Browsing by Author "Stadelmann, Herbert"
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- ItemChemical behavior of nickel sulfide in soda-lime-silica glass melts(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2002) Kasper, Andreas; Stadelmann, HerbertNickel sulfide formation from nickel-containing steel residuals in the glass batch has been assumed for quite some time. Melting trials were carried out with a soda-lime-silica glass batch containing steel particles with 20 % nickel. By this the above assumption was shown to be true and the exact cascade of the reaction of the metals with the sulfate of the glass melt could be pointed out. Five steps can be distinguished: sweating out the less noble elements (chromium, manganese, carbon); formation of a mixed iron nickel sulfide phase in equilibrium with the remaining iron nickel alloy; enrichment of nickel in the alloy and the sulfide phase, until complete elimination of iron; sulfidation of the remaining pure nickel and formation of a nickel-rich sulfide; oxidation to NiS. The reaction cascade found experimentally is confirmed by the authors' own thermodynamic calculations. Literature data show that nickel sulfides containing more sulfur than the 1:1 composition are not stable in the glass melt and decompose in a small "explosion". The exact composition of an NiS stone found in glass depends on its individual temperature/time history. It consists mainly of (Ni,Fe)S, which may transform to millerite. If the former sulfide melt still contains a nickel excess, the crystalline stone may also contain minor parts of other NiySx phases such as Ni9S8 or Ni7S6.
- ItemParticulate emissions in the flue gas of flat glass production after electrostatic precipitators(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Kasper, Andreas; Carduck, Ernst; Manges, Monika; Stadelmann, Herbert; Klinkers, JürgenAs a contribution to the current discussion about fine dust and fine quartz and cristobalite particulate emissions and immissions, the authors point out the role the flat glass industry plays in this context. The main part of the raw material used in this industry is quartz sand (about 60 %), but the latter's granulometry is such that it contains practically no fine particles. This fact is inherent in undisturbed glass production because quartz sand particles with grain size below 80 μm would cause bad glass quality. Also other possible sources for silicon dioxide in the flue gas are discussed. In order to show the composition of the dust escaped to the electrostatic precipitators (EPs), the filters exclusively used in flat glass production, a number of quartz glass fiber filters used to measure the dust content in various plants were analyzed by X-ray diffraction and scanning electron microscopy. Only in one case a quartz or cristobalite grain was identified, but with 30 μm it was bigger than the respiratory fraction (< 10 μm) under discussion. In summary, it can be said that the findings are not at all alarming. In order to finally prove that there is no need to worry about emissions of carcinogenic dust for the whole glass industry future cooperative research will be necessary.