Sintering is a process for ironmaking operations; it represents one of the main sources of production emissions of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzo-furans, NOx and SOx. In the present study, the operating conditions through which a reduction of dangerous emissions can be achieved are defined through numerical analysis. By employing a multiobjective optimisation tool, a deep analysis capable of representing the process behaviour leading to the optimal operating conditions was developed. Through such analysis, a broad range of processing parameters affecting the development of PCDD/Fs in the sintering process has been evaluated. The first aim was the possible reduction of dangerous emissions through numerical and experimental analyses allowing the definition of the optimal conditions for the minimisation of pollutants. Although the resultant optimal combination of input parameters able to reduce the dangerous emissions from the plant was determined, it was largely examined on the impact of the chosen input parameters on the sinter productivity. In such a way, it was possible to reduce the emissions close to the legal limits and with a high level of productivity and efficiency of the plant.

Cold spraying is an innovative coating technology mainly based on the high speed impact of metals and ceramic particles on different substrates. Through the employment of low temperature gases (Air, He, N2) spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) that is generated through a convergent-divergent de Laval type nozzle. Severe plastic deformation of particles impacting on the substrate occurs at temperature well below the melting point leading to the unique mechanical properties experienced by such kinds of coatings. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of processing parameters on grain refinement and mechanical properties were analyzed for different particles (Ti-TiAl3, Al-Al2O 3, Ni-Cr3C2, Ni-BN, Cu-Al2O 3, Co-SiC). The results belonging to the properties of the formed nanocomposites were compared with those of the pure parent materials sprayed in the same conditions. Many experimental conditions have been analyzed in terms of particle dimensions and composition, substrate temperature and composition, gas temperature and pressure, nozzle properties. In particular, those conditions leading to a strong grain refinement with an acceptable level of the mechanical deposit properties such as porosity, adhesion strength and hardness were underlined.

In the present paper, the microstructural and mechanical properties of metal-metal cold spray deposits are described. Different spray particles coatings (Al-, Ti-, Ni-based particles) deposited on different substrates (Al-, Ti-, Fe-, Ni-, Mg-based bulk materials) were produced and their mechanical and microstructural properties were characterized. Microhardness, porosity, grain size and adhesion strength of the coatings were analyzed as a function of processing parameters such as particle velocity, particle dimensions, gas density, substrate hardness, and temperature. The results were employed to build a database used to obtain a provisional model through a multi-objective optimization software. For each different substrate and particle type, the working points were defined in terms of processing parameters to optimize mechanical and microstructural behavior of coatings. The error calculation of the final properties of the deposits demonstrated the precision of the developed model.

The sintering operation in integrated steelworks is one of the main sources for the production of polychlorinated dibenzo-p-dioxins, polychlorinated- dibenzo-furans, NOx and SOx. In the present study, the operating conditions, through which a reduction in emissions can be achieved, were defined through numerical analysis. The following process parameters were evaluated: gas temperature, quantities of chlorine and copper and additions of hydrated lime, sulphur and urea. Using the optimisation software modeFRONTIER (ESTECO), a virtual surface that can reproduce the actual process of sintering was created. Additionally, with the application of filtering to postsintering gas, such as electrostatic precipitator and wetfine scrubber, it was possible to obtain a reduction in emission values within the limits of international protocol Aarhus.