Hi Esh , the Jan 9 ASX announcement stated they used fire assay...

Hi Esh , the Jan 9 ASX announcement stated they used fire assay with gravimetric finish it tables the proportion of Au and Ag in the buttons .
A more detailed account of how they do the test was on the 28.8.17 when they had to respond to an ASX please explain its changed since then in that they use a Cu rather than a Pb collector also ............

Apparently according to section 7 of that announcement the buttons can be dissolved in nitric acid (regic Aqua from memory) to get out the Ag filtered and then NaCl added (as I previously guessed ) to precipitate the Ag leaving the Au to be precipitated out with FeSo4 and both Au and Ag can be weighed out

As to the second melt needed that is what has stumped the metallurgists so I doubt I could have an answer , but a stab in the dark maybe in the initial melt reactive metals bind possibly due to the flux that makes them not bind to the Au in the second smelt ?

The above is just my opinion I never got past a 100 level chemistry paper