black chips containing gold and silver

[arthur kierski]

i incinerate these chips and then make a fine powder of these chips-----this fine powder ,i treat with nitric and extract ag from the solution.
to the powder left i add ar and extract the gold with smb.
the problem that i need help is?the gold extracted is lets suppose, 10grams.When i repurify these 10grams of gold,it becomes 7grams and 3grams of a grey material stays in the filter paper---what is the use of using nitric to eliminate base metals if it does not eliminate all and when using ar the gold that comes down(10grams)becomes 7grams on repurification?
this diference 3grams is a lot of gold(30%)------with the 3 grams of grey powder which i suspect of having gold i try many things, like washing with hcl and then ar ----without results

 

[nickvc]

Aurtur I'm no genius when it comes to e scrap but I had one thought, do you heat your AR when you extract your gold? I'm wondering if you do whether you are dissolving other metals Pt perhaps or one one of the other rare metals. If I'm wrong which I probably am I,ll shut up and let the experts have their say, no doubt one of the members has encountered this before and give you the right answer.

 

[arthur kierski]

nickvc,i heat the ar and after adding smb and precipitating the gold,i make a stanous test to see if any pms is left in the solution--
thanks for the reply
Arthur

 

[Barren Realms 007]

Did you run your material thru ammonia to remove the silver chloride that might have developed?

 

[arthur kierski]

yes barren i run the powder with ammonia to dissolve any posible agcl present

 

[nickvc]

Arthur as you heated the AR when you dissolved your gold try using hot AR to wash the grey residue and if it dissolves test it with stannous that might give you some answers.

 

[qst42know]

Before you drop the gold Is your AR solution, clarified by filtration or by settling overnight?

 

[arthur kierski]

qst,before dropping gold with smb,i filtrate the solution-----

 

[arthur kierski]

nickvc,i tried using ar on the grey powder and the powder remains the same weight and no gold comes out----

 

[nickvc]

nickvc,i tried using ar on the grey powder and the powder remains the same weight and no gold comes out----

Have you heated the AR with the powder in ? Just a thought if you can get it to dissolve you can test it.

 

[qst42know]

I'm no chemist so this is just a guess. Much of this is from the wiki for barium sulfate.

Barium sulfate is used in plastics as a thickener and is largely insoluble. However when incinerated with carbon (from the plastics) becomes barium sulfide which is soluble. Barium sulfide exposed to SO2 reverts back to the insoluble sulfate.

Barium sulfate is soluble in concentrated sulfuric acid. You might try some of your grey powder in HSO4.

Let me know if I guessed well. :mrgreen:

 

[arthur kierski]

qst,i will try with conc h2so4 and then i let you know
thanks for the tip
Arthur

 

[qst42know]

I know I've seen this list posted to the forum a while back, or one very much like it.

http://www.prospectorsparadise.com/html/solubility.html

It is very possible from incinerated chip pulp you have a few of these insolubles in your grey powder from the addition of SMB.