Hydrometallurgical Treatment of Smelted Low-Grade WEEE in Ammoniacal Solutions

Abstract:

Hydrometallurgical routes of copper recovery from smelted low-grade e-waste are presented. Electronic scrap was smelted to produce Cu–Zn–Ag-Sn alloys of various phase compositions. The alloys were then treated in the following ways: (a) anodic dissolution with simultaneous metal electrodeposition using ammoniacal solutions with various ammonium salts (chloride, carbonate, sulfate). This resulted in the separation of metals, where lead, silver and tin accumulated mainly in the slimes, while copper was transferred to the slime, electrolyte and then recovered on the cathode. (b) leaching in ammoniacal solutions of various compositions and then copper electrowinning. Alloy was leached in chloride, carbonate, sulfate and thiosulfate baths. This resulted in the separation of the metals, wherein copper and zinc were transferred to the electrolyte, while metallic tin and silver as well as lead remained in the slimes. Copper was selectively recovered from the ammoniacal solutions by the electrolysis, leaving zinc ions in the electrolyte. The best conditions of the alloy treatment were obtained, where the final product was copper of high purity (99.9%) at the current efficiency of 60%. Thiosulfate solution was not applicable for the leaching of the copper alloy due to secondary reactions of the formation of copper(I) thiosulfate complexes and precipitation of copper(I) sulfide.

• Periodical: Key Engineering Materials (Volume 682)
• Pages: 293-298
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.682.293
• Online since: February 2016
• Authors: Ewa Rudnik*, Iwona Dobosz, Krzysztof Fitzner, Zbigniew Miazga
• Keywords: Alloy, Ammoniacal System, Electrolysis, Leaching, WEEE

References

[1] A. Tuncuk, V. Stazi, A. Akcil, E.Y. Yazici, H. Deveci, Aqueous metal recovery techniques from e-scrap: hydrometallurgy in recycling, Min. Eng., 25 (2012) 28-37.

DOI: 10.1016/j.mineng.2011.09.019

[2] J. Cui, L. Zhang, Metallurgical recovery of metals from electronic waste: a review, J. Haz. Mater., 158 (2008) 228-256.

[3] C.K. Gupta, Chemical metallurgy. Principles and Practice, Wiley-VCH, Weinheim, (2003).

[4] E. Rudnik., I. Dobosz, Application of ammoniacal solutions for recovery of non-ferrous metals from e-waste, Rudy Metale, 59(11) (2014) 561-568 (in Polish).

[5] E. Rudnik, J. Kleczyński, Anodic dissolution of alloyed e-waste in hydrochloric acid solutions Rudy Metale, 60(6) (2015) 282-287(in Polish).

[6] D.R. Groot, J.A.N. van der Linde, The processing of e-waste. Part 2: the electrochemical leaching behaviour of a metallic alloy derived from waste printed circuit boards, J. South. Afric. Inst. Min. Metall., 109 (2009) 701-707.

[7] E. Rudnik, K. Kołczyk, D. Kutyła, Comparative studies on the hydrometallurgical treatment of smelted low-grade electronic scraps for selective copper recovery, Trans. Nonferr. Met. Soc. Chin. (2015, in press).

DOI: 10.1016/s1003-6326(15)63901-2

[8] Y. Lim, O-k. Kwon, J. Lee, K. Yoo, The ammonia leaching of alloy produced from waste printed circuit boards smelting process, Geosys. Eng., 16 (2013) 216-224.

DOI: 10.1080/12269328.2013.833486

[9] E. Rudnik, M. Pierzynka, P. Handzlik, Ammoniacal leaching and recovery of copper from alloyed low-grade e-waste, J. Mater. Cyc. Waste Manag. (2014, DOI 10. 1007/s10163-014-0335-x).

DOI: 10.1007/s10163-014-0335-x

[10] P.L. Breuer, M.I. Jeffrey, Copper catalysed oxidation of thiosulfate by oxygen in gold leach solutions, Min. Eng., 16 (2003) 21–30.

DOI: 10.1016/s0892-6875(02)00287-x