How can I separate Au from a Au and Zn mixture?

Question

i'm thinking that I should mix it to HCl solution..but i'm not sure if one is soluble and one isn't

Answer 1

Fire assay will do the trick.

Iam assuming we're talking about a mineralised ore here containing both Au and Zn.

Fire assay in basic form involves addition of litharge (PbO) flux and heating under extreme temperatures.

Silicates fuse forming a glass slag which can be smashed and removed.

The Pb button containing base metals and noble metals is then placed in a cupel and again heated to extreme temperatures.

The base metals are volatilised and/or absorbed into the cupel leaving a prill containing precious metals.

Residual Ag can be removed from Au by addition of Nitric Acid to the prill, leaving pure Au.


Alternatively, you could use 4 acid digest (HCl, HNO3, HClO4, HF) followed by solvent extraction using DIBK or MIBK to selectively extract Au into organic phase before washing back into aqueous phase using HCl. You could then electrolyse the Au onto carbon rods and burn off the carbon leaving the Au.

Hope this is of some help.
Cheers :)

Answer 2

you can heat the mixture because gold an zinc are bound to have different melting points. pour off the the one with the lowest melting point.

Answer 3

Gold is practically inert, you need something to bind the zinc.
What chemical reactions have you studied which may work?