frequency distributions and Box-Whisker diagrams have been used for the study of smaller datasets. The production of manufactures (small size metal statuary), connected to religious worship, were addressed in Alentejo, Portugal (Evora and Alcacer do Sal) and in Sardinia, Italy (Cagliari and Sassari). The mining and the production of slags and semi-finished products have been examined for Moroccan area (especially in Meknes Region) while metal artefacts of Roman period from Volubilis archaeological settlement have been analysed in the light of a probable technological conservatism between Punics and Romans. The production of bronze Punic coins was deepened for a private collection (Collection M. Viola) and through the study of Punic and neo-Punic finds in France, Belgium and in lesser extent in Northern continental Europe areas. The results have been interpreted with a unique perspective, so as to allow a new vision on the Phoenician presence an bronze production in the areas where they settled. Further result is the elaboration of a useful tool for the archaeological research that is reproducible in several fields, even different from the ancient metallurgy studies

A History of Materials and Technologies Development

The purpose of the book is to provide the students with the text that presents an introductory knowledge about the development of materials and technologies and includes the most commonly available information on human development. The idea of the publication has been generated referring to the materials taken from the organic and non-organic evolution of nature. The suggested texts might be found a purposeful tool for the University students proceeding with studying engineering due to the fact that all subjects in this particular field more or less have to cover the history and development of the studied object. It is expected that studying different materials and technologies will help the students with a better understanding of driving forces, positive and negative consequences of technological development, etc

Analysis of the conform process: a specific form of aluminium extrusion.

Since the Conform process was patented 30 years ago, there have only been approximately 200 machines sold worldwide. Given that Conform competes economically with conventional extrusion and is also reported to be a more energy efficient process, it is surprising that the use of Conform is not more widespread in today's increasingly environmentally conscious and high-production focussed world. One explanation for this is likely to be due to the fact that there is still limited knowledge of the thermo-mechanical behaviour of the workpiece during extrusion. Furthermore, for the aluminium industry, there are still issues remaining regarding the production of flash and the quality of the extrudate in terms of mechanical properties. This study provides the reader with the findings of the research and experimental work undertaken by the author, his co-workers and fellow specialists, in the field of aluminium extrusion including Conform. The experimental work includes both laboratory experiments performed with a direct extrusion press and an experimental machine set up to replicate the Conform process. The experimental work is also simulated using finite element modelling techniques. The results from these analyses are then validated by comparing industrial and experimental data. The finite element analyses are enhanced by using parallel processing technology and user sub-routines. The author proposes new models to allow for the study of the different sub-processes in Conform. These include the coining of the feedstock, formation of the upset zone, extrusion of the flash, the filling-up of the expansion chamber / feeder plate and the extrusion of the extrudate. The author also investigates methods which predict microstructure and surface cracks in the extrudate. The author suggests innovative techniques to improve the efficiency of finite element analysis in metal forming. Finally the author recommends procedures for the study of structural integrity and the optimisation of the tooling used in Conform