Why not avoid the whole issue and just reclaim the gold by selling the
contents of your solder pot to a reclaimer.  Solder analysis is under $ 50
while the solder can be reclaimed at a value of at least 50 % of your virgin
metal cost, plus a concentration of gold of .2-.3 percent will cover the
balance of the new charge.  Check with your reclaimer, get an independent
assay, negotiate the price up front..... and agree on a standard size of mold
to pour your ingots.  Do not list your shipment as gold bearing bars, but do
special tag them.  We never had a project that got a pot that far, but our
planning indicated that reclaim would actually make money if we did.