Hi All,
Applogies for the long post. I just wanted to give as much information as possible so the veterans here can better help.
So I came across a new kind of e-waste a work that appears to have gold connectors and fingers on them. They're this kind of cassette were the circuits and PMs seem to be somehow electroplated into this plastic sticker material that is then placed onto a black plastic board for single-use as a consumable. Here's a picture for reference:
Figuring I'd give it a go since it looked like pretty clean e-waste I took the following steps.
At this point, I wrapped up for the night and let the aqua regia sit. The next morning the solution appear to be a bit more a greenish color but will with yellow (I suspected copper contamination). I carried on as usually adding SMB with gentle heat and stir until the bubbles producing by whipping up the solution with a stir rod where no longer yellow. However, at this point the solution was still yellow (now with visible precipitate at the bottom of the beaker). Just to make sure I got all of the gold out of the solution, I tested with stannous chloride, and this mustard yellow precipitate formed in the spot plate with a fowl smelling gas. Thinking that there may still be gold in the solution, I continued adding SMB until the solution was clear and I started to see more precipitate forming at the bottom of the flask. After the solution was completely clear, and adding SMB no longer produced any reaction, I tested again with stannous chloride, and this mustard yellow precipitate formed in the spot plate with a fowl smelling gas.
I know my stannous works since the spot on a piece of paper was a pale purple when I tested after step five. What would this yellow precipitate be?
Applogies for the long post. I just wanted to give as much information as possible so the veterans here can better help.
So I came across a new kind of e-waste a work that appears to have gold connectors and fingers on them. They're this kind of cassette were the circuits and PMs seem to be somehow electroplated into this plastic sticker material that is then placed onto a black plastic board for single-use as a consumable. Here's a picture for reference:
Figuring I'd give it a go since it looked like pretty clean e-waste I took the following steps.
- Removed all the stickers with the PMs off the plastic cassette boards.
- Placed all the plastic stickers with the PM in Nitric acid and let it sit with a stir bar mixing overnight. (The following morning the solution as pale green and there appeared to be gold foils floating in the solution...all normal). However, I did notice that where the gold plating used to be, there appeared to be this silver-like shinny stuff in the same electroplated patten as where the gold was. Not giving it much thought, I gave the mixture a bit of heat with gentile stir and an hour later all that was left was plastic and this flaky brown crud that looked and felt like plastic, and the gold foils floating in solution.
- Filtered the liquid with a very fine lab-grade filter paper. (all of this done in a chem lab with a proper fume good...benefits of working in a chemistry lab
) - Placed the filter paper with the gold foils and plastic filtrate into a new beaker with just enough HCL to cover the material and incrementally dossed with Nitic Acid on very low heat and gentle stir until all the gold foils were gone.
- Filtered aqua regia with fine filter paper. The resulting liquid was a very pale yellow.
- Tested the solution with a spot test on a paper towel with some stannous chloride. While there was no reaction initially, after about a minute, a royal purple color developed on the spot, so I figured it as a just a very low concentration of gold in solution since this was just a test run.
At this point, I wrapped up for the night and let the aqua regia sit. The next morning the solution appear to be a bit more a greenish color but will with yellow (I suspected copper contamination). I carried on as usually adding SMB with gentle heat and stir until the bubbles producing by whipping up the solution with a stir rod where no longer yellow. However, at this point the solution was still yellow (now with visible precipitate at the bottom of the beaker). Just to make sure I got all of the gold out of the solution, I tested with stannous chloride, and this mustard yellow precipitate formed in the spot plate with a fowl smelling gas. Thinking that there may still be gold in the solution, I continued adding SMB until the solution was clear and I started to see more precipitate forming at the bottom of the flask. After the solution was completely clear, and adding SMB no longer produced any reaction, I tested again with stannous chloride, and this mustard yellow precipitate formed in the spot plate with a fowl smelling gas.
I know my stannous works since the spot on a piece of paper was a pale purple when I tested after step five. What would this yellow precipitate be?
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