-_- lemon bleach.....

[gpoon]

Hi all,
A couple of things here. So i was finally ready to dissolve my gold foils with HCL and bleach. 10 grams of foils.
I started with 500ml of HCL and then added 50 ml of bleach. Nothing happened, so i added another 50 ml. Now the solution has gone gold but there doesn't seem to be a reduction in gold foils.

Thats when i realised the bleach was lemon scented.......

So is this because of the bleach or whats going on here?

 

[g_axelsson]

That is a lot of liquid for some foils. Have you tested the liquid to see if some gold has dissolved?

What is the content of the bleach? How many percent sodium hypochlorite?

I have only tested a few times to dissolve foils with HCl and bleach, it's a lot slower than using aqua regia, my preferred method.

What I would have done (not saying it is the correct way, just my way) is to start with a lot less acid, barely covering the foils. Then add small doses of bleach with a few minutes between while constantly stirring the foils. If new bleach doesn't produces a lot of bubbles the acid is used up. Then I pour off the excess liquid, add a bit of new acid and continue with the bleach.
This way I can work with quite concentrated liquids and as the amount of foils goes down the amount of liquid needed in the beaker also goes down.
A lot of liquid leads to quite diluted solutions and slow reactions. Which often leads to overdosing the chemicals as you don't see any obvious reactions going on.

The only time that I use bleach and HCl to dissolve gold is when I redissolve gold that dropped from a dirty solution and doesn't coalesce. When the gold is extremely fine it dissolves quickly in HCl and bleach, and the gas is quick to disappear so I don't have to do a lengthy denox when redissolving the gold. Dissolving and dropping gold that clumps together takes around 15 minutes for me and saves time in the end.

Göran

 

[gpoon]

Thanks for the reply Goran. I thought 10 grams of foils was going to over saturate the solution thus I added a bit more. The bleach is 35g/L. There definitely is some gold in the solution as it is yellow. I've added about 200 ml of bleach but there doesn't seem to be any dissolving of foils. Must have not enough of something is my guess.


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[FrugalRefiner]

As Göran suggested, allow everything to settle, then decant the liquid off the remaining foils. Then you can add some fresh acid to the foils and continue dissolving the remaining foils. Try to find some unscented bleach.

There definitely is some gold in the solution as it is yellow.

Never rely on the color to tell you there is "definitely" gold in solution. Lemonade is yellow, but there's no gold in it. To be sure, test it with stannous chloride.

Dave

 

[gpoon]

Thanks Dave, have no tin ATM, will have keep the solution and make some up later. Fingers crossed.


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[g_axelsson]

Thanks Dave, have no tin ATM, will have keep the solution and make some up later. Fingers crossed.


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Virtually anything with tin in it works to make stannous. Solder from circuit boards works just fine, banged up pewter objects also works, made my stannous from a pewter lid and it lasted for years.

Göran

 

[gpoon]

Thanks for the help guys. As suggested, I poured off the excess solution (kept it to test for gold and precipitate later), added about 100ml of HCL. Added a little UNSCENTED bleach and boom! Got the reaction I was expecting. Within 5 min, all the gold had dissolved. About 10 grams of gold dissolved in that sucker!
Now to leave it overnight then precipitate it tomorrow.


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[nickvc]

I hope you are going to filter your solution before you precipitate it.

 

[gpoon]

Doesn't look filtered but certainly is[emoji106]


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[gpoon]

Hmmmm not sure what to make of this

Stannous test of solution after gold drop. Did it twice. That color seems orange brown which would indicate platinum but there's no platinum in ram fingers and boards right?


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[Slochteren]

Looks like a false positive after adding (to much) smb

 

[gpoon]

Dang, I did feel I added a little bit too much SMB, but there's no real way to tell if you've added too much or not enough is there?
I'm guessing the waste solution is probably good to dispose of? Saltwater full of smb right? What's the safe way of disposing of this?


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[g_axelsson]

Just treat it like the waste you made when dissolving the base metals.

The way to tell if you have gold or too much SMB is to compare colors of stannous test. Use a gold standard solution and make another test so you see the color from gold and then put them side to side so you learn what to look for.

Göran