Multiobjective optimization of the production process for ground granulated blast furnace slags

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The production process of ground granulated blast furnace slag (GGBS) aims to produce products of the best grade and the highest yields. However, grade and yields are two competing objectives which can not be optimized at the same time by one single solution. Meanwhile, the production process is a multivariable strong coupling complicated nonlinear system. It is hard to establish the accurate mechanism model of this system. Considering above problems, we formulate the GGBS production process as an multiobjective optimization problem, introduce a least square support vector machine method based on particle swarm optimization to build the data-based system model and solve the corresponding multiobjective optimization problem by several multiobjective optimization evolutionary algorithms. Simulation example is presented to illustrate the performance of the presented multiobjective optimization scheme in GGBS production process

Analysis and multi-objective optimization of slag powder process

open access articleSlag powder is a process with characters of multivariables, strongly coupling and nonlinearity. The material layer thickness plays an important role in the process. It can reflect the dynamic balance between the feed volume and discharge volume in the vertical mill. Keeping the material layer thickness in a suitable range can not only improve the quality of powder, but also save electrical power. Previous studies on the material layer thickness did not consider the relationship among the material layer thickness, quality and yield. In this paper, the yield and quality factors are taken into account and the variables that affect the material layer thickness, yield and quality are analyzed. Then the models of material layer thickness, yield and quality are established based on generalized regression neural network. The production process demands for highest yield, best production quality and smallest error of material layer thickness at the same time. From this point of view, the slag powder process can be regarded as a multi-objective optimization problem. To improve the diversity of solutions, a CT-NSGAII algorithm is proposed by introducing the clustering-based truncation mechanism into solution selection process. Simulation shows that the proposed method can solve the multi-objective problem and obtain solutions with good diversity

Electric Arc Furnace slag (EAF): use in concrete for structural applications

L’industria siderurgica rappresenta una delle maggiori realtà produttive nel panorama mondiale, con una produzione globale di acciaio in continua crescita negli ultimi vent’anni. Nonostante le diverse tecniche disponibili, al giorno d’oggi la produzione avviene principalmente mediante due cicli: il “ciclo integrale” o il “ciclo elettrico”, ai quali si aggiungono le successive affinazioni in forno siviera. Oltre al materiale primario (acciaio), da tutti questi processi si origina anche un ingente quantitativo di materiale secondario, le cosiddette “scorie di acciaieria”. In ragione del processo produttivo, delle materie prime, delle modalità di gestione del forno, del tipo di acciaio, dei processi di raffreddamento post-scorifica e dei successivi trattamenti, esse si suddividono in diverse tipologie, ciascuna con le proprie caratteristiche chimico-fisiche, mineralogiche e prestazionali. Il riutilizzo delle scorie di acciaieria in sostituzione delle materie prime naturali in diverse applicazioni apporta notevoli vantaggi sia dal punto di vista economico e sociale che da quello ambientale. Un loro reimpiego contribuisce infatti alla diminuzione dei quantitativi da destinare a smaltimento in discarica nonché alla riduzione dello sfruttamento delle risorse naturali e degli impatti da esso derivanti, sia in termini ambientali che di tutela della biodiversità e del paesaggio. Per poter però garantire un loro corretto trattamento in previsione di un futuro reimpiego, anche le scorie di acciaieria sono soggette al rispetto di determinati standard normativi. Infatti, a seconda della classificazione, i processi di trattamento, registrazione e le verifiche di conformità risulteranno molto diversi ed una loro conoscenza ed interpretazione saranno quindi fondamentali per la corretta gestione di questo tipo di materiale. Il presente lavoro di ricerca intende dare un ulteriore contributo alle conoscenze sulle scorie di acciaieria, con un focus completo su produzione, proprietà, classificazione, gestione e riutilizzi finali. È stata dapprima condotta un’intensa attività di ricerca bibliografica riguardante diverse tipologie di scorie di acciaieria, al fine di approfondire ed analizzare le loro proprietà fisiche, chimiche, mineralogiche, prestazionali ed i relativi aspetti correlati ad un loro eventuale impatto ambientale. Ampio spazio è stato dedicato ai loro possibili riutilizzi, con un focus sul reimpiego nel settore delle costruzioni ed in particolare per la produzione di calcestruzzo. Verrà poi mostrato un quadro generale ed aggiornato sulla normativa nazionale, analizzando le diverse possibilità di classificazione e gli iter da esse derivanti, partendo dalla produzione ed approfondendo tutte le fasi fino all’ottenimento di un materiale conforme e commercializzabile. Vista l’eterogeneità delle scorie di acciaieria, è stato poi deciso di indagare lo stato dell’arte sulla loro produzione e gestione a livello nazionale e locale, con focus su Regione Lombardia (Italia) e Provincia di Brescia (Italia). Ciò ha inoltre permesso di individuare la tipologia di scoria più consona per lo sviluppo di una campagna sperimentale, parte finale della presente ricerca. La suddetta campagna sperimentale verte sul riutilizzo della scoria derivante dalla produzione di acciaio al carbonio in forno elettrico ad arco (la cosiddetta “EAFS-C”) come aggiunta nel calcestruzzo per applicazioni strutturali. In particolare, sono state dapprima progettate diverse miscele di calcestruzzo con l’aggiunta di scorie in parziale sostituzione dell’aggregato fine e grossolano naturale, in tre diverse percentuali (10, 25 e 50%). Queste miscele sono poi state analizzate mediante l’esecuzione di test per la caratterizzazione del materiale (proprietà reologiche e di resistenza), con l’aggiunta anche di test per la valutazione di alcuni aspetti legati alla durabilità del calcestruzzo.The iron and steel industry represents one of the largest production realities in the world, with global steel production steadily growing over the last two decades. Despite the different techniques available, production nowadays mainly takes place according to two cycles: the “integral cycle” or the “electric cycle”, to which subsequent refining in a ladle furnace is added. In addition to the primary material (steel), all these processes also generate a large amount of secondary materials, the so-called “iron- and steelmaking slags”. Depending on the production processes, the raw materials, the furnace management, the type of steel, the post-slagging cooling processes and the subsequent treatments, they are divided into different types, each with its own chemical-physical, mineralogical and performance characteristics. The reuse of iron- and steelmaking slags to replace natural raw materials brings considerable advantages from an economic, social and environmental point of view. In fact, their reuse contributes to reducing the quantities destined for disposal in landfills, the exploitation of natural resources and the resulting impacts, in terms of environment, biodiversity and landscape protection. However, in order to ensure their proper treatment for future reuse, iron- and steelmaking slags are also subjected to certain regulatory standards. In fact, depending on the classification, the treatment processes, registration and conformity assessments will be quite different and their knowledge and interpretation are therefore essential for the proper management of this type of materials. This research aims to provide a further contribution to the knowledge of iron- and steelmaking slags, with a comprehensive focus on production, properties, classification, management and final reuses. First of all, an intensive literature research was carried out on different types of iron- and steelmaking slags, in order to investigate and analyse their physical, chemical, mineralogical and performance properties, as well as aspects related to their possible environmental impact. Large space has been dedicated to their possible reuses, with a focus on reuse in the construction sector and in particular for concrete production. A general and updated overview of the national regulations will then be shown, analysing the different classification possibilities and the procedures deriving from them, starting from production and going through all the phases until a compliant and marketable material is obtained. Given the heterogeneity of iron- and steelmaking slags, it was then decided to investigate the state of the art on their production and management at a national and local level, focusing on the Lombardy Region (Italy) and the Province of Brescia (Italy). This also made it possible to identify the most suitable type of slag for the development of an experimental campaign, the final part of this research. The aforementioned experimental campaign concerns the reuse of slag from the production of carbon steel in electric arc furnaces (the so-called “EAFS-C”) as an addition in concrete for structural applications. Specifically, different concrete mixtures with the addition of slag as partial replacement of fine and coarse aggregate (in three different percentages, 10, 25 and 50%) were first designed. These mixtures were then analysed by carrying out tests for material characterisation (rheological and strength properties), with the addition of tests to assess aspects related to the durability of concrete

Data-driven optimization tool for the functional, economic, and environmental properties of blended cement concrete using supplementary cementitious materials

The need to produce more sustainable concrete is proving imminent given the rising environmental concerns facing the industry. Blended cement concrete, based on any of the prominent supplementary cementitious materials (SCMs) such as fly ash, ground granulated blast-furnace slag, silica fume, calcined clay and limestone powder, have proven to be the best candidates for sustainable concrete mixes. However, a reliable sustainability measure includes not only the environmental impact, but also the economic and functional ones. Within these five SCMs, their environmental, economic and functional properties are found to be conflicting at times, making a clear judgement on what would be the optimum mix not a straightforward path. A recent framework and tool for concrete sustainability assessment ECO2, sets a reliable methodology for including the functional performance of a concrete mix depending on project-based specifications. Therefore, in this study, a recently published regression model, Pre-bcc was used to predict the functional properties of a wide grid search of potentially suitable blended cement concrete mixes. Hence, an open access novel genetic algorithm tool “Opt-bcc” was developed and used to optimize the sustainability score of these mixes based on a set selection of user-defined project-specific functional criteria. The optimized mixes using the Opt-bcc model for each strength class were compared against the mix design proposed by other optimization models from the literature and were found to be at least 70% cheaper and of 30% less environmental impact.Peer ReviewedPostprint (published version

Évaluation intégrée des conséquences environnementales indirectes de la circularité des matériaux accrue dans les symbioses industrielles multirégionales

La transition à grande échelle vers une économie circulaire est essentielle pour relever les défis planétaires actuels liés aux changements climatiques et à l’épuisement des ressources naturelles. Cette transition implique de profondes réorganisations des interactions entre différentes industries et juridictions, entraînant des perturbations la dynamique concurrentielle des marchés des matières premières et secondaires. Ces perturbations peuvent entrainer des conséquences favorables ou défavorables sur l’environnement selon les spécificités du marché et paysage industriel unique à chaque région. Actuellement, le potentiel de telles conséquences indirectes est largement sous-évalué. Les capacités des méthodes d’évaluation ex ante qui intègrent la circularité dans les flux physiques sont limitées par de basses résolutions spatiales, temporelles et/ou matérielles avec un accent restreint sur les changements climatiques. Ce projet de recherche a pour objectif de développer une méthode d’évaluation intégrée ex ante permettant d’étudier de manière holistique les conséquences environnementales indirectes de l’augmentation de la circularité matérielle au sein de symbioses industrielles multirégionales. La première partie de la thèse présente les fondations conceptuelles et mathématiques d’un nouveau modèle d’optimisation économique de chaînes Matériaux-Produits multirégionales (CMPM) à séries temporelles. Ce modèle permet d’analyser les réactions en chaîne au sein des synergies industrielles qui cherchent à minimiser les coûts liés à leurs approvisionnements en matières premières, de matières secondaires, de résidus et de produits finis en réponse à des initiatives d’économie circulaire. L’élément novateur du modèle CMPM est la combinaison des quatre aspects suivants : (i) la distinction explicite entre les flux de matières et de produits finis et leurs relations causales dynamiques, (ii) l’utilisation d’équations d’équilibre de masse pour relier l’ensemble des chaînes multirégionales de production, consommation et gestion des matières résiduelles, (iii) une décomposition multirégionale de la concurrence de marché des matières premières et de matières secondaires et (iv) l’inclusion de trajectoires de contraintes physiques évoluant dans le temps. L’étude de cas portant sur une augmentation de l’utilisation de matériaux cimentaires dérivés de sous-produits industriels dans la production de ciment dans le nord-est de l’Amérique du Nord révèle des résultats complexes et nuancés. Bien que cette augmentation soit favorable globalement en favorisant l’économie circulaire, les résultats mettent en lumière des conséquences économiques et environnementales inégales entre les régions, créant à la fois des gagnants et des perdants. Cela souligne l’importance de prendre en compte les spécificités régionales et les dynamiques du marché pour maximiser les avantages de la circularité tout en minimisant les externalités négatives. La deuxième partie de la thèse se concentre sur l’examen des trajectoires des conséquences potentielles directes et indirectes sur la santé humaine, la diversité des écosystèmes, la disponibilité des ressources et les changements climatiques résultant de mesures visant à promouvoir la récupération des ressources en boucle fermée et ouverte. Cette analyse repose sur l’utilisation combinée des outils de l’analyse du cycle de vie conséquentielle (ACV-C) et du modèle CMPM. Dans un premier temps, les capacités du CMPM sont mises à profit pour identifier et quantifier l’inventaire du cycle de vie conséquentielle des mesures d’économie circulaire. Ensuite, cet inventaire est associé à la base de données conséquentielle ecoinvent v3.7 et à la méthode de caractérisation ReCiPe 2016 afin de caractériser les variations marginales des flux physiques en impacts potentiels. Le modèle est appliqué à deux mesures de valorisation des déchets de verre post-consommation dans la province de Québec (Canada): (1) l’amélioration des systèmes de récupération des ressources en boucle fermée favorisant un recyclage de bouteille-à-bouteille et (2) le déploiement d’un système en boucle ouverte pour la commercialisation de la poudre de verre comme ajout cimentaire. Les résultats indiquent qu’entre 55% et 94% des bénéfices environnementaux de la décision québécoise sont ressentis au-delà des frontières du Québec, en raison des réactions en chaîne indirectes survenant dans les échanges commerciaux dans l’est de l’Amérique du Nord. La troisième partie de cette thèse fournit des orientations pour prioriser les efforts en vue d’améliorer l’interprétation et la fiabilité des ACV-C. Grâce aux nouvelles capacités de modélisation fournies par le modèle intégré ACV-C:CMPM, une analyse de sensibilité globale basée sur la variance est performée pour identifier et classer les sources d’incertitude les plus influentes parmi les paramètres macroéconomiques, de flux de matières, économiques, de transport et de l’inventaire du cycle de vie. Ensuite, un cadre est proposé pour identifier les sources clés où les efforts de modélisation doivent être priorisés stratégiquement pour considérer l’incertitude des paramètres dans l’interprétation des résultats d’ACV-C, et ce, en fonction des caractéristiques spécifiques des marchés régionaux étudiés. Les résultats soulignent l’importance des variables et hypothèses érigeant les interactions entre l’offre et la demande de produit et de l’intensité de la concurrence horizontale. En résumé, cette thèse élargit la compréhension des implications complexes de la transition vers une économie circulaire à grande échelle. Elle met en évidence l’importance de tenir compte des spécificités régionales et des dynamiques du marché lors de la mise en œuvre de feuilles de route industrielles visant l’accroissement de la circularité des matériaux. Il est essentiel de reconnaître que cette circularité ne se traduit pas de manière uniforme dans toutes les régions, créant à la fois des opportunités et des défis uniques. Cela nécessite des approches intégrées pour les aborder de manière holistique et crédible dans le but ultime de favoriser un avenir plus durable pour notre planète.Abstract: The large-scale transition to a circular economy is essential to address current global challenges related to climate change and the depletion of natural resources. This transition involves profound reorganizations of interactions between different industries and jurisdictions, leading to disruptions in the competitive dynamics of primary and secondary material markets. These disruptions can have both positive and negative consequences on the environment, depending on the specific char-acteristics of each regional market and industrial landscape. Currently, the potential for such multi-regional indirect consequences is widely underestimated. The capabilities of ex-ante evaluation methods that integrate circularity into physical flows are limited by low spatial, temporal, and/or material resolutions with a narrow focus on climate change. This research project aims to de-velop an integrated ex-ante evaluation method to holistically study the indirect environmen-tal consequences of increased material circularity within multi-regional industrial symbiosis. The first part of the thesis presents the conceptual and mathematical foundations of the Multire-gional Materials-Products Chains (MMPC) economic optimization model with time series. This model allows the analysis of chain reactions within industrial synergies seeking to minimize the costs related to their supplies of raw materials, secondary materials, waste, and finished products in response to circular economic initiatives. The innovative aspect of the MMPC model is the com-bination of four key aspects: (i) the explicit distinction between material and finished product flows and their dynamic causal relationship, (ii) the use of mass balance equations to link all multi-re-gional chains of production, consumption, and waste management, (iii) a multi-regional decompo-sition of competition in the raw material, secondary material, waste, and finished product markets, and (iv) the inclusion of evolving physical constraint trajectories over time. The case study on increasing the use of cementitious materials derived from industrial by-products in cement produc-tion in the Northeastern North America reveals unbalanced results in terms of cost, trade balance, and greenhouse gas emissions between Canada and the United States due to the unequal distribu-tion of secondary materials. The second part of the thesis focuses on examining the potential direct and indirect consequences on human health, ecosystem diversity, resource availability, and climate change resulting from regional circular economy measures promoting closed and open resource recovery. This analysis relies on the integration of consequential life cycle assessment (CLCA) and the MMPC model. First, the capabilities of the MMPC model are utilized to identify and quantify the consequential life cycle inventory of circular economy measures. Then, this inventory is associated with the ecoinvent v3.7 database and the ReCiPe 2016 characterization method to characterize marginal variations in physical flows into potential impacts. The model is then applied to two measures of post-consumer glass waste valorization in the province of Quebec, Canada: (1) the improvement of closed-loop bottle-to-bottle resource recovery systems and (2) the deployment of an open-loop system for marketing glass powder as a cementitious additive. Between 55% and 94% of the envi-ronmental benefits of Quebec’s decision are felt beyond the province’s borders, due to indirect chain reactions in trade with eastern North America. The third part of this thesis provides guidance to prioritize efforts to improve the interpretation and reliability of CLCA. Using the new modelling capabilities provided by the integrated CLCA:MMPC model, a global sensitivity analysis based on variance is performed to identify and rank the most influential sources of uncertainty among macroeconomic, material flow, economic, transportation, and life cycle inventory parameters. Then, a framework is proposed to identify key sources where modelling efforts should be strategically prioritized to account for parameter uncer-tainty in the interpretation of CLCA results, depending on the specific characteristics of the studied regional markets. The results highlight the importance of variables and assumptions governing in-teractions between product supply and demand and the intensity of horizontal competition. In summary, this thesis broadens understanding of the complex implications of the transition to a large-scale circular economy. It highlights the importance of taking regional specificities and mar-ket dynamics into account when formulating policies and implementing sustainable practices. It is essential to recognize that material circularity does not translate uniformly across all regions, cre-ating both unique opportunities and challenges. This calls for integrated approaches to tackle chal-lenges and opportunities holistically, with the ultimate aim of fostering a more sustainable future for our planet

Future Trends in Advanced Materials and Processes

The Special Issue “Future Trends in Advanced Materials and Processes” contains original high-quality research papers and comprehensive reviews addressing the relevant state-of-the-art topics in the area of materials focusing on relevant or innovative applications such as radiological hazard evaluations of non-metallic materials, composite materials' characterization, geopolymers, metallic biomaterials, etc

Extending BIM for air quality monitoring

As we spend more than 90% of our time inside buildings, indoor environmental quality is a major concern for healthy living. Recent studies show that almost 80% of people in European countries and the United States suffer from SBS (Sick Building Syndrome), which affects physical health, productivity and psychological well-being. In this context, environmental quality monitoring provides stakeholders with crucial information about indoor living conditions, thus facilitating building management along its lifecycle, from design, construction and commissioning to usage, maintenance and end-of-life. However, currently available modelling tools for building management remain limited to static models and lack integration capacities to efficiently exploit environmental quality monitoring data. In order to overcome these limitations, we designed and implemented a generic software architecture that relies on accessible Building Information Model (BIM) attributes to add a dynamic layer that integrates environmental quality data coming from deployed sensors. Merging sensor data with BIM allows creation of a digital twin for the monitored building where live information about environmental quality enables evaluation through numerical simulation. Our solution allows accessing and displaying live sensor data, thus providing advanced functionality to the end-user and other systems in the building. In order to preserve genericity and separation of concerns, our solution stores sensor data in a separate database available through an application programming interface (API), which decouples BIM models from sensor data. Our proof-of-concept experiments were conducted with a cultural heritage building located in Bled, Slovenia. We demonstrated that it is possible to display live information regarding environmental quality (temperature, relative humidity, CO2, particle matter, light) using Revit as an example, thus enabling end-users to follow the conditions of their living environment and take appropriate measures to improve its quality.Pages 244-250

First experiences in the development of slovenian sustainable building indicators

The construction sector is recognised as having a key impact on the life on Earth. Consequently, the EU has set clear environmental goals for 2030 and 2050, and is developing policies and tools to achieve them. One of the tools for achieving these goals is to establish a system for the evaluation of the environmental performance of buildings, with the priorities of reducing GHG emissions, saving with natural resources and preserving the environment, while maintaining sustainable development and ensuring a healthy living environment. Slovenia has joined in achieving this goal with a study on the state-of-play, commissioned a few years ago by the Ministry of the Environment and Spatial Planning, as the starting point for the development of sustainable building indicators (SBIs). The research, which included an analysis of the Slovenian legislation, commercial certification systems for sustainable buildings and development in the field of green public procurement, exposed complementary but rather different goals and views. It further showed that the Level(s), which provides a common EU approach in assessing the environmental performance of buildings, seems to be the most appropriate framework and the basis for the development of the Slovenian system of SBIs. The development of the Slovenian SBIs is currently underway within the project LIFE IP CARE4CLIMATE with the preparation of guidelines, data sources and procedures for determining the value of individual indicators for the assessment of buildings. Initial research with key construction stakeholders has shown that the solution must be linked to the national building legislation, computational methods and software tools, and also to the established planning procedures. The analyses have also shown that, parallel to developing such a system, it is essential to provide a functional supporting environment and a specific, purposely designed information platform to connect the stakeholders with the developers of the sustainable building indicators system

Use of steel slag for the synthesis of belite-sulfoaluminate clinker

Belite-sulfoaluminate (BCSA) cements are low-carbon mineral binders, which require low energy consumption and allow the incorporation of various secondary raw materials in the clinker raw meal. In this study two types of unprocessed steel slags, coming from stainless steel production, were incorporated in the BCSA clinkers. The clinker phase composition, clinker reactivity, and the compressive strength of the cement were studied to evaluate the possible use of the slag in BCSA clinkers. The cement clinkers were synthesized by using natural raw materials, white titanogypsum, mill scale, as well as two different steel slags: (i) EAF S slag, which is a by-product of melting the recycled steel scrap in an electric arc furnace, and (ii) la dle slag as a by-product of the processes of secondary metallurgy, in various quantities. Raw mixtures with two different targeted phase compositions varying in belite, calcium sulfoaluminate and ferrite phases were sintered at 1250 °C. Clinker phases were determined by Rietveld quantitative phase analysis, while their distribution, morphology and incorporation of foreign ions in the phases were studied by SEM/EDS analysis. The clinker reactivity was determined by isothermal calorimetry. BCSA cements were prepared by adding titanogypsum. The compressive strength of the cement pastes was determined after 7 days of hydration. The presence of a predicted major clinker phases was confirmed by Rietveld analysis, however periclase was also detected. Microscopy revealed subhedral grains of belite and euhedral grains of calcium sulfoaluminate phases, while ferrite occurred as an interstitial phase. The results showed differences in the microstructure and reactivity of the clinker and cement, which can be attributed to varying amounts of ettringite due to different slag type

CoMS

Zbornik pokriva številne, predvsem tehnične teme, ki so pomembne za trajnostni razvoj gradbenega sektorja, kot ključnega dejavnika pri doseganju ciljev EU za obvladovanje podnebnih sprememb in za prehod v brezogljično družbo. Vsebinsko naslavlja inovacije v gradbenih materialih in tehnologijah, vključno s komponentami za zdravo in udobno bivanje, ter interakcije med materiali in okoljem. Poleg energetske učinkovitosti stavb je v njem zajeto področje širšega razumevanja trajnostnega načrtovanja, gradnje in vzdrževanja stavb ter monitoring, ocenjevanje in modeliranje stavb. Vključuje pa tudi vsebine, ki se nanašajo na krožno gospodarstvo, kot je recikliranje materialov in komponent ter koncepti sanacij stavb, ter na digitalizacijo in avtomatizacijo področja