Question about RAM depopulation with HCL

[Bluebloomer]

There is no way to "kill the nitric" by heating the solution

That's my bad, I did read about denoxing but somehow I got the wrong idea.. And yes it's not worth it like that..
All electrolytic capacitors are manual removed from every board I have, from mobo to an old soundblaster, then all crystals, coils, resistor etc is removed and the only the soldered gold pins remain (with some other small parts) so there is little chance for any exploding parts I think..

I've modified a tool that came with my heatgun to use it as spatula,

Nice idea, points for creativity ! Seems like a very handy way to easily depopulate boards !!

That's because you haven't allowed enough time for the copper to cement.

Iron is all around us, but what is a good source of iron for such a job ? I'm betting most iron metals are an alloy of some sort, so what do you use as a source of iron to cement with ? Does it need to be as pure as possible, or would an old floppy or DVD-r housing suffice ?

 

[MarcoP]

Soft iron like an angle bar or similar is the best.

 

[Geo]

Any scrap iron will work. Keep in mind that steel containers for food storage will have a thin plastic coating on the inside. Avoid using these or incinerate the cans first. Bare metal should be used and avoid using metal that is painted or coated with any finish such as acrylic or paint or glaze. The metal will dissolve and the paint or other material will just be a contaminant.

 

[Bluebloomer]

I didn't think of that before, a piece of angle bar sounds ideal..!

Soo, if one used aluminum to precipitate all metals in a solution, what would be the best way to remove the aluminum once the precipitated salts are dried ?

And one final question, not related to the topic but oke; even if I have a good batch of AR with minor contaminants, the gold still drops as a real fine black powder, smaller than a grain of salt..

I use foodgrade SMB but I think the SMB is no good. In the description of the smb they say it's used to lower the PH in a swimming pool, because high PH might give too much chlorine in the water.

They sell it as Natriummetabisulfiet, but it also says natriummetabisylfaat which makes me doubt if it's a sulfate or sulfite, and it could be why the gold drops as a real fine particle..

http://www.polycolor.be/nl/verf/verf-zwembaden-vijvers/?pid=6774&action=info

That's the webshop I bought it from, perhaps you guys recognize the problem with the smb, or perhaps the purity is just too low I don't know but I think I'm not going to use it anymore..

 

[MarcoP]

Aluminum is way more reactive then iron causing boiling overs, it's more expensive and even if is able to precipitate more metals it won't drop them all. More over, if I correctly recall, it would make a jelly solution hard if not impossible to filter.

Use scrap iron and agitate the solution with a bubbler to recover copper (overnight will be enough), otherwise go straight to use lime stone till pH 8, decant, more lime till pH 10, decant, acidify to pH 7, decant and discharge. This is the short version of the full process, I strongly suggest you to search the forums for more in depth details.

Obviously I believe you have already used copper to cement any leftover PM.

 

[jason_recliner]

Sodium metabisulfite (...sulphite in non-US English), is Na₂S₂O₅. It will drop your gold and clean your beer brewing kit. Although not both at once.
The following, according to Wikipedia:
Sodium metabisulphate, aka sodium dithionate, is Na₂S₂O₆ and as far as I know it will not drop gold at all. It also melts at just 52°C.
Further, sodium dithionate is not to be confused with Sodium dithionite, which is Na₂S₂O₄.

So if it's food grade, I'd take a stab that you probably have ...sulphite which has plenty of food uses. The fact that it has a melting point of 150°C, whereas the others are just 52°C, gives you an easy way to test it.

 

[Bluebloomer]

@MarcoP: Yes so I've noticed ! It gives an almost exothermic reaction, and even if outside, the hydrogen gas is really plugent.. Some say to use Al for a recovery others say to say Fe. Since I have over a 100 pounds of aluminum heatsinks, I thought what the heck, recovery failed so try cement all values with Al, but now I'm sorry I did..
Luckily I got some angle bar from the scrapyard, cut it in smaller pieces and hope I never have to use it again....

Good idea about the bubbler, didn't read that before only with AP. I'll remember that, thanks!
And yes, the copper is always on hand, just in case..

@Jason: I have to correct myself; it's not food grade it's sold as a PH minus for swimming pools. So if it is the SMB we need for precipitating gold, why is the gold then always precipitated as a real fine powder ?

I see so many video's and pictures where the smb drops the gold as larger grains, not a fine powder like a grain of salt..
Perhaps too many impurities ? It does not say what the percentage is..

 

[MarcoP]

Impurities and, as I recall, concentration will give you smaller particle size. A clean and diluted solution might give you small particles but while you are washing them they will agglomerate and settle faster. Copperas will give you a constant particle size, SMB wont.

All this comes from my reading and memory, not from my own experience.

 

[jason_recliner]

@Jason: I have to correct myself; it's not food grade it's sold as a PH minus for swimming pools. So if it is the SMB we need for precipitating gold, why is the gold then always precipitated as a real fine powder ?

I don't know. Mine always drops as 18th century Spanish doubloons.

Check whether you instead have sodium bisulfate, NaHSO₄. Edit: I'm no chemist, I just Googled "pool pH reducer" and that is what I found.

 

[solar_plasma]

Mine always drops as 18th century Spanish doubloons.

:mrgreen: I need this process!!!

I see so many video's and pictures where the smb drops the gold as larger grains, not a fine powder like a grain of salt..
Perhaps too many impurities ? It does not say what the percentage is..

Marco is right. If the gold drops slowly as fine particles or quickly and well coagulated, depends in practice mostly on concentration of gold and impurities and the absence of oxidizers, not that much on the kind of precipitant. No oxidizers, no impurities, high gold concentration will cause a fast and well coagulated precipitation.

 

[butcher]

The gold starts off as ions in solution, using a chemical or metal to reduce the gold we give the ions an electron, so they form atoms of gold floating around in solution, the small atoms are too small to see, and not heavy enough sink, or to precipitate, these atoms must come together (if they do not come into contact they do not combine to a larger size), to gain a larger mass (forming clusters of gold atoms) to gain enough weight to sink in the solution, when and if they can combine to become a large enough particle, or cluster of atoms to sink, they can overcome the gravity in solution and precipitate, or stay in solution a little longer growing in size before precipitating, this size can be determined by many factors.


Concentration, temperature, what else is in the solution, contamination of solution, (base metals, oxidizers, salts ...), the reducing agent, how well the gold ions can gain back their electrons, and how well the atoms of gold can come into contact with each other to combine with each other, to form a heavier cluster of gold atoms, and their ability to grow to a larger size or cluster before the precipitate, How long these clusters of atoms stay in solution, and keep combining to bigger cluster before they overcome the gravity in solution and precipitate out of solution.

Or their growth is stunted in the process as is the case with colloidal gold formation....

Several factors can affect the size they can grow to, the clusters of gold atoms to before they sink.

Or do not sink.
As will be the case when the cluster of gold atoms which form a colloid, stunted in growth at a certain stage of growth, and size, by the colloidal forming substance (like tin or stannous, citrus acid...), (the color of the stannous is from the gold atoms cluster being a certain size), and stunted at that certain stage of growth, these clusters of gold atoms form a charge, colloids with opposing like charges, will just push each other around in solution indefinitely, without the ability to come together and combine to larger clusters, where they may have a chance to overcome gravity (or the repelling force of the other colloids in solution shoving them around all over the place in solution), and sink.
In the case of the stannous chloride test, the colloidal gold moving around in solution gives the violet color we see.

Thinking also how gold reacts in plating gold out of a solution with electrolysis, where the gold ions gain an electron at the cathode, and can plate out onto the cathode to form a deposit, a smooth layer of gold sticking well to the cathode metal in tight gold clusters of atoms. Or a powder of impure gold that falls off the cathode as black powder, there are many factors that can determine how the gold atoms combine once reduced back to a metal.
The electrolyte solution, purity of metals and the electrolyte, temperature, concentration the reducing forces. surface area current voltage...

 

[Richard NL]

I use foodgrade SMB but I think the SMB is no good. In the description of the smb they say it's used to lower the PH in a swimming pool, because high PH might give too much chlorine in the water.

They sell it as Natriummetabisulfiet, but it also says natriummetabisylfaat which makes me doubt if it's a sulfate or sulfite, and it could be why the gold drops as a real fine particle..

http://www.polycolor.be/nl/verf/verf-zwembaden-vijvers/?pid=6774&action=info

That's the webshop I bought it from, perhaps you guys recognize the problem with the smb, or perhaps the purity is just too low I don't know but I think I'm not going to use it anymore..

The page should read as follows:we sell Sodium Metabisulfite, but IF then you must use natriummetabisylfaat.

The sentence: "At too high pH too much chlorine will come in the water, use the Ph (natriummetabisylfaat))" can be interpreted in different ways and that caused the confusion.
LOL apparently only they sell natriummetabisulfit only one on the entire Internet.
https://www.google.nl/search?hl=nl&q=%22natriummetabisylfaat%22&gws_rd=ssl

I even made a comment about the incorrect spellings to the saleswoman, but she waved them away with that they felt it was correct what it said.
Maybe a dialect difference?

Some of the other writing / language errors are corrected which I passed on to the seller.
The site still contains some more incorrect spellings.

The Sodium Metabisulfite is good 8)

Edit July 25, 2015 restored link.