Aqua Regia Mess -help!

[JustMe]

Ok so I have successfully used AR many times, without issue. Normally I use SMB to precipitate. But recently I was trying for the first time a few other methods. That's where I got in trouble.

I read that using Ferrous Sulfate did not require neutralization of the nitric, a plus as far as I was concerned, so I attempted it but didn't get gold to precipitate out of the AR. I then neutralized the nitric (with urea) and still no precipitation. So I set this aside for a bit to ponder what to do next. (The source of the gold was black sands which were also present, however all the magnetic materials had been removed. I have done this successfully many times before.)

So then I saw the Butyl Diglyme solution to collecting AuCl from the Aqua Regia then precipitating with hot oxalic acid. Got myself some BD and gave it a shot. For some reason after shaking it all up and mixing it the BD did not form an upper phase. :? So I put that aside too to ponder.

Then finally I attempted another batch of the black sands, and used the normal SMB method of precipitating it, and that didn't work this time!! So I got p***** off and just poured the whole mess (all 3 batches together) and decided to just evaporate it all down and start over ... then I thought ... ooops!

I took the 1 liter of liquid with gold, other minerals and SMB, BD, Oxalic Acid, Urea and Ferrous sulfate (I am sure that these are in excess in solution), as well as some precipitates and some fine sediments, and evaporated it down to just 150 ml and stopped there when I realized that I was not sure just how to go about finishing this process off. I was going to just toss in a bunch of zinc powder and filter it and take the precipitates and start all over with the AR, but now I'm not so sure. Also, if I do use zinc, I am really not sure how much I need to put in to be sure that all the gold has dropped. All in all there isn't that much gold as these were just tests I was doing on some ores to check out their content rather than using a fire assay. So somewhere between 1/2 to 1 gram probably in gold is in solution.

Ok after screaming and yelling at me is over ... does anyone have any suggestions as to recovery the mess here?
This is a first, because I have successfully used AR 30 or 40 times without a hitch.

 

[its-all-a-lie]

Have you used the search bar in the top-right corner of the screen?

 

[JustMe]

Have you used the search bar in the top-right corner of the screen?

Yes. I didn't find anything that showed me how to undo a mess with aqua regia that included Butyl Diglyme as well as the other stuff.

Note: Depending how I search I get 435 hits or more. So far nothing that applies. Anyone else able to find a relevant post to my issue here?

 

[butcher]

JustMe,
I suggest you do several things, the main thing would be to forget what you think you know now, and begin re-learning, from what you have posted it sounds like you have read a few things on the intranet or watched a few videos, but it does not sound like you have a good grasp on recovery and refining of precious metals.

Using or adding the Butyl Diglyme to the mess you have on your hands now, being a carbon based compound C12H26O3, which could burn like a fuel may be the biggest problem of getting your gold back out of this solution, (that is if you actually do have any gold in solution), if you have verified gold is in solution after testing for it, you may have luck cementing it out of solution using copper.

Although I would not doubt if all you have in solution at this point is iron.


http://www.sciencelab.com/msds.php?msdsId=9923094

 

[bswartzwelder]

I know this post is most likely not needed, but have you tested your solution with Stannous Chloride? It could be that you overestimated the amount of gold present and even if it did precipitate, there might be so little that it is almost invisible to the naked eye. I've made my share of mistakes, had my share of unexpected results, so I can completely sympathize with your present predicament. Keep plugging away at it and please, keep us informed. I have learned a lot from other peoples mistakes, but I sure have contributed one heck of a lot for others to learn from me.

 

[JustMe]

Stannous chloride test shows almost black. Dark and inky. It looks to me that there is plenty of gold in solution. At least enough that I am not going to miss it when or if it precipitates out.
The odd thing is that I can not find the butyl diglyme upper phase, even now that I have eliminated most of the liquid. It's possible that it has evaporated, but I'm not certain of that. I don't know offhand what it's vapor pressure is.
Well adding copper is simple to do so I might as well give it a shot. Can't really muck things up much more unless I blow myself up I suppose :shock:
Will precipitate with copper then filter out the precip and then test with stannous to be sure I got all the gold out of solution.

 

[Geo]

when using the BDG and oxalic acid, did you heat the solution? try adding 20 ml's of sulfuric acid and then evaporating the mixture (well away from everything, outside preferably) down to a syrup and then adding enough hcl to re-hydrate it and start over with just SMB (after removing the BDG of coarse).

 

[JustMe]

when using the BDG and oxalic acid, did you heat the solution? try adding 20 ml's of sulfuric acid and then evaporating the mixture (well away from everything, outside preferably) down to a syrup and then adding enough hcl to re-hydrate it and start over with just SMB (after removing the BDG of coarse).

Yes, I heated the oxalic acid and the aqua regia solution. I attempted to use copper to cement it all out and it did nothing. There was no reaction. I added a small amount of zinc powder to the solution, and it appears to have worked, and now the stannous test shows only a slight coloration change when added instead of a dark inky purple-black look so most of the gold is now out of solution.

Not sure how to go about removing the BDG at this point. Now I do see an upper phase which amounts to a few oily looking patches on the surface of the solution. Certainly nowhere near the original 30ml I began with. Maybe just a couple ml now. I suppose I can soak it up with a cotton ball and discard that way.

I am certain that the cause of the problems with precipitation in the beginning were due to some chemistry in the raw material. The source of this material was new to me and there is a mine not too far from there, which I have heard, has a hard time getting the gold out of it's ore, but I am not sure what the cause is. I am thinking sulfides perhaps, but it should have all been roasted off when i prepared it for the AR as I usually do.

Whatever it is in there apparently caused the BDG to go into solution too, and only after the zinc was added did it separate.

 

[Harold_V]

I read that using Ferrous Sulfate did not require neutralization of the nitric,

Perhaps you now understand why I keep telling you guys to read Hoke's book.

Harold

 

[JustMe]

Ok let me correct myself about Urea and neutralization of the nitric acid... I suppose I meant to say "drive off the free NO2".
Also
I searched Hoke's book, 365 pages and found nothing about Butyl Diglyme, or Butyl Carbitol or Diethylene Glycol Butyl Ether, etc.

Update on what's going on here:
BDG is gone now. Tested the solution several times after adding the zinc powder and it was virtually free of gold.
Used a buchner filter, and re-tested the liquid which is now a nice lime to light emerald green (used to be a deep golden yellow). The liquid tests positive for a lot of gold, but prior to filtering it was free of gold for the most part.

But at least now the BDG is gone and the sediments are gone. Now maybe I can get somewhere.
Sulfuric acid now and boil it down?

 

[Geo]

the BDG has the gold locked into its matrix. thats what its used for. you dissolve the material, no matter how much free nitric is in solution, the BDG will absorb the gold chloride. after stirring the solution plus BDG together, stop stirring and let the BDG separate from the solution. the BDG now contains all the gold chloride (in theory) if you did everything correctly (which it sounds like you did nothing correctly) you will have a barren solution and gold impregnated BDG. you will add the oxalic acid to water and heat until it dissolves. pour this mixture into the BDG and stir while heating. at around 75 degrees C, the gold will precipitate.

 

[JustMe]

Black sands were processed. Magnetics were removed with rare earth magnet. Hydrochloric acid used to dissolve away additional materials. Roasted to remove sulfides. Remaining sands were placed in a beaker and nitric acid and hydrochloric added in a ratio of 3:1. Was let set for a few hours. Liquid was filtered then put into a separatory funnel. 30 ml of BDG were added and it was shaken vigorously for several minutes, and allowed to sit. Upper phase never showed up. I decided to separate the top portion anyhow, feeling that maybe it's coloration was too similar and index of refraction too similar to see easily. Then took the top 30ml or so and put in a separate beaker, mixed oxalic acid in distilled water and heated, and heated the AR as well and mixed the two. No precipitation. Let set for a few days to see if separation would happen and it did not either in the top liquid I added the oxalic acid to or the bulk of the liquid that was set aside. That's when I put it on the shelf for later study.

I can see now that I did it all wrong ... right? Problem is I can't figure out where, but it is clear by what you said that you know. So tell me, where did I go wrong.

NOTE: If you notice my last post, I said that the BDG is all gone now. It showed up after the zinc was added and I removed it, and now the solution without the BDG is testing positive for gold very strongly. If there was any gold gone with the BDG, then it wasn't much.

 

[Harold_V]

Ok let me correct myself about Urea and neutralization of the nitric acid... I suppose I meant to say "drive off the free NO2".

Also
I searched Hoke's book, 365 pages and found nothing about Butyl Diglyme, or Butyl Carbitol or Diethylene Glycol Butyl Ether, etc.

But you'll find more than enough information about the use of ferrous sulfate for the recovery of gold from solution. That was my point.

Harold

 

[niteliteone]

(snip)
Not sure how to go about removing the BDG at this point. Now I do see an upper phase which amounts to a few oily looking patches on the surface of the solution. Certainly nowhere near the original 30ml I began with. Maybe just a couple ml now. I suppose I can soak it up with a cotton ball and discard that way.

DON"T DO THAT
Doesn't your Aqua Regia contain Nitric Acid ???
Not to mention carbon and probably sulfur compounds.

 

[Platdigger]

What's the matter niteliteone? Don't like a little gun powder? 8)

 

[Harold_V]

and boil it down?

Please refrain from discussing evaporation by using the term "boiling". You are, with the careless use of terminology, undoing all the hard work we've tried to accomplish on this board in teaching the proper method of evaporating.

It would pay you to do some reading on this board before posting, so you get an idea of how things are discussed. While I can't speak for other moderators, I am very picky about how things are said, as readers who are careless tend to absorb everything that's destructive, and little of what is good and proper. I'd sooner ban a reader who doesn't cooperate than to work endlessly trying to correct the damage done by making comments that are not acceptable.

Harold

 

[JustMe]

Well, I used cotton swabs and just touched the bit of butyl diglyme puddles on the surface and absorbed it up. Most of the nitric is gone already due to the fact that I EVAPORATED it all down before if you noticed in my first post when you read it.

So where to go from here ... again ... sulfuric acid time as one person suggested? Carefully evaporate it all down to dry? Wonder if that would get me some gold fulminate at this point??

Maybe I can add some alcohol or ammonia and see what that gets me?? Just kidding ... don't do that... don't need to make it any worse than it is.

But at least now I am rid of some of the problem with the BDG gone.

 

[JustMe]

and boil it down?

Please refrain from discussing evaporation by using the term "boiling". You are, with the careless use of terminology, undoing all the hard work we've tried to accomplish on this board in teaching the proper method of evaporating.

It would pay you to do some reading on this board before posting, so you get an idea of how things are discussed. While I can't speak for other moderators, I am very picky about how things are said, as readers who are careless tend to absorb everything that's destructive, and little of what is good and proper. I'd sooner ban a reader who doesn't cooperate than to work endlessly trying to correct the damage done by making comments that are not acceptable.

Harold

Please note the use of the ? which is a query. And by boil it down I meant to eliminate all liquid whatsoever.
You might also want to note that in the posts prior to and after your admonishment, I used the term evaporate. But I'm glad your keeping an eye on things. I guess it was a misunderstanding of how I used the term boil.

Also note that I had 3 experiments combined into this mess, only ONE of which had used ferrous sulfate. It is a bit disturbing that I get advice on how to post on this board properly, and yet those giving me advice on how to resolve this problem in chemistry that they insist is so dangerous, are not reading what I actually wrote.

But I do know now to:
Use the search bar.
Not use the term boil.
That I might be overestimating the gold present in the solution.
That I can be insulted with impunity without a whit of evidence that I have done anything incorrectly ...

... the BDG now contains all the gold chloride (in theory) if you did everything correctly (which it sounds like you did nothing correctly)...

I described the process I used and asked where it was I made some mistake ... no answer to that yet.

That I might make some explosives with nitric in solution which is GONE because it has been evaporated off because people 'helping' here are not reading what I wrote.

Communication is a 2 part process. One initiates a communication the other perceives it. Requiring people to phrase things properly may be important in chemistry, in which I would agree. But how do you monitor the perception and comprehension part of the communication process? Obviously by the responses here, there were some giving advice or making assumptions that could be just as dangerous as my use of the term boil. Perhaps more dangerous because these people are supposedly reading and understanding the issue I have presented and are giving 'knowledgeable' advice on how to resolve it. And yet in the responses it is clear that assumptions are being made without asking first for clarification where there may be some question, or not reading what was written and fully comprehending it.

Therein is the problem in all communications ...right?

So at this point I think that I am not able to get the answer that I seek here. I apologize for upsetting your applecart, you can go back to what you were doing. I do not need this kind of help as it could be dangerous. You have the final say as to what will show or not on your forum, as you can delete it or censor it as you wish.

Oh and I solved the issue but I bet you guys knew all along that that film on the glassware was causing the issue ... right? So what exotic film that might be almost imperceptible on glassware might cause this to happen AND affect butyl diglyme.

I cleaned the glassware with an appropriate solvent, then repeated each of the previous gold precipitations and they worked flawlessly. BDG separation occured just fine, gold precipitated fine using copperas. That'll teach me to be sloppy in my housecleaning chores but what do you expect ... I'm a bachelor

Good day gentlemen.
Now I have to be about getting this mess figured out and getting that gold back out of this green stuff that is still all mixed up!!

Oh, and not everyone appreciates being a public example for others to learn from. One might keep in mind the old saying 'Compliment publicly and admonish privately' as a bit of wisdom that might be applicable. PM's would help to accomplish much of what you desire.

 

[niteliteone]

(snip)
That I might make some explosives with nitric in solution which is GONE because it has been evaporated off because people 'helping' here are not reading what I wrote.

Communication is a 2 part process. One initiates a communication the other perceives it. Requiring people to phrase things properly may be important in chemistry, in which I would agree.
(snip)

As a correction to your wrong assumption on the "Nitric", it is still their.
Only the ""excess"" nitric was removed by "evaporation", which means my earlier post is still correct. If you had a decent understanding of "Chemistry" you would know this, Hence my pointing it out for those who don't know.
It will remain in solution even after you have dropped the gold with your precipitant of choice, so keep any cotton products away from any solution that has ever contained nitric acid.

This follow up post is for those who come later and might try to follow your mistaken knowledge.

 

[Geo]

JustMe, almost all new members goes through this to some extent. if you start a process that you do not fully understand and nothing happens the way you thought it would, its because you didnt do it right. i described (in short) how BDG is used. if you didnt do it this way, its not going to work. much to learn. everything you want to do has already been spoken about and you will learn much of what you missed by reading. if you have gold in solution, its not going anywhere until you do something. it wont evaporate away.

speaking of evaporation, you cant remove the nitric from a solution by evaporation. even if you dried it completely out, nitrates will still be present. learn what you can mix and what is dangerous to mix. cotton soaked in nitric acid is a crude form of gun powder (gun cotton) which is cellulose and nitric acid.