Aqua Regia +deionized water ?

[amon13]

Hello i need help with this case:
I decided to run small experiment with ic chips- 2000 pieces SN74S112AN to recover the gold
Device Mass (mg) -1,207.8
Au (mg)-0.0593
The first step was to incinerate them after this i crushed them to fine powder then i take care of the magnetic pieces with a magnet.
After this i made 2 washes with clean water in a plastic bucket.
Adding 200 ml NHO3 in the bucket with the powder to deal with the base metals.
After this 2 water washes and incineration.
Then adding 200 ml HCL again 2 water washes and incineration.
After i prepear the Aqua regia- 60 ml NHO3 and 180 ml HCL and i put ii in to the bucket after the reaction i put urea disolved in 100ml water to eliminate the exces nitric.
Then i filter the solution and test with stanous - was positive for gold - after this adding sodium metabisulfite to precipitating the gold but nothings happened
AND I DECIDE TO ADD some water to make the precipitant work better But i DECIDE TO TRY WITH - deionized water (I think that deionized water was more clear then regular water and will be good for this procedure) The precipitating was white substance like goo. After this i test the solution-No gold indicated
So this is the result:

 

[maynman1751]

That's a good one! De-ionized water could contain traces of the de-ionizing resins. Maybe??? that's what you're seeing. I sure don't see why using that water would cause trouble. Wait for a more experienced member to chime in on this one. Good Luck!

 

[nickvc]

Looking at your photos it appears you have some brown material floating on the surface of your solution, this could be your gold.

 

[amon13]

Looking at your photos it appears you have some brown material floating on the surface of your solution, this could be your gold.

Its white - no brown material

 

[butcher]

The solution of aqua regia containing gold (even dilute) would be more yellow, or at least have more color yours looks like dirty water to me, the white could be silver chloride but I would not expect it to float, so it may not be.

The stannous chloride test is very sensitive, it will detect even very small traces of gold in solution, and there is also a false positive from using too much SMB.

At this point if this were my solution I would make sure it was acidic and cement any values out of solution using copper, and check the other material and solutions for gold that were used or came from this process.

Also are you sure the flip-flop integrated circuits contained gold to begin with?

 

[amon13]

The solution of aqua regia containing gold (even dilute) would be more yellow, or at least have more color yours looks like dirty water to me, the white could be silver chloride but I would not expect it to float, so it may not be.

The stannous chloride test is very sensitive, it will detect even very small traces of gold in solution, and there is also a false positive from using too much SMB.

At this point if this were my solution I would make sure it was acidic and cement any values out of solution using copper, and check the other material and solutions for gold that were used or came from this process.

Also are you sure the flip-flop integrated circuits contained gold to begin with?

Thank you butcher for the response .Yes im sure that ic's contains gold because i refine 2000 pieces of this ic's previously but i dilute the solution with regular water not like in this case with deionized water -the result was 0.9 g

 

[amon13]

OK the proble resolved :idea: -i filtered the solution the put it on a hot plate for 45min (medium temperature-just before boiling)
the solution turn yelow-red i let it to cool a bit after this more SMB and after 120min the precipitation lying on the bottom.I check the white sustance -no idicates for gold.
maybe the deionized water was not the worse problem by the exces nitric in the solution.
Maybe the Urea that i used is not good enough to "kill" the nitric.

SO the conclusion for me is that the deionized water must be avoid. :!:

Thanks to everyone's.