In hot metal desulphurisation (HMD) the slag will hold the removed sulphur. However, the iron that is lost when the slag is skimmed off, accounts for the highest costs of the HMD process. These iron losses are lower when the slag has a lower viscosity, which can be achieved by changing the slag composition. A lower slag basicity decreases the viscosity of the slag, but also lowers its sulphur removal capacity, therefore optimisation is necessary. In this study, the optimal HMD slag composition is investigated, considering both the sulphur removal capacity and the iron losses. In part I the theory is discussed and in part II the optimal slag is validated with plant data, laboratory experiments and a thermodynamic analysis.

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The optimal hot metal desulphurisation (HMD) slag is defined as a slag with a sufficient sulphur removal capacity and a low apparent viscosity (η slag ) which leads to low iron losses. In part I of this study, the fundamentals behind the optimal slag were discussed. In this part these fundamentals are explored by a Monte Carlo simulation, based on FactSage calculations, plant data analysis and melting point and viscosity measurements of the optimal slag. Furthermore, the applicability of knowing the optimal slag composition for an industrial HMD is discussed.

For a successful implementation of newly proposed silicon-based latent heat thermal energy storage systems, proper ceramic materials that could withstand a contact heating with molten silicon at temperatures much higher than its melting point need to be developed. In this regard, a non-wetting behavior and low reactivity are the main criteria determining the applicability of ceramic as a potential crucible material for long-term ultrahigh temperature contact with molten silicon. In this work, the wetting of hexagonal boron nitride (h-BN) by molten silicon was examined for the first time at temperatures up to 1750°C. For this purpose, the sessile drop technique combined with contact heating procedure under static argon was used. The reactivity in Si/h-BN system under proposed conditions was evaluated by SEM/EDS examinations of the solidified couple. It was demonstrated that increase in temperature improves wetting, and consequently, non-wetting-to-wetting transition takes place at around 1650°C. The contact angle of 90°± 5°is maintained at temperatures up to 1750°C. The results of structural characterization supported by a thermodynamic modeling indicate that the wetting behavior of the Si/h-BN couple during heating to and cooling from ultrahigh temperature of 1750°C is mainly controlled by the substrate dissolution/reprecipitation mechanism.

Background Integrated steelmaking is known to emit coarse airborne ‘nuisance’ dust (10–100 µm) to the production site and in the local environs. We present a method to quantitatively analyse the provenance, mineralogical and chemical attributes of the constituent particles in nuisance dust related to the integrated steelworks of Tata Steel, IJmuiden, the Netherlands. The dust is characterised per particle, using scanning electron microscopy with energy-dispersive spectrometry (SEM–EDS) microanalysis, and in bulk with quantitative X-ray diffraction (XRD) analysis. Based on mineralogical characteristics, particles in the dust are sorted into populations that can be related in detail to industrial processes and subsequent atmospheric weathering influence. The method is illustrated by application to a nuisance dust complaint sample from the neighbouring town Wijk aan Zee containing a large contribution of several dust sources from the integrated steelworks. Results Besides a background contribution from urban and natural dust, diverse sources from the integrated steelworks are identified in the nuisance dust sample, derived from coke-making, iron-ore agglomeration processes and blast furnace ironmaking, steelmaking slag processing, process fluxes, as well as steelmaking refractory materials. The most voluminous of these in the sample are directly verified by comparison with a set of reference source materials. The abundances, mineralogical and chemical attributes of the various dust particle populations in the sample are quantitatively examined including, specifically, the occurrence of the potentially toxic elements Mn and V. These elements occur with highest concentrations in dust derived from steelmaking converter slag: V is housed in dilute form (solid solution) in the phases di-calcium silicate and brownmillerite, and Mn chiefly in Mg–Fe-oxide (Mg-wustite ((Mg,Mn,Fe)O) and its oxidation product ((Mg,Mn,Fe)(Fe,Mn)2O4)). Conclusions By treating nuisance dust as a particulate, multi-phase, multi-source material, the outlined method provides crucial information for toxicological evaluation and for mitigation of emissions, which is not obtainable by bulk chemical analyses alone. It also helps address the lack of adequate monitoring options for deposits of nuisance dust from integrated steel production, necessary to evaluate the relationship between deposition and monitored emissions that are regulated by the European Industrial Emissions Directive and by local permits based on this legislation.