# neutralize nitric acid in Aqua Regia



## john_paok (Nov 20, 2012)

Hi,

How can I neutralize nitric acid in Aqua Regia? I try with Urea on hot plate and I see stop fizzing my AR when I add an equal amount Urea with nitric acid.
So, in this solution I have copper, silver and other metals because I try to refine gold directly from cell phones and pins. Now, I see white precipitate on bottom after precipitate with SMB. The color of my solution is Green.
Must I filtering and take powder and then I make another AR after boiling my powder with nitric acid?
I see growth crystals, what is this?
My scrap is 40grams of ppins and boards from cell phones and I had add 80ml Hcl acid and 10ml nitric acid and o teespoon 5grams of sodium nitrate. 
Then I had add 25 grams Urea and 20 grams of SMB.


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## butcher (Nov 21, 2012)

John,

looks to me like you need do a little more homework and less mixing circuit boards in acids and chemicals, that flask looks like a solution of dissolved copper or iron, not dissolved gold, it also looks like you do not understand the process.

Decant pour off liquid from those salts of metals, into a clean jar use a large clean piece of copper and cement out any values from that copper solution.
(If there are any values in that solution, I would not doubt that the values are still on the cell phone circuit boards, from the looks of that copper or iron solution.

The white powder can contain urea, lead chloride,lead sulfate, silver sulfate, table salt, silver chloride, copper chloride, and other metals as chlorides or fine powders and possibly some gold and all kinds of other salts.

I have made many posts on how to identify these white powders and how to separate the metals in them, search white powders.

You need to learn to remove base metals before dissolving values in aqua regia, to keep from loosing values, and creating messes like these.

You should go back and read Hokes book some more, as you still do not understand what she teaches.

Using urea is not needed, if you learn proper methods, and in this case with the platinum group metals you would have in the electronic scrap or cell phones, Using urea is a very bad idea if you plan to separate or recover these, as urea can form ammonia in your solution.

Read Hokes, and do her experiments.
Eliminate base metals without putting the valuable metals like gold into solution.
Put that urea on your grass, where it belongs, not in your aqua regia where it serves no useful purpose.
Study the forum more, and learn better methods, to process your scrap to recover values and then learn to refine the collected values.

Aqua regia is a refining method, not a recovery method, and is almost never used for a recovery method (the rare instant it is used it must be understood well how it reacts chemically in solution with metals),

You have used aqua regia for a recovery method and just made a mess and you are loosing the values in the cell phones contained with this process, be sure you also understand the use and care of a stock pot, and if you make messes like this you will need to keep your copper cementing jars handy.


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## john_paok (Nov 21, 2012)

yes I know must I make more homework  

thank butcher again, this is for homework and is not good idea, it contain low value of gold and has diferent metals. I'll try to refine gold with ore or black sand real gold and I find material for free. I know areas.


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## butcher (Nov 21, 2012)

John, 
You can recover values from this, it will be a little more work now, but as long as you have kept everything the values are still there,

If you get a black powder forming on the copper, when cementing with the copper metal buss bar in the green solution, (the black powder can be some of your values), it could take several days depending on conditions of this solution, when copper bar stays clean when brushed of and sitting in the acid it has finished doing its work. Clean off the copper and dry put in plastic bag to cement with next time.

The white salts wash in boiling water this will remove NaCl, lead chloride if decanted hot (let white fluffy powder settle before decanting), some excess water-soluble salts like urea or SMB, and other base metal chlorides.

Add a solution of sodium hydroxide to the remaining washed white powders till pH is neutral, wash with several boiling water washes, and dry powders on low heat.

Incinerate the powders red hot keeping them crushed to powder, keep red hot about 20 minutes and stir powders to expose to air, cool while stirring to oxidize the base metals in air.

Boil in HCl, add a tiny bit of water and decant warm (letting powders settle), this will remove tin and other base metal chlorides, several boiling hot water washes till solution is clear remove soluble chloride metals.

Now you should be left with any silver as a chloride and gold powders (if the white powder had these to begin with).

Also keep the cell phone circuit boards or any metals or powders that were in the bucket this green solution came from your values can be there.

Do you know how to test for gold in solution with stannous chloride, what did your stannous test show when testing the green solution?

I will let you read Hokes and before telling you more it will take a little while to get this far.

Also treat your waste using the instructions given in dealing with waste thread, found in the safety section.


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