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Trying to recover gold but the orange precipitate explodes as I try to melt it?

I have neutralized Aqua Regia solution containing gold with Liquor ammonia [on eBay or Amazon] solution ( 25% 0.91 pure)? After adding ammonia to solution, I got orange ppt. Now to melt it into fine solid form I find troubles, as it explodes. please suggests me , how can I get back gold in solid form from precipitate. please also suggest me any neutralizing agent for Aqua regia solution, so that I could directly furnace( melt) the precipitate into solid gold form. Thank you sir.

Mustafa Kantawala
plating shop - Surat, Gujarat, India
June 10, 2010

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Ok...that is funny. A little knowledge is a dangerous thing.

I think the product of the reaction is ammonium nitrate. Good thing you didn't add some diesel fuel to it before you gave the reaction energy (heat). I bet it popped pretty good.

Trent Kaufman
electroplater - Galva, Illinois

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Pranam Mustafa

You are lucky man-Never try to mix any precious metal solution and ammonia, all that compounds are explosive and very dangerous!I think that simplest way is to slowly evaporate aqua regia solution(very thick sirupy liquid must be result),then mix it with borax [affil links] and melt. From internet archive website you can download old goldsmith handbook by George Gee(free,000 $)-there you can find good chapter on that subject.Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia

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Direct link:
George Gee:Recovering precious metals from waste
liquids...(1920.)
www.archive.org/details/recoveringprecio00geeguoft
Good luck!

Goran Budija
- Cerovski vrh Croatia

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Hi Mustafa, I'm Bhupesh Mulik working as refining officer in jewellery company. you neutralised gold dissolved solution of aqua regia using urea. don't use ammonia. Then add ferrous sulphate ferrous sulphate [affil links] to precipitate gold.

Bhupesh Mulik
- Mumbai, India

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Under favorable conditions, by using ammonia, you could have produced the very explosive fulminate of gold, which can explode from mild shock. Before doing anything, I would read up on this compound on the internet. I think you can re-acidify it, but I would try to rig up a way to do this at-a-distance, outdoors, in an unpopulated area. Keep ammonia away from gold or silver solutions unless you really know what you are doing.

Next time, do things right. After dissolving gold in aqua regia, most people will have a excess of nitric acid in the solution. This must be eliminated before the gold can be precipitated. There are several ways to do this. You can evaporate the solution down to a syrup, dilute 3 times the volume with water, filter out the silver chloride and junk, and then precipitate the gold. Another way is to add small amounts of urea to the aqua regia until the pH is 1. The best way is to not use an excess of nitric to start with.

Besides ferrous sulphate ferrous sulphate [affil links], the most common precipitants for the gold are mainly the sulfite chemicals - sodium sulfite, sodium metabisulfite, or sodium bisulfite. Use these under a fume hood, since SO2 gas will be produced. You can also bubble SO2 gas through the solution. ferrous sulphate ferrous sulphate [affil links] is safer to use, since no fumes are released.

Before doing any more refining, I would strongly suggest reading "Refining Precious Metals Wastes", by C.M. Hoke. Although written in 1940, it is still, by far, the best book for learning how to refine jewelry scrap of all sorts. She primarily uses ferrous sulphate ferrous sulphate [affil links] as the gold precipitant.

Chris Owen
- Nevada, Missouri, USA
June 15, 2010

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Thank you everybody for the suggestions, and now on I will be careful with ammonia.
Now I still have the orange ppt is the same form which I cannot melt, so what to do with it now ?

Mustafa
- Surat, Gujarat, India
June 16, 2010