270 research outputs found
Defense Burden Sharing and Military Cooperation in the EU27: A Descriptive Analysis (2002–2023)
No full textThis paper analyzes defense burden sharing and defense cooperation in the European Union. The efforts to build a common defense framework within the EU have significantly increased since the 2000s. However, figures seem to highlight a reversal in defense cooperation trends that may potentially jeopardize the EU common defense framework. The underlying cause can be attributed to the Russian invasion of Ukraine in 2014. In 2022, the recrudescence of war caused a disruption to which member states answered with an old-fashioned receipt, composed of higher military expenditure driven by increasing commitment in military equipment procurement, accompanied by decreasing defense cooperation. Data related to the participation in Permanent Structured Cooperation defense joint programs seem to empirically confirm this new trend, as well as the impact the conflict has had on defense burden sharing. Fragmentation thus appears to be growing and undoing the progress made
Librettista improvvisata? Così si dice di Vincenzina Viganò Mombelli
No full textVincenzina Viganò Mombelli (second half of the eighteenth century - 1814) is among the very few women who composed verses for music: she is indeed the author of the Demetrio e Polibio’s libretto that was set to music by Gioacchino Rossini and was performed for the first time in 1812. Despite the fact that in 1813 Giovanni Berchet expressed a positive opinion, contemporary critics consider Vincenzina an inexperienced author and note in her verses only weaknesses. The Demetrio e Polibio’s libretto is actually not a masterpiece but has many merits and shows that Vincenzina was very familiar with both the tradition and the novelties of the verses form music
Jarosite wastes reduction through blast furnace sludges for cast iron production
No full textJarosite is a dangerous waste derived from the hydrometallurgical route of zinc production, and it cannot be safely disposed of due to its acidic pH and the risk of toxic metal leaching. A new process at laboratory scale for the utilization of jarosite sludges is proposed, with the aim to obtain cast iron and an inert slag, using blast furnace sludges as reducing agent. Jarosite-reducing agent mixes were reduced in a muffle furnace at 1500 °C for 15 min. Two reducing agents were used: pure graphite (as control) and blast furnace sludges. Two CaO concentrations (5, 15%wt. on jarosite mass) and four equivalent C concentrations (7.5, 15, 30, 60%wt. on jarosite mass) were analysed. Cast iron was obtained from all of the mixes, but the highest reduction yield was obtained at 15%wt. equivalent C. The slag obtained from the control batch had a fully crystalline structure, while the one related to the sample with BF sludges showed an incipient vitrified structure, that could prevent the leaching of hazardous elements. The best process parameters to profitably obtain cast iron and a glassy slag are 15% of equivalent C, 5% CaO and blast furnace sludges as reducing agent
VALORIZZAZIONE DEI MATERIALI CARBONIOSI ASSOCIATI AI PROCESSI SIDERURGICI PER LA PRODUZIONE DI ENERGIA TRAMITE DIRECT CARBON FUEL CELL
No full textCARATTERIZZAZIONE MECCANICA DI BRICCHETTE AUTORIDUCENTI JAROSITE-FANGHI D’ALTOFORNO PER L’INTRODUZIONE NEI PROCESSI SIDERURGICI
No full textManipulation of the leaching behaviour of high-alloyed steel EAF slags through the particle size modulation
No full textThe influence of slag tapping method on the efficiency of stabilization treatment of electric arc furnace carbon steel slag (EAF-C)
No full textStudies conducted over the past 10 years have demonstrated the technical suitability of the electric arc furnace slag as an alternative to natural stone in several applications. Steel slag can be profitably used as a road surface layer, for foundations and embankments, or for concrete aggregates. However, a strong limitation to their use is due to the presence of toxic metals (Ba, Cr, V, Mo, etc.) that can be released into the environment in particular conditions, especially for unbound products in which the slag can come into contact with water. Recent studies have investigated the role of chemical composition and microstructure of slag on toxic metal leaching, allowing for the design of suitable stabilization treatments for hindering such leaching. In this work, four batches of electric arc furnace carbon steel slag underwent a stabilization treatment and the obtained results were compared. In two batches, the stabilizer was added directly in the slag pot and the slag was cooled down in the same pot. The other two batches were stabilized during the downfall from slag door to slag pit. Several slag samples were collected before and after the stabilization treatment and were characterized by means of ED-XRF, XRD, and SEM analysis. Leaching tests were carried out in agreement with EN 12457-2 standard on 4 mm granulated slag, and the leachate concentration was compared with the current Italian limits listed in D.M. 3 August 2005 N. 201 and D.M. 5 April 2006 N. 186. The results clearly indicated that the cooling in the slag pot improved the efficiency of the stabilization treatment, leading to a complete transformation of the microstructure by a full development of homogeneous gehlenite matrix and a coarsening of Cr-spinels, assuring better toxic metal retention behavior. On the contrary, stabilization in the slag-pit was rapid and reduced the interaction between slag and stabilizer, leading only to partial transformation of larnite into gehlenite, and also reducing the coarsening of Cr-spinel. In addition, a layering effect was observed, resulting in an inhomogeneous product from top to bottom in terms of chemical composition, microstructure, and leaching behavior
Biochar and other carbonaceous materials used in steelmaking: Possibilities and synergies for power generation by direct carbon fuel cell
No full textThe objective of this study is the preliminary investigation of the feasibility of using a low-temperature molten hydroxide direct carbon fuel cell as an additional energy source for steel production by electric arc furnace. For this purpose, four carbonaceous materials related to the steel industry (electrographite, coke, torrefied biochar and hydrochar) were selected and characterized to predict their electrical behavior before their actual introduction as fuels. Special attention was paid to both the morphological effect (bulk/pellet or powder) and the chemical composition of the fuels on the electrical performance of the cell. Electrical measurements showed the positive influence of powder morphology, with coke powder having the highest peak power density value (49.6 mW/cm2). Electrographite was found to be useable only as a powder (18.7 mW/cm2), as the high chemical stability of the bulk morphology, provided by the smooth surface and the pitch used as a binder, acted as inhibitors of the carbon oxidation reaction. Although biochar appeared superior to hydrochar when inserted as powder (23.5 vs. 18.2 mW/cm2), the latter showed promising results also inserted as pellet. the latter also showed promising results when inserted as a pellet. Specifically, once inserted within the molten hydrochar, the binder used to produce the hydrochar is removed changing the morphology from pellet to sandy/powdery, negating the penalizing effect of the lower surface to volume of bulk morphology (15.8 vs. 18.2 mW/cm2) and offering the advantage of avoiding the milling process and related fine particulate production from an industrial point of view
Texture and Anisotropy Study on a Lightweight Steel
No full textHigh Mn and high Al steel alloys are a class a steel on which there is a wide and ongoing research. The main reasons are the lightweight-ness (density 16% lower than a typical stainless austenitic steel like AISI 306L) and the very high mechanical properties (up to 800MPa of Yield Strength and up to 55% of elongation at fracture). As a consequence of their properties, they could be very interesting for the automotive sector, but to be employed in any industrial sectors other properties must be checked and studied e.g., the formability. This class of steels are featured by the precipitation of peculiar type of carbides, called k-carbides, which can have a beneficial effect on the mechanical properties (precipitation strengthening) if they precipitate intra-granularly in the austenite matrix. To exploit such strengthening effect, different thermal treatments have been studied and performed on an austenitic lightweight steel alloy (X100MnAl30-9). The evolution of the anisotropy and the texture in different condition have been studied considering different thermo-mechanical conditions. Texture analysis has revealed different orientations, like Rt-C and α-fiber, depending thermomechanical history of the samples and, due to mechanical testing, good workability and low earing tendency is expected for the alloy in the analyzed conditions
Iron recovery from Bauxite Tailings Red Mud by thermal reduction with blast furnace sludge
No full textMore than 100 million tons of red mud were produced annually in the world over the short time range from 2011 to 2018. Red mud represents one of the metallurgical by-products more difficult to dispose of due to the high alkalinity (pH 10-13) and storage techniques issues. Up to now, economically viable commercial processes for the recovery and the reuse of these waste were not available. Due to the high content of iron oxide (30-60% wt.) red mud ranks as a potential raw material for the production of iron through a direct route. In this work, a novel process at the laboratory scale to produce iron sponge (≤ 1300 °C) or cast iron (> 1300 °C) using blast furnace sludge as a reducing agent is presented. Red mud-reducing agent mixes were reduced in a muffle furnace at 1200, 1300, and 1500 °C for 15 min. Pure graphite and blast furnace sludges were used as reducing agents with different equivalent carbon concentrations. The results confirmed the blast furnace sludge as a suitable reducing agent to recover the iron fraction contained in the red mud. For all the conditions tested, the metallization degree was higher than 70%, and the best condition to reduce red mud through blast furnace sludge was identified at 1:1 red mud/blast furnace (B.F.) sludges equal to 0.85 C/Fe2O3
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