[pt] As jazidas mundiais de minérios de ferro tendem ao empobrecimento dos teores de ferro, aumento das gangas (sílica, alumina, fósforo, etc.) e maiores ocorrências de minérios hidratados. Esta mudança vem gerando um esforço no sentido de aprimorar as técnicas de extração e beneficiamento. O fósforo é um contaminante que em certos teores provoca a fragilização dos aços, sendo, portanto, restritivo ao aproveitamento de importantes jazidas minerais, principalmente as ricas em minérios de origens intempéricas ou supergênicas. Vários trabalhos foram e estão sendo conduzidos visando desenvolver tecnologias capazes de reduzir o teor de P durante o processo de beneficiamento. Porém, até o momento não têm mostrado viabilidade econômica, face à escala de produção e a efeitos danosos ao ambiente. No caso da Samarco, os minérios foram gerados principalmente por processos de enriquecimento supergênico, nos quais é comum a presença de considerável goethita, que é apontada como principal mineral portador do fósforo. O objetivo deste trabalho foi, de forma original, a formulação de uma pelota para redução direta de forma que o fósforo se encontrasse fluxado em fases escorificadas. Essas fases, produzidas através de um adequado ciclo térmico de endurecimento e com composição química otimizada, resultaria em pelotas onde este elemento se mantivesse estável, tanto na produção do DRI quanto na fusão e refino oxidante deste no FEA. Para tanto foram realizados, além de uma ampla revisão bibliográfica, concebido um procedimento analítico original para quantificação apenas do fósforo liberado; planejado experimentos para: a avaliação cinética da migração deste fósforo em pellet feed, nas pelotas e no DRI quando submetido a diferentes aportes térmicos e auto-fluxagens; analise da influência das variáveis do processo de endurecimento sobre a liberação do fósforo e sua escorificação; e comprovação da estabilidade das fases escorificadas durante a redução, em escala de laboratório, e durante a fusão e refino conduzido em um FEA semi-industrial. Os resultados obtidos mostraram ser viável a produção de pelotas para redução direta com o fósforo auto-fluxado em fases estáveis. / [en] Actually the iron ore deposits in the world have the tendency to decrease the iron content, increasing the gangue (silica, alumina, phosphorus, etc.) and to further occurrence of hydrated ores. This change demands improvements in concentration processing techniques for feasible mining operations. The phosphorus is a contaminant that, in some contents, causes the embrittlement of steels, been, wherefore, a limitative to the use of important ore deposits, mostly regarding the weathered iron ores or supergene origins. Several studies were and have been conducted aiming to develop technologies capable of decreasing the P content during the beneficiation process. However, until now, the economic viability of such studies has not been feasible, considering the production scale and the harmful effects to the environment. In Samarco’s case, the mine geological formation is mostly supergene, which is responsible for the presence of the goethite ores, pointed as the main phosphorus carrier. The main point of this work was, with an innovating approach, formulate a new type of pellet addressed to direct reduction processes in a manner that the P could be fluxed into the slag phases. These phases, produced through an adequate thermal cycle of induration and with an optimized chemical composition, resulted in pellets with stable slags containing, as well as in the produced DRI and in the melted bath generated during the primary refining performed in the EAF. For this purpose, it was done, further to a wide bibliographic review, an original analytical procedure to quantify the released phosphorus and a series of planned experiments, such as: the kinetic evaluation of the phosphorus migration from the mineral phases of the pellet feed when subjected to different thermal treatments; analysis of the induration process variables which could affect the phosphorus release and its fluxing into the slag ; Finally, the stability of the fluxing phases during the reduction in a laboratory scale and the melting and refining process in a semi-industrial EAF, were performed. The obtained results showed the feasibility of this new approach produce DR pellets with self-fluxed phosphorus trapped in stable phases.

The electric power supply industry has evolved into one of the largest industries. Even though secure and reliable operation of the electric power system is fundamental to economy, social security and quality of modern life, the complicated power grid is now facing severe challenges to meet the high-level secure and reliable operation requirements. New technologies will play a major role in helping today's electric power industry to meet the above challenges. This dissertation has focused on some key technologies among them, including the emerging technologies of energy storage, controlled power electronics and wide area measurement technologies. Those technologies offer an opportunity to develop the appropriate objectives for power system control. The use of power electronics based devices with energy storage system integrated into them, such as FACTS/ESS, can provide valuable added benefits to improve stability, power quality, and reliability of power systems. The study in this dissertation has provided several guidelines for the implementation of FACTS/ESS in bulk power systems. The interest of this study lies in a wide range of FACTS/ESS technology applications in bulk power system to solve some special problems that were not solved well without the application of FACTS/ESS. The special problems we select to solve by using FACTS/ESS technology in this study include power quality problem solution by active power compensation, electrical arc furnace (EAF) induced problems solution, inter-area mode low frequency oscillation suppression, coordination of under frequency load shedding (UFLS) and under frequency governor control (UFGC), wide area voltage control. From this study, the author of this dissertation reveals the unique role that FACTS/ESS technology can play in the bulk power system stability control and power quality enhancement in power system. In this dissertation, almost all the studies are based on the real system problems, which means that the study results are special valuable to certain utilities that have those problems. The study in this dissertation can assist power industry choose the right FACTS/ESS technology for their intended functions, which will improve the survivability, minimize blackouts, and reduce interruption costs through the use of energy storage systems. / Ph. D.

A method of producing steel that is not used in Sweden today is direct reduction using natural gas, a method which could has enormous potential in the future of steelmaking. Historically, steelmaking prioritized productivity and profitability. However, other aspects such as safety, sustainability, and environmentally friendliness have become increasingly important to Swedish steelmakers. This study evaluates the usage of natural gas to  directly reduce iron ore into the porous form known as iron sponge, then finally processing that sponge into crude steel. The technology available today is assessed through a literature review, then two calculative data-based model: using DRI sponge in a traditional integrated steelmaking line or replacing steel scrap with it in an electric arc furnace. While this technology is used in many regions where natural gas is plentiful, it has not yet been used in Sweden. Now, when the Swedish natural gas network is expanding and the vehicular transportation of liquid natural gas is becoming more and more viable, it is a prime situation to evaluate direct reduction in Sweden. While models require assumptions and estimations, they suggest that DRI will absolutely be a viable option in the years to come. Integrated plant operators can reduce their immense carbon emissions for a reasonable price, while DRI sponge melting in an electrical arc furnace can either help steelmakers escape the volatile scrap market or be used to replace the blast furnace as a whole in the future. / En metod för att producera stål som inte används i Sverige idag är direkt reduktion med hjälp av naturgas, en metod som har en enorm potential i framtida ståltillverkning. Historiskt har ståltillverkningen prioriterat produktivitet och vinst, men säkerhet, hållbarhet, och miljövänlighet har blivit områden mer och mer viktiga för svenska ståltillverkare. Den här studien utvärderar användningen av naturgas för att direkt reducera järnmalm till den porösa formen känd som järnsvamp, och sen bearbeta den till primärt stål. Teknologin som flnns idag utvärderas genom en litteraturstudie, vars data beräknas till två scenariomodeller: användningen av järnsvamp i ett traditionellt integrerat stålverk eller genom att ersätta stålskrot med järnsvamp i ljusbågsungen. Den här teknologin används redan idag i regioner där naturgas är lättillgängligt, men har hittills inte använts i Sverige. Men nu när Sveriges naturgasnät byggs ut och fordonstransporterad flytande naturgas blir mer och mer kostnadseffektiv så är det lämpligt att utvärdera direkt reduktion i Sverige. Modellerna kräver antaganden och uppskattningar, men de pekar på att direkt reducering av järnmalm kommer att vara en genomförbar metod för ståltillverkning i en nära framtid. Integrerade masugnslinjer kan minska sina enorma koldioxidutsläpp till ett rimligt pris, och järnsvampssmältning i ljusbågsugn kan hjälpa ståltillverkare att undanfly den instabila stålskrotsmarknaden eller användas för att helt ersätta masugnsproduktion i framtiden.

Steel production is today one of the most CO2-demanding activities and causes 8% of the global emissions of GHG. It is crucial for the industry to reduce its emissions radically in order to be in line with the goals of the Paris Agreement and the Science-Based Target initiative. Ovako AB, one of the leading producers of high-strength engineering steel, has been at the forefront when it comes to sustainability initiatives within the industry. Heavy investments are being made into sustainable steel production methods and technologies and to make this viable, the company has, from January 1st, 2022, started to put a price premium on their steel products of 30 € per tonne. This study aims to answer the question of how Ovako's customers, based on the three different industries of mining, automotive, and bearing, experience this price premium and how a green steel can justify this surcharge. Furthermore, this case study aims to understand the extent to which those customers require carbon neutrality when sourcing steel. Connected to the findings from the innovation theories and the literature, this study aims to answer the question of how sustainable innovations may influence future competitiveness regarding engineering steel. To answer these questions, interviews with key individuals from different customers of Ovako were conducted. Moreover, focus groups at Ovako with relevant employees have been held at the same time as a literature study has been conducted. Based on the answers obtained from the data collection, a thematic analysis has been performed where overarching themes have been identified. Additionally, a carbon impact calculator has been used to calculate the carbon reduction potential of using a carbon-neutral engineering steel in three different applications connected to the three industries investigated, namely a complete bearing, a drill bit, and a final drive unit. The results from the calculations as well as the answers obtained regarding the research questions will be presented in the conclusion chapter of the report.