Extraction and Separation of Germanium Using Cyanex 301/Cyanex 923. Its Recovery from Transistor Waste

Abstract

The extraction of Ge(IV) from HCl, HNO₃ and H₂SO₄ media in toluene solution of Cyanex 301 and Cyanex 923 is investigated. It is almost quantitatively extracted (∼95%) in Cyanex 301 and Cyanex 923 at 8 molL⁻¹ HCl but the extractions from H₂SO₄ and HNO₃ are poor in the entire investigated range of acid molarity. Detailed investigations were carried out from HCl medium. Based on the slope analysis data the extracting species is identified as GeCl₄·2R (R=Cyanex 301/Cyanex 923). The extraction of Ge(IV) is higher and comparable in diluents like toluene, n‐hexane and kerosene (160–200°C) and there is no correlation between the dielectric constant and the percent extraction. The extractants are stable towards prolonged acid contact and there is negligible loss in their extraction efficiency even after recycling them for several cycles. The extraction behavior of commonly associated metal ions namely As(V)/(III), Sn(IV), Tl(III), In(III), Ga(III), Fe(III), Al(III), Hg(II), and Cu(II) has also been investigated. Based on the partition data conditions for attaining some binary and ternary separations involving Ge(IV) have been optimized. The separation data have been fused to develop a scheme for the recovery (93%) of pure germanium (∼99%) from semi conductor waste.

Keywords:

• Liquid‐liquid extraction
• germanium
• cyanex 301
• cyanex 923
• separations
• recovery

Acknowledgements

The authors are thankful to Prof. S.N. Tandon for his fruitful discussions. The financial support by the Department of Science and Technology (DST), New Delhi, India is gratefully acknowledged. The authors are thankful to Cytec Canada Inc. for the gift samples of Cyanex 301 and Cyanex 923.