How do you deal with the sludge created from IC chip powder?

[GolDRoger]

I have successfully extracted gold from gold fingers from RAM. However, I am having difficulty dealing with the sludge created when processing IC chips.

Here is my process:
1. Burn IC chips till they turn ash grey
2. Grind them to powder
3. Wash the powder 5~6 times. A lot of sludge is formed during the step
4. Dissolve the sludge using aqua regia (300ml hcl + 100ml hno3)
5. Start the filteration process after 24 hours
6. The sludge seems to prevent the liquid being filtered (I am using a cotton filter for the process)

What part am I missing here?
Do I need to wash away the sludge as well or use specific type of filtering equipment?

 

[Yggdrasil]

I have successfully extracted gold from gold fingers from RAM. However, I am having difficulty dealing with the sludge created when processing IC chips.

Here is my process:
1. Burn IC chips till they turn ash grey
2. Grind them to powder
3. Wash the powder 5~6 times. A lot of sludge is formed during the step
4. Dissolve the sludge using aqua regia (300ml hcl + 100ml hno3)
5. Start the filteration process after 24 hours
6. The sludge seems to prevent the liquid being filtered (I am using a cotton filter for the process)

What part am I missing here?
Do I need to wash away the sludge as well or use specific type of filtering equipment?

First, if there are Carbon left after incineration, some Gold may be bound up by it.
For best result the powders should be concentrated by gravity.
Then if it was not pre leached by HCl to remove Tin it should go through a HCl wash before it is subjected to any Nitric.
How much material are we talking about here?
Did you do the studies we recommended?