about MBS

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hello to everybody.
I have a doubt.
Hoke and in the forum is wrote:SMB= Sodium Meta Bisulfite plus water=28.3 Grams Sodium Meta Bisulfite, 240 ml
H2O. Used to drop gold from gold bearing solutions.

o- Add 65 grams to 100 ml water for saturated solution. Add to pregnant solution
until stannous chloride test on solution is negative for gold.

I don't understand the last paragraph. I must to add 65 grams to 100 ml water in the solution I've done, or I must add 65 grams to 100 ml AR?

thanks for the reply

 

[nickvc]

Ok I have got what your asking now, you add your smb to the water in either quantity to dissolve it then you slowly add that solution to your gold bearing solution, try not to be heavy handed or you will get a false positive from your stannous test, hope this clarifies things for you.

 

[[email protected]]

thanks!!!!
there is a ratio of compound of h2o + mbs and Aqua regia?
how much ml of solution per ml of aqua regia?
I think I have had a heavy hand. The precipitate is sandy white-gray .. how can I fix it?

 

[4metals]

What type of material did you digest to make your gold solution?

Depending on what other metals are in the solution, it is possible to know when you have added enough metabisulfite by the color shift.

But while you are learning, you need to go slow and test. If your solution came down sandy white gray you likely had copper in solution and dropped copper chloride along with the gold. Rinsing the gold which is loaded up with the white copper chloride crystal with concentrated Hydrochloric acid will dissolve the copper chloride.

 

[patnor1011]

What type of material did you digest to make your gold solution?

Depending on what other metals are in the solution, it is possible to know when you have added enough metabisulfite by the color shift.

But while you are learning, you need to go slow and test. If your solution came down sandy white gray you likely had copper in solution and dropped copper chloride along with the gold. Rinsing the gold which is loaded up with the white copper chloride crystal with concentrated Hydrochloric acid will dissolve the copper chloride.

He is describing it in his other thread. He is trying to dissolve whole motherboards minus battery and aluminum capacitors. His problem is caused by metastannic acid and general lack of gold in his feedstock (volume/mass ratio).