# mixing stannous chloride



## goldpete (Jul 3, 2012)

i have seen so much on the net about how to make tannous chloride but nothing about how to mix it when bought from chemical supplier.

i bought stannous chloride and it came in crystal form . i want to make it into a testing solution .
ive tried so many ways and had no luck.
some of the ways ive tried are : 2 gms with 30ml of hcl
8 gm with 100ml hcl
6 gms with 30 ml distilled water
equal amounts of stannous crystals with distilled water 

nothing is working , and i know i have gold in the solution im wanting to test , can someone please help me


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## jimdoc (Jul 3, 2012)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=2082&p=17541&hilit=stannous#p17541


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## BAMGOLD (Jul 3, 2012)

Maybe you don't really have gold in your solution? or you really don't have SMB in the end.......?


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## butcher (Jul 4, 2012)

goldpete,

Make up a small portion of stannous chloride; you will not need much few drops of the solution in a test tube. 

In another test tube make up a small gold standard solution a few shavings of gold dissolve in your choice of reagents, now you know from reading Hokes book this gold solution will need the oxidizer removed, so if you dissolved the gold in aqua regia, you will use the evaporation process to rid the gold chloride solution of nitric acid (oxidizer), this is a labor intensive process even in the test tube, Now if you used hydrochloric acid and sodium hypochlorite (bleach) to dissolve the gold in the test tube, the chlorine gas (oxidizer) is much easier to remove heating the test tube the gas will not stay in solution, now that we removed the oxidizer our gold will not re-dissolve in our test as we are trying to reduce it.

A spot plate (white porcelain dish with small wells), a white porcelain (or plastic) spoon, or Q-tips, or filter paper can be used in the test.

A couple of drops of the gold standard solution, in your spot plate or a wet spot on Q-tip or filter paper, then apply a drop of the stannous chloride solution you should see the purple of cassius color, a positive indication gold is in this solution which has been reduced by the tin chloride to colloidal metal particles of gold floating in solution that reflect this pretty violet color.

If you did not remove the oxidizer (we discussed earlier) you may see the gold try to reduce when you add the stannous chloride (a flash of purple that disappears) or it may not show violet at all, as the oxidizer will just re-dissolve your gold in the test and then you will not see the metal gold violet color.

Stannous chloride has a fairly short shelf life, so make up fresh batch, as needed, the use of a gold standard is handy to check your stannous solution to see if it is still good.

Gold is not the only metal that colors a solution yellow; iron can look just like gold in solution, (you can test for iron in solution you will read about that in Hoke's book when you get to about page 100).

Doing the getting acquainted experiments as you read Hoke’s book you will learn all of this and more. Reading her book and doing those experiments is what you need to learn from, she explains this better than I can in an answer to your question in a post.

You are doing a good job of starting off learning to use the test solutions, just keep your eyes in that Hoke’s book and you will do fine.


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## goldpete (Jul 4, 2012)

thankyou so much to everyone who replied , i really appreciate it.

i have now read hokes book and the comments that people have given me , and im now a little confused about two things.

1) in the book it says that AR is made up of 1 part nitric and 4 parts hcl . but in all the readings and videos ive seen it made 3:1 .
which is the right mixture ?

and 2) can chlorine or bleach be used instead of nitric ? , if so it would be much cheaper for me as nitric is expensive . is the mix the same and nitric ?


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## nickvc (Jul 5, 2012)

Well done on reading Hoke I'm sure it's answered many questions and has prompted a few more.
The making of AR is really not that critical, by which I mean that the amount of hydrochloric you use is not going to cause problems if you use too much but over use of nitric does and will cause problems as your gold won't precipitate if you still have nitric in your solution. The best way to dissolve your values is to work out how much acids your going to need and add all the hydrochloric to your beaker and then add the nitric slowly while heating and wait till all reaction has stopped before adding more if needed, it's always a good idea to add a little more hydrochloric when the reaction stops just to make sure you have an excess and the reaction hasn't stopped because there is no free hydrochloric in your solution.
Yes you can use bleach instead of nitric but it works best on small particles or foils and the one advantage it has is that it's easy to remove any excess by heating because again if you still have free chlorine in your solution the gold will not precipitate.


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## goldpete (Jul 6, 2012)

ok ive read the book twice , skipping through the sections that dont apply to what ime doing.
ive removed basemetals in nitric
ive filtered and then used AR.
ive filtered that and ended up with a deep yellow liquid.
ive then heated that to atleast a third of its original volume to remove the nitric acid.

now i think im ready to precipitate with smb . can someone tell me the next step


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## goldpete (Jul 6, 2012)

goldpete said:


> ok ive read the book twice , skipping through the sections that dont apply to what ime doing.
> ive removed basemetals in nitric
> ive filtered and then used AR.
> ive filtered that and ended up with a deep yellow liquid.
> ...


i should note that my source oof gold is from cell phones and computer parts , so im mostly dealing with gold flake
the reason im asking on here for the next step is because the book talks about using copperas , i only have mbs


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## gold4mike (Jul 6, 2012)

Pete,

If you have excess nitric simply evaporating it to a third of its original volume is probably not enough to expel the nitric.

You need to evaporate it down to a "syrup" consistency, then add some HCl. You'll notice the brown vapors as nitric is expelled. Evaporate again, add HCl. Repeat until you no longer see brown vapors upon the addition of HCl.

Then add to water to increase volume and add precipitant.


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## goldpete (Jul 6, 2012)

gold4mike said:


> Pete,
> 
> If you have excess nitric simply evaporating it to a third of its original volume is probably not enough to expel the nitric.
> 
> ...


thanks for your advice , i hope i boiled it long enough , ive attatched a pic of when i started boiling , you can see how much i began with.
and i boiled it till i only had about 10mm in the bottom of the pot. it became so concentrated that the colour changed and became darker till i added the hcl then it went back to the colour i started with


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## martyn111 (Jul 6, 2012)

goldpete said:


> gold4mike said:
> 
> 
> > Pete,
> ...



Goldpete, we strive to us correct terminology on the forum, please don't take offence at me pointing this out to you.
Note how gold4mike worded the post before yours, the word boiling wasn't used although 'evaporate' was.
Boiling will cause your solution to spatter as the bubbles rise through it and burst on the surface, promoting the loss of values. Your aim should be to reduce the volume of your solution by gently evaporating the excess liquid out of your container rather than splashing it and your values all around your work area. 
Looking at your pictures it does appear that you possibly have 'boiled' your solution, it looks like the solution has run down the outside of your beaker and onto your hot plate. Not only is this wasting your values but it will also serve to shorten the working life of your equipment.


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## BAMGOLD (Jul 6, 2012)

Can't you add urea to neutralize the excess nitric?


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## martyn111 (Jul 6, 2012)

BAMGOLD said:


> Can't you add urea to neutralize the excess nitric?


Yes you can, but, it isn't the recommended method on the forum. The reason being you spend an awful lot of time and effort refining your gold and then go and add something that has the potential to contaminate it all over again.


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## goldpete (Jul 6, 2012)

martyn111 said:


> goldpete said:
> 
> 
> > gold4mike said:
> ...




great point and i didnt take offence . thanks for your input ..... yes i did have the heat up a little too high but the staining you see was from earlier attempts when i didnt know what i was doing , not from yesterday . my reason for having it so hot was i was trying to hurry because rain was forecast and its going to rain for a week lol. but i understand what your saying and there is no excuse for being impatient , my bad............ thanks again for your input


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## martyn111 (Jul 7, 2012)

goldpete said:


> great point and i didnt take offence . thanks for your input ..... yes i did have the heat up a little too high but the staining you see was from earlier attempts when i didnt know what i was doing , not from yesterday . my reason for having it so hot was i was trying to hurry because rain was forecast and its going to rain for a week lol. but i understand what your saying and there is no excuse for being impatient , my bad............ thanks again for your input



Glad you took the advice as intended, hopefully future newcomers can also benefit from it when reading this thread.
At the end of the day that is what this forum is about, helping each other by advising when we see something thats not quite right so everyone can work in safety and improve their yields.


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