Metal losses, emissions of hazardous gases, and impurities removal from aluminum by chlorine fluxing

grantor: University of TorontoSecondary aluminum contains much more impurities such as magnesium, sodium, calcium, lithium, etc., than primary aluminum so that a metal cleaning process is needed in order to recycle it. For this purpose, "chlorine fluxing" is the most frequently employed technique. Such in-line treatment has some qualitative problems such as metal loss due to the formation of Al and Al-Mg droplets in salt fluxes during gas injection, emissions of hazardous gas, and impurities removal from metal. Hence, these problems were studied in four separate parts to reduce the adverse effects and improve the efficiency of the process. In Part I, metal loss due to the formation of Al and Al-Mg droplets in salt fluxes during gas injection was examined by studying the effects of oxidation of metal surface and contents of chlorine in gas mixtures. In Part II, bubbling in aluminum and Al-Mg alloys were compared based on the results obtained by measuring bubble frequency and bubble residence time. In Part III, the efficiency of NaCl-KCl capturing AlCl$\sb3$ was studied to reduce the hazardous gas emissions. In Part IV, the effect of MgCl$\sb2$ top salt addition on Na and Ca removal from Al-Mg alloys was examined by varying the concentration of MgCl$\sb2$ in salts. (Abstract shortened by UMI.)M.A.Sc