Re-using contaminated nitric?

[heliman4141]

Hello fellow refiners,
Ive done a search but can't seem to locate any info about my issue.
My problem is I am low on Nitric & am wondering if I can possibly just drop all base metals from the contaminated nitric / water mix, filter it & then reuse it again with no additional water?
All my recovery was done in a glass beaker (warmed on a hot plate) with a watch glass on it to minimize any fuming & acid loss.
Only way I know of is to use iron maybe then allow it to settle then decant & filter then re-use or is there a better way?
If this is not possible to re-use my nitric due to no way of removing contamination I need to know that then, so I can calculate how much more id need in the future to finish up my stock.
Right now I have the nitric & distilled water mix that had been mixed in a 50/50 state that id used on pins siphoned ( its green in color) into a 1 gallon jug awaiting any ideas you may have to salvage it if possible. I have several lbs. of plated pins yet to do & am running low & I don't think Ill have enough nitric to run to completion from my calculations.

Dave

 

[FrugalRefiner]

Hello fellow refiners,
Ive done a search but can't seem to locate any info about my issue.
My problem is I am low on Nitric & am wondering if I can possibly just drop all base metals from the contaminated nitric / water mix, filter it & then reuse it again with no additional water?
All my recovery was done in a glass beaker (warmed on a hot plate) with a watch glass on it to minimize any fuming & acid loss.
Only way I know of is to use iron maybe then allow it to settle then decant & filter then re-use or is there a better way?
If this is not possible to re-use my nitric due to no way of removing contamination I need to know that then, so I can calculate how much more id need in the future to finish up my stock.
Right now I have the nitric & distilled water mix that had been mixed in a 50/50 state that id used on pins siphoned ( its green in color) into a 1 gallon jug awaiting any ideas you may have to salvage it if possible. I have several lbs. of plated pins yet to do & am running low & I don't think Ill have enough nitric to run to completion from my calculations.

Dave

Dave,

The short answer is it can be regenerated to some degree, but not the way you've suggested.

[stt]I'm not a chemist, so my explanation may be flawed, but I'll risk being corrected to give you some idea. Nitric acid is HNO₃. When dissolved in water, it forms H⁺ ions and NO₃^- ions. The H⁺ ion has an extra electron, and the NO₃^- ions wants an electron. When you dissolve a metal like copper in it, the H⁺ ions, being more reactive than copper, give up their extra electrons to the copper, which is oxidized, and the solid copper becomes positively charged as Cu⁺ or Cu²⁺ ions (copper has other oxidation states, but ⁺ and ²⁺ are the most common). The H⁺ ions are reduced (they lose those extra electrons]. The solution now contains Cu⁺ or Cu²⁺ ions and NO₃^- ions. There are no more H+ ions in solution (assuming you used sufficient copper to use up all the nitric acid).

Cementation works in a similar way. Iron is more reactive than copper, so when we add iron to a solution that contains copper ions, the copper ions give up their extra electrons to the iron. The copper ions are reduced to solid metal and the iron is oxidized to Fe²⁺ or Fe³⁺ ions (like copper, iron has other oxidation states, but ²⁺ and ³⁺ are the most common). Now you have iron ions and nitrate ions, but no copper ions or hydrogen ions.[/stt]

When you use nitric acid to dissolve a metal like copper, the H⁺ ions, which are missing an electron, take one from the copper as it is dissolved into solution. The solid copper is oxidized and becomes copper ions in solution while the hydrogen ions are reduced and are lost as hydrogen gas.

If you add iron, the iron gives up an electron to the copper. The iron is oxidized into solution and the copper is reduced to solid copper, so the copper is no longer in solution.

The only way to reverse this reaction is to add outside energy to the system. You can do this, to some degree, with electrolysis. If you set up a cell like a silver cell, but using a carbon anode and a copper cathode, you'll be able to reduce some of the copper ions to solid copper which will deposit at the cathode. Since the carbon anode isn't easily oxidized, some of the hydrogen in the water can be oxidized by the force of the electric current, regenerating H⁺ ions. But just like when we started the whole process, hydrogen is still more reactive than the copper, so it will try to [stt]give up its[/stt] take electrons [stt]to[/stt] from the copper you're trying to reduce out of solution at the cathode. So the best you can achieve is a solution of weak nitric acid and copper nitrate.

I hope that helps you understand the reactions. I'm sure it's not an exact description of what happens, but it will give you some idea.

Dave

Edited to correct my reversed use of oxidation and reduction and which ion has an extra electron and which ion want to receive an electron. Thanks lysdexic for catching my error. I hope my simpler explanation is correct and makes more sense.

 

[heliman4141]

Thanks Dave,
Easy to remember name by the way.........Lots of Dave's here................. including me! 8)
I was afraid that it wouldn't be a great idea due to oxidation processes.
Maybe Ill just melt the pins into bars or just keep the pins intact & sell them on Ebay & save the rest of my nitric for AR purposes & just forget about doing the rest of the pins, would be more financially sound im certain at this point, & a LOT LOT less work. No point throwing money in a sinking ship as they say.........

Dave

 

[FrugalRefiner]

If you have several pounds of pins, you might want to consider a sulfuric stripping cell. bmgold2 created a great mini cell that might serve you well: Micro stripping cell.

Another alternative (though not a great one) would be AP, depending on the pins.

Dave

 

[heliman4141]

If you have several pounds of pins, you might want to consider a sulfuric stripping cell. bmgold2 created a great mini cell that might serve you well: Micro stripping cell.

Another alternative (though not a great one) would be AP, depending on the pins.

Dave

Its funny you mention AP,
I was thinking about doing a small test on some old heavily plated pins I have from the 80s. I was thinking adding heat might do the trick. Think Ill try a small test on some Monday & see if its viable.
Worth a shot I guess. Ill post what happens in a few days, have a great weekend.
Dave

 

[heliman4141]

Hi Dave,
I got a wild hair going last night from our discussion & I decided to go ahead & make up a tiny experiment batch of my most precious old heavily Gold plated pins using AP.......................
Had left it on my hot plate on the lowest setting with a thick damp rag over it to control venting/fuming covered again with a large glass beaker to contain all fumes.
All I can say is WOW! All the pins are gone & what is left is a green solution & Gold dust & flakes on the bottom, im one happy camper! :lol:
All I have to do is make my batches larger now, and best of all.... need no nitric now. Ill do a stannis test after adding more distilled water to dilute and to test for silver then a few drops of sulphuric just incase the pins had any tin/lead in them, then filter & do my AR drop. This is swell as no need to rid it of Nitric.
The pins are so clean I do not think any tin/lead is present, tho I do not know the composition of the pins themselves, im leaning twards copper mostly as the solution is green and there is no grey sediment of any kind on the bottom which was my one main concern.
I also have a LOT of contaminated old pins also that do have solder on them, Ill have to do a Hcl boil to rid that first before doing the AP on them, if I time the boil I think that issue wont be a prob either, just long enough to release the tin/lead then decant ASAP, then do the AP on them.
I wonder if this would also work on my Gold filled jewelry if I incernerated it first then beat it all thin on my anvil before treatment? More testing is in order me thinks............
Im using 32% HCL (muratic acid) so its working a LOT faster with low heat then id had thought it would.
Id done this on fingers in the beginning but never gave pins a thought, id thought only Nitric would do them, so many ways to skin the Gold cat. With a bit more patience & time HCL/peroxide & a lil heat works super & is 10 times cheaper! YAY!




Dave

 

[butcher]

You may find this helpful.
Reusing old copper/ iron chloride solutions
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=46&t=20006&p=204406&hilit=ferric+chloride#p204406
I have a made few other posts on this subject.

You could also use your old contaminated copper nitrate solution, in a process similar, to what I call killing two birds with one rock (stone) (use the search), with a little modification to that process.

 

[FrugalRefiner]

I'm glad it's working for you! As I mentioned, much depends on the type of pins. Thin pins with brass base metal will work pretty well, but the zinc in the brass will eventually make the AP less effective. Thick pins with iron base metals will consume a lot more HCl and will take more time. Bronze pins can also cause problems, as the tin can create colloidal gold that will be difficult to recover. I would suggest small tests of each different type of pin to make sure there are no problems before ramping up too much.

I'm not sure I understand what you meant when you said "Ill do a stannis test after adding more distilled water to dilute and to test for silver then a few drops of sulphuric just incase the pins had any tin/lead in them, then filter & do my AR drop." If you're talking about diluting and testing the AP with stannous, I'd say just filter the flakes from the AP and reuse it till it no longer dissolves any more pins. That will cause any gold that may be in the AP to cement out along with the flakes. Unless you have water with a lot of minerals, you can use tap water when working with AP. AP already has clorine ions in it from the HCl, so chlorine in tap water will not cause any problems. Save the distilled water for silver work and your final refining. You won't find any silver dissolved in AP. It's converted to AgCl which is only sparingly soluble and only in concentrated acid solutions like AR.

You may or may not have success with gold filled. Some will have tin content from solders, so again, small scale testing is in order.

Dave

 

[lysdexic]

Dave,

The short answer is it can be regenerated to some degree, but not the way you've suggested.

I'm not a chemist, so my explanation may be flawed, but I'll risk being corrected to give you some idea. Nitric acid is HNO₃. When dissolved in water, it forms H⁺ ions and NO₃^- ions. The H⁺ ion has an extra electron, and the NO₃^- ions wants an electron. When you dissolve a metal like copper in it, the H⁺ ions, being more reactive than copper, give up their extra electrons to the copper, which is oxidized, and the solid copper becomes positively charged as Cu⁺ or Cu²⁺ ions (copper has other oxidation states, but ⁺ and ²⁺ are the most common). The H⁺ ions are reduced (they lose those extra electrons]. The solution now contains Cu⁺ or Cu²⁺ ions and NO₃^- ions. There are no more H+ ions in solution (assuming you used sufficient copper to use up all the nitric acid).

Cementation works in a similar way. Iron is more reactive than copper, so when we add iron to a solution that contains copper ions, the copper ions give up their extra electrons to the iron. The copper ions are reduced to solid metal and the iron is oxidized to Fe²⁺ or Fe³⁺ ions (like copper, iron has other oxidation states, but ²⁺ and ³⁺ are the most common). Now you have iron ions and nitrate ions, but no copper ions or hydrogen ions. ...

Dave

Dave,

Either that's backwards or I need to go back to square one and start my chemistry lessons over. I'm not a chemist by any means either and I've been trying to understand by looking at the CuCl leach process.

Oxidation = increase in oxidation state (loss of electron or electrons), which gives the ion a + charge.
Reduction = decrease in oxidation state (gain of electron or electrons), which gives the ion a - charge.

When Cu is oxidized by CuCl₂ the Cu gives up an electron and the Cu²⁺ ion gains an electron leaving us with 2Cu⁺ ions ...apparently one of the Cl^- ions joins with the "new" Cu ⁺ ion and one remains with the reduced Cu²⁺ (now a Cu⁺ ion). (I don't know if anything other than the oxidation state of the copper actually changes, meaning that the Cu⁺ and one of the Cl^- "literally join" to form CuCl.)

I could be wrong, I've only taken a few baby steps in chemistry so far, it just looks backwards to me. GSP was nice enough to provide a link to redox reactions for me:

https://en.wikipedia.org/wiki/Redox

I know nothing about chemistry involving nitric just yet, that's for a future date. I hope you take my comments in the spirit they are given, I'm kind of socially awkward and tend to say things outright.

Doug

edit - fixed missing punctuation

 

[FrugalRefiner]

Oh, bother... See, I told you my explanation was probably flawed! I believe you're right. I reversed the terms oxidation and reduction as well as which ions have an extra electron and which ones are missing one.

The principal I was trying to convey is still valid, but I stated things backward. If I try to correct the post, I'll probably foul it up beyond all recognition, so I'll rely on future readers to follow the thread to this point.

Thanks for catching my error.

Dave

 

[lysdexic]

It is indeed valid and I pay attention when someone who knows about this than is giving advice. There's always some PM's in there. Thanks Dave.

Doug

 

[heliman4141]

Not a problem with me from a chemistry point as nothing dangerious was implied anyway,
The complex chemical exchanges go in one ear & out the other mostly still to me so.........LOL. :mrgreen:
Its doing things safely that I focus on mostly & memorize easily, like not accidently mixing an explosive mixture or have a boil over from impatience & over adding acids etc...
And im still pretty much stuck with AP verses nitric anyway once the last few ml I have are exhausted.
The 32% Hcl does work even better then I had hoped & I have more patience then Gold so all is well.

Dave

 

[heliman4141]

You may find this helpful.
Reusing old copper/ iron chloride solutions
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=46&t=20006&p=204406&hilit=ferric+chloride#p204406
I have a made few other posts on this subject.

You could also use your old contaminated copper nitrate solution, in a process similar, to what I call killing two birds with one rock (stone) (use the search), with a little modification to that process.

Butcher,
I have to say that was a very heady topic you posted for me that you had written. Sounded like College textbook read. If I didn't know you better from your personal posts ive read, id easily assume you were a professional Chemist or a Professor. Id have a hard time memorizing all that even if I read it 100 times ..............I just turned 56 last Tuesday & trust me, my memory is well.........lets just say ive forgotten more then Ill ever remember in the future. Of that im certain............LOL.
That being said, it was very informative & interesting & I did learn a bit, thanks for posting the link.
I always enjoy reading posts from seasoned members, its interesting stuff and I usually learn something new ea. time also. Just can't soak it in all at once is all but im trying.

The Hcl is working well for me so Ill be able to save quite a lot on acids, doubt Ill ever go back to nitric just too expensive.
If I had a weather protected area such as an unused garage id install a hood vent & maybe a sulfuric cell etc... but all I have is a concrete pad & a few glass beakers with watchglass covers so I have to do everything in very small batches. Weather here can change in hrs. so I have to be very careful what I start, & time its completion accordingly.
Been more then one time that I had to cover my beaker in the middle of a reaction with a 5 gallon bucket due to rain coming in on me. Another good reason for someone who does it this way to never leave a reaction alone ever.
When I have the time im going to re-read that topic a few more times & hopefully.................. learn a bit more. Im the type that learns from doing much easier then from reading, always been that way for me. Drove my poor Mother crazy as she was a middle school teacher & expected me to have the same level of study skills that she possesed, she always made straight As...........I was later told I had the worst case of ADHD she ever saw from any student she ever had so that FINALLY helped her to understand why I had the hard time I had in school. My school IQ tests would always place me in demanding classes, but my memory skills & ADHD turned it all into a nightmare.
Today they have drugs for that issue im told, back then all they did was beat me daily over it, its no wonder my lower back is now shot. I remember one yr. I got a beating every single day I was in school, that was in 3rd grade, and yes it was every single day. Gotta love Hoosiers right?
Today, teachers get in big trouble for beating kids with paddles, I was born in the wrong times I guess. :roll:
I ended up studying hard & got my GED then went self employed & never was without a job ever & was never sued or had a business fail so im proud of that, ive seen many College grads in my day fail businesses they started, my Mom eventually told me how proud she was that I succeded in my business even tho I know its all teachers dreams & expectations to be able to brag about their kids educations to others & I understand why due to her education & profession. Anyway now you know a bit about me same as I know your background from what ive read from your past posts. I think we would of had fun together as kids. :twisted:



Dave

 

[butcher]

Dave,
I did not really learn to read until years after I was out of school, the only books I can read is something that interests me usually technical or work related, I have learned several sciences, because of my many interests.

Like electronics, I wanted to learn, so I found a couple of magazines that were of electronics, when I began to read them, I had no clue at all what they were talking about. But I figured I would read it anyway, little by little I would learn a few things, and learn a little of the language, using the simple schematics to build simple circuits, the more I kept this up, the more I would learn, and the easier it was to understand even the more complicated aspects of this science, I got really good in certain areas of electronics (it can be a very vast science with many branches), I got to where I could build most anything I wanted to from electronics, and I could troubleshoot and work on circuits with some of the best technicians in the business, who spent many years getting a formal education in the science.

Do not put limits on yourself, any man can do anything he puts his mind to (within reason of coarse), If something interests you and you wish to learn it you can, you just have to be interested, willing, and not be one to give up easily, find answer to your questions, when more question pop up find the answers for them.

Some people learning comes easier, in school they can remember things and pass tests on the questions later, I had no memory, I can not do that, if it not something that interests me you could teach a monkey easier than you could force it between my ears.


I am someone who cannot learn something someone would try to teach me, or memorize something.
But If I have an interest in it, I become like a bloodhound looking for answer to my questions. Once I find the answers things make more sense and I do not have to remember it, (I know how it works), I do forget many things I have learned before, but I also now where to find that information easier next time I look, (knowing more of the details of what I am looking for, and the basic principles involved).

The chemistry of these metals just interested me. I had a question, I found the answer to one question, and each question that would arise, I would look for the answer to it, I am no smarter than you or any one else, I just do not give up until I find the answer to my questions.

Interested in getting gold with chemicals, stick around on the forum, read what interests you, when a question comes up search for your answer to that question, if you get 5 questions write them down so you can remember them and find their answers, you would not be able -to not learn. As long as this science continues to hold your interest. Read even the things that do not make sense to you at this point, you will pick up something from it, soon you will be understanding the language, and most everything you are reading, your skills in this science will grow as you practice more of what you are learning.

 

[heliman4141]

Butcher,
We have a lot in common,
Don't have any Rogers in your background do you? 8) Sound like brothers seperated at birth. LOL..........
My main interest was always & still is anything mechanical, from childhood I was taking things apart to see what made them tick, then re-assemble them back later .......as I got older.
Today with no formal training other then reading my Chiltons manuals I can tear down & rebuild any tranny or auto engine or anything automotive & re-install and adjust tolerances & diagnose any code issues.
That has saved me a LOT of money as I don't trust mechanics anyway. Moved onto custom building choppers after that, built many custom bikes & rode them all. Once had a Harley with an 18" custom springer, I had raked out the frames neck so it would still sit level. Quite a beast on a tight turn LOL.......... Welding is another interest, Mig, Arc, & Acl/Oxy.
Decided to become a Home builder in the 80s & 90s with my father .....then I told my father something didn't feel right around 1992, bankers were lending way way too much out for mortages & Real Estate agents were pushing homes way way out of the average persons level financially so I told him we need to stop home building & branch into remodeling & additions period to be safe. I saw the financial disaster coming long before it hit in 2008. The next one when the dollar is totally worthless from endless printing & inflation will make 2008 look like a vacation. Gonna see the greatest transfer of wealth from the middle class to the wealthy in History. Its that day when Gold & Silver will be ones salvation since paper money will be only good for the outhouse. That is the main reason im getting into Silver & Gold last few yrs. How many trillions can we go till the middle class can no longer eat and heat?
The poor already are screwed, costs more to drive to work & eat then to work period at poverty level.
I have no clue when we are going to go bust at a Federal level, but I think its coming sooner then later from what has happened in just the last couple yrs.

May have to learn some Chinese eventually as we owe them so much & are too stupid to not see this debt eventually has to be paid back either by war or just defaulting on the dollar & going to another currency which will have to be PM backed. All ancient history, its happened to every single Government since Rome. I remember whgen they started making pennys & Silver coins out of junk metals that was the start of the money deflation. So I started hoarding pre-83 pennys yrs. ago have almost 1000lbs of em now, if they ever stop making the penny like Canada did Ill have a nice chunk of copper to take to the local salvage yard, LOL..........Or Ill sell them online its a can't loose situation either way.

Scary stuff for those who do not plan ahead & have all their wealth tied up in worthless paper IOUs on Wall street or are hoarding cash. Even Silver & Gold purchases backed by paper will be worthless only PMs in hand is secure & certain. Debt is the real enemy. They LOVE putting us all in debt to fuel the Feds printers. Im debt free in 2 yrs! No way will I ever go back to CC or mortgage debt ever again. Counting the days down...........


Dave