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A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Office of Science U.S. Department of Energy Recycling Aluminum.

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Presentation on theme: "A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Office of Science U.S. Department of Energy Recycling Aluminum."— Presentation transcript:

1 A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Office of Science U.S. Department of Energy Recycling Aluminum Salt Cake J.N. Hryn and E.J. Daniels Process Engineering Section Energy Systems Division Argonne National Laboratory

2 Pioneering Science and Technology 2 About U.S. Department of Energy (DOE) Maintains 5 major National Laboratories -Argonne, Oak Ridge, Sandia, Livermore, Brookhaven -19 smaller laboratories and technology centers Mission includes: -Advance the national, economic, and energy security of the United States -Promote scientific and technological innovation

3 Pioneering Science and Technology 3 About Argonne National Laboratory Founded in 1943, designated a national laboratory in 1946 Managed by The University of Chicago for the Department of Energy -~4000 employees and 4000 facility users -~$500M budget acre site in Illinois -800-acre site in Idaho Broad R&D portfolio -Argonne partners with DOE, other federal labs, academia, and the private sector

4 Pioneering Science and Technology 4 About Process Engineering Section Part of Energy Systems Division -Interdisciplinary, focus on applied research Three R&D areas: -Recycling and separation process development - Aluminum and Magnesium - Automotive Shredder Residue - Plastics (recycled appliances and automotive) - Glass -Process modeling and simulation - Glass and aluminum melting furnaces -New materials applications - Diamond coatings - Thin films (atomic layer deposition)

5 Pioneering Science and Technology 5 Recycling Aluminum Salt Cake Opportunity: -Aluminum recycling generates salt cake by-product - Aluminum metal - Sodium chloride and potassium chloride salt - Non-metallic product (mainly aluminum oxide) -Salt cake is disposed in landfills - Only a few companies use responsible disposal methods - Environmental concern Project Objective: -to develop a cost-effective salt cake recycling technology - recover aluminum, salts, and non-metallic product (NMP) - NMP is converted to value-added oxide products

6 Pioneering Science and Technology 6 Recycling Aluminum Salt Cake – Overview Salt Cake Aluminum Salt Non-Metallic Product Refractory Feedstock Ironmaking Feedstock Steelmaking Feedstock Recovery of Salt Cake Constituents Conversion to Value-Added Products

7 Pioneering Science and Technology 7 Project Summary History: -1990: US DOE-sponsored assessment study -1994: bench-scale work begins at Argonne -1996: Argonne & Alumitech begin collaboration -1998: Argonne begins pilot-scale tests -2001: Experimental work suspended Preliminary conclusions: -Many technical solutions possible -No economical solutions yet for salt cake recycling - Best option is maximize aluminum recovery and disposal of residues in controlled landfill -Economic and environmental analysis suggested that recycling salt cake is not desirable

8 Pioneering Science and Technology 8 Average Salt Cake Composition Non-Metallic Product 66% Salt 28% Aluminum 6%

9 Pioneering Science and Technology 9 digester screen filter evaporator aluminum (to smelters) NMP (to market) salt (to smelters) crusher condenser water steam salt cake Suggested Approach to Recycling Salt Cake

10 Pioneering Science and Technology 10 Salt Cake Recycling Barriers in U.S. salt recovery by evaporation is too expensive -high energy and capital costs, low product value

11 Pioneering Science and Technology 11 Salt Cake Recycling Barriers in U.S. no market for recovered NMP -high levels of impurities, variable composition

12 Pioneering Science and Technology to 80% up to 40% up to 10% up to 5% up to 8% up to 10% alumina ( -Al 2 O 3 ) spinel (MgAl 2 O 4 ) magnesia (MgO) aluminum hydroxide (Al(OH) 3 ) aluminum impurities (silicates, iron oxides, calcium fluoride, aluminum nitride) NMP Composition In addition, washed NMP can contain up to 2% salt -Detrimental to many potential products

13 Pioneering Science and Technology 13 Best Practice – Recycling Aluminum Salt Cake Recycling in US is driven by business opportunities -U.S. best practice is to maximize Al recovery and dispose of residues (salt and NMP) in controlled landfills Recycling salt cake in Europe is driven by legislation -No economically viable solution yet -Best practice is to maximize Al recovery with minimum salt flux, and dispose residues in controlled landfills

14 Pioneering Science and Technology 14 Environmental Impact of Salt Cake Recycling In all cases: -Salt recovery consumes more energy than can be recovered from the energy value of the recycled salt -Salt recovery generates more waste than would normally be generated if it was disposed in controlled landfills -NMP recovery becomes an environmental hazard when washed - Entrained aluminum becomes excessively reactive - Excessive energy and water consumption if dilute salt solutions are generated Best environmental solution: -Do not recover salt, NMP -Maximize aluminum recovery -Use controlled landfills (RCRA C)

15 Pioneering Science and Technology 15 Project Conclusions Many technical solutions possible for recycling salt cake -None economical yet ($35/t landfill) -Best economic option is to maximize aluminum recovery and disposal of residue in controlled landfill - Use best process technology - TTRF furnace, quality flux, energy efficient process - Keep salt cake dry - Crush and recover metallic aluminum by screens and/or eddy-current magnetic separators Best environmental option is to minimize salt cake generation -Maximize Al recovery, minimize salt use, minimize aluminum nitride, and dispose residue in controlled landfill


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