8 6 Helmut Gutenberger and Wojciech Pastuszczyn on ... - Messer

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8 : Cover story Lead by the bar: recycling the heavy metal also involves the use of industrial gases. Lead – from ore or scrap to metal Lead is a heavy metal that was used as long ago as the early Bronze Age thanks to its low melting point. Today it is mainly used in lead acid accumulators such as car batteries. The process of lead smelting is made particularly efficient by the use of industrial gases. on air 09 · 2008
Today we need lead as much as we ever did, though the number of applications has decreased sharply. “The popularity that this metal enjoyed just a few decades ago has declined markedly. This is due partly to the health hazards <strong>and</strong> environmental pollution associated with lead compounds, which were caused by outdated production methods, <strong>and</strong> partly to the issue of economic efficiency”, explains Burkhardt Holleis from Application Technology Metallurgy at Messer Austria. Nevertheless, the heavy metal is still of great value, particularly for special applications such as radiation shields or in accumulators such as car batteries. Lead (latin Plumbum, chemical symbol Pb) is a very soft <strong>and</strong> malleable heavy metal with a low melting point. It very rarely occurs in its pure form in nature, with lead sulphide (PbS, blue lead, galenite) being the most important lead mineral. The most frequent natural deposits are found in seams where the galenite is mainly found in combination with zinc blende (ZnS, sphalerite) <strong>and</strong> pyrite (FeS2, iron pyrite). Primary lead “Lead metal can either be produced from lead ores (primary lead) or recycled products (secondary lead)”, says Holleis. In primary lead production, the lead ore is first converted, by means of physical processes, into a fine-grained concentrate with maximum metal content - this process is called ore dressing. The ore is crushed <strong>and</strong> graded in several stages. on air 09 · 2008 During the subsequent flotation in an emulsion, the fine-grained solids are separated from one another. In order to convert the enriched lead sulphide into metals in classic smelting, it is roasted in the sinter plant with the addition of hot air. The liquid lead oxide that is separated in this process is reduced to metallic lead bullion <strong>and</strong> slag in a shaft furnace with the aid of coke, lime <strong>and</strong> iron. “By adding oxygen, this process becomes even more effective”, explains Burkhardt Holleis. Modern technological methods involve direct reduction processes. The advantage here relates to the greater efficiency of the plants, in which the roasting <strong>and</strong> reduction processes take place in one step. “Accordingly, environmental pollution is reduced <strong>and</strong> economic efficiency increased”, says the expert. Roasting is not fully completed <strong>and</strong> lead oxide can react with lead sulphide to form metallic lead. This produces lead bullion <strong>and</strong> slag with a higher lead concentration than with the previously mentioned process. The reduction of the slag means that the remaining lead in it can also be recovered as a resource. “Here, too, oxygen is used in order to keep down the production costs”, says Holleis, highlighting another advantage of the use of oxygen in smelting. The raw lead now has to be refined before further processing. Secondary lead Liquid lead being tapped from a short rotary furnace It is not just the lead in lead-acid batteries that is recycled, but also the plastic housing <strong>and</strong> the sulphuric Cover story : 9 YOUR CONTACTS: Burkhardt Holleis Application Technology Metallurgy Messer Austria GmbH Tel.: +43 (0) 50603-281 burkhardt.holleis@messergroup.com Languages: Dr. Martin Demuth Application Technology Metallurgy Messer Austria GmbH Tel.: +43 (0) 50603-205 martin.demuth@messergroup.com Languages: continued on page 10
Page 1 and 2: on air No. 9 · November 2008 The m
Page 3 and 4: The editorial team Editor-in-Chief:
Page 5 and 6: New “old” customer The Krefeld-
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Page 11 and 12: Controlled system for a natural gas
Page 13 and 14: Children marvel at Messer experimen
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8 6 Helmut Gutenberger and Wojciech Pastuszczyn on ... - Messer

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