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

Refining and Casting of Steel

Steel has become the most requested material all over the world during the rapid technological evolution of recent centuries. As our civilization grows and its technological development becomes connected with more demanding processes, it is more and more challenging to fit the required physical and mechanical properties for steel in its huge portfolio of grades for each steel producer. It is necessary to improve the refining and casting processes continuously to meet customer requirements and to lower the production costs to remain competitive. New challenges related to both the precise design of steel properties and reduction in production costs are combined with paying special attention to environmental protection. These contradictory demands are the theme of this book

Towards Circular Economy for Steel - Assessing the Efficiency of Yellow Gypsum Synthesis from BOF Slags

The large quantities of basic oxygen furnace (BOF) slag produced at the Tata Steel Port Talbot steelworks has no existing recycling scope and has formed a large legacy “slag mountain” over the years. Closure of all Britain’s coal power plants by 2025 potentially could create a shortage of the supply of gypsum in the UK and elsewhere. A solution to the problem may lie in production of gypsum from a by-product of the steelmaking. This will afford a potential opportunity for commercialisation in Port Talbot. This research applies the findings of ‘A method of producing calcium sulphate from LD slag waste produced during the recovery of metallic iron from LD slag’ of which patent 572/KOL/2014 has been filed, to assess the efficiency of yellow gypsum synthesis from BOF slag, while determining the feasibility for commercialisation of this process at the Port Talbot steelworks. To provide this knowledge, an assessment of the chemical composition and particle size distribution of the BOF slag produced at the Port Talbot steelworks was undertaken, whilst developing methods to assess the efficiency of the process. X-ray fluorescence analysis was undertaken on the BOF slag samples acquired and synthetic yellow gypsum produced to determine the calcium conversion at the defined particle size distributions outlined in the thesis. Cost and market analysis were also undertaken to determine feasibility of commercialisation at the Port Talbot steelworks. This study, therefore confirmed that commercialisation of this process in the Port Talbot steelworks is feasible but would require large scale operation and further processing of the synthetic yellow gypsum produced. In addition, processing the synthetic yellow gypsum produced to products within the agriculture and construction industry would provide a higher valued final product

Iron and steel slag valorization through carbonation and supplementary processes

Alkaline industrial wastes are considered potential resources for the mitigation of CO2 emissions by simultaneously capturing and sequestering CO2 through mineralization. Mineralization safely and permanently stores CO2 through its reaction with alkaline earth metals. Apart from natural formations, these elements can also be found in a variety of abundantly available industrial wastes that have high reactivity with CO2, and that are generated close to the emission point-sources. Apparently, it is the applicability and marketability of the carbonated products that define to a great extent the efficiency and viability of the particular process as a point source CO2 mitigation measure. This project investigates the valorization of iron- and steel-making slags through methods incorporating the carbonation of the material, in order to achieve the sequestration of sufficient amounts of CO2 in parallel with the formation of valuable and marketable products. Iron- and steel-manufacturing slags were selected as the most suitable industrial byproducts for the purposes of this research, due to their high production amounts and notable carbonation capacities. The same criteria (production amount and carbonation capacity) were also used for the selection of the iron- and steel-making slag types that are more suitable to the scope of this work. Specifically for the determination of the slag types with the most promising carbonation capacities, the maximum carbonation conversions resulting from recent publications related to the influence of process parameters on the conversion extent of iron- and steel-manufacturing slags, were directly compared to each other using a new index, the Carbonation Weathering Rate, which normalizes the results based on particle size and reaction duration. Among the several iron- and steel-manufacturing slags, basic oxygen furnace (BOF) and blast furnace (BF) slags were found to combine both high production volumes and significant affinity to carbonation. In the context of this research, two different procedures aiming to the formation of value added materials with satisfactory CO2 uptakes were investigated as potential BF and BOF slags valorization methods. In them, carbonation was combined either with granulation and alkali activation (BOF slag), or with hydrothermal conversion (BF slag). Both treatments seemed to be effective and returned encouraging results by managing to store sufficient amounts of CO2 and generating materials with promising qualities. In particular, the performance of the granulation-carbonation of BOF slag as a method leading to the production of secondary aggregates and the sequestration of notable amounts of CO2 in a solid and stable form, was evaluated in this work. For comparison purposes, the material was also subjected to single granulation tests under ambient conditions. In an effort to improve the mechanical properties of the finally synthesized products, apart from water, a mixture of sodium hydroxide and sodium silicate was also tested as a binding agent in both of the employed processes. According to the results, the granules produced after the alkali activation of the material were characterized by remarkably greater particle sizes (from 1 to 5 mm) compared to that of the as received material (0.2 mm), and by enhanced mechanical properties, which in some cases appeared to be adequate for their use as aggregates in construction applications. The maximum CO2 uptake was 40 g CO2/kg of slag and it was achieved after 60 minutes of the combined treatment of alkali activated BOF slag. Regarding the environmental behavior of the synthesized granules, increased levels of Cr and V leaching were noticed from the granules generated by the combination of granulation-carbonation with alkali activation. Nevertheless, the combination of granulation with alkali activation or that of granulation with carbonation were found not to worsen, if not to improve, the leaching behaviour of the granules with regards to the untreated BOF slag. The formation of a zeolitic material with notable heavy metal adsorption capacity, through the hydrothermal conversion of the solid residues resulting from the calcium- extraction stage of the indirect carbonation of BF slag, was also investigated in this project. To this end, calcium was selectively extracted from the slag by leaching, using acetic acid of specific concentration (2 M) as the extraction agent. The residual solids resulting from the filtration of the generated slurry were subsequently subjected to hydrothermal conversion in caustic solution of two different compositions (NaOH of 0.5 M and 2 M). Due to the presence of calcium acetate in the composition of the solid residues, as a result of their inadequate washing, only the hydrothermal conversion attempted using the sodium hydroxide solution of higher concentration (2 M) managed to turn the amorphous slag into a crystalline material, mainly composed by a zeolitic mineral phase (detected by XRD), namely, analcime (NaAlSi2O6·H2O), and tobermorite (Ca5(OH)2Si6O16·4H2O). Finally, the heavy metal adsorption capacity of the particular material was assessed using Ni2+ as the metal for investigation. Three different adsorption models were used for the characterization of the adsorption process, namely Langmuir, Freundlich and Temkin models. Langmuir and Temkin isotherms were found to better describe the process, compared to Freundlich model. Based on the ability of the particular material to adsorb Ni2+ as reported from batch adsorption experiments and ICP-OES analysis, and the maximum monolayer adsorption capacity (Q0 = 11.51 mg/g) as determined by the Langmuir model, the finally synthesized product can potentially be used in wastewater treatment or environmental remediation applications

The viability of renewable energy and energy storage for the provision of power for desalination

This research investigates the viability of renewable energy and energy storage to meet a significant and fundamental human need (in this case, large-scale drinking water supplies) unassisted by conventional power. The use of renewable energy to power reverse osmosis desalination plants to provide potable water for around 50,000 people in Newhaven, in South East England, and in Massawa in Eritrea, was investigated. The following energy sources, in a variety of combinations were specifically assessed: • Wind Power • Wave Power • Solar Power • Tidal Current Power • Hydrogen production, storage and use in Fuel Cells. The following types of reverse osmosis plants were studied: • No Brine Stream Recovery (BSR) reverse osmosis plant • Pelton Wheel BSR reverse osmosis plant • Pressure Exchanger BSR reverse osmosis plant. Modelling was conducted to derive the amount of water that each reverse osmosis plant would deliver from various combinations and amounts of renewable power input, at varying feedwater temperatures. Scenarios that were not able to deliver enough water to meet the users' needs were scaled-up so that they could. The cost of the scaled-up scenarios that were able to meet the users' water demands were compared with the costs associated with the equivalent conventionally-powered scenario over a 25-year life. Specifically, the following were considered: • A coal-fired plant with carbon capture and storage (CCS) at Newhaven and • A diesel generator at Massawa. This comparison was made with and without the external costs associated with conventional energy production and use. The most financially-attractive scenario at each site was then assessed for its ability to meet the daily demand for water, over the course of a year. A comparison of the most financially-attractive renewable energy option and the equivalent conventionally-powered scenario at Massawa was undertaken, based on Net Present Value (NPV) methodology