The Development of Bi-Ag Sandwich Sheets for Fire Assay Applications

P. Ruethaitananon; Narong Praphairaksit; Kageeporn Wongpreedee

doi:10.4028/www.scientific.net/AMM.752-753.444

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HomeApplied Mechanics and MaterialsApplied Mechanics and Materials Vols. 752-753The Development of Bi-Ag Sandwich Sheets for Fire...

The Development of Bi-Ag Sandwich Sheets for Fire Assay Applications

Abstract:

A Fire assay is method to verify the fineness of gold with use lead in its process. In this research, Bi-Ag sandwich sheets for a lead-free fire assay method were developed. Bi-Ag sandwich sheets were produced by a hot-dipping method at temperature 300 °C and 400 °C. Samples were characterized the microstructure by SEM along the process. A fire assay method was used to verify and correlate the results of gold fineness to various kinds of wrapping sheets which are Bi-Ag sandwich sheets and lead. The Bi-Ag sandwich sheets shows the layer of 14-20 µm at 300 °C and 8.5-10.5 µm at 400 °C. After cupellation process, the metal beads were observed by SEM and mapping techniques to analyze the remained copper. XRF characterization was confirmed the results of compositions showing an increasing amount of copper as increasing temperature dipping on Bi-Ag sandwich of 0 wt%, 1.58 wt% and 1.34 wt% at S1, S2 and S3, respectively. Higher amounts of copper left on bead buttons consisted with the accuracy of fire assay results which were S1, S2 and S3 obtaining 99.99 wt%, 99.87 wt% and 100 wt% of gold, respectively.

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Periodical:

Applied Mechanics and Materials (Volumes 752-753)

Pages:

444-447

DOI:

https://doi.org/10.4028/www.scientific.net/AMM.752-753.444

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Online since:

April 2015

Authors:

P. Ruethaitananon, Narong Praphairaksit, Kageeporn Wongpreedee*

Keywords:

Bismuth, Cupellation, Fire Assay, Gold, Hot Dipping

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* - Corresponding Author

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