Aqua regia (if using it is works best if base metals eliminated first) and only the amount of acid needed to disolve metals is used,
to prcipitate(drop) the gold, the nitric acid needs elimninated from solution the ntric is the oxidizer that allowed the gold to dissolve in the chlorides, and if not removed will keep the gold in the solution disolved.
nitric can be eliminated with Urea(usually dissolved in hot water),
or another way I prefer to eliminate the nitrate is to (heat solution slowly not boiling) the nitrates evaporate at a much lower temperature than the chlorides,evaporating down to a syrup consistancy and adding a little HCl (to keep acidic chlorides and to wet) this is repeated 3 times total, (if your solution contains lead few drops fo sulfuric acid), then water to dilute solution (3 times or more in volume) ( if silver it usually drops most now, table salt can be used to check or drop more silver)
tthe solution containig the gold is decanted (or filtered)
then the chemical to Precipitate the gold is used like ferrous sulfate, or sodium meta bisulfite ,ect many different types can be used,
the gold precipitates (drops) as a fine brown powder of Gold Chloride which can be melted back to gold, usually it is refined several times to a purer state before melting.
