Please help me to choose the best gold refining method

[makhlaghi]

Hello to all
Please help me for choosing the best method for recovery of gold from jewelry waste. I read several booksand article and studied several methods.
In all methods the first step “dissolving in aqua regia and filtering” and second step “ neutralizing with urea” are same.
The difference is in third step “reducing of Au cation to gold particle and detecting final point with Precious metal detection liquid”.
There are several reducing agents such as: Sodium metabisulfite, Zinc, ferrous sulphate, hydrazine hydrate.
Which one is best method? and which one has the high refining yield ? and which method is the fast one?
Please help to select the best method and write me how I can detect the final point of reducing step.

somewhere I read that the zinc is not selective to reduce gold it reduces all metal and this not good.
somewhere I read taht the hydrazine hydrate is the fastest way but in this method we should not use urea. and hydrazine hydrate will reduce all metal cations.
I am confused about selecting method!!!

Thanks,
Mehdi

 

[butcher]

http://www.scribd.com/doc/2815953/Refining-Precious-Metal-Wastes-C-M-Hoke

This book will give you all of the answers you seek, please read it, reading Hoke's book will be better than asking here on the forum, when you run into something you do not understand then someone here will be able to help,

 

[makhlaghi]

Dear butcher,

Thanks for book.
As your advise I will read it "Again". but this time more better to find the best method.
thanks

 

[trashmaster]

It might help to know what type of material you plan on processing. :roll:

Each thpe of material will have a differant process to recover.. :?:

 

[makhlaghi]

It might help to know what type of material you plan on processing. :roll:

Each thpe of material will have a differant process to recover.. :?:

Dear trashmaster

I am going to recover gold and silver from jewelery waste. But I cant test various methods. I Should try Just one time to reach best recovering condition.

thanks

 

[Harold_V]

It might help to know what type of material you plan on processing. :roll:

Each thpe of material will have a differant process to recover.. :?:

Dear trashmaster

I am going to recover gold and silver from jewelery waste. But I cant test various methods. I Should try Just one time to reach best recovering condition.

thanks

You've missed the point. Jewelry waste manifests itself in many ways---including solid pieces of gold, gold filings, solutions and polishing wastes, including filters, and even carpets, assuming there's such a thing in your work area. It's not all that uncommon here in the States.

There is no one operation that is proper for all of them. You simply must come to terms with the idea that you must understand refining principles, so you'll know which process is acceptable for each type of waste material.

Harold