Thermodynamic criteria for the removal of impurities from end-of-life magnesium alloys by evaporation and flux treatment

Takehito Hiraki, Osamu Takeda, Kenichi Nakajima, Kazuyo Matsubae, Shinichiro Nakamura, Tetsuya Nagasaka

    Research output: Contribution to journalArticle

    21 Citations (Scopus)

    Abstract

    In this paper, the possibility of removing impurities during magnesium recycling with pyrometallurgical techniques has been evaluated by using a thermodynamic analysis. For 25 different elements that are likely to be contained in industrial magnesium alloys, the equilibrium distribution ratios between the metal, slag and gas phases in the magnesium remelting process were calculated assuming binary systems of magnesium and an impurity element. It was found that calcium, gadolinium, lithium, ytterbium and yttrium can be removed from the remelted end-of-life (EoL) magnesium products by oxidization. Calcium, cerium, gadolinium, lanthanum, lithium, plutonium, sodium, strontium and yttrium can be removed by chlorination with a salt flux. However, the other elements contained in magnesium alloy scrap are scarcely removed and this may contribute toward future contamination problems. The third technological option for the recycling of EoL magnesium products is magnesium recovery by a distillation process. Based on thermodynamic considerations, it is predicted that high-purity magnesium can be recovered through distillation because of its high vapor pressure, yet there is a limit on recoverability that depends on the equilibrium vapor pressure of the alloying elements and the large energy consumption. Therefore, the sustainable recycling of EoL magnesium products should be an important consideration in the design of advanced magnesium alloys or the development of new refining processes.

    Original languageEnglish
    Article number035003
    JournalScience and Technology of Advanced Materials
    Volume12
    Issue number3
    DOIs
    Publication statusPublished - 2011 Jun

    Fingerprint

    Magnesium alloys
    Magnesium
    Evaporation
    Thermodynamics
    Impurities
    Fluxes
    Yttrium
    Recycling
    Gadolinium
    Vapor pressure
    Lithium
    Distillation
    Calcium
    Ytterbium
    Cerium
    Plutonium
    Lanthanum
    Strontium
    Remelting
    Chlorination

    Keywords

    • distribution ratio
    • end-of-life products
    • impurity removal
    • Recycling of magnesium
    • thermodynamic analysis

    ASJC Scopus subject areas

    • Materials Science(all)

    Cite this

    Thermodynamic criteria for the removal of impurities from end-of-life magnesium alloys by evaporation and flux treatment. / Hiraki, Takehito; Takeda, Osamu; Nakajima, Kenichi; Matsubae, Kazuyo; Nakamura, Shinichiro; Nagasaka, Tetsuya.

    In: Science and Technology of Advanced Materials, Vol. 12, No. 3, 035003, 06.2011.

    Research output: Contribution to journalArticle

    Hiraki, Takehito ; Takeda, Osamu ; Nakajima, Kenichi ; Matsubae, Kazuyo ; Nakamura, Shinichiro ; Nagasaka, Tetsuya. / Thermodynamic criteria for the removal of impurities from end-of-life magnesium alloys by evaporation and flux treatment. In: Science and Technology of Advanced Materials. 2011 ; Vol. 12, No. 3.
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