Non-Chemical Hi all, a few questions

[samuel-a]

ok
first of all, gold precipitation , i have made my first test batch of fingers in AP (50g of fingers) to see that every thing going as it should.
the foils came out perfect, rinsed and washed, it yielded around 0.05 - 0.1 g of foils as expected.

View attachment 1

afterwards dissolved with HCL+Cl (around 100ml of HCL and 40ml of Cl) dissolved perfect until no more bubble appear. after rinsing the glass rod i'v come up with a 150ml solution +-

now, 1st Q. - i have purchased ready solution of sodium bisulfite (SBS) 40%, and ended up needed to add 40-50 ml of SBS to the main solution until it got clear and started to drop the gold. is that normal? cause it seems a bit to much for my opinion... but, maybe i'm wrong...?
tomorrow , i'll of course test for remaining gold in the solution.


next sobject: header pins with HCL



i have placed a test batch of those kind in a HCL (33%) overnight, thinking only the tin solder and some other base metal (copper?) will dissolve,
but............
the gold plating is gone as well.... and a redish color is now where the gold plating was. 2nd Q. - what happend? did the gold dissolved?how do i reclaim it? or on the other hand, i miss understand and every thing is ok... what would be the next step?


final sobject (for now )

i have thrown in an AP solution (2:1 ratio) a mix of flatpacks (with the tin solder), PII cpu and and the kind with the gold plated pins (i think it's Pentium 75 type) and some fingers 3 days now in the bucket... i'v ended up with very turbid solution and some floating foils.... 95% of the foils are still attached, added up some more peroxide... but still, the solution is not reacting any more and i don't want to dissolve the gold...

3rd Q. - what should i do now to salvage the foils that ware separated? and what process should i choose for a better success in processing this batch?



Thank you very very much for any kind of answer
SAMUEL...

 

[LeftyTheBandit]

1st Q. - i have purchased ready solution of sodium bisulfite (SBS) 40%, and ended up needed to add 40-50 ml of SBS to the main solution until it got clear and started to drop the gold. is that normal? cause it seems a bit to much for my opinion... but, maybe i'm wrong...?

Generally the use of Sodium Meta Bisulite (SMB) is used, and I'm not 100% sure but it is close to being pure. The idea is once the the sulfite is introduced to solution small bubbles of Sulfur Dioxide gas are created and it is this gas that causes the gold to precipitate. SBS may have less available Sulfur to create Sulfur Dioxide gas. This may be the reason you need more to create the same gas that SMB provides.

I think the link to buy SMB is http://www.chemicalstore.com/navigation/detail.asp?MySessionID=294-987651973&CatID=&id=S025, and its cheap.

the gold plating is gone as well.... and a reddish color is now where the gold plating was. 2nd Q. - what happend? did the gold dissolved?how do i reclaim it? or on the other hand, i miss understand and every thing is ok... what would be the next step?

It is possible that the gold plating still exists but it is covered by a red sludge. Try removing the item and see if you can remove the sludge as it may be hiding the gold plating.

If you have added any hydrogen peroxide in large amounts this would dissolve gold but from what I have read it does not seem you added any peroxide.

The color red generally indicates iron. Tin and aluminum both cause problems with sludge and sludge will cover the plating and guard it from making contact with the AP. Agitation may help circulate the liquid to hopefully knock off enough sludge to expose the metal that the gold is bonded to.

AP is great on fingers because it attacks the copper (extremely well) that the gold is bonded too. If the pins are not copper with a gold plating, the AP may work, but not with the same clean result. You will have sludge factors. Try vigorous agitation see if the sludge breaks free. Be careful of the vigorous agitation as acid may splash so gear up and use your head.

i have thrown in an AP solution (2:1 ratio) a mix of flatpacks (with the tin solder), PII cpu and and the kind with the gold plated pins (i think it's Pentium 75 type) and some fingers 3 days now in the bucket... i'v ended up with very turbid solution and some floating foils.... 95% of the foils are still attached, added up some more peroxide... but still, the solution is not reacting any more and i don't want to dissolve the gold...

What is the ambient temperature? Is it cold where you are? A heated solution works much better than a cold one. Agitation is also a major factor. You should have a fish tank bubbler as it helps provide O2 and reduces need for peroxide AND it helps agitate your solution.

Remember AP attacks copper. If you have other metals involved it is not as effective.

3rd Q. - what should i do now to salvage the foils that ware separated? and what process should i choose for a better success in processing this batch?

Nitric acid or poor man's AR. This will attack base metals aggressively not just copper. If you have time use very dilute nitric, saves money and works over time....

 

[samuel-a]

lefty, thank you for your replay

1 - the SBS supplier insisted that SBS is basiclly the liquefied version of SMB, and i have read some wher on the forum here the same thing...
BTW, he gave me 1 litre (40%) for free to test
i'm not loaceted in the US, i'm in israel... i gut from them 66lb of 32% HCL for 20$, i guess it's agood price...

2 - i have read somewere that dissolved tin in acid will dissolve gold aswell, so what method should i take? beside electrolysis cell for that pins....
i of course don't rule out this option... but if i choose electrolysis cell, does the pins most be clean of tin silder?

3 - the climate here is pretty warm 80-104 F. i don't heat my solution, and had very little time to Agitate.... now 4 days...
i think i'll separate the components and treat each type separatly.... and treat the sludge with hcl/water washes....

3a - you mean, to put the sludge in nitric acid? or the cpu/flatpack themself?

i would love to hear more opinions, as i'm just starting my way and learning through experimenting and mistakes....

Thank you, SAMUEL

 

[LeftyTheBandit]

If you have access to nitric acid then that's your best bet in my opinion.

Make sure you rinse the items exposed to HCl very well with a lot of water . If any HCL is still around when you treat with Nitric Acid you will dissolve gold.

The idea is eliminate as much base metal before you dissolve the gold. As LaserSteve say's, "Keep your eyes on the gold". Once you get the base metals out of the picture use AquaRegia or Acid Clorox to dissolve the filtered material (gold flakes) with your choice of precipitant.

If you are worried about your first solution dissolving your gold test it with Stannious Chloride. If positive, dilute your mixture and place a piece of copper in solution. If gold is in solution the copper will cement it out.

 

[samuel-a]

well....

i'v decided to drop the hcl,ap,or whatever for the pins...

builted a cell, just missing the lead cathod to which i'll melt next week.

does the pins have to be clean of solder and fine wires that sometimes come out with them in the cell or it dosn't matter?

Thanks again
SAMUEL

 

[patnor1011]

in my opinion pins has to be as clean as possible of solder/lead. you can make lead cathode out of fish sinkers - cheapest way.

 

[samuel-a]

thank you pantor.

but i don't know how to clean of the solder in an efficient way....

will the tin dissolve in the sulfuric acid? if so, than it's good, cous the gold isn't.... do i understand correct?

 

[butcher]

if unsoldering dropping hot pin knocks off most of lead/tin solder,
lead passivates in sulfuric, this passivated layer protects it from dissolving in sulfuric.
HCl will attack tin, but lead is insoluble as chloride, so lead can form a powdery coating, also slowing attack, brushing or vigerous stirring can assist to remove lead chloride coating,
HCl and 3% peroxide, will work better to dissove tin in solder, and bubbling action of oxygen from peroxide helps to clear away insoluble lead powders, air from fish tank bubbler assist's here, stirring briskly often also helps.
tin in nitric avoid unless you like to deal with messes.

 

[samuel-a]

Thanks butcher for your insights.

but, please, once and for all, does HCL containing dissolved tin will dissolve also the gold?

 

[Barren Realms 007]

I think the answer you are looking for is yes the HCL w/tin will disolve gold if mixed with Clorox or other additive that is used to disolve gold. But not with just a mix of HCL/Tin.

 

[markqf1]

Tin dissolved in hcl makes stannous chloride (sncl2).
It is used to test for gold and other substances but, to the best of my knowledge, doesn't dissolve gold.

An hcl/cl solution will retain both gold and tin.

Mark

 

[samuel-a]

Thank you guys for your answers.
really helped

 

[butcher]

tin will dissolve gold in a melt even at soldering temperature's.
tin will not dissolve gold in a solution, but it will precipitate gold from solutions, as in the stannous chloride test for gold.

 

[Harold_V]

tin will dissolve gold in a melt even at soldering temperature's.

I wonder how many of the readers understand the solvent power of molten metals?

Harold

 

[Barren Realms 007]

Harold,

I wonder if they know how it changes the metal structures? I know little about this myself. I use to mix linotype with my lead as a hardener and then would heat treat the cast bullets to harden them further. Didn't have the leading problems you hear most reloaders have.

 

[Harold_V]

Harold,

I wonder if they know how it changes the metal structures? I know little about this myself. I use to mix linotype with my lead as a hardener and then would heat treat the cast bullets to harden them further. Didn't have the leading problems you hear most reloaders have.

That's an interesting approach, one I hadn't considered.

Many of the heat treat methods employed are based on the carbon cycle. That, of course, implies an iron alloy (steel).

There are non-magnetic alloys that heat treat by other means. While I don't fully understand the process, I have a basic understanding, being that crystals are developed in the metals, often simply by allowing time to pass. Some of the aluminum alloys are amenable to that process, although it can be artificially induced by heat treatment.

17-4 PH stainless is one of (many) metals that does not rely on carbon for hardening.

Harold

 

[Barren Realms 007]

We use to use wheel weight's for our casting. The lead from these had a BNI hardness of 18-20. When we added 10% of the linotype ( which was a tin based linotype from printers presses) it changed the hardness to around 24-26. When we went further and heat treated the cast bullets to just under melting temp and then cooled them it changed the BNI hardness to 29-32. These are the figures I remember they might be a little off it was 20 years ago that I did this. This dosen't sound like a big diffrence but belive me it was. We didn't loose much weight from the castings with the addition of the linotype. The diffrence in the bullets after the process was dramatic, penetration was a lot better and deformation of the bullet was lesss.

The heat treatment of the metal realighns the atomic structure and makes the metal more dense if I'm correct. This is also being done by super cooling items as well.

In iron the carbon makes the metal stronger. And if the metal is treated like the old oriental swords made where it is layered and carbon added between layers and folded many times. The diffrent layers in the fold make the metal srtonger and more flexible because you have many layers working together to resist opposite forces rather than one single layer. You can also get a better edge on the sword because you are feathering many layers rather than one.

If I'm not correct on the following let me know. Pure Platinum jewelery is not used because it is too brittle. Pure gold is too soft and bends.

JMHO, I'm probably wrong in these assumptions and this post will probably look stupid to me in a week or two when I read it again. So I cannot be held responsable for my actions. :roll:

 

[Harold_V]

If I'm not correct on the following let me know. Pure Platinum jewelery is not used because it is too brittle. Pure gold is too soft and bends.

Pure platinum is anything but brittle. It is very ductile. I have a ribbon of platinum that came from my refining experiences. It's about 18" long, and came from just a small percentage of an ounce of platinum. It is the small coil shown in the picture, below.

Platinum is not used in the pure state for the same reason gold isn't used in the pure state (not commonly, anyway). It's because it, too, is too soft and is easily deformed.

Harold

 

[Barren Realms 007]

Thanks for clearing that up for me. I take it that the three glass jars are diffrent states of platinum. I'v seen it discussed about gold craking on the edges because of work stress. Does platinum do this as well? And that is a nice looking coil, I guesss you rolled this yourself?

 

[Oz]

Platinum can become brittle even if pure, if it is melted with an acetylene torch.