All Issue

2020 Vol.30, Issue 8 Preview Page
An Oxidative Chloride Stripping Solution for 14K Gold Alloys
Kwangbae Kim
,
Ikgyu Kim
,
Ohsung Song†
Department of Materials Science and Engineering, University of Seoul, 163, Seoulsiripdae-ro, Dongdaemun-gu, Seoul 02504, Republic of Korea
†Corresponding author E-Mail : songos@uos.ac.kr (O. Song, Univ. of Seoul)
August 2020. pp. 393-398
PDF XML Citation
Abstract

We propose a novel stripping solution containing acids (HCl and HNO3), an oxidant [(NH4)2S2O8], and complexing agents (NaCl and citric acid) to remove surface passivation layers from 14K gold alloys fabricated using an investment casting process. The optimized solution employing only HCl acid is determined by varying molar fractions of HCl and HNO3 on 14K yellow gold samples. Stripping properties are also identified for red and white gold alloy samples under the optimized stripping conditions. The removal of passivation layers, weight loss, and microstructure evolution are characterized using Raman spectroscopy, a precision scale, and optical microscopy. The proposed stripping solution effectively removes passivation layers more rapidly than conventional cyanide stripping. Weight loss increases linearly for up to 5 min for all 14K gold alloys. Red gold exhibits the greatest weight loss, followed by yellow gold and white gold. The results of microstructural analysis reveal that the conformal stripping occurs according to time. These results imply that the proposed oxidative chloride stripping might replace conventional cyanide stripping.

Keywords
gold stripping
oxidative chloride
14K gold alloy
passivation layer
References
1.
S. Pattnaik, D. B. Karunakar and P. K. Jha, J. Mater. Process Tech., 212, 2332 (2012). 10.1016/j.jmatprotec.2012.06.003
2.
T. Phetrattanrangsi, C. Puncreobutr, A. Khamkongkaeo, C. Thongchai, B. Sakkomolsri, S. Kuimalee, P. Kidkhunthod, N. Chanlek and B. Lohwongwatana, Thermochim. Acta, 657, 144 (2017). 10.1016/j.tca.2017.09.008
3.
J. V. Lorea, T. F. O`Rourke, US patent 2,612,898 (1952).
4.
M. Grimwade, Gold Technol., 26, 16 (1999).
5.
M. E. Wadsworth, X. Zhu, J. S. Thompson and C. J. Pereira, Hydrometallurgy, 57, 1 (2012). 10.1016/S0304-386X(00)00084-0
6.
S. S. Konyratbekov, A. Baikonurova and A. Akcil, Miner. Proc. Ext. Met. Rev., 36, 198 (2015). 10.1080/08827508.2014.942813
7.
S. Alviti, In processing 23rd Santa Fe Symposium Jewelry Manufacturing Technology, (New Mexico, USA, 2003) p.25.
8.
S. I. Galanin and I. V. Kalinnikov, Surf. Eng. Appl. Electrochem., 44, 359 (2008). 10.3103/S1068375508050037
9.
G. Senanayake, Miner. Eng., 17, 785 (2004). 10.1016/j.mineng.2004.01.008
10.
X. H. Wang, In processing 3rd international symposium Electrochemistry in Mineral and Metal Processing, (1992) p.425.
11.
M. I. Jeffrey, P. L. Breuer and W. L. Choo, Metall. Mater. Trans. B, 32B, 979 (2001). 10.1007/s11663-001-0086-7
12.
M. Baghalha, Int. J. Miner. Process., 82, 178 (2007). 10.1016/j.minpro.2006.09.001
13.
E. G. Baglin, J. M. Gomes, T. G. Carnahan and J. M. Snider, United States Department of the Interior, Bureau of Mines Report of Investigation 8970 (1985).
14.
A. Alzate, M. E. Lopez and C. Serna, Waste Manag., 57, 113 (2016). 10.1016/j.wasman.2016.01.04326860423
15.
F. D. R. Thesauro, V. Brusic, C. C. Thompson and B. P. Bayer, US Patent 7,161,247 (2007).
16.
C. Cretu and E. V. D Lingen, Gold Bull., 32, 15 (1999). 10.1007/BF03214796
17.
M. A. Diaz, G. H. Kelsall and N. J. Welham, J. Electroanal. Chem., 361, 25 (1993). 10.1016/0022-0728(93)87035-T
18.
J. Vinals, C. Nunez, and O. Herreros, Hydrometallurgy, 38, 125 (1995). 10.1016/0304-386X(95)94407-N
19.
G. M. Ingo, G. Chiozzini, V. Faccenda, E. Bemporad and C. Riccucci, Thermochim. Acta, 321, 173 (1998). 10.1016/S0040-6031(98)00457-2
20.
A. Bello, D. D. Arhin, K. Makgopa, M. Fabiane and N. Manyala, Am. J. Mater. Sci., 4, 64 (2014).
21.
J. O. Marsde and C.L. House, The chemistry of gold extraction, 2nd ed., p.118 (2006).
Information
  • Publisher :Materials Research Society of Korea
  • Publisher(Ko) :한국재료학회
  • Journal Title :Korean Journal of Materials Research
  • Journal Title(Ko) :한국재료학회지
  • Volume : 30
  • No :8
  • Pages :393-398
  • Received Date : 2020-05-13
  • Revised Date : 2020-05-13
  • Accepted Date : 2020-07-14
  • DOI :https://doi.org/10.3740/MRSK.2020.30.8.393
Journal Informaiton Korean Journal of Materials Research Korean Journal of Materials Research
Online Submission
  • scopus
  • NRF
  • KOFST
  • crossref crossmark
  • crossref cited-by
  • crosscheck
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close