# AuSn 80/20 alloy



## Joe cocker (Dec 26, 2021)

Hi everybody,

I got AuSn (80% gold) preforms debris (small foils 100 micrometers thick (a few millimeters length and width) and I would like to know if it was possible to refine it by separating Tin from gold?
I have 100 g to refine. 
If not refine it is less interesting when you sell it !
Thanks a lot for your help !!!


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## Lino1406 (Dec 26, 2021)

Just boil in HCl


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## galenrog (Dec 27, 2021)

Lino is right. Personally, I would take it down a notch. Warm HCl will do, but will take a bit longer. With my physical limitations, boiling acids are always a concern.

Time for more coffee.


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## Joe cocker (Dec 27, 2021)

Thanks for your reply but can you give some details? what HCl % and which quantity?
I put AuSn preforms in a ceramic up or in stainless cup ? And then in a oven or on fire ? 
Then what happened ? Tin is vaporized with HCl and gold stay in the bottom of the cup !! 
Thanks a lot !!!


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## Yggdrasil (Dec 27, 2021)

First and foremost, according to your statements above, I'd say you are not we quite ready yet. 
Read dealing with waste and search for dissolving tin.
Ideally we recommend reading C.M. Hoke's book, but at least download it from the forum and start reading it.

HCl and stainless, not good combination.
Ceramic is better but not good.

Get yourself some borosilicate beakers. Coffe machine mugs are acceptable, kind of.
When heating use a catchbasin of some kind. We recommend Corningware pyrocerams.
Glass forms for the oven can be used, but not ideal.

Use a sand bath or something to spread the heat so it is heated evenly.
All this has to be done outside or in a good fumehood.

Do it inside and you will damage all metals in the vicinity. Nails, bolts anything and everything.
A good way to "kill" your house.

When these things are in place add HCl (muriatic) is fine, heat it until it is warm 70-90 centigrade is plenty and the acid will do its thing dissolving the tin.
What is left is the gold, filter it, and if you think there are more tin do it again with fresh acid.
Dissolve the gold, precipitate, wash and melt.


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## snoman701 (Dec 27, 2021)

Melt with excess borax with an oxidizing flame.


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## Joe cocker (Dec 27, 2021)

Thanks a lot
After a few reading and video, it is seem that 20% tin is to be considered as a base material rather than as impurities …
Then shall I use HCl or Aqua regia?
The process would be:
1- put solder residual AuSn 80/20 in a becher
2- put HCl (30%) [ + nitric acid ? Or aqua Regina only)
3- heat to accelerate ??
4- filter and rinse residuals with deionized water ? (Vacuum is necessary ?)
5- precipitate gold using Sodium metabisulfite (is that right ?)
6- how to be sure all gold is precipitated? (Stannous test?)
7- keep solids (mud) by removing the liquid
8- dry on a hot plate (by adding alcohol ?)
9- melt and borax for a shiny color

Thanks for you help !


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## FrugalRefiner (Dec 27, 2021)

Joe cocker said:


> Thanks a lot
> After a few reading and video, it is seem that 20% tin is to be considered as a base material rather than as impurities …
> Then shall I use HCl or Aqua regia?


Do NOT use aqua regia. The nitric acid will turn the tin to metastannic acid which is a pain to filter. Use HCl for the first step to dissolve as much tin as possible. You may not get it all, but eliminate as much as possible.


Joe cocker said:


> The process would be:
> 1- put solder residual AuSn 80/20 in a becher
> 2- put HCl (30%) [ + nitric acid ? Or aqua Regina only)


Again, just HCl. And the combination of HCl and nitric is aqua regia, not aqua regina.


Joe cocker said:


> 3- heat to accelerate ??
> 4- filter and rinse residuals with deionized water ? (Vacuum is necessary ?)


Tap water is fine.


Joe cocker said:


> 5- precipitate gold using Sodium metabisulfite (is that right ?)
> 6- how to be sure all gold is precipitated? (Stannous test?)
> 7- keep solids (mud) by removing the liquid


Before drying it, it would be good to wash the powder/mud. No need to dry it first.


Joe cocker said:


> 8- dry on a hot plate (by adding alcohol ?)


No alcohol. Just dry the washed powder.


Joe cocker said:


> 9- melt and borax for a shiny color


You only need enough borax to glaze the dish before you put your gold in it to melt it.

Dave


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## Joe cocker (Dec 27, 2021)

Thanks Dave !
How do you clean the mud before drying it ? And how do you know that all gold is dissolve into HCl ? (Is it linked to HCl quantity and time ?)
Thanks


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## Joe cocker (Dec 28, 2021)

Hi
I don’t know if you can do that (because of properties) : do you know if there is a section dealing with AuSn refining in Hoke’s book ? 
Or if I am following the process I describe above , I have great chance of success ?


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## Yggdrasil (Dec 28, 2021)

Joe cocker said:


> Thanks Dave !
> How do you clean the mud before drying it ? And how do you know that all gold is dissolve into HCl ? (Is it linked to HCl quantity and time ?)
> Thanks


Gold do not dissolve into HCl, Tin(Sn) do.
The mud will be the gold.

If you suspect more Tin is left.
Dissolve the powder in HCl Peroxide or HCl Bleach.
Do NOT use AR, because Tin and Nitric makes metastannic acid.
After dissolving, precipitate with SMB, wash and melt.


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## Joe cocker (Dec 30, 2021)

Thanks a lot !! I am quite ready to try something but what about the quantity ? 
For example for 100 g of AuSn (80 / 20), how many HCl shall I add and then how many SMB to precipitate ? 

Thanks a lot


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## Yggdrasil (Dec 30, 2021)

Many is for things you can count and much is for things like flour, sugar and other.
Cover what you want to dissolve in HCl and heat a bit. When the reactions seem to stop add more heat or HCl.
If it then stops pour of the liquid and add more HCl.
And so on.

Edit to add.
There is no need to add SMB because what is left is the gold, it will not dissolve.

Do you actually read and understand the advice you are given?

Maybe you should study more?


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## Joe cocker (Dec 30, 2021)

you are right ! I misunderstood something!! 
I read and looked videos where it is said that gold was dissolve and then that you need SMB to precipitate ! 
Maybe it was with another alloy and/or acid ??
It is then easier !


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## Joe cocker (Dec 30, 2021)

(And in that post, Dave told me that my described process was fine …)
I am lost .. need to study more !


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## butcher (Dec 30, 2021)

Joe, if your lost, and do not understand the answers before you even begin on your journey, you will surely be lost after getting started and when things do not work the way you expect them to. then asking questions to get out of that problem, may not be as helpful as you expect if you do not understand the language or the instructions or what even to expect.

Your gold will still be there when you are ready and have spent some time to gain an understanding of the process you plan on exploring, you will still run into problems or things will happen with the chemistry that you will not understand, but with study, you will have enough understanding to work your way through the problems and find yourself out of the wilderness, and if you do need help you will understand the answers.

I have been studying and doing this for many years now, and yet I still need more study.
I learn something new or gain a better understanding almost every day.
Gaining a little understanding is like planting a seed, with that seed you planted, your skills grow tremendously, with fertilization of study, and little water of practice, you plant your skills in firm ground, and that seed flourishes and grows large.

Asking a question half understanding and you rush out and toss that seed out in poor soil without understanding what it needs to flourish or knowing how to care for it, you may not be very successful getting your seeds of gold to grow.

I can study this my whole life and only learn a very small portion of what all there is to learn.


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## Joe cocker (Dec 30, 2021)

Hello butcher! I understand the wording but information I am receiving are not going in the same way …
I just need to know if HCl 33% will dissolve the gold in AuSn (80/20) or the Tin …
Thanks again for your help


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## manorman (Dec 30, 2021)

HCI will not resolve gold, it will resolve the tin and what you have left will be gold.


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## manorman (Dec 30, 2021)

manorman said:


> HCI will not desolve gold, it will desolve the tin and what you have left will be gold.


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## Joe cocker (Dec 30, 2021)

Thanks a lot !!


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## Joe cocker (Dec 30, 2021)

I will then try this first « beginner » process:
- 50 g AuSn in a beicher
- 100 mL HCl 33%
- heat 70 degrees
- filter
- dry the powder and weight to evaluate if quantity is closed to 40 g
a- if not: re process with HCl
b- If yes: melt by adding borax in the recipient before ( a few grams?)

What do you thing about that ?

Thanks a lot


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## Joe cocker (Dec 30, 2021)

Yggdrasil said:


> Gold do not dissolve into HCl, Tin(Sn) do.
> The mud will be the gold.
> 
> If you suspect more Tin is left.
> ...


Hi Yggdrasil,
When you said that mud is gold, I thought I can directly melt this mud! But you wrote « after dissolving, precipitate with SMB.. ». Does it mean that I need to dissolve the mud in a solvent ? 
Thanks a lot


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## goldshark (Dec 30, 2021)

At 20% tin, in a button, will the HCL adequately dissolve through it? Also, will Sn adsorb into a cupel? I don't mean to jack the thread.


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## Joe cocker (Dec 31, 2021)

Hey! Happy new year ! Anyone could validate the process here above ? Can I try that or am I wrong ? 
Thanks a lot !!!!


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## kurtak (Dec 31, 2021)

Joe cocker said:


> 1- put solder residual AuSn 80/20 in a becher



If I understand this right Joe cocker is dealing with an 80/20 alloy of Au/Sn - NOT - a mix of gold - and - tin 

Like say gold powder that has tin powder mixed in with it

IF (the big if) it an alloy of Au/Sn he can not separate the tin from the gold with HCl 

So - we need to clarify - is he dealing with an alloy - or a mix of two different/separate metals

Kurt


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## kurtak (Dec 31, 2021)

manorman said:


> HCI will not resolve gold, it will dissolve the tin and what you have left will be gold.



If it's an alloy HCl will not dissolve ether the gold or the tin - at least not when the gold is at 80% & tin at 20%

If it was the other way around - 80% tin & 20% gold then yes HCl would dissolve the tin leaving gold behind

Kurt


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## Joe cocker (Dec 31, 2021)

Hi Kurtak,
Thanks for your reply! 
It is well an alloy containing 80% of gold!
Then , there is no “home process” to refine gold ?

Thanks a lot


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## kurtak (Dec 31, 2021)

Yes it can still be refined at home - because of the tin it is more difficult to refine then other gold alloys

Because causes problems that you don't normally have with other alloys it will depend on you set up, experience & understanding

Now that we know it is an alloy - we can better help you through it

Kurt


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## Joe cocker (Dec 31, 2021)

Up up ! Hope someone will be able to separate this tin from the alloy !
Thanks


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## Joe cocker (Dec 31, 2021)

Happy new year to all !!!


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## snoman701 (Dec 31, 2021)

I don't think you followed my comment about the borax. If you melt Au80/Sn20 with an excess of borax, with an oxidizing flame, you can nearly purify the Au by selectively oxidizing the SnO2.  At high temperature, SnO2 is readily soluble in the flux, leaving you with nearly pure gold.


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## goldshark (Jan 1, 2022)

Still wondering if Tin will cupel. Am almost done with my new furnace, so haven't been able to try yet. Just wondering if anybody else has tried it.


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## goldshark (Jan 1, 2022)

Snowman, do you do your process in a roasting dish (ceramic, pretreated with borax), or what? Any tell tale signs the reaction is complete? Thank you.


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## Joe cocker (Jan 1, 2022)

snoman701 said:


> I don't think you followed my comment about the borax. If you melt Au80/Sn20 with an excess of borax, with an oxidizing flame, you can nearly purify the Au by selectively oxidizing the SnO2. At high temperature, SnO2 is readily soluble in the flux, leaving you with nearly pure gold.


Thanks a lot , I understand better , I can try that !!!!


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## silver1 (Jan 1, 2022)

Try a Fizzer cell. Hcl and electricity. Both will go into solution. Drop Au with choice of percipient.


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## Joe cocker (Jan 3, 2022)

Hi all and happy new year again ,
Last question before I order the materials I need to start …
Is Sn oxidation (SnO2) with borax is the best option to separate AuSn alloy?
Thanks a lot


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## kurtak (Jan 3, 2022)

snoman701 said:


> I don't think you followed my comment about the borax. If you melt Au80/Sn20 with an excess of borax, with an oxidizing flame, you can nearly purify the Au by selectively oxidizing the SnO2. At high temperature, SnO2 is readily soluble in the flux, leaving you with nearly pure gold.


 snoman

Have you actually done this ?

I ask because I don't believe it is that simple

at best - an oxidizing flame "*on the surface*" of the molten gold will yes oxidize the tin atoms to SnO2 - BUT - ONLY the tin at the surface (which will then carry of in the borax flux/slag)

I could be wrong - but I believe in order to oxidize the Sn "*inside*" the molten gold you need to get oxidation of the tin "*inside*" the molten gold --- that is normally done by purging oxygen/air "*through*" the molten gold in order to oxidize the tin *IN* the gold thereby bring the SnO2 to the surface to be slagged off

Without purging air through the molten gold the tin IN the gold is going remain molten tin along with the molten gold & the only tin that will oxidize - by the oxidizing flame - is the tin on the surface of the molten gold --- when you hit it with the borax the borax will slag off the "surface" oxidized tin - but then the borax is also going to shield the molten metal from the oxidizing flame preventing further oxidation of tin at the surface 

Without oxidizing the tin inside the molten gold it's not going to come to the surface to be slagged off --- they normally do that by bubbling air through the molten gold --- otherwise only a trace of tin - at the surface will be oxidized & slagged off

At least that is my understanding - I could be wrong - but I believe if you don't purge air through the molten gold (or silver) it won't oxidize the base metals enough to bring them to the surface to slag off - other then the base metals at the "very" surface of the molten metal 



Joe cocker said:


> Hi all and happy new year again ,
> Last question before I order the materials I need to start …
> Is Sn oxidation (SnO2) with borax is the best option to separate AuSn alloy?
> Thanks a lot



I would wait to get a better explanation of the process

Kurt


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## orvi (Jan 3, 2022)

Joe cocker said:


> Hi all and happy new year again ,
> Last question before I order the materials I need to start …
> Is Sn oxidation (SnO2) with borax is the best option to separate AuSn alloy?
> Thanks a lot


I will recommend to chill down, read some literature about it, because it appears (from your questions and misunderstandings) that you do not have much experience in refining. Certainly try small batches (like 1-2 g).  It is always easier to recover mess from 2 g than from whole batch. Never discard anything from the reactions and refining unless you are sure that it dont contain precious metals.
In general, there is no certain guideline, which assure you with best yields and straightforward procedures which work 100% times. Refining don´t work this way  material vary from piece to piece, slightest changes make huge differences in behavior of chemical reactions. 

From this point, it is all about what is easier for you to catch/what you are more familiar with. Hydrometallurgy (dissolving in acids) or pyrometallurgy (smelting/melting/oxidizing/reducing in furnance) are quite different in many things. But your output (if everything is performed well) should be the same. 

If you opt for oxidizing tin from molten alloy, do NOT use graphite/clay-graphite/SiC-graphite crucible - graphite will reduce formed tin dioxide back to metallic tin (just eating up your crucible and not doing anything).


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## orvi (Jan 3, 2022)

kurtak said:


> snoman
> 
> Have you actually done this ?
> 
> ...


I think about this as some kind of scorification - i don´t see any major issues with this attempted process. 
Tin dioxide have very high melting point, so formed slag will be solid. Periodically crushing the formed slag on top of the molten puddle will slowly oxidize everything.
As with cupellation (which need not to be stirred), convection and diffusion will mix the molten metal anyway, and at these temperatures relatively quickly. Altough, the crust which form will need to be broken periodically, to expose fresh surface of molten metal. Not overshot the temperature (not to vaporize gold) and it should go.


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## snoman701 (Jan 3, 2022)

As was said, it's basically a scorification. It's the basis of a reverberatory furnace. 

Mixing is crucial, but my molten metals don't exactly sit in one rigid spot, they are always moving all over the place from the turbulence of the torch. 

So, have I done it with this particular alloy, no....plenty of others though. I do it most commonly with brass to get the zinc out. I doubt he'll get 999, but it'll get a majority of the tin out given enough time.

Tin oxide is particularly nasty as it's more of a refractory, so I'd expect that an addition of sodium carbonate will be necessary to thin it out. I want to say it goes to tin oxide then sodium stannate which is readily soluble, but I'm not that good with the chemistry.


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## orvi (Jan 3, 2022)

I am worried that fluxing the melt with soda or anything would cover the metal in slag, blocking the access of air to the metal surface. It could be solved by bubbling hot air through the molten puddle anyway.

"Tin oxide remains in suspension in vitreous matrix of the fired glazes, and, with its high refractive index being sufficiently different from the matrix, light is scattered, and hence increases the opacity of the glaze. The degree of dissolution increases with the firing temperature, and hence the extent of opacity diminishes.[9] Although dependant on the other constituents the solubility of tin oxide in glaze melts is generally low. Its solubility is increased by Na2, K2 and B2O3, and reduced by CaO, BaO, ZnO, Al2O3, and to a limited extent PbO.[10]"

Text from wikipedia on SnO2. Solubility in melts is generally low. But it is a different system 
I would give it a try with soda/air bubbling, and if it does not work, it will be easy to recover the button from the crucible and process it in a different way.


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## snoman701 (Jan 3, 2022)

I know I'm not the only person that melts with a cutting torch. Getting oxygen to interact at the surface of the metal is not difficult. Usually I have about 1/4" of flux on top of my melt and the oxygen jets right through it. Gotta be careful though, gotta throttle the oxygen just right or you'll blow right through the melt pool and make a mess of your melt dish.


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## snoman701 (Jan 3, 2022)

I mean, you could also add sodium nitrate to the flux if you've got adequate ventilation.


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## Noggin (Jan 3, 2022)

how ridiculous is this idea? Inquart with tin until 6k and dissolve in sodium hydroxide? I don't have enough tin around to test, it'd be interesting to hear your thoughts.


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## Yggdrasil (Jan 3, 2022)

Noggin said:


> how ridiculous is this idea? Inquart with tin until 6k and dissolve in sodium hydroxide? I don't have enough tin around to test, it'd be interesting to hear your thoughts.


Interesting angle of attack.
It would be interesting to know how the hydroxides will behave.
It seems straight forward, maybe too straightforward, which stumbling blocks are there in this approach?
I'm hoping the gurus chime in on this one.


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## butcher (Jan 4, 2022)

I would consider a fusion process.

Inquartering may not be needed depending on the thickness of the alloy.
A hammermill can reduce the size and thickness.
If quartering is needed I would consider using zinc with this proposed process.
(taking caution of the fumes or breathing of the white spider webs, night chills sick with fume fever are not any fun, but who knows it could be a cure for covid)

I would probably start off by concentrating some used copper chloride solution, evaporating the water until the solution is a thick syrup (that forms salts when cooled), adding the gold alloy thin foils or the in-quartered gold alloy. and a dose of sulfuric acid.

This process will work with an alloy silver and gold, as long as the alloy contains less than 10% copper and almost no lead...

Similar to what Hoke's book speaks of using hot concentrated sulfuric (often with a splash of nitric or nitrates) to part gold and silver. But here we are working with a fusion of salts, not an iron pan full of hot boiling sulfuric acid which if we are careful, is easier to manage and can be much safer to deal with, basically doing the same thing or work.

The little bit of sulfuric acid has a very high boiling point and will not leave the fused salts, the more volatile chlorides will give off fumes with the moisture of air will form HCl gases, converting the copper chloride salts to copper sulfate salts, in the hot fusion of these acidic salts the silver or tin (zinc if added) will dissolve from the gold (much like parting your quartered gold in nitric acid)...

Sn (s) + CuSO4 (aq) --> Cu (s) + SnSO4 (aq).

The little bit of sulfuric acid we added to our copper salts will keep the copper in the form of copper sulfate (as long as we do not roast our salts during the fusion process)...


Diluting these salts while still hot, most of the base metal sulfate will stay soluble, such as tin or zinc will stay soluble, but if silver was involved or dissolved most all of it will precipitate (as silver sulfate has low solubility in water) chloride can precipitate any remaining silver from the solution (where involved).

The salt fusion can be done in a Corningware dish on an electric solid iron burner hot plate, with a fiberglass tray under the hot plate for a catch basin.

The salts are slowly heated until they fuse to form a solid, allowed to cool the fused salts are, crushed to powder, and then heated again to complete the conversion, water then added first with a spray bottle, after well wet than by pouring water in, the idea is to keep the salts hot while rehydrating them to get them to dissolve into the water easier (the cold dry copper salts can be very difficult to get dissolved and will generate more waste solutions) wetting the copper salts hot they dissolve easier in less water and take less added heating to get them back into solution...

.


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## Yggdrasil (Jan 4, 2022)

butcher said:


> I would consider a fusion process.
> 
> Inquartering may not be needed depending on the thickness of the alloy.
> A hammermill can reduce the size and thickness.
> ...


One learns something new every day.
Thanks Butcher


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## Noggin (Jan 4, 2022)

butcher said:


> I would consider a fusion process.
> 
> Inquartering may not be needed depending on the thickness of the alloy.
> A hammermill can reduce the size and thickness.
> ...


Butcher, the claim that the alloy is 80% gold means that it's 18k. Mechanical processes like hammermills or even a roller seem like they could help if already owned. If.
Solubility of Tin Sulfate is 33g/100ml of water, which is not bad!
Zinc's solubility is even better, however dealing with any traces of zinc in a high-temp process (either decomp of the sulfate or melting of the recovered gold) will generate bad fumes, so should be done outside or in a place where fumes are managed.
According to some quick research, sodium stannate (tin and sodium hydroxide's result) is easily soluble in water. I might just try this with my next karat scrap.


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## orvi (Jan 4, 2022)

With 100 g... Maybe the AR process won´t hurt that much  filtration on Buchner with mesh underneath the paper, hour or so and its hopefully done. I process 90/10 copper tin based gold plated pins, and in AR there is no problem with tin while filtering. Traces of tin will be washed easily with sodium hydroxide solution from dropped gold. And last trace will be fluxed when melting the dropped gold with pinch of borax.


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## Noggin (Jan 4, 2022)

orvi said:


> With 100 g... Maybe the AR process won´t hurt that much  ...


Good point Orvi. It would still be nice to figure out a scalable method though!


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## Joe cocker (Jan 6, 2022)

My 2 cents if it helps to say if it is possible…
At this ratio (80%), this is an eutectic meaning that both are melting on the same time … tin is not going to become liquid before gold ….
Then is it possible to get Sn oxidized by the torch ?

Hope it helps to find the right process


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## orvi (Jan 6, 2022)

I was discussing this material with a guy where I refine metals. He said that tin is stubborn when in slag, many times forming problems due to low solubility in melts. According to him scorification should work, but will be tricky to perform. Oxy-acetylene/propane was suggested to move the metal around the crucible while baking it, not to crust the surface with forming oxide - breaking it with carbon rod frequently. Also you could try some fluxes. Burn some regular tin and try to flux the remaining oxide , basic stuff like soda should be tried. High temperature will be probably required to properly flux it - as tin dioxide is particularly insoluble in glazes and also SiO2 (with silica phase diagram shows eutectic with only 1,1% of SiO2 at 1670°C). High temperature on the other hand will vaporize gold to some extent if prolonged heating is applied.
With sucessful trial on just slag move on to the actual metal.


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## Joe cocker (Jan 16, 2022)

Hey, 

I will try that with for example 10 grs of alloy! Do I add sodium carbonate when the alloy is melt !? And how many grams ?
Thanks a lot


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## orvi (Jan 16, 2022)

Conversion and Distribution of Lead and Tin in NaOH-NaNO3 Fusion Process - Metallurgical and Materials Transactions B


Oxidizing alkali fusion process has been studied to extract amphoteric metals. Transformation and distribution behaviors of typical amphoteric metals Pb and Sn in the NaOH-NaNO3 fusion process are systemically studied by theoretical analysis and experimental verification done in this work...




link.springer.com




DOI number: 10.1007/s11663-016-0862-z

I cannot currently use sci-hub to download this article, but it seems from abstract, that it will contain some interesting info about fluxing the tin and lead metal in oxidizing NaOH/NaNO3 fluxes.


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## Abdoulapapatte (Jan 24, 2022)

Yggdrasil said:


> First and foremost, according to your statements above, I'd say you are not we quite ready yet.
> Read dealing with waste and search for dissolving tin.
> Ideally we recommend reading C.M. Hoke's book, but at least download it from the forum and start reading it.
> 
> ...


good job , just very important ,
SECURITY:
protect skin , vision, and use brosilicate 3.3 (mandatory,obligatory)
use good aeration.
use mask (more good for you)
and becarful with acide , always


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## Yggdrasil (Jan 24, 2022)

Abdoulapapatte said:


> good job , just very important ,
> SECURITY:
> protect skin , vision, and use brosilicate 3.3 (mandatory,obligatory)
> use good aeration.
> ...


There are "no" masks good for NOx or HCl. Only remedy is ventilation, preferably into a scrubber.
Besides that gloves, splash proof clothing (painters overall), face mask/goggles and such are recommended.


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## nickvc (Jan 25, 2022)

Noggin said:


> how ridiculous is this idea? Inquart with tin until 6k and dissolve in sodium hydroxide? I don't have enough tin around to test, it'd be interesting to hear your thoughts.


I like this approach but instead of lye why not use HCl which will dissolve the tin leaving the gold


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## Yggdrasil (Jan 25, 2022)

nickvc said:


> I like this approach but instead of lye why not use HCl which will dissolve the tin leaving the gold


When we are at it, why "inquart" with tin? Why not Zinc if you have it readily available.
It dissolves even easier.


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## snoman701 (Jan 25, 2022)

This is all academic right? Like, you don't think you have to refine this to get paid?


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## Noggin (Jan 28, 2022)

Yggdrasil said:


> When we are at it, why "inquart" with tin? Why not Zinc if you have it readily available.
> It dissolves even easier.


Read the original post for the answer.


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## Noggin (Jan 28, 2022)

nickvc said:


> I like this approach but instead of lye why not use HCl which will dissolve the tin leaving the gold


The discussion around avoiding Stannic acid was the reason.


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## Yggdrasil (Jan 28, 2022)

Yggdrasil said:


> Gold do not dissolve into HCl, Tin(Sn) do.
> The mud will be the gold.
> 
> If you suspect more Tin is left.
> ...


Look at bold text, if you dissolve it like this, you have to use SMB or similar.

And this was the reason I asked if you understand the advice you are given.
HCl do not dissolve gold, HCl and Peroxide or chlorine do.
Metastannic acid is the result of Nitric (AR) and tin.


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## Yggdrasil (Jan 28, 2022)

Noggin said:


> The discussion around avoiding Stannic acid was the reason.


I believe there is a serious language barrier here, and he do not understand much of the advice he was given.


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## Yggdrasil (Jan 28, 2022)

Noggin said:


> The discussion around avoiding Stannic acid was the reason.


*HCl and tin do not make metastannic acid.*


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## Yggdrasil (Jan 28, 2022)

Noggin said:


> Read the original post for the answer.


There is no thing in the original post contradicting the use of Zinc, I'm sure Zinc was not even discussed before I mentioned it as an input to "inquarting", which has no place here.

There is no part of this alloy that will warrant inquarting. The easiest would be to go directly to HCl peroxide, since it already are in "powder" form.


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## orvi (Jan 28, 2022)

Yggdrasil said:


> When we are at it, why "inquart" with tin? Why not Zinc if you have it readily available.
> It dissolves even easier.


I will only add the fact that zinc and tin do not mix very well. If you are familiar with Parkes process for recovering of silver from lead, you know that zinc is used to "extract" the silver from bulk of the molten lead - because zinc and lead do not mix.

Similarly, tin and zinc do not mix very well and you could use "Parkes-like" process to scavenge silver out of molten tin with zinc - but only to some extent, it is not nearly as effective as with lead.

Zinc will alloy with gold persumably, but you will probably get two-phase alloy - AuZn phase and AuSn phase. Maybe they form some terenary mixture, but this is only guessing  However, temperature will be the key point, as the mixing of the three components will be largely affected by temperature.
If you allow the mixture to cool slowly, phases will start to separate and you get non-homogenous crystal phases = you could possibly create quite a mess 

Inquarting with more tin and making the cornflake could work quite nicely with good strength HCl. Good surface area will be the key. Also, if you cannot get the last bit of tin out, I think it won´t be that bad - just bit of metastannic in AR workup of resulting sponge. Filters much more easily than whole 20% in the starting material 
Also, inquarting and whole preparation will be much more easy when considering quite low melting point of tin.







According to the binary phase diagram, somwhere near 300°C should be theoretically enough to create homogenous liquid phase with 25% gold. Personally I will go as high as 500°C and shot this into the ice water - very quick cooling could help retain the homogenity of the alloy.


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## Yggdrasil (Jan 28, 2022)

orvi said:


> I will only add the fact that zinc and tin do not mix very well. If you are familiar with Parkes process for recovering of silver from lead, you know that zinc is used to "extract" the silver from bulk of the molten lead - because zinc and lead do not mix.
> 
> Similarly, tin and zinc do not mix very well and you could use "Parkes-like" process to scavenge silver out of molten tin with zinc - but only to some extent, it is not nearly as effective as with lead.
> 
> ...


Thanks Orvi.
It was not a serious suggestion, just a reaction to the proposal of inquarting. Totally unnesccessary for this issue. The solder was in "micro" whisker form according to the original poster, hence HCl-H2O2 will dissolve it quite fine. Problem solved.

There are plenty challenges within refining. We don't need to create more of them.

The comments of the OP also indicates that he do not neccessarily read the advice he is given, or may have a language issue that makes it hard for him to see it clearly.

He have not replied to this.


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## orvi (Jan 28, 2022)

Yggdrasil said:


> Thanks Orvi.
> It was not a serious suggestion, just a reaction to the proposal of inquarting. Totally unnesccessary for this issue. The solder was in "micro" whisker form according to the original poster, hence HCl-H2O2 will dissolve it quite fine. Problem solved.
> 
> There are plenty challenges within refining. We don't need to create more of them.
> ...


Yeah. I know. 
But it is a good-to-know fact, and could be of interest for more people, if they intend to refine similar material somewhere in the future 
Just to prevent unpleasant findings with expensive material.

I previously advised just to use regular AR for that relatively small quantity of material. Filtering will be slow, but doable on that scale.


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## Yggdrasil (Jan 28, 2022)

I have not made metastannic acid to my knowledge, but guess there have been some present from time to time.
My feedstock has been quite suitable for HCl Peroxide so far. I just used the sledge hammer (AR) a few times.


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## Noggin (Jan 28, 2022)

Yggdrasil said:


> *HCl and tin do not make metastannic acid.*


Completely correct, and also that was NOT the reason for the discussion - I misremembered the context.
The question about inquartation /w tin was in response to some conversation about various ways to deal with tin since the source material is said to be an alloy of tin/gold. I did some research and it looked like it's possible to get better dissolution of tin in lye than HCL. Note, this was a left-field question from me, and not at all posed as advice. Further, I thought the topic was sorted, and I'm not sure why it's brought up now.


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## Yggdrasil (Jan 28, 2022)

I was also of the impression that it was sorted, then it suddenly start rolling again.


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