Non-Chemical Aqua Regia without inquarting for 18k gold 1oz - Need Help

[gtron]

Hi,

I wanted to refine 1oz of 18kt gold but I did not do inquarting and then purifying with nitric acid. I went straight to Aqua Regia. I had 1 oz of 18kt gold added 300ml of Aqua Regia. Proceeded with reaction. At end of reaction, there was a gray powder on bottom of beaker and the solution was dark green. I could see some of the gold was not dissolved. What to do next?

Should I evaporate the solution and add more aqua regia?
Should I evaporate and inquart with copper or silver and then add aqua regia?

I am lost at this point. Please help.

 

[4metals]

You have a reaction frozen over with silver chloride. There was a high silver percentage of silver in the alloy which stopped the reaction. Here's what you should do.

1, Filter the solution and dissolve the remaining solids in ammonium hydroxide. This will dissolve the silver chloride.
2, The clean gold solids should be weighed, and inquarted in silver.
3, The silver / gold alloy should be parted in 50% nitric acid (half nitric half distilled water.)
4, The solids should be collected and rinsed and dissolved in aqua regia.
5, Filter the aqua regia and mix it with the original aqua regia which froze over and proceed normally to drop the gold.
6, Acidify the ammonia solution and filter out the silver chlorides for processing.
7, Cement the silver from the parting solution to recover the inquarting silver as a metal.

Here's what you should have done;

READ HOKE!!!!!!!

Which I have no doubt you will do before you proceed!

 

[Harold_V]

An excellent example of not wanting to use a procedure known to work, thinking it's not important. A common ailment amongst people---never enough time to do it right, but all the time in the world to try to bail out when things go south.

Why you did not inquart I do not understand, especially if you've been reading this forum for any length of time. Inquartation assures success.

Read Hoke.

Read Hoke again.

Harold

 

[gtron]

4metals,

1. Can I use sodium hydroxide instead of ammonium hydroxide to dissolve the silver chloride? And where can I buy ammonium hydroxide?

2. You mention to mix the new aqua regia solution with the old aqua regia solution (that has copper and other base metals and gold). Would that be a problem? When precipitating with sodium metabisulfate would the base metals precipitate also? Why not just add sodium metabisulfate to the old aqua regia solution and precipitate the gold?

 

[butcher]

It is the (ammonia) ammonium that reacts with silver chloride to dissolve it, (we are not using the hydroxide here in this reaction),and sodium would not do any good.

house hold ammonia is ammonium hydroxide (or ammonia in water), make sure to acidify solutions and powders with HCl acid so as not to create a dangerous substance if dried, and by mistake form an explosive mixture with the silver and ammonia compounds (silver diamine complex Ag(NH3)2 + Cl-) which are temperature and shock sensitive.

Sodium metabisulfite (note: not sodium metabisulfate), the ending in these words are very important.
The metabisulfate would not work to precipitate gold.

Most of the base metals would stay in solution as you precipitate the gold using SMB, depending on how much SMB you used and other factors the gold will precipitate with some base metals, re-refining and good washing techniques will give you good results.

gtron,
you seem to be going about this all backwards, starting the project before studying how to do it, this would seem to me to be a very difficult way to learn something, spending your time getting out of mistakes and learning ways to undo problems (it would make learning the proper way of doing this harder to learn in my opinion.

Are you studying Hoke's book if not why.

 

[SoCal gold]

so what is the material he had at the bottom of his container? I believe he said it was grey.

 

[butcher]

Most likely it was silver chloride powders.

 

[Alentia]

Grey powder at the bottom is silver chloride. I went through somewhat similar experience, not because I did not enquarted, but because, I could not see some of the pieces had not dissolved in nitric completely prior to AR treatment. Batch was about 2kg of inquarted material in a big vessel. After filtering the solution I picked leftovers and moved to separate bowl.

Rather than using ammonium hydroxide, I actually used H2SO4 and Iron stick to quickly free gold pieces from Silver Chloride and effectively converting chloride into Silver cement right in the bowl. Works much faster than ammonium and no need need to reduce silver further. Freed visible chunks of gold went to new batch and silver into the cell.

Even if any tiny bits and pieces of gold are in the leftovers with silver, they can be recovered later when when processing dried mud from silver cell.

 

[skullsbox01]

Hi,
i have the same problem, because i must remove the stones from gold jewellery 18kt, then i can't inquarting the gold.
With white gold 18k, i haven't problems, because the silver is under 10%, but with yellow gold the silver is more than 10%.

There is a method to dissolve yellow gold 18k, without inquarting?

Thanks

 

[jeneje]

Hi,
i have the same problem, because i must remove the stones from gold jewellery 18kt, then i can't inquarting the gold.
With white gold 18k, i haven't problems, because the silver is under 10%, but with yellow gold the silver is more than 10%.

There is a method to dissolve yellow gold 18k, without inquarting?

Thanks

As far as I know, any gold with a karat rating above 10K or better should be inquarted with silver or copper before dissolving in (HNO3) nitric. Reducing the gold to 6Kt.
Ken

 

[skullsbox01]

Thanks Ken,
but i can't melt the gold jewelery to do the inquart, so i must dissolve the gold whitout inquarting.

 

[jeneje]

Thanks Ken,
but i can't melt the gold jewelery to do the inquart, so i must dissolve the gold whitout inquarting.

Your gold will not dissolve completely without inquarting. All you will do is encapsulate the gold with the silver chloride. I have been there done that. I can tell you, you don't want too go there.

Some of the senior members may know of another way but, I don't think there is.
Ken

 

[butcher]

If the diamonds are large I cut them out, if they are small they just go thorough the melt, and I recover them later, the small diamonds are not worth much (that I know of) and most of them make it through the process anyway if you do collect them and wish to sell them.

 

[4metals]

If the job is 18K and has stones it can be processed in aqua regia until the chlorides "freeze" it over, remove the undissolved solids with coarse filtration and rinse them and tumble them in a concentrated sodium thiosulfate solution. The gold will clean up and appear yellow again and it can be put back in aqua regia. It may take a few repeats of this process to effectively digest enough of the gold to loosen the stones so they fall out. When the stones come out, the balance of the undissolved gold can be inquarted in silver and parted in nitric to recover the gold. Any gold which has dissolved from the aqua regia treatment can be recovered normally. I have seen refiners re-use the aqua regia after filtering for the necessary re-dissolves as it still has its ability to dissolve the gold when the silver chloride coating is removed. The gold recovered after parting can also be digested in the same aqua regia and in that way you will consume more of the nitric to make further processing easier.

 

[skullsbox01]

Thanks for all replies,
so, if i have well understood, the correct way to release the stones and to completly dissolve the yellow gold 18k is:

- Aqua Regia until the stones fall down on the bottom
- Filtering the solution to remove gold and silver chloride
- Soaking the gold and the silver chloride in a concentrated sodium thiosulfate solution
- After that silver chloride is dissolved, filtering the solid from the solution and then dissolving again it in aqua regia, to completly dissolve the gold.

 

[butcher]

Actually you will only be able to attack the gold with aqua regia, until the silver chloride builds a crust and the action stops, the silver crust coating protecting the undissolved metal from the acid, passivisation protects the metal from the acid.

At this point, taking the ring out of the aqua regia and dissolving the silver chloride crust to remove it.

Sodium thiosulfate, or ammonia will dissolve silver chloride, but not silver or gold metal, this can be used to remove the silver chloride crust.
(Ammonia can form dangerous explosive compounds if dried and not dealt with properly).

After the silver chloride crust is removed the ring is took back to the aqua regia to repeat the process.


The ring is moved back and forth in these two solutions until the diamond comes loose. Then the gold can be in-quartered with silver without the diamond in the melt.

 

[skullsbox01]

Thanks