# when boiling hcl



## jimmyreece (Jun 16, 2011)

when boiling hcl, can i seal the flask to keep fumes down or would it develop to much pressure ?


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## Barren Realms 007 (Jun 16, 2011)

You should have a vent for it.


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## Claudie (Jun 16, 2011)

Are you boiling it or evaporating it? The moisture has to have a way to escape. Never let pressure build up in a container or you will blow a cork, or worse.


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## jimmyreece (Jun 16, 2011)

no i wasnt going to do any evaperating, i was going to rid some base metals that are in a AuCL solution i need to clean. its quite a bit. i was just thinkn about cutting down on the fumes a little. i need to get that hood built !


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## samuel-a (Jun 16, 2011)

jimmyreece said:


> i need to get that hood built !



Before that, you need to reflux vapors.
for example, place watch glass on cups while boiling or vertically attach a condenser to the falsk.

This of course will treat only fumes, not gasses. So a hood is still necessary.


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## jimmyreece (Jun 16, 2011)

i do all this outside of course, and even so it still gets a bit of fumes.as a matter of fact, this weekend im going to build that portable fume hood i been planning.
with the hcl your talking using (A) my flask(B) a pyrex bowl with water my flask sits in and (C) a large pyrex glass to go over the flask so any vapors can get condensed into the water ?


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## goldenchild (Jun 16, 2011)

The fumes/gases are going to escape no matter what. What you need to work on is the rate at which they escape. The slower the better. You can get as creative as Samuel, or as simple as a watch glass or wet rag. It depends on your needs. Also, keep in mind that the less vigorous the reaction the slower fumes/gases will escape. Do this with techniques such as adding acids in small increments and not all at once.


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## samuel-a (Jun 16, 2011)

Basic reflux setup







Reflux basically means, that vapors are returning to reaction vessle where they were generated, while gasses escape (and can be captured as well).

You can also see a makeshift condenser in my video about gold recovery from fiber cpu (bottom of page)

It is advised to implement refluxing techniques in your setup for most reactions, even if you do have a good fume hood.


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## goldenchild (Jun 16, 2011)

Looks like a Allihn condenser. Samuel, I've been wanting to experiment with my distillation rig and maybe you have tried this. Or anyone else for that matter. I want to try digesting scrap in my rig and recycling the nitric. I understand that the nitric won't be pure and will be less potent after each use due to the escaping nitric that doesn't condense. I was just wondering if it would work. I dont see why it wouldnt. I envision a bunch bottles with blue and green colored nitric laying around 8)


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## samuel-a (Jun 16, 2011)

Mario

You will need a high precentage, ice cold H2O2 scrubbing for this to work at best efficiency.

A more realistic rig would be 2-3 water/3% H2O2 scrubbing flask.
Where water + air bubbling is first to capture nitric acid vapors and absorbe some NOx.
With the next one or two flasks with cold H2O2 and air bubbling to dissolve NOx.

I have tried it, but never finished the experiment, so i have no insights to share.

The reasone for air bubbling is to keep the water oxygenated so it could absorb more NOx.


Well, that is the theory.... 8)


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## Harold_V (Jun 17, 2011)

jimmyreece said:


> no i wasnt going to do any evaperating, i was going to rid some base metals that are in a AuCL solution i need to clean. its quite a bit. i was just thinkn about cutting down on the fumes a little. i need to get that hood built !


 Are you thinking clearly? (No, I'm not trying to be rude!) 

You can not eliminate base metals from a gold solution by boiling. 

If you have a dirty solution that contains gold, simply precipitate with the precipitant of your choosing, with the idea in mind that you'll re-refine the gold (after washing) to remove the excessive base metals that will be dragged down. Alternately, cement the values on copper and start over. 

Harold


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## jimmyreece (Jun 17, 2011)

after reading my own words....that does sound foolish. what i meant to say was i plan on boiling the powders in Hcl (after precipitation) from a dirty AuCL solution.
Thank you for correcting me 
i failed to get(im guessing) all the copper out of the AuCl prior to Hcl+Cl dissolution. i say that because of the green color solution i ended up with after i added Cl.(is that common?) but like dtectr said, it could be a number of different base metals.


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## Harold_V (Jun 17, 2011)

jimmyreece said:


> after reading my own words....that does sound foolish. what i meant to say was i plan on boiling the powders in Hcl (after precipitation) from a dirty AuCL solution.
> Thank you for correcting me
> i failed to get(im guessing) all the copper out of the AuCl prior to Hcl+Cl dissolution. i say that because of the green color solution i ended up with after i added Cl.(is that common?) but like dtectr said, it could be a number of different base metals.


Heh! No problem. 
If you haven't eliminated copper and/or nickel, you can expect your normally golden yellow solution to be green---yes! It's not fatal---it just means you'll have drag down beyond what you might have had had you eliminated all of the base metals (which may even include iron). A good wash will drastically improve the quality, but my experience dictates that no amount of washing will yield high quality. It was the chief reason I started refining my gold a second time. The results are obvious, not only in the color of the gold, but the solution after precipitation. While it often was colorless, it had a tendency to be tinted blue. It was quite obvious to me that copper was the chief contaminant, but that may not always be the case. 

If you intend to sell your gold for less than spot, I'd suggest you melt and sell as is. It most likely will end up being refined again, anyway. If, however, your objective is to achieve high quality, a second refining is quite beneficial. You'll be able to see the contaminants you removed by the color of the barren solution after precipitation, as I made mention.

Harold


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## jimmyreece (Jun 18, 2011)

thanks once again harrold for giving me clear answers. you always seem to cover all the details not only in your answers but also to the surrounding questions that come to mind when reading your replies. 
you would have made a great teacher.
anyway. no i hadnt planned on selling any of what little gold i have aquired since last january, just yet....ive worked way to hard and way to long to give up my little residual returns from a 1/2 dozen 1st attempt processes that easily.
no harold, im going to get good at this and when im finaly proud enough to take some pics. then maybe i will sell to get some returns back.
everything precipitated okay, tonight im going to decant and wash the gold real good several times. then run it through Hcl+Cl one more time


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## Harold_V (Jun 19, 2011)

jimmyreece said:


> you would have made a great teacher.


Heh! Matter of opinion, I guess. Most folks think I'm too pushy-----and narrow of mind. Typical of a guy with perfectionist tendencies. (Note I didn't say I was a perfectionist!)



> anyway. no i hadnt planned on selling any of what little gold i have aquired since last january, just yet....ive worked way to hard and way to long to give up my little residual returns from a 1/2 dozen 1st attempt processes that easily.
> no harold, im going to get good at this and when im finaly proud enough to take some pics. then maybe i will sell to get some returns back.
> everything precipitated okay, tonight im going to decant and wash the gold real good several times. then run it through Hcl+Cl one more time



I fully understand your objective. I refined for several years and didn't sell a lick of gold. Only when I started refining full time did I begin selling. My objective wasn't to make money--it was to accumulate gold. Nothing quite like it!

Good luck with the re-refine. I expect it will go smoothly. It's in good hands. 

Harold


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## jimmyreece (Jun 19, 2011)

i have the same objective...thanks harold


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## Oz (Jun 20, 2011)

Precious metals may go down in value nominally, but only paper can go to zero.


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## 4metals (Jun 20, 2011)

Samuel,

In your basic reflux setup pictured above there is no path for the pressure to escape, generally the mixing shaft is placed in a second neck of the vessel leaving room for gasses to vent. 

I usually use a straight walled reflux condenser packed with glass beads for refluxing, I have no experience using the Allihn condenser pictured as a reflux condenser. 

At the end of the day, venting is more important than mixing, if you can't get a 2 necked flask, opt for venting.


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## samuel-a (Jun 20, 2011)

4metals said:


> At the end of the day, venting is more important than mixing, if you can't get a 2 necked flask, opt for venting.



Sure 4metals, no argue here.

I just pulled that picture from google pics to demonstrate what is reflux and how it work for the OP.

I'm using Allihn type condenser regularly for refluxing.

EDIT:

Here's a nice MIT demonstration of proper refluxing apparatus.
[youtube]http://www.youtube.com/watch?v=fHEk2WFgmXQ[/youtube]


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