Recent Research
Occurrence of Selenium in Aluminum and Steel Manufacturing
John Heinze and Karen Hagelstein, Metals Industry Air Metals Emissions and Hazard Rankings, presented at TMS 2008, the 137th Annual Meeting & Exhibition, New Orleans, Louisiana, March 9-13, 2008.
Total releases of metal air emissions (18 metals) from the metals manufacturing industry (SIC33XX) were over 3400 tons in 2005, based on the latest US EPA Toxic Release Inventory data. These emissions represent the largest source of metal air emissions of any industry sector in the US. Metal air emissions can be prioritized not only by the amount of metal compounds released, but also by their hazard properties. This “toxicity weighting” is based on the well recognized human health and environmental hazard properties of metals. The Indiana Relative Chemical hazard Score (IRCHS) and other methods of hazard ranking are evaluated and compared as methods for prioritizing hazard impacts and environmental management practices in metals manufacturing. Based on this review, international efforts should focus on arsenic, chromium and selenium as well as mercury, cadmium, and lead. For the metals industry, especially aluminum, steel and aluminum recycling we recommend: 1) metals monitoring of all wastes; 2) occupational & biological metals monitoring and 3) environmental audits.
John Heinze and Karen Hagelstein, Comparison of Current Metal Emissions: Mercury, Cadmium, Lead and Selenium, presented at the SETAC North America 28th Annual Meeting, Milwaukee, Wisconsin, November 11-15, 2007.
The United Nations Environment Program has called for further research and regulatory activities on mercury, cadmium and lead. This review of environmental and health data suggests that international efforts should focus on arsenic, chromium and selenium as well. An analysis of US EPA Toxic Release Inventory (TRI) data indicates that: 1) total metal releases in the US are increasing; 2) the metals manufacturing industry is now the major source of airborne metal emissions; 3) in the metals industry, mercury emissions are low but selenium emissions are large and increasing; and 4) more data are needed in the metals industry on site-specific stack emissions and air pollution control efficiencies to reduce metals emissions.
John E. Heinze and Karen Hagelstein, US Metal Emissions Trends, 2001-2005, presented at the International Emissions Inventory Conference Raleigh, NC, May 14-17, 2007.
The metals industry is the major source of airborne metal emissions and these emissions are increasing. Metal air emissions are mainly from point sources and thus controllable. The most hazardous metal emissions, based on EPA Toxicity Characteristic Leaching Procedure criteria, are mercury > cadmium, selenium > arsenic, lead. In the metals industry, mercury emissions are decreasing but selenium emissions are large and increasing. Additional metals industry data is needed on site-specific stack emission monitoring and environmental audits, and on air pollution control efficiencies for metals.
Karen Hagelstein and John E. Heinze, Environmental Management Of Airborne Metal Particulate Emissions In The Recycling Industry, in Light Metals 2007 Volume 6: The Materials Recylcing Industry (edited by Morten Sorlie), TMS, The Minerals, Metals and Materials Society, 2007.
Ambient air quality is improving and indicator compounds have been identified which simplify environmental assessments. The major hazardous air pollutants are total particulates, particulate metals and measurable volatile organic compounds reported at low concentrations. The primary metals industry is the major source of total bioaccumulative particulate metals, contributes about one third of the total airborne metal releases, and one third of the urban air lead levels. Air pollution technologies have been successful in reducing mercury emissions from coal combustion sources and selenium metal emissions are now reportedly greater than mercury releases. Metal recycling contributes to reducing air and other emissions by reducing energy consumption 65-95% compared to primary metal production. Since the metals industry is now the major source of metal air emissions, air pollution control technology which has been successfully applied in the coal power industry should be effective in the metals industry. The limited human health and environmental data in the metals industry suggest a need to further reduce airborne particulate metal emissions and to improve workplace ventilation and hazard communication.
John E. Heinze, Karen Hagelstein, Material Selection and the Impact on Recyclability, Green Purchasing and Corporate Social Responsibility – The Manganese Metal Case, in Light Metals 2006 (edited by Travis J. Galloway), TMS, The Minerals, Metals and Materials Society, 2006.
Manganese metal is widely used as an alloying agent in the aluminum industry and is available from two distinct production processes. The environmentally preferred process uses sulfur as the catalyst and results in a typical purity of 99.9%. The other process, favored by almost all Chinese manufacturers, uses selenium as the catalyst with the result that the manganese metal contains up to 0.15% selenium but is produced at a lower cost. This has resulted in over 75% of the global market in recent years consisting of selenium-contaminated manganese. A case study demonstrates that use of this material has an impact on the recyclability of the aluminum dross and scrap, where recyclers face metal dust exposure issues and may not be aware of the selenium content that likely triggers hazardous solid waste disposal requirements. Downstream recycling is an important consideration of green purchasing and corporate social responsibility.
Full paper (pdf, 66kb)
R. Antolin, T. Posada, G. Borge, J.C. Raposo, G. Arana, and N. Extebarria, A Method for Analyzing Se in Mn Electrolytic Metal and Al Materials Coming from the Casthouse,in Light Metals 2005 (edited by H. Kvande), TMS, The Minerals, Metals & Materials Society, 2005.
Costs for production of electrolytic manganese metal can be reduced by the addition of selenium derivatives. Selenium then becomes incorporated into aluminum when manganese metal is added to the molten bath in the cast house. Problems related to selenium exposures and releases during aluminum processing and especially during the recycling of aluminum dross have been reported in recent years at TMS conferences. Despite this, the actual content of selenium is rarely certified or even reported in the documentation provided by manganese metal producers although this information is essential for compliance with the numerous regulations on selenium workplace exposures and environmental releases. This paper reports the development of an analytical method based on the HG-ICP-OES technique (hydride generation-inductively coupled plasma-optical emission spectrometry) which provides the high sensitivity and reproducibility required for analysis of industrial metallic matrices, including manganese metal and aluminum baths and dross.
The publication is available at libraries and by ordering from TMS at the following link http://www.tms.org/pubs/Publications.html
K. Hagelstein, The Environmental Management of Selenium in Aluminum Processing, JOM, The Member Journal of the Minerals, Metals & Materials Society, August 2003, pp. 51-54.
This studies identifies worker and environmental exposures to selenium at three U.S. aluminum facilities: A) a reduction facility that used manganese alloys containing selenium; B) a rolling mill facility that used manganese alloys free of selenium; and C) a recycling facility that received aluminum dross and scrap from sites A and B. Results indicate that the major environmental management issues were selenium particulates in the stack emissions from site A and baghouse dusts classified as hazardous due to selenium from the rotary furnaces at C.
The journal is available at libraries and the article may be ordered on line for $15 from the publisher at the following link http://doc.tms.org/servlet/ProductCatalog?container=JOM+2003+August
K. Hagelstein, Environmentally Friendly Manganese Metal Production, Mining Environmental Management, September 2003, pp. 12-13.
This study reviews the environmental regulations and impact of selenium compounds, emissions of selenium during manufacturing of aluminum using selenium-contaminated manganese and in metal recycling facilities using aluminum. Treatment technologies to reduce hazardous waste costs and options for reducing hazardous wastes are discussed.
The journal is available in libraries.
M. Reza Aboutalebi, M. Isac and R.I.L. Guthrie, The Behavior of Selenium Impurities During the Addition of Se-Containing Manganese to Steel Melt, Steel Research Int., vol. 75 (2004), No. 6, pp. 366-372.
Manganese is an important addition for alloy steels. It is normally added to steel melts as ferromanganese. However, for the adjustment of melt composition, manganese metal is used as a trimming addition since it has lower levels of impurities than ferromanganese. The manganese used for this purpose is obtained from the electrolytic processing route where selenium-containing additives are added to the electrolytic bath to improve the current efficiency and reduce processing costs. This practice contaminates the manganese metal with selenium. Given that selenium and its compounds are potentially toxic and damaging to the work place and environment, effluents have to be treated in a controlled manner. In order to determine how selenium typically distributes between molten steel, slag and gas phases, a laboratory-scale study was carried out to evaluate the fate of selenium following the addition of selenium containing manganese to steel melts at 1600 °C. The results of this study indicate that significant amounts of the selenium added to the melt evaporate, reacting with air to form selenium dioxide. Only 16-75% of the added selenium remains in the solidified steel.
The journal is available in libraries.
C.J. Horng, P.H. Horng, S.C. Lin, J.L. Tsai, S.R. Lin and C.C. Tzeng, Determination of Urinary Beryllium, Arsenic and Selenium in Steel Production Workers, Biological Trace Element Research, vol. 88 (2002), pages 236-244.
This work reports the determination of beryllium, arsenic and selenium in the urine of steel production and quality control workers in comparison to healthy control subjects in Taiwan. The urine samples were digested by a microwave system. Graphic furnace and hydride atomic absorption was used for the quantitative measurements of Be and As and Se, respectively. The results show the urinary levels of these elements in steel production and quality control workers are significantly higher than in controls. The authors suggest the need for improved environmental conditions in the workplace through better ventilation and industrial hygiene practices.
The journal is available in libraries.