Aqua Regia Refining InstructionsHaving described it's hazards, it must be pointed out that, like most industrial processes, refining gold in acid is quite safe when performed under controlled ...
Platinum- If you had platinum in your gold, it will not dissolve, to any appreciable degree, in the room temperature aqua regia. It will be left behind when you pour off the aqua regia, prior to precipitation. To insure high purity of the platinum, you will need to re-refine this material. Put ...
Monday, 14 September 2009
Saturday, 12 September 2009
How To Recover Gold Aqua Regia
Not quite the answer to the question, but, I used to work with a gold process. We used to recover gold as gold sulphide precipitate, by making alkaline, then adding sodium hydrosulphite. The sulphide was then sent to a refinery company, to recover the gold
Thursday, 10 September 2009
Gold Aqua Regia Precipitate Method
How do i Precipitate gold from aqua regia solution by using reducing agent ferrous sulphate?
by using ferrous sulphate for precipitation of gold from aqua regia solution,i wish to know the procedure step by step when will i put the ferrous sulphate in solution,is it necessary to neutralize the solution first or it wont be necessary when using ferrous sulphate and dilution of ferrous sulphate in salt form or first make the solution in water then add to aqua regia solution also the quantity of ferrous sulphate and how many time it takes after dilute in solution and further process of pour off the gold mud. Thank you
by using ferrous sulphate for precipitation of gold from aqua regia solution,i wish to know the procedure step by step when will i put the ferrous sulphate in solution,is it necessary to neutralize the solution first or it wont be necessary when using ferrous sulphate and dilution of ferrous sulphate in salt form or first make the solution in water then add to aqua regia solution also the quantity of ferrous sulphate and how many time it takes after dilute in solution and further process of pour off the gold mud. Thank you
Tuesday, 8 September 2009
What Sort Of Chemical Reaction Will Gold Aqua Regia Have in Gold Dissolution....
Question
I would like to know what are the chemical reactions (equations) involved in gold dissolution in aqua regia.
Answer
There's a combination of reactions going on when aqua regia dissolves gold.
Aqua regia combines the presence of a strong oxidizer (nitric acid) and the free chloride ions (from HCl) which readily dissolves gold.
Other strong oxidizers are also formed in the mixture, most notably chlorine gas and nitrosyl chloride. However, the main reaction is the oxidation of gold by nitric acid and the subsequent stabilization of the gold ion by chloride ions.
I would like to know what are the chemical reactions (equations) involved in gold dissolution in aqua regia.
Answer
There's a combination of reactions going on when aqua regia dissolves gold.
Aqua regia combines the presence of a strong oxidizer (nitric acid) and the free chloride ions (from HCl) which readily dissolves gold.
Other strong oxidizers are also formed in the mixture, most notably chlorine gas and nitrosyl chloride. However, the main reaction is the oxidation of gold by nitric acid and the subsequent stabilization of the gold ion by chloride ions.
Sunday, 6 September 2009
Methods Of Dissolving Gold Aqua Regia
If gold is dissolved in aqua regia how can you separate it back out?
The method I know of is used in large-scale mining firms, so I'm not too sure that you could do it yourself. The process involves:
1. Removal of nitric acid: Add urea until no more visible reaction (fizzing stops) 2. Precipitation of Gold: Add ferrous sulfate. This causes the gold chloride to "reduce" to gold, yielding a cloudy solution ready for filtering. 3. Filtration: Allow precipitation to occur for as long as possible (1 night here). Siphon and filter gold. Clean and cast.
2.
Not very easily! I don't know of any ways... Presumably you'd want to either use a precipitation reaction or an electrochemical method, but in both cases I don't know of any reagents that wouldn't get destroyed by the aqua regia themselves in the process
The method I know of is used in large-scale mining firms, so I'm not too sure that you could do it yourself. The process involves:
1. Removal of nitric acid: Add urea until no more visible reaction (fizzing stops) 2. Precipitation of Gold: Add ferrous sulfate. This causes the gold chloride to "reduce" to gold, yielding a cloudy solution ready for filtering. 3. Filtration: Allow precipitation to occur for as long as possible (1 night here). Siphon and filter gold. Clean and cast.
2.
Not very easily! I don't know of any ways... Presumably you'd want to either use a precipitation reaction or an electrochemical method, but in both cases I don't know of any reagents that wouldn't get destroyed by the aqua regia themselves in the process
Friday, 4 September 2009
History And Gold Aqua Regia
Hydrochloric acid was first discovered around the year 800 by the alchemist Abu Musa Jabir ibn Hayyan (Geber) by mixing common salt with vitriol (sulfuric acid). Jabir's invention of gold-dissolving aqua regia, consisting of hydrochloric acid and nitric acid, contributed to the effort of alchemists to find the philosopher's stone.
When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck into aqua regia to prevent the Nazis from stealing them.
He placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute.
It was subsequently ignored by the Nazis who thought the jar—one of perhaps hundreds on the shelving—contained common chemicals. After the war, de Hevesy returned to find the solution undisturbed and precipitated the gold out of the acid.
The gold was returned to the Royal Swedish Academy of Sciences and the Nobel Foundation who recast the medals and again presented them to Laue and Franck.
When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck into aqua regia to prevent the Nazis from stealing them.
He placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute.
It was subsequently ignored by the Nazis who thought the jar—one of perhaps hundreds on the shelving—contained common chemicals. After the war, de Hevesy returned to find the solution undisturbed and precipitated the gold out of the acid.
The gold was returned to the Royal Swedish Academy of Sciences and the Nobel Foundation who recast the medals and again presented them to Laue and Franck.
Wednesday, 2 September 2009
Chemistry Involved In Gold Aqua Regia
Dissolving gold
Aqua regia dissolves gold, though neither constituent acid will do so alone, because, in combination, each acid performs a different task. Nitric acid is a powerful oxidizer, which will actually dissolve a virtually undetectable amount of gold, forming gold ions (Au3+).
The hydrochloric acid provides a ready supply of chloride ions (Cl-), which react with the gold ions to produce chloroaurate anions, also in solution. The reaction with hydrochloric acid is an equilibrium reaction which favors formation of chloroaurate anions (AuCl4-).
This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the free chlorine present in aqua regia
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