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Steel for Modern Railway Bridges
Published in John F. Unsworth, Design and Construction of Modern Steel Railway Bridges, 2017
Carbon and manganese are hardening and strengthening alloys. Carbon is the principal element controlling the mechanical properties of steel. The strength of steel may be increased by increasing the carbon content, but at the expense of ductility and weldability. Steel also contains deleterious elements, such as sulfur and phosphorous, that are present in the iron ore used to manufacture steel. Manganese also combines with sulfur to preclude the detrimental effects associated with the presence of elemental sulfur. Aluminum and silicon are alloyed to promote deoxidization and improve general steel quality. Chromium and copper are alloyed to increase atmospheric corrosion resistance. Table 2.1 indicates the effects of various alloying elements on the physical and mechanical properties of steel.
Applications in Iron and Steel Making
Published in Nirupam Chakraborti, Data-Driven Evolutionary Modeling in Materials Technology, 2023
Deoxidation of steel, as Kopeliovich and Kopeliovich (2021) explained, is the technology of removing the dissolved oxygen in the hot metal till its activity reaches an acceptable level. Deoxidation can be done by adding metallic deoxidizing agents, through vacuum treatments and also through a diffusion process that would transfer the excess oxygen to a slag phase. Ma et al. (2020) studied the deoxidation process using the historical data of a steel plant. Their approach involves a data-driven modeling and they have used genetic algorithms for minimizing the production cost. They were reasonably successful in predicting the observed trends; however, additional independent studies or any further follow-up are still lacking.
Chapter 4 The Weld Metal
Published in Svensson Lars-Erik, in Steel Arc Welds, 2017
The elements that are supplied with the coating and can take part in the deoxidation process are (apart from silicon and manganese) usually magnesium, titanium, zirconium, calcium, and aluminum. The driving force for the possible reactions can be found from the diagram in Figure 4.11, showing the free energy change versus temperature. The sequence of deoxidation products in decreasing strength is CaO, MgO, A12O3, TiO2, SiO2, and MnO. At very high temperatures, carbon can also act as a deoxidizer, forming CO. The deoxidation process is very efficient. It is estimated that at least 90% of the oxygen in the melt is removed before the weld solidifies.
Review of applicable desulphurization models for crude ferronickel refining
Published in Mineral Processing and Extractive Metallurgy, 2018
Alvin Ma, Sina Mostaghel, Kinnor Chattopadhyay
In general, refining procedure will vary from plant to plant. The most common ones are deoxidization, desulphurization, degassing and decarburization. Because different chemical and physical environments are required for these processes, the ladle slags need to be especially cared for. Optimizing slag properties is essential for manipulating the impurity levels in the melt. The ability for slag to remove impurities can be identified from overarching factors, fluxing and stirring. In the former, understanding the effects of different slag components is paramount to optimizing impurity capacity, and equilibrium partition, while the latter attempts to ensure that gradients, which impede removal, are mitigated. For desulphurization, the ability for slag to dissolve sulphur is commonly referred to as sulphide capacity (Cs) and, its distribution between slag and metal as the sulphide partition coefficient. Currently, the data directly related to ferronickel refining are quite sparse. The sulphide capacity work and physical modelling have existed largely in the steelmaking domain. However, similarities are shared between these two processes and therefore parallels can be drawn.
Modified activated carbon catalytic reduction of dissolved oxygen in reclaimed water
Published in Environmental Technology, 2021
Meisheng Liang, Long Li, Yichen Chen, Haitao Tian
There are two principal methods for DO removal in water: physical and chemical methods [8]. Physical method is eliminating DO from water by increasing temperature or reducing pressure, mainly including thermal deoxygenation, vacuum deoxygenation and diffusion deoxygenation [9,10]. Chemical method commonly uses the added chemical deoxidizer to react with oxygen in the water and to achieve the purpose of oxygen removal, mostly including sodium sulfite deoxidation method, sponge iron oxygen removal and hydrazine deoxidation method [11,12]. However, the traditional thermal deoxygenation method needs water to be heated up to 105°C to be deoxidized with serious huge energy consumption and extremely high investment and operation cost. Vacuum deoxygenation requires more complicated vacuum system, whose daily operation and maintenance are expensive. The primary disadvantage of diffusion deoxygenation is that the effect of deoxidization is unstable in the process of deoxidization. Chemical deoxidizers can generally meet water quality standards, but they have higher operating costs and increase the salinity of the water. Thus, the traditional oxygen removal methods are not appropriate for DO removal in reclaimed water. However, among many new technologies emerging in recent years, the catalytic reduction is one of the most effective methods for removing DO in reclaimed water. Studies have shown that it is feasible to load a metal onto a redox resin as a catalyst and then add a chemical agent, such as sodium sulfite or hydrazine to remove oxygen [13]. Seo et al. 1998 loaded noble metal platinum on mesoporous materials as a catalyst for the removal of DO in water using hydrazine [14]. Moon et al. 1999 loaded metal platinum on activated carbon fibres as a catalyst, and synchonously, DO in the water was almost completely removed by hydrazine [15]. More importantly, the products of hydrazine as a strong reducing agent reacting with oxygen are N2 and H2O, having no effect on water quality, and hydrazine has certain passivation protective effect on metal while removing oxygen [16]. It should be noted that hydrazine reacts slowly with oxygen at ambient temperature. Thus, it is worthwhile devoting much effort to develop a catalyst to accelerate the reaction rate. But the prohibitive cost and scarcity of the noble-metal catalysts needed for catalyzing hydrazine to remove DO in reclaimed water limit the engineering application of catalytic reduction technology. Therefore, considerable attention has been paid to find a cost-effective alternative catalyst.