AU not completely dissolving/ copper mud appearing HELP?

[crip53]

Ok, so I tried the sodium nitrate and muriatic acid processing approach to stripping the gold off of some fingers and unpopulated boards that I had preciously stripped off the solder mask. Trying to save a few bucks.

I then rinsed them clean from the stripping solution - lye, salt, water.

I then cut and broke up the boards to make the whole load more manageable. Approx 6 lbs total board/finger weight. Divided it into 3 lbs each in 2 buckets.

I then added a premix ratio of 1/2 lb of Sodium Nitrate prills to 2 cups of boiling water (to dissolve the prills) to each bucket.

I then added 4 cups of Muriatic Acid to each bucket.

Since this did not cover the materials completely, I exactly repeated the ratios and added the same amount to each bucket.

During the next 24 hours, I stirred the material around and even placed a high speed vibrator under each bucket for a few minutes so that there would not be any sticking of flat boards to each other. The vibrator really does a nice job of making sure a liquid layer gets between every piece. I got the vibrator from a lapidary shop a couple of years ago for $75...and worth every penny.

Anyway, what I ended up with in both buckets was the traditional dark green more like black solution...

HOWEVER, it was filled with thousands of little undissolved gold flakes and as I poured the solution thru my coffee filters, that nasty old copper blue sludge started appearing!

I do not understand what happened.

I expected copper in solution since the gold would have been plated to it on the boards, but after removing all of the solder mask first, along with NOTHING else on the boards, the questions arise:

Why didn't all the gold dissolve?
(Too weak? Not only is there a lot of gold floating all over, but a lot of gold is STILL on the boards AND fingers.
Should I have used better, but more expensive 70% Nitric Acid and the real HCL from my chem supply shop?)

Where did all the copper mud and blue/green color come from (Color only appears after entering filter)?
(Was the solution over saturated? I have no way of knowing how thick the plating was on the boards, and the fingers were older decent layered style...not the high-shine cheapy newer puter stuff.)

How do I salvage this?

I am assuming that SOME gold got dissolved.
So, do I just divide everything in half once again...materials in the filter too, and whack it with the strong nitric and hcl pure stock and hope it finally dissolves it once and for all....or....YOUR SUGGESTIONS!!!!!????


I've added some pics to show what I am talking about and sending out THANKS in advance for any help

 

[nicknitro]

I would have to say you got lucky the solution was overly saturated. If you read up on the board/finger processes in the forum, and also on lazer steve's website. You should try to dissolve the base metal holding the gold flake onto the board first. Either with just nitric acid / maybe diluted, or lazersteve's preferred method, which is to use a solution of HCl and Hydrogen peroxide, to get the gold flakes off the boards. These methods will not dissolve the gold into solution, only the copper, leaving the flakes floating around for filtering. Later you can use HCL and Nitric or HCl and Sodium Nitrate"Poor Mans AR or even better just plain HCL and Bleach, to dissolve the seperated gold flakes , then usin SMB to precipitate the purer gold powder from the solution.

For now I would reccomend you try to filter out the floating gold flakes out of the solution, before they dissolve any further. Look into washing, and filtering processes. You wanna get any onld acids off the flakes, so they don't interfere with later processes. Then also look into using Stannous chloride to test your solution from the botched batch for any dissolved gold. If there is, try neutralizing the Nitric in the solution with a little Urea , then drop the powder with Sodium Meta-Bisulphite , set this powder aside for further processing. As it will undoubtedly contain a lot of Copper.

Any other questions, this was just a quick intro for ya. I suggest you look into more of the process section of the forum. And definnitely check out LazerSteves' Website he has great videos, on this process.

Good Luck,
Nick

 

[Harold_V]

Please understand that all of my refining revolved around karat gold, with rare exception, and always with commercially prepared acids.

From your words, I get the idea that what you tried to do is remove the gold using poor man's AR. That is a mistake.

I trust you have Hoke's book? If not, you should acquire a copy, even if it's just a download, and read it until the concept of refining makes sense. It's important that you do not dissolve values along with base metals. There is no benefit in doing so in that the same amount of acid is used in the process, plus the end result is almost always troublesome. When you don't use an appropriate amount of acid to dissolve all of the base metal, it will, in turn, precipitate some, or all, of the dissolve gold. Assuming you are successful in dissolving everything, you have such a dirty solution that the quality of gold that is precipitated will be of poor quality, in spite of careful washing.

If I do not understand what you did, and this doesn't apply to what you've done, sorry---only trying to help.

As far as salvaging the values from the mess----start by testing the solution with stannous chloride. I expect it will be barren, due to the remaining copper traces and un-dissolved gold. If that is the case, eliminate the copper solution, but save anything that is solid, that which is trapped in your filters.

Steve is likely the best person to address what to do next, but you must eliminate the copper traces, which will, in turn, liberate the gold that is plated on them. Do not discard any of the fine material. Your gold will be finely divided now, and may not look like gold in all cases. All of the fine sludge should be processed for values.

Do everything in your power to never attempt to dissolve gold that is accompanied by copper based alloys. It's always best to eliminate the base metals first.

Harold

 

[nicknitro]

P.S. Sorry, I was ranting so much, I forgot to say

#1. Nice job cleaning off the boards of the green coatings, with the caustic Lye, not too many people rallize there can be gold underneath it as well.

#2. Nice Boards, may I pry and ask what these were out of? Older computer system?

 

[butcher]

your powders will contain nitrates and chlorides, which can dissolve gold, these should be driven off with heat, before moving to a step that will eliminate base metals.

 

[crip53]

Thanks guys for all of your comments.

I had tried the AP type of thing with fingers and chips and got the same kind of mess I got this time...lol And I still have the hard dried out mix in the filters.

Yes, I have downloaded Hoke's book and read it...yes I actually did ~

What I have learned from all of this....besides getting some acid burns on me and getting them infected... (I got a shot of penicillin in my butt today and am on steroids for the next week, so I got a 'refresher course' in humility and not being in a hurry!) is this:

I am going to stick to ripping metals apart in my furnace!

At least when I do that, I can add my combo of flux materials, let the metals separate in the crucible, and then I can rip them apart afterwards withing the confines of my fume hood and contolled acid extractions.

No more of this low budget stuff for me.
Though I APPLAUD ALL OF YOU for how well and how helpful this forum is and I am VERY THANKFUL for all of your assistance and insights.

Sometimes, though, we just have to go with the ways that work for us, and I've learned I've gotta do it the way I KNOW it works for me.

I got into this electronic recycling stuff more of as a break of routine, and it was fun...and still is...tearing stuff all apart. But, the values are just not there to justify all the time and expense, versus my mining and extraction work. I am a geologist first, and a raw precious metals refiner second....and an electronics recycler a distant third.

But, I'll keep sticking my head in the forum from time to time to see what's new and cooking.


Thanks again all!


(For nicknitro....the boards were test boards that failed inspection, which is why they were never populated. The guy that I got them from is whack and got thrown off eBay. Fortunately I did not pay much for them.)


(For Harold_V....I appreciate all your info. One thing though, and maybe this belongs more in the raw field of refining than in the methods this forum addresses, but one can toss all sorts of metals together, take it to the furnace with the right flux combo (with a collector metal like fine silver shot to bring all the melting points down) and let the heat and specific gravities do their thing to separate, settle in the mold, and the flux rips out the nasties.
After pouring; cooling; and removing the flux waste...which is never thrown out, but ground into fine powder for further recovery at another time;.....reheating and pouring into shot for acid separations will pull all the goodies out nice and clean one at a time.)

Just a variation on what you do But, one that I am more comfortable with. I burn myself less too!

And that's a good thing!

 

[Harold_V]

(For Harold_V....I appreciate all your info. One thing though, and maybe this belongs more in the raw field of refining than in the methods this forum addresses, but one can toss all sorts of metals together, take it to the furnace with the right flux combo (with a collector metal like fine silver shot to bring all the melting points down) and let the heat and specific gravities do their thing to separate, settle in the mold, and the flux rips out the nasties.

Actually, I, too, used that method. I processed several hundred pounds of incinerated wastes from over 20 years of refining.

In the waste was considerable silver chloride, which I allowed to accumulate purposely, to act as a collector for the greater values, gold, palladium and platinum. When combined with the flux I formulated, I achieved a recovery of values that rendered the flux virtually valueless after the process. It contained no prills, thanks to the aggressive formula, which included the use of fluorspar for a very fluid flux.

I used a cone mold to pour the contents of the tilting reverberatory furnace I built, one of my own design. The buttons were easily separated from the solidified flux.

One comment on gravity for separation. You likely understand that the majority of metals we deal with will not stratify for separation. That process has been known to be used to separate gold from iron by the introduction of silver, but otherwise there are few, if any, metals one is likely to encounter that permit gravitational separation in the furnace.

The only regular occurrence I experienced where gravity played a role was when I had sulfates. The sulfate layer was always directly above the metal mass, with the flux on top. There is a distinct line that separates each layer, each of which is easily parted from the other.

In the case where the sulfide includes silver, by roasting an iron bar with the heat, iron displaces the silver in the sulfide layer, allowing for a full recovery. I used that method routinely with excellent results.

From my years of accumulation I recovered over 200 troy ounces of gold, along with a like amount of silver, plus many ounces of platinum and palladium. It is, without a doubt, the best possible way to recover values when conditions are proper.

Harold

 

[nicknitro]

That did it Harold,

My mind is officially blown. :shock:

I will just stick to simple inquartations, and acid reductions. It seems fairly easy, if you follow all safety precautions, and standard procedures.


"Whack?" LOL Wow, I guess so crip53. Thats too bad, they looked very promising. How cheap is cheap if I'm again not prying too much. I have gotten lucky buying about 25 pounds of cell phone boards on EBAY that were listed in a obtuse category, for 0.99 cents, 5 bucks shipping, itwas a deal including batteries and sim cards. I sold the lithium batteries to a cell remanufacturer for $20, and kept the boards and NIMH batteries. I am currently working out a deal to sell the LCD's to the remanufacturer as well. Will update.

P.S. I respect my elders, I was just trying to help a friend in need. Especially if this was your first try in the "E-Crap " refining. LOL I would be hard pressed to argue with you that the values are not there. I enjoy this adventure as more of a learning experience. I have been told by many of old timers here, " The main way to turn a profit, at least from the E-scrap, is to basically have it given to you.

Good Luck Sir,

Nick