| 1. |
- Bidola, Pidassa M., et al.
(författare)
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A high-speed X-ray Radiography Setup for in-situ Electron Beam Powder Bed Fusion at PETRA III
- 2023
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Ingår i: Advances in X-Ray/EUV Optics and Components XVIII. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- A high-energy white synchrotron X-ray beam enables penetration of relatively thick and highly absorbing samples. At the P61A White Beam Engineering Materials Science Beamline, operated by Helmholtz-Zentrum Hereon at the PETRA III ring of the Deutsches Elektronen-Synchrotron (DESY), a tailored X-ray radiography system has been developed to perform in-situ X-ray imaging experiments at high temporal resolution, taking advantage of the unprecedented X-ray beam flux delivered by ten successive damping wigglers. The imaging system is equipped with an ultrahigh-speed camera (Phantom v2640) enabling acquisition rates up to 25 kHz at maximal resolution and binned mode. The camera is coupled with optical magnification (5x, 10x) and focusing lenses to enable imaging with a pixel size of 1,35 micrometre. The scintillator screens are housed in a special nitrogen gas cooling environment to withstand the heat load induced by the beam, allowing spatial resolution to be optimized down to few micrometres. We present the current state of the system development, implementation and first results of in situ investigations, especially of the electron beam powder bed fusion (PBF-EB) process, where the details of the mechanism of crack and pore formation during processing of different powder materials, e.g. steels and Ni-based alloys, is not yet known.
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| 2. |
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| 3. |
- Mäkitalo, Maria
(författare)
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Green Liquor Dregs in Sealing Layers to Prevent the Formation of Acid Mine drainage : From characterization to implementation
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the mining industry’s main concerns is the management of waste rock and tailings generated by sulfide ore extraction. Upon exposure to atmospheric oxygen, iron sulfides oxidize producing acidity. In the absence of alkaline minerals to neutralize this acidity, elements including harmful heavy metals may be transported with percolated water, forming acid mine drainage (AMD). A common solution to prevent oxygen and water entering sulfide-bearing mine waste, thereby minimizing the formation of AMD, is to construct a dry cover comprised of soil. In Sweden, clayey till is often used. Due to a shortage of fine-grained till close to mines, other sealant materials must be considered. This thesis presents an alternative to the traditional materials used as sealing layers in dry covers. Green liquor dregs (GLD) are a residual waste originating from the recycling of chemicals in sulfate pulp mills. The objective was to evaluate the suitability of GLD for use in sealing layers for sulfidic mine waste. This was carried out by analyzing samples both in the laboratory and in the field in a pilot-scale study. GLD was characterized physically, mineralogically and chemically to determine variations in the properties of the material. Based on the characterization results, the difference between batches was small both mineralogically and physically. In addition, it had favorable qualities with respect to reducing water percolation and oxygen diffusion, as it exhibited low hydraulic conductivity and high water retention potential. However, the shear strength was insufficient for cover applications. In an attempt to improve shear strength, but also to reduce the amount of GLD to save transportation costs, fly ash, tailings and till were blended with GLD. All of these additives increased the shear strength. Humidity cell tests were used to study the effect of GLD on the mobility of elements found in the tailings that are considered to cause major environmental issues. They showed that the alkaline capacity of the GLD raised the pH, thereby stabilizing the tailings and reducing the leaching of Zn, Cd, Cu, Ni, Co and Cr. The amount of leached elements could be directly related to pH. Mo and As leaching increased as a result of the application of GLD. This is explained by the chemical behavior of these elements and their tendency to become mobile at high pH. Because covers on mine waste should be efficient over the long-term, the aging of GLD was studied with material ranging from 0-13 years old. Aged GLD showed a hydraulic conductivity of 10-8 m/s. This is not expected to affect the function of the sealing layer to minimize oxidation because older GLD exhibited a high water retention capacity and a degree of water saturation of >91%, which would effectively limit oxygen diffusion. Leaching, mainly of S and K, was observed but had no major effect on the hydraulic properties of the material. The effects of aging are largely related to the quantity of water passing through the GLD, thereby changing its chemical composition and, in the long term, its pH. An implementation study using GLD as an additive to improve the hydraulic properties of till in the construction of sealing layers in a cover system design was carried out. The results showed that the quality of till, i.e., hydraulic conductivity and water retention capacity, could be improved by the addition of GLD. Addition of 10% GLD was found to be sufficient to take full advantage of its hydraulic properties and sufficient compaction could be achieved. Based on the results, GLD is expected to be a viable alternative to traditional cover materials. The pilot-scale study, as well as a full-scale trial that is currently in progress, will be used to evaluate further the function of a GLD-based sealing layer.
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| 4. |
- Weimer, Lucas, et al.
(författare)
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Arbeitssicherheit und Gesundheitsschutz in der Rohstoffindustrie im Kontext moderner Hochschulbildung : das SafeMine-Programm
- 2019
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Ingår i: Berg- und Huttenmännische Monatshefte (BHM). - : Springer. - 0005-8912 .- 1613-7531. ; 164:12, s. 505-513
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Tidskriftsartikel (refereegranskat)abstract
- Unternehmen auf der ganzen Welt stehen vor steigenden Herausforderungen bei der Rekrutierung von qualifizierten Arbeitskräften. Obwohl die verstärkten Sicherheitsbemühungen in der Rohstoffindustrie in den letzten Jahrzehnten erfolgreich waren, bleibt das Arbeitsumfeld durch seine spezifischen Anforderungen anspruchsvoll und einzigartig. Die Arbeit in der Rohstoffindustrie ist nach wie vor mit dem Vorurteil belastet, dunkel, staubig und gefährlich zu sein. Daher soll die Schaffung attraktiver und noch sichererer Arbeitsplätze dazu beitragen, die Lücken einer alternden Belegschaft zu schließen. Das vom EIT Raw Materials geförderte SafeMine-Projekt zielt darauf ab, ein ganzheitliches und belastbares Graduiertenprogramm für Arbeitssicherheit und Gesundheitsschutz in der Rohstoffindustrie zeitnah zu entwickeln. Die besonderen Ziele des SafeMine-Projekts sind die Ausbildung einer neuen Generation von qualifizierten Fachkräften und die Generierung fortschrittlicher wissenschaftlicher Erkenntnisse. Auf Grundlage einer Gap-Analyse, welche aktuelle Ausbildungsangebote zu Arbeitssicherheit und Gesundheitsschutz in der Rohstoffindustrie (MHS – Mine, Health and Safety) thematisierte, wurden die Bedürfnisse der Industrie identifiziert. Bei dieser Suche wurde kein spezifisches postgraduales Ausbildungsprogramm gefunden, welches sich umfassend und detailliert mit MHS-Themen befasst. Um die Ergebnisse zu ergänzen, wurde eine Branchenumfrage durchgeführt. Insgesamt reichten 43 Teilnehmer rund 1250 Antworten ein. Die Teilnehmenden kamen überwiegend aus Europa (76 %) mit einem beruflichen Hintergrund aus der Bergbauindustrie (47 %). Die Ergebnisse zeigen eine deutliche Lücke zwischen den aktuellen Bildungsaktivitäten im MHS-Sektor und den Erwartungen der Industrie. Auf der Grundlage der Ergebnisse wird ein angepasstes Graduiertenprogramm entwickelt. Die verbesserte Ausbildung von Führungskräften in der Rohstoffindustrie ist die Grundlage für fundierte strategische Entscheidungen in technischen und personellen Fragen und stärkt die Wettbewerbsfähigkeit der Unternehmen – so wie es auch von der Europäischen Union unterstützt und gefördert wird.
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