Help with Nitric Acid Elimination

[4metals]

I constantly face a situation where the client wants to refine gold, mostly from jewelery scrap. Again they are paying on assay so inquarting is not used as any gold remaining in the chlorides is recovered in the reduced chlorides bar. But these guys are not chemists, and they need a number. I can't tell them to do what GSP just explained, they want a concrete number.

So I have to give them a number, the number I work off of is 1 liter of acid will digest 7.5 troy ounces of karat scrap, any karat. I then tell them to make up acid at a ratio of 4:1. So if you have 7.5 ounces, divide 1000 by 7.5 and come up with 133.3 ml per ounce, total acid. Divided by 5 gives you 26.6 ml for Nitric and times 4 gives you 106.6 ml Hydrochloric. This number proves to be close, and generally provides a good digestion. (If silver is under 8%) Often when doing diamond removal, the scrap is not melted first (for obvious reasons) and some pieces stubbornly resist digestion. I have found that after the acid has had a good boil and is no longer blowing red, an addition of 10% of the startup Hydrochloric will again kick off the nitric reaction and result in a more complete digestion. Kind of counter intuitive to add HCl to get the solution to blow red again, but it's the free HCL that matters here.

These guys always have nitric left over after digestion. It's a production environment and often some of these guys have "refiners" who aren't the sharpest crayons in the box. If they haul their wastes, I suggest adding urea prills. If they treat their waste, I do not. Then we gas with SO2 and gas off the nitric. Never do they boil down to remove nitric.

If there were an easy works every time formulation to use I would use it, but I think for the most part the readers of this forum are better informed and more responsible and capable of not using too much nitric and that is the best approach, as masterfully spelled out by GSP.

 

[briguy2112]

Brother bri, you haven't been read'n. If you would have read you would know that the best way to recover gold GP & GF items is to use lazersteves sulphuric cell. Go to his website & watch the video; over & over, before the 3rd batch! You have a big mess in your hands & is 'cause you didn't do your home work! :lol:
Slow down, I know how you feel, anxiuos. Be patient & learn "why" it has to be done "this" way, & NOT "that" way. There's a reason. I made the same mistake; trust me, read.

Have a good one brother!

philddreamer

I watched every vidoe in there. Are you talking about the antiquating method?

 

[philddreamer]

Do you mean "inquarting"? No, that's for karat gold; you melt 25% gold/ 75% silver. Its the video of the gold sulphuric cell. Here is a photo of mine.
You use it to de-plate the GP & GF items with it.

 

[briguy2112]

awesome video now after this would I do the same SMB method to extract the gold from the liquid of the cell?

 

[lazersteve]

Here's how to proceed starting with a full cell:

Black Powder from Cell

Steve

 

[shyknee]

ok Batch 2 a total bust also. I am working with 8 oz of filled and plated jewelry. I am using 300 ML of HCl and 100ml of Nitric. I let it sit for 2 days i added about 100ml more AR after day 1. I end up with a dark green, black solution. I filter it about 4 times to get all the solid material out. I then did the reduce via heat. I added about 100ml more HCL to get all the solids clean. So I had about 400ml of liquid. I reduced it down to about 200ml and then added more hcl to back to 400ml. reduced again, add more hcl to 400. then on the third time I reduced it down to about 150ml. There was a sivelry film on the top and a powdery substance on the bottom. I let it cool for about 6 hours or so, I added about 500ml of distilled water It turned a light green. Then I filtered it like 4 times . I added about 10 grams of SBM in 2 gram increments, but no gold to be seen. No mud, and no gold spongy material. Where did I go wrong? I know there was gold in the material. It was all marked 14k ge or 1/10 GF. I need advice before I try the 3rd batch. I envy all of you that worked to get this process down, because the theory and the practice is 2 totally different thing. Thanks again everyone.

I reread your post ,and it is obvious you did not go to completion and removed the values when you filtered(hope you did not throw it out).

you should always remove the base metals first then use AR.

You will have to process your filters and solids to get at the values

 

[briguy2112]

ok so after I reduce and add hcl and reduce again and add more hcl. then I filter and add 4x distilled water, what color should I have? I seem to have a very light green to blueish color. It this correct? All the vids and post list you end up with a yellow liquid. I don't want to add the SMB if this is wrong. I am sorry for being such a huge newb at all of this, but I am learning LOL. Hope I don't spend a fortune to do it tho. I made a pretty cool Fire brick smelter that I will post pics of when my wife tells me where the camera is. Lazer Steve when I grow up I wanna be just like you

P.S. I the cell method do you make the positive side just like you made the negative side with the lead? only it does not go into the liquid?

 

[lazersteve]

Don't go by color, go by a stannous test. If the stannous test positive, you have gold in the solution.

Steve

 

[briguy2112]

Don't go by color, go by a stannous test. If the stannous test positive, you have gold in the solution.

Steve

Cool I did that and it tested positive. So I mixed about 8 grams on SBM in hot water to dissolve. I dumped it in and mixed it up very well. I think I can see black stuff in the bucket, The liquid went from a light green to a dark brownish color. but the SO2 smell is awful. I mean really pungent. Does that mean there was still Nitric acid in the mix? Will the smell go away with time? Does that mean I added to much SMB or not enough, or is it normal? I am a very smart guy but I really suck at this SIGH :*(

 

[lazersteve]

That's nasty smell is normal. It's a choking odor that will make you cough and sneeze.

Nitrogen dioxides are red-brown and tend to smell similar to chlorine gas. Don't breath any of these as they are very bad for your health and can have delayed health effects.

The dark sediment is your gold.

Steve

 

[briguy2112]

will it go away or will it be there when I go to dump the extra liquid out? Its been sitting for like 5 hours and its still very green and very pungent smelling. Should I add more SMB or no? It is the SBM that makes that smell correct?

 

[philddreamer]

Don't dump the solution. Check w/ stannous & see if there still gold in solution. If + for gold, add a bit more SMB. If -, pour solution in a container w/ lid. Read the post on how to dispose of waste properly.

 

[briguy2112]

Don't dump the solution. Check w/ stannous & see if there still gold in solution. If + for gold, add a bit more SMB. If -, pour solution in a container w/ lid. Read the post on how to dispose of waste properly.

Ok dump was a bad choice of words, i meant when I dump it into another bucket to get the the mud at the bottom. LOL

 

[Harold_V]

(5) I'm not going to go into details on using this method, since I have gone over it many times on this forum. All I will say is that it is simple and fast (especially when the alternative is boiling-down) and it works. Like Steve just said, you just have to adjust your mentality.

That, of course, wouldn't work for me because of my method of precipitation.

Fact is, Chris, I worked much the same way. Big difference was starting with a known amount of nitric (mixed @ 1:5 with HCl), then allowing it to work. When it was exhausted, I then added that which was necessary to complete dissolution, often by decanting the pregnant solution so the remaining values were not in a large, dilute volume. Much faster action, with only a tiny amount of unknown level of free nitric, if that.

In my case, I had no choice, especially when processing filings. Everything had to be dissolved, otherwise the rightful owner was shorted. I was not afforded the luxury of returning that which didn't dissolve to the next batch. I relied on a small excess of nitric to insure that didn't happen, just as I relied on evaporation to condense my solutions (only to concentrate----remember, I added a gold button to deal with traces of unused nitric).

I did not use plastic buckets in my operation, nor would I. I was not fond of the way gold would doggedly adhere to plastic, so the decision was made early on to use glassware, only in pristine condition---no scratches. I was restricted to the largest glass (that could be heated) without special ordering large vessels, thus my routine revolved around 4,000 ml beakers (the largest. I used all sizes, down to 50 ml). Without concentration, I wouldn't have been able to handle the volume that I did.

In the end, there is precious little difference in our systems---the time you spent back and forth adding acids was likely no longer than the time I spent concentrating mine. Mine also didn't demand any of my time. Set the container on a burner and go about my business, processing other lots of gold. I ran many lots daily, often having ten or more in process at the same time.

No right or wrong here in either example---just different preferred refining styles. Mine worked for me perfectly well, and evolved by need. I had no need to make a change from the first day, having allowed my customers to dictate their expectations, then discovering ways to meet their demands. That, my friend, is why what I started as hobby became an overwhelming success as a business. I took care of my customers and gave them fair and honest treatment.

Harold

 

[briguy2112]

Sigh I made the cell exactly like steve did. I bought glycerin and battery strength sulfuric acid. I made leads with alligator clips and wire coat hanger. But when I put filled or plated items in I see almost no reaction. I let them sit in there for over 10 minutes and still nothing. I am using a self adjusting battery charger. I see a little bubbling going on the negative side of the cell on the iron bar. But nothing from the scrap jewelry. Where did I go wrong? I use glycerin from micheals that is normally used for cake icing. Was that the right stuff? Do you think the charger is screwing it up, or did I do something else wrong? I used 3 cups acid and 1/4 +1/8 tsp glycerin. Please help, I am attaching photos of the cell and the charger.

]

 

[butcher]

try just a 12 volt car battery it may be your charger regulator is shutting down, note also the polarity.

 

[lazersteve]

The electrolyte must be 90% or better sulfuric acid, battery acid is only around 35%. Boil it down to 1/3 of it's starting volume before you put it in the cell.

Your positive lead should not be in the acid at all, it is a hanger for the clips that hold the scrap. The clipped scrap is then submerged in the electrolyte just enough to strip the gold.

You'll need a manual charger, not the automatic type, they don't work.

Glycerin is not needed. This was discovered after the video was filmed. When I get a chance I'll fix the video.

Steve

 

[briguy2112]

The electrolyte must be 90% or better sulfuric acid, battery acid is only around 35%. Boil it down to 1/3 of it's starting volume before you put it in the cell.

Your positive lead should not be in the acid at all, it is a hanger for the clips that hold the scrap. The clipped scrap is then submerged in the electrolyte just enough to strip the gold.

You'll need a manual charger, not the automatic type, they don't work.

Glycerin is not needed. This was discovered after the video was filmed. When I get a chance I'll fix the video.

Steve

So should I use the liquid drain cleaner sulfuric then? and the pos. lead is above the liquid. So get stronger acid and then a reg charger, cool ty.

 

[philddreamer]

Yeap, concentrated sulphuric liquid drain opener. I got "Liquid Fire" its 96%.
It will look dark & thick, but that's the one. :lol:
And like Steve said, be careful with water nearby...

 

[briguy2112]

Yeap, concentrated sulphuric liquid drain opener. I got "Liquid Fire" its 96%.
It will look dark & thick, but that's the one. :lol:
And like Steve said, be careful with water nearby...

Well I used the Drain opener sulfuric, and ran the charger to a car battery and then hooked the battery to the cell. It worked like a charm. Ya'll heave been awesome, thanks for all the help. Now getting the gold out of the acid :*(. This is where the wheels have been falling off the wagon. But i'll give it a shot. I'll let ya'll know how it turns out.

P.S. I filtered some gold out of my last batch of AR and let it sit over night. Now the gold is stuck to the filter paper. I tried to spray it down to losen it, to no avail. Can I just burn the paper down during melting, or will that nerf it all up. Also the cathode that was in the liquid is covered with a greasy black residue is that gold or by products? If it is gold how do you get it off of it?

P.P. S. I'm a moron y'all can go ahead and say it LOL