Gold,Gold,and More Gold!!!!

[Anonymous]

Cool your jets lads, this is actually a really good thread, let's keep it on track fellas. 8) 8)

Jerry - Enterprise carrier grade microwave telecoms kit mate.

Jon

 

[modtheworld44]

Cool your jets lads, this is actually a really good thread, let's keep it on track fellas. 8) 8)

Jerry - Enterprise carrier grade microwave telecoms kit mate.

Jon

spaceships

I agree,I would like to try and keep the integrity of this thread in tact this time around.My goal is to share my knowledge without getting beat in the head for doing so.I want the knowledge to exist beyond myself so others can use and expand on it if they so choose to.Without the knowledge that exists here in this great forum,I would not and could not be able to do what I do.

Here's the dimensions of my boxes in case yall wanted to know.

Big Box
2 5/8ins L
6/8ins W
2/8ins T

Small Box
2 1/8ins L
11/16ins W
2/8ins T

modtheworld44

 

[4metals]

This must be the first time I've heard someone talking about calcining gold powder. What exactly do you mean? Do you know what calcining means?

When doing a fire assay the fine gold resulting from the parting process is usually heated to a red heat before it is weighed. This is done to do a visual inspection as impurities (often PGM's) discolor the gold and it is obvious. This process is called annealing the gold. Perhaps this is what they meant when they said calcine.

 

[kurtak]

I have been very, very busy lately - hardly enough time to read let alone post but thought I would take time to post the results of the 14.5 lbs gold plated SS I talked about in this thread

The gold was first "recovered" from solution (after stripping from SS) by cementing with copper - then twice refined - first drop done with ferrous sulfate - second done with SMB

Gold delivered back to costumer - I was paid (cash) 20% spot - total working time on it about 12 -14 hours

I have a $300 minimum or 20% (which ever is greater) for this type material so made a bit more then the minimum

Kurt

Edit to ad; - round on right is 1 ozt round on left is remainder - customer had choice of gold poured as rounds or as bars

 

[g_axelsson]

Nice work and thanks for sharing!

8)

Göran

 

[4metals]

The gold was first "recovered" from solution (after stripping from SS) by cementing with copper

I think this is a perfectly acceptable method in this case. I know that on this forum it may be considered a sacrilege to add base metals to a solution. This made me consider why we think that way, and I think I have got it worked out.

If you were to be killing the excess nitric with copper and stopping short of cementation, yes that is indeed a bad technique. But you are using copper as a means of recovery not as a means of refining. The resultant cemented gold, which comes down pretty clean already, leaves a solution which tests easily with stannous chloride so it is easy to know when you have it all out. And without adding excess copper you should have very little contamination from other metals. Finely divided copper powder is perfect for this type of drop. Easy to add just enough to get the gold out but not too much to leave copper behind to mix with the gold.

The reason we do things like inquartation when applicable or other selective leaches, is to minimize the metals in solution when we drop the gold selectively with metabisulfite, SO2 or Ferrous Sulfate. The less metals in solution, the less drag down of impurities, the purer the precipitate. But in this case, the choice was either add 1200 grams of sulfamic acid (and in 800 ml of solution that would require heavy dilution) which would generate considerable waste, or recover the gold by cementation and redissolve the resultant metal (finely divided already so it dissolves quite easily) in 200 ml of Aqua Regia and recover the gold with a precipitant of choice.

I think Kurt chose well!

 

[Anonymous]

I agree 4metals. Heck you're a chemist and might discount my agreement as irrelevant but regardless of that people need to look at practical solutions not theoretical ones.

Jon

 

[4metals]

Heck you're a chemist and might discount my agreement as irrelevant

The one thing life has taught me, and this forum has actually reinforced, is that there is value in everyone's opinion. Just because I'm a chemist doesn't mean I have tried every conceivable process to get to a desired endpoint. So I always listen to those marching to the beat of that different drummer. It can never hurt to listen.

 

[Barren Realms 007]

When in a similar situation as this thread I dropped my gold with SMB.

Might want to revisit this post that is almost 3 years old and read it.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&start=120#p87562

 

[kurtak]

If you were to be killing the excess nitric with copper and stopping short of cementation, yes that is indeed a bad technique. But you are using copper as a means of recovery not as a means of refining. The resultant cemented gold, which comes down pretty clean already, leaves a solution which tests easily with stannous chloride so it is easy to know when you have it all out. And without adding excess copper you should have very little contamination from other metals. Finely divided copper powder is perfect for this type of drop. Easy to add just enough to get the gold out but not too much to leave copper behind to mix with the gold.

Correct on both points (underlined above) I used a copper bus bar simply because I have a couple hundred pounds of them & copper powder is expensive (though I also do have copper powder)

The point being that yes - you can actually stop the cementing process before all the free nitric is used up (so you do not have to consume copper to the point of no more free nitric) when you first add the copper to your (yellow) gold solution it shifts to green as the copper starts to go into solution

Because of the "high" nitric concentration & the "low" HCl concentration (therefore the HCl being the "weaker" reacting acid) the copper goes into solution at a very rapid pace pushing the gold out & with the HCl being the weaker acid it really doesn't have time to re-dissolve the gold --- this reaction is very vigorous so I would be a bit concerned about using copper powder due to foam up & possible boil over - you would have to make your Cu powder additions slow & leave plenty of head room in your vessel

Anyway - you can somewhat tell when the gold is coming near to being all cemented out (though there is still free nitric) because the reaction starts to slow a bit & the color starts to shift from green to more blue --- its at this point that you want to start testing with stannous - it doesn't take long after the solution starts to shift to blue that you get a negative stannous test (2 or 3 maybe 4 tests)

once I get my negative stannous test I vacuum filter & water wash "right away" - even though the nitric was still reacting with the copper when the copper is pulled out & the solution is quit hot (from the reaction) & I don't give it time to settle --- doing this give any possible now "very" weak HCl little or no time to re-dissolve gold

Frank --- I think that may explain your question in the link to the thread you provided - in the first part of your process you were only trying to dissolve base metals with nitric --- but you also had "traces" of Cl in it so it dissolved "some" gold during the "extended" time & heat of the base metal dissolving reaction --- then when you hit it with SMB the SO2 dropped the gold even though you still had nitric - its just that the Cl was so weak it really didn't have the strength &/or time to re-dissolve the gold when you decanted &/or filtered the gold

Kurt

 

[Barren Realms 007]

That is what I figured too. I'm sure the trace amount of HCL that was on the chips had been used up and I'm pretty sure the nitric had been exhausted as well.

 

[g_axelsson]

I've been thinking in similar tracks for some years now, how to remove the gold from nitric acid without destroying the nitric acid in the process...

This is so far a purely theoretical solution. I haven't had the opportunity to test my theory yet.

The clue is to get rid of all chloride ions so the gold doesn't redissolve. As long as you have gold chloride or other soluble chlorides there exists free chloride ions in solution and with the nitric acid it can be seen as free hydrochloric acid.
Now, we have one easily acquired chemical that removes virtually all free chloride ions from a solution, silver nitrate. If we mix silver nitrate into our leach until no more silver chloride is formed then we have a chloride free gold nitrate solution.
From this we can drop the gold with SMB, SO₂ or possibly even electrowinning.

When the gold is gone from the solution the only thing left to do is to add a bit of hydrochloric acid again and then continue to use the reverse aqua regia.

Using SMB / SO₂ will probably add small amounts of sulfuric acid to the mix and that could be a problem with nitric acid. Electrowinning the gold would not add any contaminants.

Anyone sees a problem with this process?

The gold would probably need to be refined again to remove palladium if SMB / SO₂ is used. Electrowinning will probably also give a mixed product of gold, silver and copper.

As a byproduct this would produce a solution with both gold and silver in solution... and whatever Harold says I think there is another way to have both silver and gold in solution besides using cyanide. :mrgreen:

Meet hydrogen tetranitroaurate(III)

Göran

 

[Barren Realms 007]

I've been thinking in similar tracks for some years now, how to remove the gold from nitric acid without destroying the nitric acid in the process...

This is so far a purely theoretical solution. I haven't had the opportunity to test my theory yet.

The clue is to get rid of all chloride ions so the gold doesn't redissolve. As long as you have gold chloride or other soluble chlorides there exists free chloride ions in solution and with the nitric acid it can be seen as free hydrochloric acid.
Now, we have one easily acquired chemical that removes virtually all free chloride ions from a solution, silver nitrate. If we mix silver nitrate into our leach until no more silver chloride is formed then we have a chloride free gold nitrate solution.
From this we can drop the gold with SMB, SO₂ or possibly even electrowinning.

When the gold is gone from the solution the only thing left to do is to add a bit of hydrochloric acid again and then continue to use the reverse aqua regia.

Using SMB / SO₂ will probably add small amounts of sulfuric acid to the mix and that could be a problem with nitric acid. Electrowinning the gold would not add any contaminants.

Anyone sees a problem with this process?

The gold would probably need to be refined again to remove palladium if SMB / SO₂ is used. Electrowinning will probably also give a mixed product of gold, silver and copper.

As a byproduct this would produce a solution with both gold and silver in solution... and whatever Harold says I think there is another way to have both silver and gold in solution besides using cyanide. :mrgreen:

Meet hydrogen tetranitroaurate(III)

Göran

As far as I know using SMB will not produce sulphuric acid. Adding sulfamic acid to remove the nitric will though.

 

[g_axelsson]

I think that the SMB reaction in nitric would turn into something like...

With gold chloride : 3 NaHSO₃ + 3 H₂O + 2 HAuCl₄ = 3 NaHSO₄ + 8 HCl + 2 Au

With gold nitrate : 3 NaHSO₃ + 3 H₂O + 2 HAu(NO₃)₄ = 3 NaHSO₄ + 8 HNO₃ + 2 Au

The NaHSO₄ dissolved in acidic solution would correspond to at least a weak sulfuric acid. H⁺ + HSO₄^-

Göran

 

[Lou]

Goran,

The silver doesn't quite work (see freechemist post where I myself got schooled by the late Professor) unless conditions are super tightly controlled. There is another way.

We use tributyl phosphate for Au(III) and then resin for Pt/Pd.

 

[g_axelsson]

Thanks Lou, I'll dig that post up. 8)

I surely miss FreeChemist, I've learned a lot from him.

Göran

 

[Justincase]

Has any one run the comparative cost's on each method.
I still proffer a good rotary evaporator to trying short cut's.
Sulfamic is handy for small quantity's and so you only need to reduce down once as I do.
Solvent extraction is good also and help's with high purity refinement.
"Versenol 120" made by Dow chemical looks very interesting as it is meant to let you drop form a solution with 50% nitric acid .but it is a bit pricey.Has any one tried it and compared cost's?
Cost's are not an issue at the moment,but when you look at scaling up even a slight saving could mean the difference between having a stable business and going hungry.
But it is the simplicity of evaporation I am drawn to and the reduction of low solubility impurity's is a bonus,apart form specialist precipitant's the other solution's add complication to the process and require intensive work,where as a batch evaporating can just be left to reduce down by it's self while you get on with other work so increases productivity.

 

[modtheworld44]

Has any one run the comparative cost's on each method.
I still proffer a good rotary evaporator to trying short cut's.
Sulfamic is handy for small quantity's and so you only need to reduce down once as I do.
Solvent extraction is good also and help's with high purity refinement.
"Versenol 120" made by Dow chemical looks very interesting as it is meant to let you drop form a solution with 50% nitric acid .but it is a bit pricey.Has any one tried it and compared cost's?
Cost's are not an issue at the moment,but when you look at scaling up even a slight saving could mean the difference between having a stable business and going hungry.
But it is the simplicity of evaporation I am drawn to and the reduction of low solubility impurity's is a bonus,apart form specialist precipitant's the other solution's add complication to the process and require intensive work,where as a batch evaporating can just be left to reduce down by it's self while you get on with other work so increases productivity.

justinhcase


I have done many comparisons in my head,I just made $1368.14 on this gold at a spot of $1149.70.I used about $25.00 in chemicals and reagents to refine it,to me that's a great price for what I made and I still have some supplies left.I did 72 pieces of the boxes in this thread,which was around 13-14lbs total.It would have taken at least a gallon or better of nitric to do the same batch.The average price for nitric these days vary dramatically depending on whether you have good or bad access to it.The variation of this process that I choose to use gives me several options to use depending on what type materials I run through it.It all comes down to process preference in the end for me and the speed in which it allows me to turn over my gold.I don't know if this is the type of comparison you are looking for,this is just my opinion on the things I look at when I compare things of this nature.Thanks in advance.



modtheworld44

 

[JHS]

Very nice 8)

 

[Anonymous]

Jerry, what percentage purity did that gold come out at?

Jon