Christel Kupsch

Impact of the use of waste on trace element concentrations in cement and concrete

The results of model calculations carried out to identify and quantify the input pathways of trace elements into cement and concrete and to estimate the extent to which trace element concentrations in cement may change due to waste utilization are presented. As expected, primary raw materials represented the most important input pathway for trace elements into cement, but the contribution from wastes was not negligible. The use of waste led to a slight increase of the concentrations of cadmium, antimony and zinc in cement. For cobalt, lead and vanadium, this increase was less distinct and for all other trace elements considered, the effect of the use of wastes on trace element concentrations in cement could not be demonstrated clearly. The trace element content of concrete was governed by the aggregates for most elements considered. However, for arsenic, cadmium, lead and zinc, both cement and the additive coal fly ash contributed noticeably to the total trace element concentration in the concrete.

Cadmium Flows Caused by the Worldwide Production of Primary Zinc Metal

Material flows of the economic cycle can contain toxic substances, which enter the economy as impurities in raw materials or are intentionally added as minor or even main constituents during the manufacture of industrial or consumer goods. Cadmium, predominantly associated with zinc minerals, is a by-product of the primary zinc production. Cadmium is generated when zinc is extracted from zinc ores and concentrates, an intermediate product resulting from flotation processing after the zinc ore has been mined and milled. Information on the amount of cadmium generated from zinc extraction is rarely published. In this article, we assess generation and fate of cadmium accumulating worldwide in the production of primary zinc from ores and concentrates. Model calculations for the beginning of the 21st century show that annually about 30,000 tonnes of cadmium were generated, but only approximately 16,000 tonnes were converted to primary cadmium metal, key material for the production of other cadmium compounds (e.g., cadmium oxide), and cadmium-containing goods (e.g., nickelcadmium batteries). Hence, about 14,000 tonnes of cadmium must have been transferred somewhere else. The fate of about 5,500 tonnes can be plausibly explained, but it is difficult to determine what happens to the rest.

Ressourcen- und Abfallmanagement für eine nachhaltige Entwicklung dargestellt am Beispiel von Cadmium

KurzfassungIm vorliegenden Beitrag werden erste Ergebnisse einer Zusammenführung zweier im Institut für Technikfolgenabschätzung und Systemanalyse (ITAS) des Forschungszentrums Karlsruhe bearbeiteter Projekte zu den Themen „Abfallwirtschaft und Nachhaltige Entwicklung” und „Unterschung der Verteilung ausgewählter Schwermetalle bei Abfallentsorgungsmaßnahmen” präsentiert. Dabei werden Probleme und Zielkonflikte des Cadmiumstoffstroms vor dem Hintergrund des im ITAS entwickelten integrativen Nachhaltigkeitskonzeptes identifiziert und diskutiert.SummaryThis paper presents the first results of a project uniting two projects carried out by the Institute for Technology Assessmenind Systems Analysis (ITAS) of the Karlsruhe Research Centre. “Waste management and sustainable development” and “Analysis of the distribution of selected heavy metals due to waste management measures”. The problems involved in the material flow of cadmium are identified and discussed agains the background of an integrative sustainability concept developed by ITAS.