And what is the remaining 97.6%, pure zinc metal, zinc oxide, zinc hydroxide? Water logged or dry? Is the pH acidic, neutral or basic?
Have you tried to use lye, sodium hydroxide? It will dissolve all of the above forms of zinc, forming sodium zincate which is water soluble. The zinc can be electrowon directly from solution, keeping the amount of waste down. The leach could even be reused after electrowinning. Gold and silver should be left in a concentrate that can be leached with nitric acid for recovery of silver first and then adding hydrochloric acid to dissolve gold and anything left by the nitric acid. The gold should be easily recovered at this point by standard precipitants like SMB or copperas.
Cementing silver on copper gives a more pure silver than if you are using zinc. Zinc will cement iron, nickel, tin, ... almost any other metal. If what you have is silver, gold and zinc only then you could use zinc to cement the silver without any extra contamination. It's hard to give any better advice without more details.
Göran