Recovery of Gallium and Arsenic from Gallium Arsenide Waste in the Electronics Industry

Authors

  • Wei-Ting Chen,

    1. Doctoral Program, Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology (NYUST), Douliou, Yunlin, Taiwan, ROC
    Search for more papers by this author
  • Lung-Chang Tsai,

    1. Department of Safety, Health, and Environmental Engineering, NYUST, Douliou, Yunlin, Taiwan, ROC
    Search for more papers by this author
  • Fang-Chang Tsai,

    1. Key Laboratory for the Green Preparation and Application of Functional Materials, Ministry of Education, Faculty of Materials Science and Engineering, Hubei University, Wuhan, P. R. China
    Search for more papers by this author
  • Chi-Min Shu

    Corresponding author
    1. Department of Safety, Health, and Environmental Engineering, NYUST, Douliou, Yunlin, Taiwan, ROC
    • Department of Safety, Health, and Environmental Engineering, NYUST, 123, University Rd., Sec. 3, Douliou, Yunlin, Taiwan 64002, ROC.
    Search for more papers by this author

Abstract

Gallium arsenide (GaAs) has both high saturated electron velocity and high electron mobility, making it useful as a semiconductor material in a variety of applications, including light-emitting diodes (LEDs), integrated circuits (ICs), and microwave appliances. A side effect of the use of gallium (Ga) is the production of a relatively large amount of hazardous waste. This study aimed at the recovery of Ga and arsenic (As) from GaAs waste using hydrometallurgical methods involving leaching and coagulation and a dry annealing process that involves annealing, vacuum separation, and sublimation by heating. Our research has shown that GaAs can be leached using nitric acid (HNO3) to obtain 100% Ga and As with a leaching solution at pH 0.1, with subsequent adjustment of the leaching solution to pH 3 with sodium hydroxide (NaOH). Another method used a leaching solution at pH 2, then adjusting to pH 11 using NaOH. Ferric hydroxide (FeO(OH)) was added at 90°C after NaOH was added to the leaching solution. At pH 2 and 11, 55.5 and 21.9% of the As could be removed from the hazardous waste, respectively. The Ga could also be precipitated. When GaAs powder was heated to 1000°C over 3 h, 100% As removal was achieved, and 92.6% of the Ga was removed by formation of 99.9% gallium trioxide (Ga2O3). Arsenic was vaporized when the temperature was elevated to 1000°C, allowing arsenic trioxide (As2O3) to condense with 99.2% purity. The Ga2O3 powder produced was then dissolved and electrolyzed, allowing for 95.9% recovery of Ga with a purity of 99.9%.

Ancillary