Issue with e-waste, 2nd time dissolving previously dropped gold.

[DelawareDave]

Had a little issue today with some e-waste I was farther refining. This batch started with approximately 700g of gold bearing pins and connectors. A few months ago (sorry only do this when I have free time, it’s a hobby) I dissolved off all the base metals with straight nitric acid, filtered and washed this off and then dissolved the gold with Aqua Regia. The liquid was the classic gold color you would expect from dissolved gold. Drop the gold out with SMB and then it sat for probably 3 months with about a 1/2” of water over the gold powder. Finally had a chance to redissolve it, which I had a heck of a time getting it to dissolve because it’s below freezing at my house, had to apply a bit of heat. This time around there was some particles at the bottom that wouldn’t dissolve. Also before filtering I added a few ml of sulfuric acid to precipitate any lead as lead sulfate. As you can see from the picture, I ended up with a bunch of gray powder in my filter paper after filtering off the liquid, and my dissolved gold is very hazy…. Any help or insight would be greatly appreciated.

 

[Yggdrasil]

Had a little issue today with some e-waste I was farther refining. This batch started with approximately 700g of gold bearing pins and connectors. A few months ago (sorry only do this when I have free time, it’s a hobby) I dissolved off all the base metals with straight nitric acid, filtered and washed this off and then dissolved the gold with Aqua Regia. The liquid was the classic gold color you would expect from dissolved gold. Drop the gold out with SMB and then it sat for probably 3 months with about a 1/2” of water over the gold powder. Finally had a chance to redissolve it, which I had a heck of a time getting it to dissolve because it’s below freezing at my house, had to apply a bit of heat. This time around there was some particles at the bottom that wouldn’t dissolve. Also before filtering I added a few ml of sulfuric acid to precipitate any lead as lead sulfate. As you can see from the picture, I ended up with a bunch of gray powder in my filter paper after filtering off the liquid, and my dissolved gold is very hazy…. Any help or insight would be greatly appreciated.


View attachment 66585

Welcome to us.
Is this after filtering?

 

[DelawareDave]

Welcome to us.
Is this after filtering?

Yes, the beaker you see is after filtering

 

[4metals]

Your first dissolve in nitric to yield the foils should have taken care of any lead or silver, taking it into solution. Your filtrate is not very clear but from what you showed on the filter paper it seems some details are missing. Plus from less than 2 pounds of pins you are only looking for 2 grams of gold. That is a lot of spent acid for so little gold.

 

[DelawareDave]

It was only about 150ml of acids, which I know is still excessive. The picture is after diluting with a bunch of distilled water before filtering.

 

[Yggdrasil]

It was only about 150ml of acids, which I know is still excessive. The picture is after diluting with a bunch of distilled water before filtering.

Now I'm confused.
Before or after filtering.
If after, you need better filters or pass it through the same filter multiple times until it is crystal clear.
Make sure it is sufficient acidic before you precipitate the Gold.