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Title: Experimental processing of salt slags from an aluminum dross furnace

Abstract

The Federal Bureau of Mines has developed a hydrometallurgical method to recover aluminum, aluminum oxide, and fluxing salts from aluminum salt slags. The slag is leached with water at room temperature to produce a saturated brine slurry. Screening of the slurry yields an aluminum-rich fraction that can be returned to the dross furnace. The remaining slurry is vacuum filtered, yielding a clear brine solution and an aluminum oxide filter cake. Evaporation of the clear filtrate produces a high-purity fluxing salt for reuse in the dross furnace. Over 80 pct of the metallic aluminum is recovered in the aluminum-rich oversize fraction, while essentially all the fluxing salts are recovered by evaporation. This report contains the final results of an investigation on a process research unit scale, an economic evaluation of the method, and recommendations to further improve the process.

Authors:
; ;
Publication Date:
Research Org.:
Bureau of Mines, Washington, DC (USA)
OSTI Identifier:
5029178
Report Number(s):
BM-RI-8446
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ALUMINIUM; MATERIALS RECOVERY; ALUMINIUM OXIDES; INDUSTRIAL WASTES; RECYCLING; SALTS; SLAGS; FURNACES; MELTING; METAL INDUSTRY; WASTE PROCESSING; ALUMINIUM COMPOUNDS; CHALCOGENIDES; ELEMENTS; INDUSTRY; MANAGEMENT; METALS; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PROCESSING; RECOVERY; WASTE MANAGEMENT; WASTES 320305* -- Energy Conservation, Consumption, & Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management

Citation Formats

Magyar, M.J., Kaplan, R.S., and Makar, H.V. Experimental processing of salt slags from an aluminum dross furnace. United States: N. p., 1980. Web.
Magyar, M.J., Kaplan, R.S., & Makar, H.V. Experimental processing of salt slags from an aluminum dross furnace. United States.
Magyar, M.J., Kaplan, R.S., and Makar, H.V. 1980. "Experimental processing of salt slags from an aluminum dross furnace". United States. doi:.
@article{osti_5029178,
title = {Experimental processing of salt slags from an aluminum dross furnace},
author = {Magyar, M.J. and Kaplan, R.S. and Makar, H.V.},
abstractNote = {The Federal Bureau of Mines has developed a hydrometallurgical method to recover aluminum, aluminum oxide, and fluxing salts from aluminum salt slags. The slag is leached with water at room temperature to produce a saturated brine slurry. Screening of the slurry yields an aluminum-rich fraction that can be returned to the dross furnace. The remaining slurry is vacuum filtered, yielding a clear brine solution and an aluminum oxide filter cake. Evaporation of the clear filtrate produces a high-purity fluxing salt for reuse in the dross furnace. Over 80 pct of the metallic aluminum is recovered in the aluminum-rich oversize fraction, while essentially all the fluxing salts are recovered by evaporation. This report contains the final results of an investigation on a process research unit scale, an economic evaluation of the method, and recommendations to further improve the process.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1980,
month = 1
}

Technical Report:
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  • The secondary aluminum industry annually disposes of large amounts of dross residues and salt cake, which are by-products from the processing of scrap aluminum for reuse. These wastes contain as much as 50% salts and are presently disposed of in conventional landfills. As the costs of landfill space increase and the availability of landfill space decreases, disposal of the residues will increasingly compromise the economics of recycling aluminum. Alternative processes exist by which the major constituents of the various drosses and salt cakes can be recovered for recycling. In this study, we review available recycling technologies and processes relevant tomore » the recycling of black dross and salt cake and discuss new concepts that have the potential to improve the cost-effectiveness of recycling technologies.« less
  • The secondary aluminum industry annually disposes of large amounts of dross residues and salt cake, which are by-products from the processing of scrap aluminum for reuse. These wastes contain as much as 50% salts and are presently disposed of in conventional landfills. As the costs of landfill space increase and the availability of landfill space decreases, disposal of the residues will increasingly compromise the economics of recycling aluminum. Alternative processes exist by which the major constituents of the various drosses and salt cakes can be recovered for recycling. In this study, we review available recycling technologies and processes relevant tomore » the recycling of black dross and salt cake and discuss new concepts that have the potential to improve the cost-effectiveness of recycling technologies.« less
  • The bibliography contains citations concerning aluminum reclamation from dross. Topics include dross treatment technology, the environmental benefits of aluminum recovery from dross, and the economics of aluminum reclamation in dross processing systems. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)
  • The Bureau of Mines, U.S. Department of the Interior, conducts research on methods to minimize the requirements for mineral raw materials through conservation, substitution, and increased minerals and metals recovery from primary and secondary domestic resources. To further this goal, prior Bureau research had devised a pyrometallurgical technique (RI 8211) to recover metallic iron and copper from molten copper smelting furnace slags by carbothermic reduction. As a continuation of this Bureau research on the carbon injection technique, reverberatory and electric furnace slags were treated in an 800-kva electric arc furnace by simultaneously top feeding the slag and injecting coke breezemore » into the bottom of the molten bath.« less
  • Dross, a major by-product of all processes involving molten aluminum, forms at the surface of the molten metal as the latter reacts with the furnace atmosphere. It generally represents 1 to 5 wt% of the melt, depending on the process, and contains on average about 50% free aluminum dispersed in an oxide layer. Since aluminum production is highly energy-intensive, dross recycling is very attractive from both the energy and the economic standpoints. The conventional recycling process using salt rotary furnaces is thermally inefficient and environmentally unacceptable because of the salt slags produced. Hydro-Quebec has developed and patented a new salt-freemore » technology using a rotary furnace heated by an electric arc between two graphite electrodes, called DROSCAR{reg_sign}. A 600-kW pilot plant in operation at LTEE is in use to demonstrate the process. This process provides aluminum recovery rates for over 90%, using a highly energy efficient, environmentally sound production method. In 1994, 400 tons of aluminum dross were treated in this facility and several tests on various types of dross have also been conducted in early 1995. A report on the results will be presented.« less