Minhye Seo

Optimization of germanium enrichment from waste optical fibers: A validation experiment using a hybrid approach

Abstract A batch-type and lab-scale germanium recovery method was developed via a hybrid approach combining pyro– and hydrometallurgical reactions to prove the feasibility of mass production and economic recovery of germanium from waste optical fibers. More specifically, the extent of pyro-metallurgical separation reaction was carefully examined to determine by trial and error its completion time which was 2 h at 700 °C. The post pyro-metallurgical reaction product was leached at 50, 65, and 80 °C for a maximum 8 hr retention at each temperature, using an optimized composition of aqueous HCl solution: maximum germanium recovery of 26 ppm was thus experimentally substantiated by using the ICP-OES method. XRF analysis was performed on the post-hydrometallurgical leaching residue to detect any significant composition of remaining Ge: The confirmation of Si, Cl, and Na as sole residual elements thus cogently substantiated the complete separation of germanium in accordance with the present hybrid approach. The...

Study of nickel recovery and organic compound reduction from electroless nickel plating wastewater

The electroless nickel plating is one of the important plating technologies, and high concentration of its large amount of waste solution is generated with nickel, phosphate, hypophosphite and various organic acids [1]. Electroless plating process is simple and it does not use external electric current to produce deposit. Therefore electroless nickel plating is applied to many electronics industries due to possible the uniform layer formed onto different geometry and the possibility to control the thickness [2]. Electroless nickel plating reactions are as follows [3]: H2PO2 + H2O HPO3 + H + 2H (1) Ni2+ 2H Ni + 2H (2) 2H H2 (3) H2PO2 + H H2O + OH + P (4) With time, nickel and phosphate ions are simultaneously reduced to form the coating and the spent plating solution is discarded to maintain plating quality. However this wastewater is a valuable source of Ni with other hazardous organic compound and phosphate. Currently, the spent baths are treated by alkaline precipitation, but this process generated a large amount of hazardous sludge [4]. In this study, the purpose of electroless nickel plating wastewater treatment was performed to effectively remove the harmful species (COD, P, N) and recover Ni metal. For Ni recovery, selective precipitation and electro-winning process were utilized and the organic species were removed by advanced oxidation process. Reference [1] R.E. Miller, Plat. Surf. Finish, 74 (12) (1987) 52-56. [2] A. W. Mohammad , R.Othaman, N. Hilal, Desalination 168 (2004) 241-252. [3] C.L. Li, H.X. Zhao, T. Tsuru, D. Zhou, M. Matsumura, J. Memb. Sci. 157 (1999) 241-249 [4] D.W. Grosse, J. Air Pollut. Contr. Assoc. 26 (5) (1986) 603-614. Minhye Seo Advanced materials and process center, Institute for Advanced Engineering 633-2, Goan-ri, Beagam-myeon, Cheon-gu, Yongin-si, Gyounggi-do, Republic of Korea Tel: +82-31-330-7689 FAX: +82-31-330-7116 E-mail: minhye_s@iae.re.kr Key Word: Elctroless nickel plating, Ni recovery, wastewater treatment, chemical precipitation process, Electro-winning FB-8 24 2013