# recovery silver from waste in electroplating industry



## nutty (May 2, 2012)

The waste is scrap electronic which is come from cutting process.
First step
I dissolve scrap in nitric acid 65% and then dilute with distillated water
Second step
I precicptate silver ion with potassium chloride 
Third step
I brought silver chloride salt and dissolve it in 10% ammonia. Then electrolysis with two stanless steel electrode 2.8 V
Result
After 10 minutes found that cathode have a gray flake silver but it did not coated in cathode.
Questions
1. Can I electrolysis in first step ? why? (Because i have ever heard that if ph too low it will no have silver deposited)
2. Why deposited silver is gray flake?(not crystal flake)
3. What different between cemented silver and crystal silver? 
4. Can cemented silver occur in electrolysis?


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## qst42know (May 2, 2012)

That is not how you convert silver chloride to metallic silver.

Before you create an explosive silver compound and hurt yourself playing with ammonia, read the forum for a few ways to convert silver chloride easier and safely.


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## butcher (May 3, 2012)

I agree this sounds very dangerous, and I see many things wrong with the process.

The nitric acid should be diluted to begin with.
You could cement the silver using a copper buss bar; the cemented silver powder could be washed and then melted without conversion, as it will be elemental silver powder, 

I see no reason to make silver chloride, which would need converting to silver before melting.

There are several processes to convert the silver chloride to metal, like sodium hydroxide and Karo syrup method, (caustic soda and hydrogen peroxide also works). or the dilute sulfuric acid and iron method, some use the HCl and aluminum method), 

Silver chloride is not converted to metal in an electrolytic cell, and especially not mixing silver with ammonia, which makes a dangerous compound (if dried) if not handled properly can explode in your face.

The silver cell is used to further purify fairly pure silver metal and also collect values the silver may collect as impurity.

Nutty, 
For your safety add HCl to precipitate the silver from your ammonium solution, make sure the ammonium chloride solution is neutral Ph, (do not dry any of the powder of silver and ammonium solutions).

Welcome to the forum, go to the book section and download a copy of Hoke's book, or you can buy the book, Hokes explains the basics well, this book will help you understand much of what we discuss here on the forum, if your dealing with silver reading this section (silver section) will explain how to recover and refine your silver, read also the safety section and do not miss the dealing with waste topic.
There is also the general reaction list in the general chat section read the welcome to new members it will give you a guided tour.


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## nickvc (May 3, 2012)

As the guys have pointed out your methodology is incorrect, I would also look at the costs of this operation especially if your dissolving base metals along with silver, nitric is usually expensive and the solution created will need treating, further costs, to remove the base metals before safe disposal. You may well struggle to sell the base metals after removal from solution and in fact be better off selling the scrap as is as contaminated scrap which is at least identifiable without the costs of acid, chemicals and time.


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## nutty (May 16, 2012)

thank you for all recommendation. I'm a newbie in this forum


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