Merril crowe gold and silver refining

Hello all, I am a refiner and im having trouble getting rid of the lead in our dore(bars) I Can't seem to find a good flux ratio to help oxides the lead into the slag. We are a Merrill crowe plant that uses lead nitrate in our zink addition.
.Our flux.
:borax
:sylica
:soda ash
:nitter
Does anyone have any suggestions?

Hello and welcome to the forum.

Can you tell us the percentages of each ingredient in your flux and what is your flux to feedstock ratio? Also how long is your soak time at temperature?

Great name! Welcome Dave. Are you actually doing this in the US? I only ask because some of your spelling is unusual, and where you're working may affect the advice you receive.

Dave

Stop adding lead nitrate - add small amounts of copper nitrate instead. The copper will do the same thing to activate the zinc and your refiner will not penalize you for the extra copper. The copper chemicals will be a bit more expensive but it will eliminate the problem with the refiner.
With the copper you will have no need to modify your flux, and besides, you cannot add some magic flux and eliminate the small amount of lead as you were requesting.