Just dropped my first gold (wanted dirty gold drop) . Where did i mess up?

[Ellias]

Hey all! Just dropped my first gold. I did not have much gold but i thought id have at least .1g from around 100g of some gold plated cleaned circuit boards.i wanted to dirty gold drop.

Here is what i did.

1. Desolder everything via desoldering tool (suction to remove more lead and tin)
2. Cleaned solder mask with lye solution
3. Cut up circuit boards and placed it all in AP solution for 2 days.
4. Mixed around 250ml hcl, 56g NaNO3 and 125 ml water to make poor man AR. (I did a stanneous test and it looked like there was quite a bit definitely noticable)
5.placed in solution until no no2 gases release
6. Added water and sulfamic acid (my solution was emerald green after adding to neutralize excess nitric)
7. Added SMB to drop gold. This is when my solution became VERY brown/black.
8. Filtered with lab grade cellulose filter.

This is my small yield.

Questions i have that you might be able to help me with.

1. After ading SMB why is my solution dark? I did not dilute with water here

2. This yield seems way to small for the stanneous test i did. Where in the process did i lose gold ir the board yields are just so small?

3. If i DID NOT spend my AR solution on metals does this affect? (Note i did another stanneous test after solution turned black and no presence of gold)

Ive added a picture of what my cleaned circuit boards might look like (pre depopulation)

 

[Ellias]

Hey all! Just dropped my first gold. I did not have much gold but i thought id have at least .1g from around 100g of some gold plated cleaned circuit boards.i wanted to dirty gold drop.

Here is what i did.

1. Desolder everything via desoldering tool (suction to remove more lead and tin)
2. Cleaned solder mask with lye solution
3. Cut up circuit boards and placed it all in AP solution for 2 days.
4. Mixed around 250ml hcl, 56g NaNO3 and 125 ml water to make poor man AR. (I did a stanneous test and it looked like there was quite a bit definitely noticable)
5.placed in solution until no no2 gases release
6. Added water and sulfamic acid (my solution was emerald green after adding to neutralize excess nitric)
7. Added SMB to drop gold. This is when my solution became VERY brown/black.
8. Filtered with lab grade cellulose filter.

This is my small yield.

Questions i have that you might be able to help me with.

1. After ading SMB why is my solution dark? I did not dilute with water here

2. This yield seems way to small for the stanneous test i did. Where in the process did i lose gold ir the board yields are just so small?

3. If i DID NOT spend my AR solution on metals does this affect? (Note i did another stanneous test after solution turned black and no presence of gold)

Ive added a picture of what my cleaned circuit boards might look like (pre depopulation)

Another note: after filteration, i added copper to liquid to see if anything else drops.

Update: nothing dropped and copper did not react...i guess my AR is fully concentrated. Ill cement my copper with iron rods now!

 

[4metals]

You are looking for a very small quantity of gold and it is easy to miss. If you are new to refining I suggest you start out with a few grams of karat gold scrap and do some familiarization experiments.

 

[Shark]

A .1 yield from that board alone is quite high. Even allowing for everything on the board (chips require different processing), it still very good and seems a bit high for the board.

 

[Ellias]

You are looking for a very small quantity of gold and it is easy to miss. If you are new to refining I suggest you start out with a few grams of karat gold scrap and do some familiarization experiments.

1.when I drop gold with SMB. Is the color okay (turned brown/black)

2.should i wait a day for gold to settle instead of filtering?

 

[Ellias]

A .1 yield from that board alone is quite high. Even allowing for everything on the board (chips require different processing), it still very good and seems a bit high for the board.

So i processed mostly things this picture attached. looked like this - i did split it in half around probably 1 - 2 pounds actually haha. I tested everything with stanneous and even my trash....it looks like good plating really is that thin.

 

[4metals]

3. Cut up circuit boards and placed it all in AP solution for 2 days.

Typically AP is to allow the gold to come away from the underplate by eroding the underplate. The gold should appear as loose foils. At this point rinsing the foils free and checking to be sure the process was complete should allow you to collect the foils on a filter and separate the mass of the circuits from the recovered foils. The AP process is a way to concentrate the gold as foils and process them separately.

The AP process should not dissolve any of the Gold.

Your next step can be poor mans nitric on a much smaller quantity of material.

 

[Shark]

56 grams of sodium nitrate in 250ml of hydrochloric is a lot. How did you deal with the excess nitric and salts?

 

[Ellias]

56 grams of sodium nitrate in 250ml of hydrochloric is a lot. How did you deal with the excess nitric and salts?

sulfamic acid - i only had to add the tinest bits since the ratio was quite good. Salts i added additional diluted water so it wouldnt bead at end.

In terms of cleanup - NAOH from the lye bath i gave to clean the solder mask

Also my HCl was 32%, not concentrated.

UPDATE:

So i now know why people say to let the gold settle overnight. My filter paper didnt not catch it at all. Ive made the mistake of trying to filter immediately after dropping SMB. I am pretty sure i lost a ton because i see small specs of floating gold in my "garbage acid" :/ oh well a hard lesson learned!

 

[eaglekeeper]

If these are ENIG (electroless nickel immersion gold) plating.... I wouldn't expect much from them.

​