Precipitating Au from AR using SMB

[kurt]

Ok – just got done reading the thread stated by nighthawk title precipitating gold & I see discussion came up about expelling the nitric from AR using sulfuric & HCL before preciping (as explained in Hokes)

However – she is using copperas as her precip agent instead of SMB --- So my question is --- do you need to expel the nitric from your AR in this same way when preciping Au with SMB

I have not heard (or don't remember hearin) of doing so in anything I have read about using SMB to precip Au from AR & I just dissolved a bunch of Au wires from chips (flat packs) yesterday & was planning to precip it with SMB today --- So????

Kurt

 

[nickvc]

Gold will not precipitate from solutions while you have free nitric so yes you have to either evaporate to remove the nitric or use urea, but most members dont like to use urea as it adds another element to the mix.Sulphuric is used to remove the lead as it forms lead sulphate which can be filtered out of your solution, hydrochloric is used to remove the nitric during evaporation. The best method is to make sure you have no free nitric or failing that use Harolds method and dissolve a gold button to help consume any nitric left over. Your smb will also remove the nitric but it can take a large quantity depending on how much nitric is left.

Corrected thanks GSP.

 

[Claudie]

I would be interested in knowing the what you yield from the flatpacks.

 

[kurt]

Thanks nick - it now make sense - It was some how going over my head the way Hoke was explaining it

Claude - will post my results when I get it done - worked on some silver instead today - got that drying right now so I can melt it tommorow

Kurt

 

[nickvc]

Thanks nick - it now make sense - It was some how going over my head the way Hoke was explaining it

Claude - will post my results when I get it done - worked on some silver instead today - got that drying right now so I can melt it tommorow

Kurt

The whole thing with this hobby is your metals are going nowhere unless you throw them out. Take your time and start small until you know the processes inside out, enjoy and learn, it's very simple when you know how!

 

[Harold_V]

The whole thing with this hobby is your metals are going nowhere unless you throw them out. Take your time and start small until you know the processes inside out, enjoy and learn, it's very simple when you know how!

Thanks for those comments, Nick. All too true!

What amazes me is the sheer number that won't study (or haven't studied) Hoke. It truly is the key to freedom and success.

Harold

 

[Oz]

Hoke is a good book about refining generally speaking.

What makes it great (which many other refining books lack) is the testing explained.

What makes it the most recommended book on this forum, is the acquaintance experiments. Taking the time to follow these experiments will teach you what will happen to different elements in different conditions and solutions. You want to know this before you see them for the first time in a solution with several thousand dollars of precious metals in it, and do not know what to do because of a problem like a gel or crystal formation. Better yet these expiriments teach you how to avoid such a problem in the first place.

The acquaintance experiments are what really makes this book shine.

Just one man’s opinion.

 

[kurt]

I agree totally about reading Hokes & doing the Acquaintance tests --- & not just reading Hokes - but "studying" it - taking notes that you can reffer back to & reffering back to the book often

I asked the question because Hokes does not cover using SMB & in all the reading I have done over the last year & a half I cann't for the life of me ever reamember hearing about doing this when using SMB --- So I asked the question - not because I haven't take the time to read &/or do research (I've spent countless hours doing just that) but because I simply had never heard of doing it when using SMB as your precip agent.

Sorry - didn't mean to ask a stupid question - I do my best to try to find answers before asking questions & then only do so if "hours" even days of research have not turned up the answer &/or if I am confussed by an answer I my have found.

Kurt

 

[Harold_V]

I agree totally about reading Hokes & doing the Acquaintance tests --- & not just reading Hokes - but "studying" it - taking notes that you can reffer back to & reffering back to the book often

That's a shining example for others. There is much to be learned in her book, and it's not readily absorbed when the entire concept of refining is not understood.

Sorry - didn't mean to ask a stupid question - I do my best to try to find answers before asking questions & then only do so if "hours" even days of research have not turned up the answer &/or if I am confussed by an answer I my have found.

Kurt

It is my opinion that you have not asked a stupid question----and it's equally apparent that you are putting forth an effort to learn.

I hope I speak for all of the moderators when I say that none of us have a problem with answering questions when a reader is putting forth an effort, in particular when they pay attention to information provided instead of hoping to find someone to agree with their preconceived notions. Anyone that spends time trying to learn can earn my full attention. It's the guy that has done nothing beyond dumping a mix of ill matched items in a solution of who knows what, then comes to the forum hoping for someone to magically convert them from an idiot that knows nothing to a professional refiner, in spite of the fact that they don't have a clue about what they're doing, or why.

I would hope that you, and all readers, don't get the wrong impression about my ravings. I gladly help those that try to help themselves, but I refuse to raise a finger for those that refuse to put forth an effort on their part. I feel the same way about people that prefer living on welfare to holding a job. I'd rather see them starve to death than help them work the system.

I am proud to say that in all my working years, from age 18 until I retired at age 54, I was never unemployed, nor did I EVER receive even a dime in unemployment pay. I earned my way in life, and I expect nothing less from all others.

Harold

 

[Remuck]

Congrats Harold, on your career and work ethics. I started my career at the age of seven by taking over my older brother's paper route -- which, by age fifteen, turned into four routes and by age eighteen, turned into my first back surgery. I was the "news guy", my, late brother, God bless him, was the quarterback guy.

Enough on work ethics, etc., I'm going to take a flying leap and ask a question related to this string of topics. I, too, did not note Comrade Hokes' making any mention of SMB as a precipitant and found the previous dialogue interesting and a bit informative as well --- I understand that H2SO4 will allow AR to thicken as it is heated and will also prevent lead from becoming an issue; however, I'm still not getting the recovery from karat gold that I anticipated.

To set the record straight, I will, ultimately, be working with ore (last assay - 1.5 oz's/ton) and for the past eight plus months have been designing and fabricating a small columnar leach plant as a test of concept devise --- volume wise, definately NOT going to be a money maker --- Sodium Thiosulfate leach agent, well I don't even want to go there.

After the plant and the electrolytic cell that was incorporated in line with the system failed to produce with the thiosulfate leach, I came to the realization that, even if the thio worked, I had no idea as to how to approach the refining of whatever "product" happened to cling to the copper cathodes, sans getting rid of the iron with dilute nitric and digesting whatever is left with AR -----.

Questions are really coming up soon

Following the "rules of engagement," I have been reading and greatly appreciating Comrade Hokes' treatise on waste recovery and have been successful in my efforts to refine karat Au utilizing AR as a digester of gold rolls, AND the addition of H2SO4 (for previously mentioned reasons), and --- here comes the BIG one --- EVAPORATION !!!!!! ( NO BOILING, heat below 200 degrees F from 12 volt coffe cup warmer), EVAPORATION, and EVAPORATION until syrupy, whence HCL is slowly added as a "nitro chaser."
SMB has been my precip. of choice; however, I have a supply of sulfamic acid that someone highly recomended (can't seem to find the thread) and I would greatly appreciate a compare & contrast of the two as precipitation agents. Finally, per "the rules/VERY WELCOME suggestions," I have kept my HCL:HNO2 ratios above 8:1 just to be on the safe side AND incinerated and redigested all prior to the final melt.

Here come the questions:



Question #1


Is karat gold homogeneous? I comitted 6.0gm of 14 karat material (tuxedo pins, links, and tacks) that had been "partially digested" in AR. Realizing that I wanted to get a quantitative measure, I neutralized the digestion and "ribbonized" 2.7 gm of material and recommensed AR digestion. From the 2.7 gm of material that I worked, I expected to net 1.575 gm 24 K (yea, we all wish) Au. Unfortunately, I yielded just about 1/3 that amount of some VERY prety product (will be tested by jeweler friend tomorrow), but not the expected mass. At no step in the process did ANY material come to a boil, sans the fizzing that accompanies the Au/AR reaction that "looks" like boiling (but is not, or ---?) and I'm just a bit confused by the outcome. I actually did recover a relatively large volume from the first run on the tux gear before I decided to get quantitative, but I assumed that ALL would be equal until ALL was digested. Am I wrong in this assumption?

Question #2:

Is 195- 201 degrees F. sufficient to boil Au off? I thought that I had a pretty sweet system with the coffee mug warmer, but if I'm getting too close to the "see ya later temp," I'd sure like to know about it.

Love the forum and, thanks to Palladium who provided a pic, believe that I'm developing a thing for our dear Comrade Calm. Will greatly appreciate any and all input.

Regards, Lance

 

[nickvc]

By using partially digested material you will never know how plumb the gold was, was most of the gold already gone and just silver and a small amount of gold left? Have you tested your solution to see if it's barren of values? A small amount of gold will escape in the fuming hence the use of scrubbers to capture any values as well as neutralizing the acid fumes.

 

[butcher]

If 14k, did you inquarter with silver? Then use nitric to remove base metals before dissolving gold?
If not silver chloride may be a roadblock to get gold to dissolve (and you may use more nitric than needed trying), and the base metals in solution can also give you trouble later (when trying to precipitate the gold).

When solution contains water (from the HCl used) the solution would not evaporate gold by heating below 100 deg C (212 deg F) the boiling point of water.

But we are very close to boiling the nitric at this temperature; remember it is not necessary to boil a liquid for the liquid to evaporate off as vapors,

Nitric acid boiling point changes with concentration (water involved) at 30% nitric acid boils at 103 deg C, and at 70% (this would be as concentrated as it would get azeotrope) nitric boils at 121 deg C. it will evaporate below its boiling point just as water will evaporate well below a boiling point.

HCl (azeotrope) 20% has a boiling point of 108 deg C (227 deg F), here again it will vapor off at lower than boiling point.

But now we have a mix of acids water and metal in solution so these numbers will not reflect the true boiling point of our solution (but we also know the boiling point will change with concentration).

We want to stay below the boiling point, we just need to heat to evaporate, we could evaporate by just letting it sit in the sun, but that would take forever (or a long time). so we can heat it to a higher temperature, but we do not want it to boil, just evaporate (letting vapors escape).

You do not want large bubbles forming from a boil (very small bubbles are acids reacting not boiling), we just want to vapor gas off of solution, I have never measured the temperature so I cannot give a number, but I just heat till I see fumes vaporing off, and keeping solution below boiling points of solution (large bubbles rising to surface), aqua regia when evaporating I keep a close watch on it, as the nitric gets concentrated in solution there comes a point where it will start foaming (small bubbles start first, at this point I turn heat down) at this concentrated point the nitric seems to want to come out all at once, and will easily foam over if you are not careful, after you lower heat (so it will not foam over), and let nitric vapor the NOx gasses out of solution, then I am able to raise the temperature back up and resume evaporation (note not all the free nitric has been eliminated) but once I pass this point I usually relax somewhat.