The sodium bisulfite is what will allow the gold to precipitate.
3 NaHSO3 + 2 AuCl3 + 3 H2O -> 3 NaHSO4 + 6 HCl + 2 Au
Now we need to recover the powder by filtering the solution, then allow it to dry.
Let It Dry
It still doesn’t look like gold, and yet…
Melting The Gold Powder
After drying the gold powder, we need to melt it in a crucible. Our oxy-butane torch can do the job, since the melting point of gold is around 1064°C.
A Golden BB
The result is a pretty gold BB! As with the silver, our homemade process can’t extract perfectly pure gold, which is one reason why industrial operations use other, more dangerous processes. But that’s another story...