Browsing by Author "Holtzer, Mariusz Andrzej"

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Access status: Open Access ,
Charakterystyka pyłów z suchego odpylania stacji przerobu mas z bentonitem w aspekcie ich użytkowego wykorzystania
(Data obrony: 2009) Bobrowski, Artur
Wydział Odlewnictwa
The following work concerns an important issue from the environment protection point of view - recycling the dust from dry dust extraction of green sand processing plant, which is a by-product of casting in green sand. The subject of the work is very up-to-date because of European Union requirements in the range of Best Available Techniques. Three ways of recycling dust were suggested. Vast structural, physicochemical, and technological researches were performed. Appraisal of the influence of dust addition to moulding sand on the natural environment was conducted (EGA examination, gases emission, and leaching).
Access status: Restricted ,
Ograniczenie szkodliwości pyłów stalowniczych poprzez ich zestalanie/stabilizację
(Data obrony: 2008-02-18) Malinowska, Agnieszka Agata
Wydział Odlewnictwa
One of the most important environmental problems in metallurgical processes is how to use dusts produced while preparing the liquid metal. These dusts are often classified as dangerous waste. The paper consists of research findings on leaching of selected heavy metals ( Cr, Cr( VI), Zn, Cu, Fe) out of the dust coming from the dry dust cleanings of furnace arc in one of the foundries. These dusts may contain considerable quantities of harmful metals depending on the scrap used and on the type of smelted steel. Most of these metals tend to leach easily causing real danger for the environment. In case of reduction of heavy metals leaching from steel dusts by solidification / stabilization method using cement. It is not only solidification dusts, but also immobilization of heavy metals by C-S-H phase. The leaching of dusts in raw state as well as solidified with Portland cement has been researched. Cement mixtures had 10 %, 20 %, 40 % and 66 % content of dust. Leavens, training norms and concretes based on cement mixtures with dust were prepared and then technical measures of these were executed. Concrete was also a subject to microscopic research made in order to observe C-S-H phase and how it is influenced by the examined heavy metals. Leaching of heavy metals from so-called TANK METOD concretes was also examined. Average effective diffusion factor for examined heavy metals mobility has been calculated according to Dutch standards concerning leaching. According to those standards a computer program assisting in calculation and simulation of effective diffusion factor has been prepared. The research showed that solidification considerably lowers the leaching of heavy metals in comparison to row dust. This concerns mainly such elements as chrome and lead.
Access status: Restricted ,
Planowane!
Zjawiska zachodzące w procesie utwardzania soli poli (kwasu akrylowego) oraz ich wpływ na właściwości masy formierskiej
(Data obrony: 2005) Grabowska, Beata
Wydział Odlewnictwa
W ramach pracy przeprowadzono szereg badań mających na celu próbę wyjaśnienia zjawisk przebiegających podczas utwardzania mas ze spoiwem akrylowym. Zastosowano kilka metod utwardzania, a mianowicie $Ca(OH)_{2} + CO_{2}$, temperatura, mikrofale i promieniowanie UV. Przeprowadzone badania strukturalne (spektroskopia: FTIR, Raman, NMR) i technologiczne wykazały jednoznacznie, że rodzaj zastosowanego czynnika sieciującego ma istotny wpływ na przebieg reakcji utwardzania masy ze spoiwem akrylowym oraz na jej właściwości technologiczne. Wykazano, że reakcja sieciowania za pomocą $Ca(OH)_{2}+CO_{2}$ ma charakter jonowy. Stwierdzono, że istotną rolę w procesie utwardzania mikrofalami odgrywa aktywowany mikrofalami proces adsorpcji chemicznej. W przypadku sieciowania poliakrylanu promieniami UV przebieg reakcji jest rodnikowy. Analiza wyników badań technologicznych wykazała, że istnieje zależność pomiędzy właściwościami chemicznymi spoiwa - poliakrylanu (masa cząsteczkowa polimeru, lepkość, pH, stężenie), a właściwościami technologicznymi masy formierskiej.
Access status: Metadata only ,
Zmiany zachodzące w bentonitach odlewniczych pod wpływem temperatury
(Data obrony: 2012) Żymankowska-Kumon, Sylwia
Wydział Odlewnictwa
The Ph.D. Thesis concerns changes occurring in foundry bentonites under an influence of a temperature. This problem is very important for the foundry industry since moulding sands with bentonite constitute still 70 – 80 mass % , in which castings of ferrous alloys, mainly cast iron, are made in the world. In consideration of various bentonite origins it is essential to determine, by means of modern analytical methods, at which temperature and after what time this material losses its binding properties. Thermal stability of montmorillonite, the main component of bentonite, decides on its suitability for the foundry industry. In order to estimate this stability a broad structural (infrared spectroscopy, X-ray diffraction analysis, nuclear magnetic resonance spectroscopy), physical-chemical (chemical, thermal and granulometric analysis, montmorillonite content, free growth index) and technological (compression strength) investigations were carried out. Structural changes at the molecular level were, among others, assessed. Three kinds of calcium bentonites, activated by sodium carbonate, originated from various European producers were tested. Their different behaviour in the dehydroxylation process was found (single or two-stage), which is probably related to the structure of montmorillonite particles. This process pathway is also related to the bentonite origin: volcanic or weathering of rocks product. Investigations were performed for bentonites heated up to $1200^{\circ}C$. Laboratory examinations were also verified experimentally. The degradation degree of moulding sand with bentonite under a temperature influence was estimated in dependence of the size and shape of castings. The performed investigations indicate, that the application of the selection of moulding sands with bentonite in dependence of the overheating degree is advantageous, since due to that a lot of rebonding materials are saved, which – in turn – is favourable for the ecology and economy of technological processes.