Guys I screwed up...

[Goldman94]

I'm just gunna start by saying, please dont roast me and please just help fix what I did. I would really really appreciate it...

So I added probably about 1/4 cup of baking soda to my AR mix to denox the nitric, which I know was a bad idea now. What can I do now? I'm stuck here guys, please help

 

[Lou]

Evaporate and reconstitute in HCl. Then invest in sulfamic.

 

[Goldman94]

Evaporate and reconstitute in HCl. Then invest in sulfamic.

What's this thing about cementing with copper too? I see that people do that as well. Do I have to do that? Or can I just evaporate and add more HCL?

 

[anachronism]

Evaporate and reconstitute in HCl. Then invest in sulfamic.

What's this thing about cementing with copper too? I see that people do that as well. Do I have to do that? Or can I just evaporate and add more HCL?

Compared to using Sulphamic and something like SMB, cementing with copper is slow and laborious. Adding HCl and evaporating is what you would be told to do 100 years ago- Sulphamic is the modern, up to date version.

 

[butcher]

Sodium hydroxide NaOH will not effectively deNOx aqua regia gold solution, although it will convert the acids to salts.

Sodium hydroxide and hydrochloric acid form a salt, we often call table salts NaCl and water.
HCL + NaOH --> NaCl + H2O

Sodium hydroxide and nitric acid form a salt of sodium nitrate.
HNO3 + NaOH --> NaNO3 + H2O

Aqua regia and sodium hydroxide would produce salts of both NaCl and NaNO3 and water, once evaporated if gold or base metals were involved in these salts later additions of HCl would reform aqua regia (poor-mans) and put the base metals and gold back into solution...

Base metals in a solution like copper would form salts with lower oxidation states CuCl or form oxides CuO and hydroxide salts Cu(OH)3 of the base metals with the sodium hydroxide depending on concentrations...
CuCl2 + NaOH --> NaCl + Cu(OH)3

Base metals forming like CuCl forming would begin to bring gold out of solution even before these base metals formed hydroxides of the metals.
AuCl3 + 3CuCl --> Au + 3CuCl2

Sodium hydroxide will also precipitate gold as a hydroxide.
AuCl3 + 3NaOH --> Au(OH)3 + 3NaCl

Excess of hydroxide can the amphoteric metals back into solution.

With an excess of sodium hydroxide, the gold can be redissolved back into the liquid solution as a soluble sodium gold hydroxide solution.

Au(OH)3 (s) + NaOH --> NaAuO2 (aq)

With gentle heat, the base metal hydroxides can form base metal oxides, around 500 deg the gold hydroxide will decompose to gold and oxygen (Higher heat can put gold into vapors with the chloride salts losing gold in the smoke).

Au(OH)3 --> Au2O3
Au2O3 --> Au + O2 (reaction not balanced)

Now we have the solution evaporated the water and the acids converted to salts like NaCl, NaNO3, CuCl, Cu(OH)2, Au(OH)3, adding HCl at this point can put gold back into the newly formed poor-mans aqua regia...

NaCl + NaNO3 + HCl + Au(OH)3 --> gold dissolved back into the poormans aqua regia along with the other base metals in solution ...

So here your back to having an aqua regia solution that may need to be DeNOxed to recover your gold...

 

[anachronism]

Excess of hydroxide can the amphoteric metals back into solution.

Yoda? 8) 8) 8)

 

[goldenchild]

Are you just looking to get your gold out of solution? If so why not just add HCL until the solution is acidic again? It shouldn't take much. Then proceed as normal.

ETA: Urea also works well to get rid of nitric

 

[Goldman94]

Are you just looking to get your gold out of solution? If so why not just add HCL until the solution is acidic again? It shouldn't take much. Then proceed as normal.

ETA: Urea also works well to get rid of nitric

I tried but the SMB just wouldn't work. I am currently reducing the solution to a syrup and will then add in more HCL then SMB in hopes of then precipitating the gold.

If that doesn't work, what should I do next?
And if it does work should I redo everything to clean it up some more or would it still be in its purebred state?

Thank you guys for all the help, I really appreciate it

 

[Goldman94]

So this is my current situation...

After reducing down the solutions to a syrup consistency I added in some HCL then some SMB and this is currently what it looks like. I have no idea why one is yellow and the other is brown. They were both like that before this and and both has baking soda in them...

I would really love to just start all over but I'm lost now
There should be about 9 grams of gold in there between the 2 so I really can't afford to lose it

 

[galenrog]

You may have already done this, but you did not mention it. Did you test your solution for gold?

Time for more coffee.

 

[Goldman94]

You may have already done this, but you did not mention it. Did you test your solution for gold?

Time for more coffee.

I just tested it and it was positive in the yellow one. Not so much, if any in the brown one. I'm confused. In both it seems like some metallic gold may have precipitated out somehow too.

 

[anachronism]

Please show us a picture of the test.

 

[Goldman94]

Please show us a picture of the test.

The yellow solution turned brown/purple instantly and the brown solution had almost no change to the stannous.

Here's some updated pictures as well. It does look like theres some brown powder on the bottom of both along with some gold metallic flakes.

I also decanted off some of the yellow clear solution into another beaker with hopes of using SMB to precipitate but all that happened was a bunch of fizzing and nothing came out.

 

[butcher]

Testing may not show gold in all of its different oxidation states, it will not detect reduced gold...

Excess of hydroxide can the amphoteric metals back into solution.

Yoda? 8) 8) 8)

Sorry for the confusion, I forgot to put the word put into that sentence.



Excess of sodium hydroxide can put the amphoteric metals back into solution.

Many metals will precipitate from a solution when a basic solution like sodium hydroxide is added, the amphoteric metals will redissolve back into solution if you add an excess of a basic solution (in this case caustic soda), you can precipitate gold and then if not careful you can re-dissolve it back into solution with an excess of sodium hydroxide...

Gold can be precipitated with the use of NaOH, using an excess NaOH will redissolve gold back into solution...
https://en.wikipedia.org/wiki/Amphoterism

 

[Goldman94]

Testing may not show gold in all of its different oxidation states, it will not detect reduced gold...

Excess of hydroxide can the amphoteric metals back into solution.

Yoda? 8) 8) 8)

Sorry for the confusion, I forgot to put the word put into that sentence.



Excess of sodium hydroxide can put the amphoteric metals back into solution.

Many metals will precipitate from a solution when a basic solution like sodium hydroxide is added, the amphoteric metals will redissolve back into solution if you add an excess of a basic solution (in this case caustic soda), you can precipitate gold and then if not careful you can re-dissolve it back into solution with an excess of sodium hydroxide...

Gold can be precipitated with the use of NaOH, using an excess NaOH will redissolve gold back into solution...

What do you suggest I do then? I have so much contamination in there I have no idea what to do next. Theres a thick layer of baking soda in there along with probably some undisolved SMB and paper from the filter that I tried to dissolve when I made the AR, since the first time I did it I wasnt happy with the debris that came thru the paper as well as how much yellow AR solution was still in the paper.

 

[butcher]

Evaporate and reconstitute in HCl. Then invest in sulfamic.

 

[anachronism]

No worries butcher I was smiling with you not at you. Its hard when you crack off a fast informed post.

 

[Goldman94]

Evaporate and reconstitute in HCl. Then invest in sulfamic.

I tried that and nothing happened...except for the sulfamic part. What happens to the baking soda layer? That's probably an inch or 2 thick. And I should add the sulfamic instead of the SMB?

 

[butcher]

After evaporating the solution, adding HCl will dissolve the salts back into solution, any excess sodium hydroxide will dissolve with the HCl forming a sodium chloride solution, along with the other metals also dissolving as chlorides.

This may or may not put your gold back into solution ---depending on how much nitric was formerly involved or how much sodium nitrate salts are involved in the mix of salts...

When adding HCl to the evaporated salts, I would add just a little acid at first, to form a very concentrated syrup-like solution, taking note if any brown gas is formed, indicating NOx gases being produced from the acidic HCl and possible nitrate salts reacting.

Evaporate the solution again to almost syrup, add just a little HCl to rewet and take note of any gases formed...

Evaporate the solution for the third time...

If you invested in sulfamic you could avoid some of the evaporation steps here...

Depending on circumstances everything may not dissolve, back into the concentrated solution as you added the small additions of HCl, some gold may have dissolved into the syrup and some gold foils may remain...

If everything did dissolve back into solution as you finished your third evaporation to a syrup consistency, then you could just add water as suggested in Hoke's and continue as instructed.

Personally I would prefer everything was back into the solution before proceeding, including gold if it did not all go back into the solution I would put it back into solution with controlled additions of nitric along with HCl as needed...


If your still lost, sit this mess aside and then Read Hoke's book...

 

[Goldman94]

After evaporating the solution, adding HCl will dissolve the salts back into solution, any excess sodium hydroxide will dissolve with the HCl forming a sodium chloride solution, along with the other metals also dissolving as chlorides.

This may or may not put your gold back into solution ---depending on how much nitric was formerly involved or how much sodium nitrate salts are involved in the mix of salts...

When adding HCl to the evaporated salts, I would add just a little acid at first, to form a very concentrated syrup-like solution, taking note if any brown gas is formed, indicating NOx gases being produced from the acidic HCl and possible nitrate salts reacting.

Evaporate the solution again to almost syrup, add just a little HCl to rewet and take note of any gases formed...

Evaporate the solution for the third time...

If your still lost, sit this mess aside and then Read Hoke's book...

I dont know how much of a difference there is between the 2 but I used sodium bicarbonate (baking soda) not hydroxide