Using gold to denox

[bhilton]

Hi All,

I am curious, I typically keep nitric acid use to a minimum, and it does not take very much sulfamic acid to denox.

I want to experiment with adding a button of gold to my AR (after all reactions have stopped and the gold I am refining is dissolved).

Will it be obvious to the naked eye, that the reaction to the gold button has stopped when all Nitric acid in solution is used up?


Thanks!
Bill

 

[Martijn]

Hi All,

I am curious, I typically keep nitric acid use to a minimum, and it does not take very much sulfamic acid to denox.

I want to experiment with adding a button of gold to my AR (after all reactions have stopped and the gold I am refining is dissolved).

Will it be obvious to the naked eye, that the reaction to the gold button has stopped when all Nitric acid in solution is used up?


Thanks!
Bill

This is actually a trick used by many members to get rid of free nitric from the pregnant solution. The partially dissolved gold button can be weighed and substracted from the result.
It was harold or goldsilverpro who came up with it long ago i think.

Edited to add:
You can see the reaction stop in hot AR.
If any nitric traces are still left, precipitating the gold with SMB will get the rest out.

 

[FrugalRefiner]

It was Harold_V who taught us that trick. Because he was refining as a business, and turned his customers' gold around in three days, he routinely used an excess of nitric to speed the dissolution of his customers' gold. He would then weigh a refined gold button, introduce it to the reaction, and push the reaction to completion with heat. He would then remove what was left of the button, weigh it again, and know how much gold he had added to the customers' gold. It's a very useful technique.

Dave

 

[anachronism]

Certainly does the trick when refining. If it's a dirty drop i.e. Recovery that's already full of contaminants then equally copper can be used.

I'm going to add an edit. It takes common sense and skill to use copper to ensure you don't go too far and precipitate out your gold, but it's incredibly easy to judge just how much extra Nitric you have in solution using it because the reaction is so much more visible. Chalk it down as "advanced" if you will and only use it once comfortable with dealing with mistakes.

 

[kurtak]

It was Harold_V who taught us that trick

Yes - that is where I first learned that from (MANY years ago now) & is my preferred method for de-NOxing

Like Harold I would use an excess of nitric with plenty of heat to get the gold dissolved faster - then after dissolving the "batch" of gold I would put the gold button in (as Dave described) turn the heat on the hot plate down to low & let it sit over night which would use up the excess/free nitric

In all my years of refining I only used sulfamic one time to de- NOx & that just to see how it worked - went back to the gold button trick --- or as Jon said ------

Certainly does the trick when refining. If it's a dirty drop i.e. Recovery that's already full of contaminants then equally copper can be used.

Per the bold print - copper can/will de-NOx a solution AND not only can you use copper to de-NOx but also use copper to drop (cement) your gold AND have that gold come back at 999 (plus)

There is a trick to doing that (cementing gold with copper & having it come back at 999) --- I have posted about that several time

Kurt

 

[bhilton]

This is actually a trick used by many members to get rid of free nitric from the pregnant solution. The partially dissolved gold button can be weighed and substracted from the result.
It was harold or goldsilverpro who came up with it long ago i think.

Edited to add:
You can see the reaction stop in hot AR.
If any nitric traces are still left, precipitating the gold with SMB will get the rest out.

Thanks Martijn!

I tried it and it worked like a charm. The reaction was very obvious when the nitric was used up.

Very easy & cool!

I will still use sulfamic acid on the dirty stuff, to rule out any possible lead, but the subsequent refining's, I'll just use a button to burn up the excess.

 

[bhilton]

Certainly does the trick when refining. If it's a dirty drop i.e. Recovery that's already full of contaminants then equally copper can be used.

I'm going to add an edit. It takes common sense and skill to use copper to ensure you don't go too far and precipitate out your gold, but it's incredibly easy to judge just how much extra Nitric you have in solution using it because the reaction is so much more visible. Chalk it down as "advanced" if you will and only use it once comfortable with dealing with mistakes.

That's a good idea, definitely useful, but I also want to make sure I drop a little sulfamic acid in my dirty solutions to get out any possible lead.

 

[goldshark]

That's a good idea, definitely useful, but I also want to make sure I drop a little sulfamic acid in my dirty solutions to get out any possible lead.

Sounds like you are confusing Sulphamic with Sulphuric.

 

[Shark]

Sounds like you are confusing Sulphamic with Sulphuric.

Sulfamic will react with the AR in two ways. It neutralizes the nitric and creates sulfuric in the reaction, thereby helping to reduce any potential lead in solution. “Killing two birds with one stone”, would be how butcher would have put it.

 

[anachronism]

Sulfamic will react with the AR in two ways. It neutralizes the nitric and creates sulfuric in the reaction, thereby helping to reduce any potential lead in solution. “Killing two birds with one stone”, would be how butcher would have put it.

Most definitely Shark. For the chem geeks that lurk amongst us... HNO3 + H3NSO3 → H2SO4 + N2O + H2O.

 

[goldshark]

Most definitely Shark. For the chem geeks that lurk amongst us... HNO3 + H3NSO3 → H2SO4 + N2O + H2O.

A couple drops of Sulphuric prior to dropping with SMB, then filtering, will clean the solution. As long as you filter after Sulphamic, will accomplish the same thing.