I've got a mess on my hands

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V

ViperCV

Member
Joined
Dec 31, 2012
Messages
8
Hello,
I've got a mess on my hands...well not on my hands really, i'm safe about everything I've done so far. Anyway, I need to start my process over again because something is not right. I started off with 3 pounds of Pentium Pro processors in nitric acid, filtered the remaining gold non-dissolved gold plating, washed in distilled water, and put it through the AR process using 1:3 ratio. all the gold dissolved great. I then added a few drops of sulfuric acid to drop any lead. i filtered it to remove any dropped lead/dirt. I then added Urea to neutralize the nitric, and the urea stopped fizzing, added a little more urea to make sure all the nitric was gone, and it didn't fizz any more. I added SMB, and it continues to fizz and release nitric fumes. and bubble brown. In the bottom of the jar it looks to be urea crystals growing (possibly too much urea), or silver chloride...not sure which one. I just know if i keep adding SMB it will continue to fizz and not precipitate the gold. I have been reading other posts on the forum, and reading Hoke as well, but I am still unsure of what is happening in the reaction. If i were to start over the process, and wanted to drop all metals at once, would i be correct to use sodium hydroxide to drop all metals? I've also got another batch of 9kt to 18kt jewelry dissolved in AR, and it is doing the same thing as the processors batch...I know i need to start over, and learn a lot from Hoke and the forum before I try a second time...In the mean time, i just need to get all metals out so I can start this over when I have a bit more understanding of what is happening, and what I need to do. I know this is a long post, but thank you to anyone that can help answer the questions, in the mean time, I'm still reading Hoke...
Thanks, Craig
 
Hey Viper,

You can do a couple of things at this point, 1) suspend a sheet of copper or copper buss bar in your solution to cement out all the values, 2) evaporate (do not boil a gold baring solution) the solution down to a thick syrup like consistency then dilute with Hcl to expel the excess nitric, repeat until no more brown fumes are formed upon diluting with Hcl.

I would not recommend the addition of sodium hydroxide to try and precipitate all the metals, that would just create an even larger headache.

I am happy to hear you are focused on safety, it is one of the most important aspects of what we do here. But before you start over please read and study more.

I hope this helps,

Chris

Edit: Sometimes I have a hard time conveying through written words what is in my head (assuming people can read my mind, scary thought :twisted: ), so if something seems unclear please say so.
 
I've had a similar problem when adding dry SMB to a solution with a lot of hydrochloric acid. Try mixing a bit of SMB with water and add it to the solution. It might work for you too.

Happy new year! :)

Göran
 
You still have free Nitric in there... Eurea will not get rid of it...
Cover and read up on what you are doing so you will learn what to do.
If we just give you a fix, it might work but you wont learn why.
You have 2 sepeate batches of something.... PMs? probably, but learn why and what's happening...
You used too much Nitric to begin with so now you need to use it up, not neutrilize it.

BS.
Good luck and hope you find lots of gold in the new year...
 
Urea will get rid of nitrous acid HNO2 from solution, or dissolved NO2 gas, but it will not remove nitric acid HNO3 from solution.

If you used way too much nitric acid urea would not help much.

Urea is sometimes added to concentrated nitric acid to remove the NO2 dissolved in solution, it does not decompose the nitric acid.

Urea adds more chemicals and salts to your solution, in some cases it can also add unwanted results (like with refining gold with the platinum group metals), or even can add dangers in certain circumstances.

After you get out of this problem, I would look into using minimum nitric in your processes, and other tricks of the trade so you will have no use for urea except to fertilize the grass, it is not needed at all in a process as far as I am concerned, except for very rarely and then I would only use a single prill once in a great while to see if it will fizz if I need to test a solution, besides for testing I think it is useless except for fertilizer.

Proper nitric usage and the evaporation methods when needed will serve you much better, relying on urea in my opinion will just cause you troubles, it may work sometimes but the trouble is not worth the small benefit, When I first began refining I tried it many times and always had trouble, but then too I was like most who are new and used way more of the acids than were needed, it’s a wonder I got much gold at all back then.

For a tiny over usage of nitric on occasions I will use sulfamic acid (GSP has made several posts on minimum nitric and sulfamic acid use).

Adding more gold to your solution (a trick Harold has taught, and posted on often) is a great way to use up the nitric in excess in a solution, or leaving a little gold undissolved (with heating) is a method to insure the nitric is consumed using this same principle.

when I here of someone suggesting urea, or promoting its use I normally just shake my head, and think why when there are such better ways to deal with it.
 
Awesome help all. Thank you for the info. I read hoke yesterday and finished it today and understand where I went wrong with too much nitric leaving free nitric in the solution and also that evaporating it will be much easier and less troublesome than urea. I didn't resize that urea will not neutralise nitric. One question that I do have that I couldn't seem to find is ... What if sodium hydroxide was added to one of the batches? I have added it before I was part of this forum and I know it is a mess on my hands. That is another reason why I need to start the process over I believe I now have an alkaline solution on my hands that most definitely contains gold. I am not looking for the easy way out on this but the only info that I have found with sodium hydroxide is relating to silver refining. I do have a little chemistry background but not very understanding of how to reduce unwanted solutions back to start over. Once again I really appreciate everyone's input. And HAPPY NEW YEAR. :).
 
A lot would depend on how well you eliminated all of the other metals from your gold before dissolving it; base metals in solution with gold can create problems of recovering the gold from solution also.

Sodium hydroxide will precipitate almost all metals in solution (depending on pH somewhat), it will also create salts of the acids in solution with HCl it forms NaCl, with nitric acid it would form NaNO3, it really would not be my choice here.

It can be very hard to give advice with messes, as we are not the ones who know exactly what all has been done or how much of each chemical or steps were or were not performed, we are not there and cannot see the solution or all of the reactions that went into making the mess, so answers of how someone may deal with it may differ, and also depending on the conditions of what you have the best approach to solving the problem can differ.

I assume this solution is loaded with base metals also, if from electronics tin can be a problem (just a guess here), also it sounds like you have way more acid than needed, free nitric in solution, too much SMB, and too much Urea, evaporating at this point I feel would only cause more problems unless you took it to dry powders, cementing on copper is a good option and probably the best at this point, if conditions are favorable you could try sulfamic acid to remove free nitric acid.

Your best bet at this point I feel is cement on copper.
Study dealing with waste found in the safety section.

Spend time reading Hoke's book and the forum, you have a lot of learning to do, there are many small details to learn, these small details can mean success or failure in chemistry, it can also mean how much gold you get or lose in a process, practice what you learn in Hokes book, do the getting acquainted experiments. These experiments will give you a tremendous understanding of what is happening and what to expect, and will help you learn not to make a mess or help you get out of one you make.

It will also help to study the forum, and learning with some experiments on a simple material like memory fingers, with simple processes like copper chloride leach (HCl acid 3%peroxide) to remove base metal in this case copper (be sure no tin or solder in the finger foils either trimmed well or removed with HCl process), washing and dissolving the foils in the HCl/NaClO (sodium hypochlorite or bleach), vapor off chlorine with heat, settling decanting and filtering and then precipitating gold, these more simple processes can also help you learn the basics, before moving to materials, or processes that are harder to deal with, in many of these processes it sounds, or seems so easy to read about them or see them in a video, it is easy if you understand the many details involved, but if you do not understand these finer details it is very easy to find your self buried in a mess wondering how to get your gold back or trying to figure out what happened to it.
 
Thank you for everyone's help. I'm sorry I haven't posted on here in a while. My wife wound up in the hospital for the past 5 days from a possible mild heart attack and has been diagnosed with diabetes...on top of that were in the process of moving...too much stuff going on. Anyway, I've put copper into the solution to cement everything out a few days ago and now its in a flask on a hot plate to evaporate all the liquid. From there i will take the residue powder and store it until i am satisfied i know what exactly is going on.

one question that I do have, and I haven't been able to find it in a search or on Google too well is...If gold is still in the solution as Auric Chloride, is it possible to lose gold by evaporation?...Such as can gold evaporate into the air? I know it seems like a dumb question, but I've found things that it is possible, and things that it isn't possible.

Anyway, thank you again all for the help. Once my wife is out of the hospital, and were all moved into our new house I will have more time to post and learn.
 
ViperCV said:
one question that I do have, and I haven't been able to find it in a search or on Google too well is...If gold is still in the solution as Auric Chloride, is it possible to lose gold by evaporation?...Such as can gold evaporate into the air?
Click to expand...

If you evaporate it no if you boil yes. I once had 10g boil out. I found some on the solution next to it as a gold plating on top of the solution.

Eric
 
ViperCV,

Sorry to hear your wife is having trouble with her health; send her our best wishes.

there is not much need to evaporate all of the solution, it would not hurt anything if you did, but if you tested the solution for value's with stannous chloride and the test was negative, you can treat the solution as waste: You could just decant the solution from your cemented powders, add a sheet of steel or iron to cement copper from the solution let the copper powders settle decant solution to another container, then raise the pH to 9 to precipitate the insoluble metals, settle decant solution from the sludge of metals, then bring the pH back to 7, this should give you a clear salt water free of poisonous metals, which can be discarded, dry the copper and the sludge before disposal.

AuCl has a reported boiling point of 290 deg C (~554 deg F) (decomposes).
Gold chloride can be volatile and can vapor off when roasting or incinerating material at around 700 degrees,
Even salt NaCl in ore in a roast or in a melt (or other source of chloride salts) involved can cause lose of gold as vapors.

Even though gold is not volatile in a boiling solution, you can lose a considerable amount of gold from boiling solutions through carry over.

Before I do any roasting, on any powders that contains chlorides. I will usually add a solution of hydroxide to neutralize them, and form water soluble salts, and rinse these salts well with water before drying and incinerating the powders.
Get Hokes and sit a while and read it, you will have a better understanding when you’re ready to begin working, you can do this while taking care of your wife.
 
Ok...So just low heat so it slowly steams is okay...just don't make it bubble and splatter...Thank you :)
 
thank you for the information. My wife is doing a bit better, she is going to be transferred to a better hospital in Cambridge UK, and hopefully released soon after her tests are done. I have been reading Hoke in the meantime, and have read it once, but i need to read it again and again to get a better understanding. The solution has been evaporated to a muddy substance, about 400ml and its a bunch of different colors at different layers, anywhere from green and yellow, to grey, and black... Im sure that there is a combination of Urea, and different salts in there...just need to figure out where to begin. Its just going to sit for a while until i can figure something out, and after my wife is 100% again. Thanks.
 
Test any solutions with stannous chloride, (if free nitric acid is a problem for the test, a small amount of sulfamic acid can be used to remove nitric from a small amount of this solution to be tested in a spot plate if needed).

The waste solution which tests negative for values can be treated using the instruction, you will find in the dealing with waste thread found in the safety section.

The powders from the cementing process can be washed well (I usually want to neutralize them in a NaOH wash to remove chlorides as salt water, and rinse the salt out well with hot water) and dried.

(Heating to red hot, chloride in these powders can vapor off some gold, this is the reason I try to remove the chloride salts before incinerating the powders)

The powders can then be incinerated, keeping powders crushed, as they may fuse together as the salts concentrate with heat before all moisture and acids are driven off, re-crush if they fuse, burn them to red hot, this will drive off salts and previously used acids, the base metals will oxidize under this heat in the air (oxygen from a torch will help if you have it handy), keeping the powders crushed and stirring while red hot can help to expose them to oxygen.

If your solution these powders came from was hard to filter you most likely had tin involved, in this case we need to remove tin form these powders with a boil in HCl adding a little water and decanting (some of the other base metals may also be washed away here, more hot water washes will wash out the lead chloride. (If tin was not involved we can skip this step) if we do this and wish to use nitric acid in the next steps these powders will need incinerating again to drive off traces of chlorides, in that case I would again wash them in hydroxide and wash out salts with several hot water washes before drying and then returning to the incineration process.

Now the incinerated powders can be treated to remove base metals using nitric acid. And from your study with Hoke’s you should read or have already read the processes from here.
 

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