I would to know how or what chemicals can I use to reduce silver,nickel and sulphur concentrations in lead during refining process.
Lead is refined in a pot. An air compressor pumps air into the molten mass of raw lead using either a ceramic tube or one made of steel (the steel one is corroded and must be extra long, like a automobile brake line). Sulfur, copper, base metals are oxidized along with a little lead. Skim these off and the sulfur is a gas. Silver, gold and a little platinum group metal remain within the lead. Melt zinc metal in the absence of air, then stir it vigorously into the lead. When you stop and allow the zinc to float to the top, it takes the silver (witch takes the gold etc.) with it as silver is 3000 times more soluble in zinc than in lead (Parkes Process). zinc and silver are both lighter than lead and especially when mixed.
Lead and zinc are mostly unmissable. Any remaining zinc is picked up by more zinc and finally the mass is aerated again with the air pump. I am Doctor Poe