AR evaporated to a crust

[j200]

Hi!

I had some gold dissolved in aqua regia. It was clear and yellow. I wanted to evaporate the nitric acid that was left in it but I left it for to long in the water bath. Everything evaporated leaving a yellow/orange crust at the bottom of the jar. I added distilled water and applied some heat in hope that all will just dissolve. Now I've got a cloudy orange/green mixture with black sediment on the bottom.

What now?

 

[philddreamer]

Add a bit of HCl.
Phil

 

[Geo]

it wouldnt hurt to add a few drops of Cl to the solution after adding the hcl. it may not benefit much but ive done the same thing and the bleach will make it clear again.

 

[j200]

After adding some hcl and bleach the solution looks more clear. The color is more like before but the black residue is still there. Should I add more acid o bleach? I'll just leave it for a couple of hours and see what happens.

I can't upload any pictures now because I'm not at home. If it will work, what should I do next? Evaporate the acid and bleach?

 

[philddreamer]

What was the source of the material processed?
Did you filter properly?
Maybe add a bit more bleach, then heat in order to evaporate the bleach. Check the volume when you add the bleach, thus having an idea of when you've got rid of the bleach.
Then let cool; filter; precipitate; test with stannous; rinse properly.

Take care!
Phil

 

[j200]

The material I was working with were pins from Eltra. Boiled first with 30% hydrochloric acid, then with sulfuric acid (about 80% and with nitric acid at the end.

 

[Geo]

it looks like you might still have some elemental gold powder in the solution. add a little more (30 ml) hcl and another (50 ml) of bleach.add the bleach at 10 ml increments and swirl after each addition.let it sit for a few minutes and add another 10 ml. after that, you can be pretty sure any solids left should be dissolved. let the solution settle and decant into a clean container. keep any solids that did not dissolve in the original container (you will determine if it has values later). warm your solution until it is steaming for about 15 minutes and remove from the heat. let the solution cool completely.test with stannous chloride to insure the presence of gold. precipitate the gold with what ever precipitant you choose.

any solids that were left.to this add enough hcl to cover it. to this,add a drop of nitric acid and give it a gentle shake. watch for a reaction. if you do not get an immediate reaction, leave it for awhile and come back later and test the solution with stannous chloride. if you do see a reaction, wait for the reaction to stop and add another drop of nitric acid. repeat this until there is no reaction to the addition of nitric acid.test with stannous chloride. free nitric should not be an issue.you should be able to precipitate any gold without neutralizing the nitric first.