The Unplatable

[IGutYa]

ok so i got a pound of gold plated military radio connectors from india, things are loaded! problem is ive soaked them in AP for 3 days and hardly anything has deplated. they are just as golden as 3 days ago when i put them in. ive tried nearly pure nitric acid + h2o, it dissolved a little but ultimately had the same result. so since the nitric was just a test run with about 50g of connectors, i threw in some hcl, hoping it would turn into AR & dissolve everything. which it did.

when i went to check on it there was a layer of golden-brown on the bottom with green liquid on top. checkd to see if all the metal was gone, it was. so now its chilling waiting for me for the next step. im just wondering if there is anything special i need to do, knowing it is not pure gold in the digest.


i was able to get part of some of the connectors to digest in AP, but i was constantly adding fresh h2o2 when the bubbling stopped & bubbling air threw it + stirring the jar, and then just a little bit digested leaving 90% of it plated. this was actually how i found out that more than what you see is plated as some is pressed into other metals & not visible.


so, in a situation like this, where the only way of deplating is AR, can i just run it threw AR twice and get a rather pure product?

 

[Harold_V]

so, in a situation like this, where the only way of deplating is AR,

That, of course, is nonsense. There's almost always another way to process, with the use of AR the last on the list, with rare exception. This case is NOT one of them.

can i just run it threw AR twice and get a rather pure product?

Yes, you can, but there are hazards associated with the use of AR when base metals are involved. You have most likely experienced one of them in this case, but you are likely not aware that is has occurred.

You are in dire need of reading Hoke's book, so you have a clear understanding of the refining process. You also must learn that testing is your friend---testing with stannous chloride. No one on this board can second guess the status of your solution with reliability---but you can make perfectly reliable determinations, assuming you understand how. That's where Hoke's book comes in.

Read Hoke.

Harold

 

[IGutYa]

so, in a situation like this, where the only way of deplating is AR,

That, of course, is nonsense. There's almost always another way to process, with the use of AR the last on the list, with rare exception. This case is NOT one of them.

can i just run it threw AR twice and get a rather pure product?

Yes, you can, but there are hazards associated with the use of AR when base metals are involved. You have most likely experienced one of them in this case, but you are likely not aware that is has occurred.

You are in dire need of reading Hoke's book, so you have a clear understanding of the refining process. You also must learn that testing is your friend---testing with stannous chloride. No one on this board can second guess the status of your solution with reliability---but you can make perfectly reliable determinations, assuming you understand how. That's where Hoke's book comes in.

Read Hoke.

Harold

actually i have read hokes book, twice. its mostly clippings from different web postings i have read in the forums. i have some stannous chloride, not afraid to use it either. ive used AP for etching pcb's for years so i always have that laying around.

im aware that there are hazards i currently am are unaware of. < sounds like one of those lines from one of them movies > haha.

i was trying to find a reason to dispose of my remaining hno3 so thats when i went with the nitric prewash ive read about in attempt to do what the AP could not do. with practically no success. it did less than the AP. and being it contains only a little bit of items i figured since it was already mixed & the only other option ive seen here is a sulfur cell & i really dont want to have to build one of them too, so what the hell its in a fume hood its only a few g what can go wrong? ill at least feel better about seeing it being digested. :lol:

NO2 & Cl are not a problem, but out of my curiosity, what hazards are present that you are speaking of?

i am aware of how to recycle copper, and was intending on ending up with either aluminum or iron as the final metal in solution. most likely iron.

i have a copy of "Flinn: Chemical & Biological Catalog Reference Manual 2001" that i will be referencing to when it comes to disposal of wastes.

Thanks again for any info! Greatly Appreciated!

 

[Harold_V]

what hazards are present that you are speaking of?

The one that is most important is the fact that when you dissolve values along with base metals, unless you totally dissolve the base metals, you risk loss to cementation. The values may not look like what you expect, and may well be discarded. Lesser of the concerns is the fact that you create filthy solutions, from which you can only hope to achieve clean gold. That, of course, isn't as critical.

If you have a considerable amount of experience and understand the ramifications of processing directly with AR, surely,there's not so much of a risk. The problem is, AR has been promoted as the last word in processing, and that is totally misleading. It should be looked upon as a refining process, not a recovery process. They're very different from one another, although the line has been well blurred by individuals that think they know how to refine, when they don't.

I'm going to relate to you somehthing I experienced in my refining years. A customer provided me with some gold plated items for processing. They were defense items, likely from the Korean War era. I identified them as pieces form wave guides of some description. While many will not believe what I say, they ran rougly 2% in gold. As heavily as they were plated, nitric acid would have permitted proper processing, although that is not how they were processed.

The pieces you described would have responded perfectly well to dilute nitric. It may have taken a little time for the acid to penetrate the areas that offered limited protection, but it would have worked. You should have heated the solution and allowed it time to work. I am DEAD AGAINTS the processing you chose to do. There are processes that are known to work, that offer little or no risk of losing values. Those are the processes you should pursue, leaving the experimentation to those that have a firm understanding of refining.

Please note that my comments, above, are based on the assumption that your objecitve is to process gold, not to experiment. If your objective is to attempt to build a better mouse trap, then I'm clearly wrong.

Harold

 

[machiavelli976]

when i am about to recover plated or filled gold i use to grind as small as possible the items. concentrate nitric works only very hot but with low efficiency. if not very hot will allow salt growing over the contact area and stop reaction. much better to use dilute nitric as Harold said.if you don't hurry instead.

 

[IGutYa]

what hazards are present that you are speaking of?

While many will not believe what I say, they ran rougly 2% in gold. As heavily as they were plated, nitric acid would have permitted proper processing, although that is not how they were processed.

i started with red fuming nitric & diluted with distilled water & left it overnight. perhaps i didnt dilute it enough?

i still have the bulk of the pins to process, about 400 grams worth. i would rather not digest them in AR as my only method. that was like you said, more of an experiment. id rather do things "right". so for the remaining, you suggest i should re-soak in nitric? only more diluted?

how exactly did you process your heavily plated items?

 

[goldsilverpro]

I would say that the use red fuming nitric would produce a great enough hazard that I wouldn't want to deal with. Why on earth did you decide to use that?

 

[IGutYa]

I would say that the use red fuming nitric would produce a great enough hazard that I wouldn't want to deal with. Why on earth did you decide to use that?

it was laying around. was tired of storing it. now that i have my calc program i can just calc what i need & make only what i need, preventing the need for storage.

but since it has been done, and after sitting overnight, today i found a very dark green liquid with a golden-brown super fine suspended dust in the bottom of the jar. ive tried filtering it, it just clogs the filter. its under vacuum right now, hoping eventually it will filter. just trying to separate the solids from liquids.

i seen on goldmineworld.net the use of AR for exactly what i did, its the reason i decided to try it. again, just an experiment. as grinding them smaller would be rather difficult without special tools i dont have.

 

[jimdoc]

Why didn't you try the sulfuric cell?
You can see videos of it on Steve's site.
Thats how I would do plated material.

Jim

 

[IGutYa]

Why didn't you try the sulfuric cell?
You can see videos of it on Steve's site.
Thats how I would do plated material.

Jim

honestly, i have not built one yet. of all things i know it is probably the best (the little voice in the back of my head would agree). im getting some pictures together of the material in question, it consists of multiple tubes that are plated on both sides press fit into each other with a little bit of plastic. close to a 2.4ghz for your lan only MUCH heavier duty.

 

[IGutYa]

So i filtered the brown gunk, it is insoluble in HCl & appears to dissolve in water, but if allowed to sit it all settles so it is a REALLY fine particle suspension.

i tested the filtered dark green AR liquid with stannous chloride and it didnt change color, i did a for-the-hell-of-it test with the hcl + powder & the water + powder and they returned negative as well.

so this golden brown powder....

could the metal in the pins (i think zinc or nickle) have pushed the gold out of solution as it saturated? there was some still undigested metal in the bottom when i filtered it. leaving me with a fine gold powder + liquid hazardous waste???

ill have pictures up soon, i need my laptop to dl the pictures from the sim card.

 

[machiavelli976]

IGutYa,you don't need to grind very fine your stuff. a pair of pantograph pliers is all you need. just cut them to increase the contact surface. use dilute nitric. maybe some H2O2 with it.

 

[goldsilverpro]

I think machiavelli976 is on the right track. This whole thing sounds like the acid, whether nitric or AP, is not penetrating through the gold into the base metal. The words, "military", "Radio", and "India". For some reason, when you put together those three things, it sounds like thick gold to me.

In general, gold plating is porous until it gets about 100 millionths (100 u") of an inch thick. If the gold's too thick, nothing will happen. However, once the acid finds a way in, it will eventually eat all of the base metal on the inside. Most pins, fingers, etc., are around 30 u" thick and the gold is porous enough to allow the gold to pass through and get after the base metals.

I just did an assay for a guy on some pins and the gold figured out to be 90 u". He was having the same problem you are. I put some of the pins in hot 50/50 nitric and, in about an hour, about 1/2 of the copper base was dissolved. If if gold was a little thicker, none of the copper may have dissolved.

This guy scarred up the pins somehow. Anything to either get places where the base metal is exposed or get the gold thin enough in a few areas and the acid will find a way through it.
I think the first thing I'd try is using some real big nuts and bolts in a cement mixer. Rollers would work. I sure wouldn't do them one by one.

 

[IGutYa]

so what do you make of the brown powder left behind & all stannous chloride tests returning negative? could what i said earlier have happened?

 

[Harold_V]

I would say that the use red fuming nitric would produce a great enough hazard that I wouldn't want to deal with. Why on earth did you decide to use that?

it was laying around. was tired of storing it. now that i have my calc program i can just calc what i need & make only what i need, preventing the need for storage.

but since it has been done, and after sitting overnight, today i found a very dark green liquid with a golden-brown super fine suspended dust in the bottom of the jar. ive tried filtering it, it just clogs the filter. its under vacuum right now, hoping eventually it will filter. just trying to separate the solids from liquids.

i seen on goldmineworld.net the use of AR for exactly what i did, its the reason i decided to try it. again, just an experiment. as grinding them smaller would be rather difficult without special tools i dont have.

There is no need to grind or otherwise reduce the items to be processed, nor is there need to filter. You can allow gravity to do your separating. It's generally fast (much faster than filtering, assuming you avoid creating any colloidal gold), and totally efficient. You can get the solids to settle all the faster by rinsing with hot water if time is an issue. Decanting the solution is best done by small hose, so you avoid disturbing the solids which will have settled on the bottom.

There is no need to create work (by grinding, or otherwise reducing in size) when you are processing such materials. They will respond perfectly well to dilute nitric acid, particularly if you incinerate first.

Again, avoid, at every opportunity, dissolving base metals along with the values. It's nothing short of stupid to do when there are alternative methods that yield better results. There simply is no advantage in doing so, and more than enough disadvantages when you do. Do keep in mind, however, there will be occasions when it can work to your advantage.

Harold

 

[qst42know]

This guy scarred up the pins somehow. Anything to either get places where the base metal is exposed or get the gold thin enough in a few areas and the acid will find a way through it.
I think the first thing I'd try is using some real big nuts and bolts in a cement mixer. Rollers would work. I sure wouldn't do them one by one.

Perhaps this might be a good time for a harsh incineration with lots of stirring. Some brasses become brittle at red heat and may just crumble, and the gold or base metals may slump and thin in areas.

Could be worth a try on a small batch. I'm with Harold on this one give it a good burning.

 

[IGutYa]

Again, avoid, at every opportunity, dissolving base metals along with the values. It's nothing short of stupid to do when there are alternative methods that yield better results. There simply is no advantage in doing so, and more than enough disadvantages when you do. Do keep in mind, however, there will be occasions when it can work to your advantage.

yea i know it wasnt that smart. for the small amount it was & the fact it was just a trial & error run, i was willing to loose what was there just to see. ive read on other websites that AR can be used that way, figured what the heck.

i vacuum filtered the liquid after it settled (poured the most off first) & washed the filters off in water. the particles are so fine that they are still dispersed in the water. when i filtered it the first time, some of the dust made it threw the filter even!

its all in water now, ive tested the AR with stannous and got a Negative result & ive tested the water just for the hell, Negative. so the AR is just base metals? then that means the powder Must be the gold ???

i need to re-filter it to try a burn test... dont know why i didnt try it b4.

as for the rest of the batch, im going to re-attempt nitric i guess, ill have to make more tho.

~50% wasnt diluted enough? (10ml RFNA + 10ml h2o (ended up with more than 10ml h2o)) actually i started with a little, added more, added more, added more, until it got going... a little h2o2 for the no2... then when it stopped, i added a bit more h2o... nothing, a littler more... nothing. let it sit over night & then the next day there was a nice golden-brown dust in the bottom of the liquid. poured off most of the liquid into a jar then vacuum filtered the powder & washed with water.

i havent done the NH4OH wash yet, will do after it vacuum filters.

 

[IGutYa]

ok so i added some ammonia to the solution & all the fine particals clumped together & now are filtered.

i really feel like i am wasting time here. i think im gonna put off the nitric wash of the other parts for a little while, need to clean up what wastes i have now before i go making more.

 

[IGutYa]

here http://www.mediafire.com/?sharekey=34b45564cece51eaab1eab3e9fa335ca4dc4ba9d6628ca50 is a link to all of the pictures ive taken.

the connectors ive soaked in AP were only stained ( IMAG0692 ), i scratched 2 of them to show this ( IMAG0693 & IMAG0695 ). the small pieces in IMAG0674 were all that was left over from the AR, along with Gold foils from IMAG0673.

IMAG0684 shows 2 pieces After AR compared to Before AR & IMAG0686 is before anything.

IMAG0630 - ...37 are of the filters of brown muck.

and a few others showing gold plating that was under other metals (press fit).