AR Crystallized on 3xboil down

[Anonymous]

im just starting out, and have been surfing the forums for awhile now, have thumbed through some of hokes book,. which i intend to read more of tonight, but my question is,. i mixed up some AR 120ml Hcl with 2 tbs of sodium nitrate i mixed a small amount of hot water with the sodium nitrate before adding the Hcl to predissolve it a little,. i ended up with 1500ml of AR that i added 10oz of my material too,. it looks as though it had a really high copper content as well as i know it had decent gold in it, do to the fact i could see it,. it all disolved in the AR as it was supossed too,. was a really dark royal green,. almost black if you didnt swirl it some or hold it close to a light,. all appeared great, i assumed,. i had messed around before in the past on a different batch,. and tried to use Urea to de noxx the AR and it was a nightmare,.so i decided to do as many suggest and skip the Urea,. and do the 3xboil down method this time,. the problem i have though,. is i started with 1500ml,. boiled,..lightly, just a small simmer, over a flame, down to about 500ml,. all still looked fine,. just got alot darker green,. i had to leave for awhile so i shut off my heat,. and when i came back about 4-5 hours later, my AR had almost all turned to a large clump of white crystal,. had a small amount of dark green AR above, and through it,. it was kinda soft, and could be moved around with a glass stir rod,. i figured it would reconstitute back if i went ahead and added the 1000ml of hcl to it to bring it back to original volume to get ready to reboil for the second time,. but it hasnt,. now i have like 500ml of white crystal and 1000ml of dark dark green AR above it,. i havent tried heating it yet

is that normal, or did i get it to hot or what? have looked around and havent seen anyone write of this,. i know some get it to turn into a brownish mud,. but havent heard of it turning to crystal?

sorry for the large cluster of a question,. im not a good writer,.and its late lol,. thanks in advance for any help

 

[Harold_V]

One of the things you will slowly come to understand is it's not smart to process base metals along with values. From all indications, you have avoided the attempt to eliminate the copper that is present. That is a mistake, and it is manifesting itself with the problems you are addressing. Evaporating solutions with large volumes of contaminants is just not a good idea. It is a rare situation whereby I endorse the use of AR for gold recovery (note I did not say refining---recovery and refining are not the same thing).

You might consider attempting to recover the values by cementing on copper, then starting over, properly. Alternately, you may consider adding some pure gold to consume any unused nitric that may be present. You would be wise to heat the material until it was liquid, then insure that you have some free HCl present, so the nitric can be consumed.

Harold

 

[g_axelsson]

... with 2 tbs of sodium nitrate ...

I assume that is a typo and it should read 2 lbs? I'm not so familiar with the imperial system.

... and tried to use Urea to de noxx the AR and it was a nightmare ...

Poor Noxx, everybody wants to de Noxx! :lol:

Enough joking... I think that what you are seeing is pure salt crystals. You put in a lot of sodium nitrate (NaNO3) and hydrochloric acid (HCl). The nitrate can be boiled off as HNO3 leaving Na and Cl in the mix. as long as the solution is close to boiling point it could dissolve a lot of NaCl but when it cools down it can't hold all that salt any longer and you get a lot of NaCl crystals. Try to put one in a bit of water and it should dissolve.. It can take some time but if you heat your liquid you should get it into solution again.

What I wonder is what was the source material you started with? Just to be able to see the gold is no guarantee that there are any significant amounts of gold. How much gold do you believe there is?

And as many on this forum will tell you, you should start with removing as much of the base metals as possible before taking the gold into solution.

/Göran

 

[Anonymous]

yeah,. i didnt realize it had such a high copper content,. guess i shoulda thought it through a little more,... so Harold, i should slowly reheat until liquid, but i have no gold button,. so should i boil down again? then reconstitute to get the nitric out,. there shouldnt be much i think,. cause the reaction really slowed down and took awhile to disolve the last of the material, or should i just get it back to a liquid, and hang chunk of copper in it and let the last, if any nitric wear out on it before it cements my values out? and just to be sure,. as im a little confused about cementing,. should the values stick to the copper? or will they fall off it to the bottom of the container,.


i pulled some of the crystal out,. and it does as G_axel says,. it disolved away in water quickly and with ease,. so im sure hes right about what it is,.

 

[Harold_V]

Assuming you know you have free nitric present, and you don't have a button of gold that can be used to eliminate said nitric, what I would then do is to dilute the solution with tap water until everything that is a solid (the salts that have formed) dissolves. At that point, introduce a piece of copper, which will cement the values. They'll come down looking like black mud, not like gold. When the solution no longer tests positive for gold, remove the copper, cleaning it well of the black deposit. I'd suggest you simply allow everything to remain in the same solution. Once it has settled, decant the solution, leaving behind any of the solids that are present. Test the solution for values (again) before discarding, using stannous chloride.

Once I had the solution away from the solids, I think I'd give the remains a wash with a little nitric, insuring all of the base metals were in solution. I'd do this by using a small amount of dilute nitric, and bringing the lot to a low boil. Rinse well, decant, then process the solids for values, using the solvent of choice. Test the solution for values, always.

When you have a huge volume of base metal in solution along with values, it's a good idea to approach the mess from the position of getting rid of the base metals first. That's about the only time I suggest you use copper----- for recovery----never when refining.

Harold

 

[Anonymous]

thanks,. im on it,. ill take some pics and post em as i go through it

 

[g_axelsson]

Once I had the solution away from the solids, I think I'd give the remains a wash with a little nitric, insuring all of the base metals were in solution. I'd do this by using a small amount of dilute nitric, and bringing the lot to a low boil. Rinse well, decant, then process the solids for values, using the solvent of choice. Test the solution for values, always.

But the solution contained chlorides, if you wash it with nitric acid without incineration before you would probably dissolve some gold.

If the only thing you have is finely divided gold and precious metals from the original mix that cemented on the copper would it be such a bad thing to go straight to AR again? You would probably remove some copper and possibly a bit of the PGM:s but any silver is already in the form of silver chloride. I don't see any big advantage with a nitric wash, just a small problem with some gold dissolving.

Better add a disclaimer here... I'm just a small time hobbyist that is doing all my refining on my balcony while Harold is a professional with a lot of experience. Trust his advice more than mine.

:lol:

Btw, mregier, you haven't told us yet what the source of your gold was. Gold filled, carat, electronic scrap... any chance of silver or PGM:s in the original mix? How much gold are we talking about here, grains, grams, ounces? The more details you provide us with the better advice we could give you and other members could benefit from the discussion too.

/Göran

 

[Harold_V]

Once I had the solution away from the solids, I think I'd give the remains a wash with a little nitric, insuring all of the base metals were in solution. I'd do this by using a small amount of dilute nitric, and bringing the lot to a low boil. Rinse well, decant, then process the solids for values, using the solvent of choice. Test the solution for values, always.

But the solution contained chlorides, if you wash it with nitric acid without incineration before you would probably dissolve some gold.

Good catch! My general process would be to filter (the remainig solids), incinerate, then process further. That would eliminate traces of chlorine. (Am I losing my touch?)

Harold

 

[g_axelsson]

Don't worry Harold, I've learned about incineration from you... so in a way it's still your advice in the end.



/Göran

 

[Anonymous]

man its going pretty slow on the copper droping the values,. i wonder if i need to add a little HCL to it? i dont want any nitric in the solution to cement the values out with the copper ,.. correct?

is also kinda hard to see whats going on,. due to the fact the liquid is such a dark dark green its almost black, was like that before i added the copper piece though,.

 

[g_axelsson]

In what way would the added HCl speed up the cementation process?

Patience is a virtue when dealing with chemical processes.

Some ways to speed up the process in this case is to agitate, to increase the area of copper present (ie add more copper plates) and possibly heating. I think that to dilute the mixture with HCl would only slow things down.

/Göran

 

[Anonymous]

the reason i asked is cause i had it boiled down pretty far,. then the salts formed when it cooled,. and i done as Harold said,. and added the water until all salt was back in solution,. it has no nitric in it,. and i just didnt know if it had to have a little Hcl to make it cement,. the copper has been in it 4-5 hours and theres not much thats happened,. no little bubbles,. only a slight amount of tarnish onto the copper,.

ill try to get the solution move'n a little so more of it runs across the copper

 

[Barren Realms 007]

the reason i asked is cause i had it boiled down pretty far,. then the salts formed when it cooled,. and i done as Harold said,. and added the water until all salt was back in solution,. it has no nitric in it,. and i just didnt know if it had to have a little Hcl to make it cement,. the copper has been in it 4-5 hours and theres not much thats happened,. no little bubbles,. only a slight amount of tarnish onto the copper,.

ill try to get the solution move'n a little so more of it runs across the copper

If it is setting outside there is no need to create movement in the fluid. The sun hitting the solution will cause a natural moving effect without you having to do anything to it. It will find it's way to the copper if it is there just be paitent and let it sit.

 

[Anonymous]

got it,. ,. one other question,. to make sure,.

after it cements for a periode of time,. i am to test solution to make sure values drop'd,. if not,. let it set,. if they have,. then i am to decant/filter sludge away from liquid, retest liquid,. if neg, dispose of it,.

then the black sludge i am to incenerate to remove clhorides, and then put it in a nitric dilute to remove any further base metals, then once done,. filter/decant and put the remaining sludge in AR and proceed as normal,.. correct?

and how long some i incenerate it? just until its red hot and has stopped smoke'n for awhile? or is there a set time everyone use's as a fail safe? sorry for my questions,.. and thanks alot for everyones help

 

[Barren Realms 007]

got it,. ,. one other question,. to make sure,.

after it cements for a periode of time,. i am to test solution to make sure values drop'd,. if not,. let it set,. if they have,. then i am to decant/filter sludge away from liquid, retest liquid,. if neg, dispose of it,.

then the black sludge i am to incenerate to remove clhorides, and then put it in a nitric dilute to remove any further base metals, then once done,. filter/decant and put the remaining sludge in AR and proceed as normal,.. correct?

and how long some i incenerate it? just until its red hot and has stopped smoke'n for awhile? or is there a set time everyone use's as a fail safe? sorry for my questions,.. and thanks alot for everyones help

Even testing your solution might not show that you have values in the fluid with as much imbalance as you have injected into your solution. Too much SMB can show a false positive. A solution that has set for a while can show no reaction at all but still have values in it. Once you think you have dropped the values out and filter the solution save it and put it to the side with the copper plate still in it just to be sure you have recovered everything.

You should incinerate till the material is red and no more reaction. Then the AR.

Do a small sample when you rework you material. 4 oz HCL/1 oz nitric will dissolve 1oz of gold.

It realy dosen't take a lot of fluid to accomplish a task. Do your calculation on how much fluid you need and develope paitence and start small.

How do you eat an elephant: One small bite at a time! 8)

Good luck.

 

[Anonymous]

How do you eat an elephant: One small bite at a time! 8)

thanks for the info,. and lol as far as the Elephant, i think id have to watch someone do it first,. im sure the elephant wouldnt agree to much after the first bite