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http://dx.doi.org/10.5762/KAIS.2017.18.4.608

Pyrometallurgy Process for a Low Graded Gold Alloy with PbO and CaO  

Song, Jeongho (Department of Materials Science and Engineering, University of Seoul)
Song, Ohsung (Department of Materials Science and Engineering, University of Seoul)
Publication Information
Journal of the Korea Academia-Industrial cooperation Society / v.18, no.4, 2017 , pp. 608-613 More about this Journal
Abstract
We proposed a pyrometallurgical process to achieve gold alloy with an Au content of more than 80wt% from low grade (<35wt%) gold alloys. We performed the heat treatment at a temperature of $1200^{\circ}C$ for 5 hrs using Au35wt%-Ag5wt%-Cu60wt% gold alloys mixed with 1/2 weighed PbO and CaO flux by varying the ratio of PbO/(PbO+CaO) from 0 to 1. We investigated the change in content of the samples with energy dispersive X-ray spectroscopy (EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). The EDS results showed that the Au content increased from 35.0wt% in the PbO-only sample to 86.7wt% (in the PbO/(PbO+CaO) 1:1 sample), while the other samples achieved more that 84wt%. In addition, the 2/3 flux ratio sample showed the lowest Ag loss into the flux. In the ToF-SIMS results, the PbO only and CaO only fluxes had Au+ peak intensities of 349 and 37, respectively. Although the CaO-only flux might be more favorable considering the loss of Au into the flux, we concluded that the amount of Au lost into the flux could be ignored. Our results imply that that the pyrometallurgical process using a mixed flux is an effective hydrometallurgical process.
Keywords
EDS; flux; gold alloy; pyrometallurgy; ToF-SIMS;
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