WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

Browse

Filters

2021 - 20223

Settings

Access Right: Open AccessInstitution Author: search.filters.institutionAuthor.Gökelma, Mertol

Search Results

Now showing 1 - 3 of 3
  • Conference Object
    Pre-Study of the Dissolution Behavior of Silicon Kerf Residue in Steel
    (Springer, 2022) Lazou, Adamantia; Nilssen, David; Gökelma, Mertol; Wallin, Maria; Tranell, Gabriella
    Silicon kerf residue is generated during the wafering process of pure silicon in the photovoltaic value chain. The generated by-product has a high volume, and the particle size is typically below 1 μm. Although the fine particles are partly oxidized, the material may be beneficial in different metallurgical applications such as grain refining and alloy composition adjustments. This work studies the dissolution behavior of silicon kerf in low alloy steel melts with the aim to upcycle the kerf material in the steel industry for different purposes. In this study, a steel alloy and the kerf residue were melted (at 1580 °C) in an alumina crucible placed in an induction furnace. The amount of added kerf residue was varied. The behavior of the particles in the solidified alloy was characterized by using an optical microscope, electron probe microscope (EPMA), and wavelength-dispersive X-ray spectroscopy (WDS) in order to study the dissolution behavior of the Si-kerf residue in the steel.
  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Behavior of Al4c3 Particles During Flotation and Sedimentation in Aluminum Melts
    (Springer, 2021) Gökelma, Mertol; Storm Aarnaes, Trygve; Maier, Juergen; Renkel, Maria F.; Ekstrom, Kai Erik; Friedrich, Bernd; Tranell, Gabriella
    Al4C3 particles form during the primary production of aluminum via molten salt electrolysis due to the carbon solubility and direct contact between bath, metal, and carbon anodes. Additional Al4C3 may form during melt processing through direct contact between the melt and carbonaceous materials. As a result of their small size and similar density to aluminum, removal of aluminum carbide particles can be challenging. If not removed, carbides can produce inclusion defects or poor surface condition in aluminum products. The current work studies the removal and behavior of Al4C3 particles during flotation with different gas mixtures, as well as sedimentation. The interaction between carbide particles and Al2O3 films during the melt treatment processes was also studied and reported. Factsage thermochemical software was used to model the interactions at the interface of inclusions and bubbles covered by films. The highest degree of carbide removal was obtained after flotation with an H2O-containing argon gas mixture, where the carbide concentration dropped below the measured solubility limit of carbon at the corresponding temperature. Strong interaction between Al4C3 particles and Al2O3 films was observed during sedimentation which worked as an efficient removal method for the particles. Oxidation of carbides and formation of oxycarbides were suggested as the mechanisms promoting the attachment of carbides on oxide films.
  • Article
    Citation - WoS: 25
    Citation - Scopus: 27
    Characteristic Properties and Recyclability of the Aluminium Fraction of Mswi Bottom Ash
    (Elsevier, 2021) Gökelma, Mertol; Vallejo-Olivares, Alicia; Tranell, Gabriella
    The increasing use of aluminimum in packaging applications results in many different aluminium-based products ending up in consumer mixed-waste bins. This waste is typically incinerated, generating an aluminium-containing bottom ash. The current work investigates the recyclability of the aluminium fraction in the bottom ash from waste incineration plants in the USA, UK and Denmark. Incinerated Al samples from different size fractions (2-6 mm, 6-12 mm and 12-30 mm) were characterized in terms of inherent oxide thickness, re-melting yield/coagulation and composition. The measured average oxide thickness on Al particles was 68 mm (SD=100), with the metal yield and coagulation efficiency measured to between 76 and 92% and 87-99% respectively. Larger particle size fractions resulted in a higher metal yield due to their higher mass to surface ratio. A simplified model correlating metal yield and particle size was proposed. The aluminium content of the melted material was determined to between 95.6 and 98.5% with main impurities being Fe, Si, Mn, Zn, Mg and Cu, corresponding to major aluminium alloying elements and waste charge components. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).