Kinetic model for quartz and spinel dissolution during melting of high-level-waste glass batch
The dissolution of quartz particles and the growth and dissolution of crystalline phases during the conversion of batch to glass potentially affects both the glass melting process and product quality. Crystals of spinel exiting the cold cap to molten glass below can be troublesome during the vitrification of iron-containing high-level wastes. To estimate the distribution of quartz and spinel fractions within the cold cap, we used kinetic models that relate fractions of these phases to temperature and heating rate. Fitting the model equations to data showed that the heating rate, apart from affecting quartz and spinel behavior directly, also affects them indirectly via concurrent processes, such as the formation and motion of bubbles. Because of these indirect effects, it was necessary to allow one kinetic parameter (the pre-exponential factor) to vary with the heating rate. The resulting kinetic equations are sufficiently simple for the detailed modeling of batch-to-glass conversion as it occurs in glass melters. The estimated fractions and sizes of quartz and spinel particles as they leave the cold cap, determined in this study, will provide the source terms needed for modeling the behavior of these solid particles within the flow of molten glass in the melter.
Conversion of Nuclear Waste into Nuclear Waste Glass: Experimental Investigation and Mathematical Modeling☆
Abstract The melter feed, slurry, or calcine charged on the top of a pool of molten glass forms a floating layer of reacting material called the cold cap. Between the cold-cap top, which is covered with boiling slurry, and its bottom, where bubbles separate it from molten glass, the temperature changes by up to 1000 K. The processes that occur over this temperature interval within the cold cap include liberation of gases, conduction and consumption of heat, dissolution of quartz particles, formation and dissolution of intermediate crystalline phases, and generation of foam and gas cavities. These processes have been investigated using thermal analyses, optical and electronic microscopies, x-ray diffraction, as well as other techniques. Properties of the reacting feed, such as heat conductivity and density, were measured as functions of temperature. Investigating the structure of quenched cold caps produced in a laboratory-scale melter complemented the crucible studies. The cold cap consists of two main layers. The top layer contains solid particles dissolving in the glass-forming melt and open pores through which gases are escaping. The bottom layer contains bubbly melt or foam where bubbles coalesce into larger cavities that move sideways and release the gas to the atmosphere. The feed-to-glass conversion became sufficiently understood for representing the cold-cap processes via mathematical models. These models, which comprise heat transfer, mass transfer, and reaction kinetics models, have been developed with the final goal to relate feed parameters to the rate of glass melting.
The Austro-Prussian War: Austria's War with Prussia and Italy in 1866 . By Geoffrey Wawro. Cambridge: Cambridge University Press. 1966. Pp. 313. $59.95. ISBN 0-521-56059-4.
This expanded and reworked Yale dissertation ventures into a topic done spellbindingly two decades ago by one of the grand masters of German military affairs, Gordon Craig, whose Battle of Koeniggraetz (Philadelphia: J. B. Lippincott, 1964), was published in a series commissioned by Hanson W. Baldwin. NewYork Times military affairs editor. Wawro does not approach the literary brilliance of Craig, but his work goes beyond it in several important respects. First, although Craig dealt with a good deal of the preliminary background and also the aftermath, his book focused squarely on the major battle which decided the war, whereas the book at hand deals with the entire war, which included several other battles, notably Langensalza, between Prussia and the Hanoverians in north-central Germany and Custoza between Austria and Italy in northern Italy. Secondly, whereas Craig knew the German sources as well as anyone, Wawro here uses not only German, but Austrian, French, British, and Italian ones. Of the last two, the former are important for the diplomatic background, the latter for the southern campaign area as well as for the problematic PrussianItalian relations. Thirdly,Wawro has dug deeper than Craig into primary source archives. Especially for the central emphasis of the book, the Austrians and Italians, he has mined the archives in Vienna, Rome, Naples, Milan, and Venice. For example, he uses a number of war diaries which officers from captain to field marshal kept and later deposited in military archives. Interestingly, both authors use Hans Delbriick andTheodor Fontane. Delbriick wrote half a dozen essays on the war and after his death in 1929 two of his colleagues published a fifth volume of his classic Art of War in the Framework of Political History which dealt substantially with 1866, partly on the basis of Delbriick's Berlin University lecture notes. Fontane covered the war as a newspaper correspondent and published more than a thousand pages from his eyewitness experiences, Der deutsche Krieg von 1866, 2 vols, (Berlin, 1871-72).