stannous chloride test time lag?

[Justincase]

I have just just finished my latest batch and am in the process of washing my AU .
It look's lovely thanks to you chaps,Thank you.
And I tested my S.M.B. and wast solution ,it had a slight blue ting which was a good sign that I had dropped my desired substance and left the rest in solution.
The stannous chloride did not give a color change and I waited a full ten minutes before dumping the wast as valueless.
Ran up stairs for half an hour to do some paper work and when I came back found that I had had a reaction on the spot plate.
It is a very week reaction but it is a reaction so I have obviously thrown some AU away.And I will never know how much which is what really gets' me I would have liked to have known how hard to kick my self..
From now on I will try a second drop with Ferrous Sulphate on wast just to be sure ,but I was just wondering how long a delayed reaction I should look out for in the future.
little damper on a 99.9% success I will have to wait to find out how meany impurity's I managed to eliminate.
Thanks All.

 

[kurtak]

Justin

You should "always" send your solutions to the stock pot after you are done precipitating - then use copper in your stock pot to cement out any trace values that may not have dropped when you precipitated --- that is what the stock pot is for - it your insurance that no trace values are lost

Kurt

 

[Justincase]

Yes I do keep some stock pot's but try to only put wast into them when I think they might contain some value.
I had not realized that the stanntous test was lightly to take so long before presenting it's self or I would not have put it in my final standing tank.(Old steel and two months worth of gunk left over from my silver )Any one know how to get one part Au per billion of gunk sorted out.LOL
I will have to add an other one to my collection.
Thanks Kurt

 

[g_axelsson]

When precipitating gold it can take a long time for that last fine gold to settle. I always use the stock pot for any solution that I've precipitated gold from. Also for the acid and water washes, after an ammonia wash I always adjust the stock pot pH back to acidic if needed. The stock pot will also catch any PGM:s that's coming with the gold.
That way I catch the fine gold and I can be quite aggressive in my washing without loosing any gold, I only misplace it for a while.

The gold that precipitated but didn't settle in time is not detectable with stannous so there could be small amounts of invisible gold floating around in the liquid after the drop, so the stock pot is a great way to catch it... it will add up in the end.

If you want to get an idea about how much gold is in your solution, you can prepare a standard gold solution with a known amount of gold. Take a small sample of that and dilute it until you get the same reaction as in your unknown solution, then you can calculate the concentration in your unknown solution.

Göran

 

[Pantherlikher]

"I waited a full ten minutes before dumping the wast as valueless."

Wow... no one caught this sentence? Dumped the waste to where?. Down the drain? The ground? Where do you Dump your waste?
Everything should go into the stock pot and run down the line till you raise the PH and drop everything and then lower the PH some to make sure and to create Salt water which can then be safely disposed of...Never dumped...

Any way...
After the initial drop and pour off, you might leave the solution sit for a day or 2. You will most likely see something at the bottom as it can take a long time for eveything to drop and then settle out of solution.
This is a good reason for the stock pot as well to catch anything.

B.S.

 

[Justincase]

Yes I did leave it 24hrs before decanting.
and no I did not dump it down the drain.
It went into my standing tank with old iron,I have not neutralized this present tank yet but I do neutralize and and settle before the liquid is put into the drainage system.
The solid is dried to a crisp and will eventually got to land fill.
As specified by one of my consultants so as to make sure I was up to U.K. guidelines.

"As regards the waste waters, as long as you alkalise the waste to pH 9 – 10 (using a master NaOH solution but not NH3) there’s basically nothing that can stay in solution, except the non-toxic alkali and earth alkali metal cations. Any residual heavy metals precipitate as oxides or hydroxides. Allow the alkalised waste to stand overnight, decant or filter off any solid residue and your water is good to go into the main drains. The solid waste will be small in volume and can go with non-recyclable waste (landfill).
Best regs,
Gert Meyers,Oxford ChemServe ."

I hope that was up to expectation's I looked into that point first before I even found this forum and made sure it was up to scratch.
Was just looking for conformation on the expected time delay's with Stannious test.
O well insight is much like AU it some time's requires you move a lot of dirt in order to find any thing of value.

 

[niteliteone]

Where do you collect the traces of gold and PGM's that did not drop with the SMB :?: :shock:
How much in values have gone to the trash from an improper recovery and disposal process :?:
That is the whole purpose of the stock pot and dropping those traces with "Copper" not iron, from the stock pot. Then the liquid goes on to the treatment process where iron drops base metals and then ph adjustments, before disposal.

 

[Pantherlikher]

I just wanted clearification for future newbies to see that "dump" is not in our vocabulary.
Thanks

Take any solids in your "iron pot" and begin your new stock pot system.
Put it in the first pot and eventually base metals will be removed which is ment to be copper to drop any PMs. Might take a long time depending on how much solution you use but you'll at least be sure you did not miss anything.
Then move solution into the iron pot to drop copper and anything under it. Then on to the PH adjustments to drop anything and everything to render solution non toxic.

Since I do not do alot of stuff, I don't have alot of spent solution. So I let the stock pots sit for long periods. A week or so which also allows for evaporation, less volume.

I lock my shed when I'm not inside working so it's secure and has a fan in 1 window with all solutions and work area very near an outlet window.
I do have an experiment where the draft flows nicely out the window but I have broken VCRs and DVD players all around the shed. I'll take pictures when the weather lets me get started again to see what damage CL can do. It currently looks like I put them outside in the weather for 2 weeks. Not bad but no longer usuable.

B.S.