Stannous chloride testing

[Jazzy]

Hi guys,

I am in the process of precipitating gold from a stack of scrap computer parts.

I am up to the stage where I have liquidfied the gold using HCL and a dash of bleach and no traces of the gold foils remain.

I have added a couple of teaspoons of Sodium Metabisulfite and it seems that things are precipitating well with a fair bit of black powder forming at the bottom of the beaker.

I am completely new to all of this, so it has been a bit of trial and error. But so far so good, I think.

I bought some stannous chloride power (which I received today) and mixed 0.3 gm to 10 ml of HCL and heated for about ten minutes (as per information I have found on this site - no instructions came with the powder itself).

I just tested the solution that has been precipitating for a few days and it gives a strong dark indication on some filter paper.

My question is, can this test indicate a false positive with other elements/chemicals, or is this a clear cut sign that there is more gold to precipitate?

Again, first time doing this and chemistry wasn't a subject that I studied many decades ago in High School. SO hopefully this doesn't come across as a silly question.

Thanks in advance.

 

[butcher]

The reaction should be a violet color.

if precipitating gold from dirty (copper or base metal-rich) solutions, adding too much sodium metabisulfite can reduce other metal ions like copper II to form a brown reaction of copper I chloride...

 

[Jazzy]

Ah ok. That's good to know.

I'll do another test in the morning. There is no doubt going to be copper in the solution given the origin of the material.

Will letting the precipitate sit in HCL break down the copper again leaving just the gold precipitant? Or is there something else I need to do to make sure I am left with just the gold particles?

Thanks again.

 

[butcher]

Are you refining gold or are you refining copper?
What method did you use to recover your gold and get it pure enough to refine?




if you working with a material and the majority of the material is copper and other base metals with very little gold you are in the copper refining business, trying to recover a little bit of gold.

If you are working with a high percentage of gold and almost no base metals we are in the gold refining business.

We recover gold before attempting to refine it, basically trying to eliminate troublesome metals like tin and the other majority of base metals like copper.

You do not refine gold from dirty solutions loaded to the hilt with base metals, we recover gold from them, and then refine the recovered gold.

a very good tool to use for the recovery of gold is the displacement reaction, as we can see by viewing the chart of the reactivity series of metals, copper will displace, gold, silver, and the platinum group metals from solution which may contain these metals, making cementing with copper a great recovery tool.

 

[rickzeien]

Are you refining gold or are you refining copper?
What method did you use to recover your gold and get it pure enough to refine?




if you working with a material and the majority of the material is copper and other base metals with very little gold you are in the copper refining business, trying to recover a little bit of gold.

If you are working with a high percentage of gold and almost no base metals we are in the gold refining business.

We recover gold before attempting to refine it, basically trying to eliminate troublesome metals like tin and the other majority of base metals like copper.

You do not refine gold from dirty solutions loaded to the hilt with base metals, we recover gold from them, and then refine the recovered gold.

a very good tool to use for the recovery of gold is the displacement reaction, as we can see by viewing the chart of the reactivity series of metals, copper will displace, gold, silver, and the platinum group metals from solution which may contain these metals, making cementing with copper a great recovery tool.

Speaking of gold. There is quite a bit of pure gold in your post. Very well written and explained. Thanks

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[Jazzy]

Hi @Butcher,

I am trying to recover a small amount of gold from material that is predominantly other materials.

What I have done so far.

• 100gm of scrap material (fairly dirty, as in lead copper and who knows what)
  300ml of HCL
  50ml of Hydrogen Peroxide
  Sit of a week or so stirring frequently
  Filter the solid rubbish through a fine strainer
  Filter the gold foils with filter paper

Then the next step

• Place the gold foils including filter paper in to about 250ml of HCL
  Add a small dash of bleach and stir
  Leave to stand for a few minutes
  If there are foils remaining add another tiny dash of bleach
  By then all of the gold appears to have dissolved
  Left for a day (was called away)
  Filter again leaving a nice clear liquid
  Add sodium metabisulphite

This is where I may have been heavy handed with the sodium metabisulphite, as I didn't know how quick it is to precipitate. Maybe six teaspoons or so.

But definitely getting a reasonable amount of black power forming at the bottom of the solution.

How am I doing so far?

 

[butcher]

Basically, it sounds good, you are using a cupric chloride leaching process to recover your gold, eliminating most of the tin and base metals as you can with the methods your using, well then it sounds like you are getting into the gold refining business.


I do not like the description of your cupric chloride leaching process, you do not want to dissolve any gold with tin in solution, the tin will reduce the gold to colloids, basically locking the gold into solution with no way to test for it and making it a nightmare to recover, the hydrogen peroxide is only used to jump-start the reaction to get just a little bit of copper II chloride in solution, it is the cupric chloride which dissolves the metals, converting it to cuprous chloride, introducing air with a fish tank air compressor, sometimes small additions of HCl will convert the cuprous chloride back to cupric chloride ready to dissolve more metals below copper in the reactivity series...

You are new to this, there are many small details that will trip you up along the way, that's life, the more you understand the more educated you will become in what to expect and how to proceed, gaining skills to assist you in troubleshooting problems as they arise, as they will, and the knowledge of how to recover from the problems, through your education, you will also gain a better understanding of the chemical processes and how and why they work, giving you more of an understanding of what you can and cannot see.

My guess is you are getting a (brown) false reaction in the stannous chloride test for gold, if it is dark you could try diluting it and see if it is violet for gold or not.

We can also test for gold using ferrous sulfate crystals (which you can make yourself) in a spot plate...

The black powder is gold reduced from a dirty (base metal-rich) solution, which will need refined again.

Any gold left in the solution can be displaced (cemented) from solution with copper, before removing the copper from solution and properly treating it for waste disposal...

 

[Jazzy]

Thanks mate. Awesome information!

Yes, I am very new to this. Already made plenty of mistakes that I wouldn't do again, mainly rushing things and trying to filter too fast, etc...

One thing I have learned is that patience is key (obviously safety being paramount).

Got a few batches on the go, so I'll accumulate the black precipitate together in the next couple of weeks and see if we can work out the best strategy to properly purify the contents.

Will post some pic's of the current stannous tests shortly anyway. No doubt the expert eyes around here will be able to identify if they look normal or not.

Thanks again BTW. Great information!


[edit]
Pic of the stannous test.




Looks black in the photo, but is actually a very dark brown. So no idea what that is telling me.

Gold may have all been precipitated out though with the SMB. Would too much SMB give this sort of indicator?

I found this pic on another thread to use as a reference.




Admittedly I didn't to a test before precipitating as my powder did not arrive until yesterday.

 

[Jazzy]

Oh and just for clarification this is all for learning / hobby purposes. I am not intending to get rich quick here :lol:

If I can come away with a sub-gram piece of gold, that would be fantastic.

It is more the learning process that I find fascinating.


[edit]
Just did another small test batch, so I can see how the SC test goes (before the addition of bleach) and I do in fact get a nice purple result, albeit faint.

 

[anachronism]

Oh and just for clarification this is all for learning / hobby purposes. I am not intending to get rich quick here :lol:

If I can come away with a sub-gram piece of gold, that would be fantastic.

It is more the learning process that I find fascinating.


[edit]
Just did another small test batch, so I can see how the SC test goes (before the addition of bleach) and I do in fact get a nice purple result, albeit faint.

From the way you posted so you think there is something wrong or to be ashamed of if you were looking to get rich here? 8) 8)

 

[Jazzy]

Oh and just for clarification this is all for learning / hobby purposes. I am not intending to get rich quick here :lol:

If I can come away with a sub-gram piece of gold, that would be fantastic.

It is more the learning process that I find fascinating.


[edit]
Just did another small test batch, so I can see how the SC test goes (before the addition of bleach) and I do in fact get a nice purple result, albeit faint.

From the way you posted so you think there is something wrong or to be ashamed of if you were looking to get rich here? 8) 8)

Not at all. Each to their own.

 

[Shark]

Nothing wrong with getting rich. I am working on my 5th million dollars. I gave up on the first 4. :lol: :lol:

 

[rickzeien]

Nothing wrong with getting rich. I am working on my 5th million dollars. I gave up on the first 4. [emoji38] [emoji14] [emoji38]

They say the 1 million is the hardest to make. Each million after that apparently gets easier.

So I'd say your plan is solid. Give er up on the hard ones and go for the easier ones.

As they say across the pond "brilliant!"

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