First I wanna take a second to say thanks to everyone on here as reading through the forums has helped out a bit already. Long time reader first time poster. Also I have read enough to first ansewer yes I did read Hoke's book and thank goodness too as I learned alot from it. I admit I didn't cling to every word but spent several hours with it.
On to the point.I have A LOT of gold leads, pins, connectors, ect from several years of saving off PC's. All leads of RAM and cards are broken off to only have the PCB with the visible gold on it. (Rest of PCB gets recycled at our electronic scrap dealer) There are also hundreds of CPU's from all eras and manufacturers thrown into the mix. Altogether I have about 20 kilos of gold scrap. (obviously much less in actual gold weight) So after reading through these forums and playing around with different scrap methods such as electroplating to reclaim copper, zinc, tin ect I decided to opt for AR to start on my gold.
I currently have two batches of approx. 500ml each Both batches have about 40 grams of scrap dissolved in them. I did not weight the scrap after the metal was eaten off as I didn't see the point. (please tell me if I am wrong)
The first batch I admit I was a little heavy handed on the nitric acid putting 150ml to about 350ml of hydrochloric acid. As expected a good reaction ensued and soon all metal was dissolved and the reaction stopped. I filtered off the solution (dark green at this point) and proceeded to add enough water to rinse the scrap and filter to top it off at about 500ml of total AR solution. Stannous chloride test shows the presence of gold but took about 45 seconds to do anything at all. Since this is my first time I am unsure as if this is good or bad. Either way at this point I decided to opt for the boil method to get rid of the nitric acid. Not to mention since I was heavy with the nitric I figured it would be the best way to do so. About 4 hours of medium heat and never bringing the solution to a rolling boil eventually yielded about 220ml of liquid. At his point I was thinking that there was no nitric acid left. Due to the lack of testing material I held a piece of gold leaf in the solution with no reaction so I am hoping this means that there is no nitric left. Precipitating the gold out is where I am stuck and I think it is because of what I am using. I bought 500ml of sodioum bisulfate but when it shows up in the mail it says sodium bisulfate monohydrate. I am unsure if the two are truly the same and after reading further and seeing that others use sodium metabisulfite I am unsure if it will even do anything. When I put the sodium bisulfate in nothing happens but that is what I was expecting. A slow process of letting it sit. I waited overnight and nothing but a very light grey dust on the bottom. I then poured it off to find that there is not brown mud
I decided to make a second batch and change a few things around this time. Stannous chloride also had about the same result. Unfortunatly this is the where I used the last of it though and can no longer test. I used approx all the same measurements as before but instead of boiling the nitric out i used urea. I added pinch by pinch until there was no fizzing or fuming left. I then added my sodium bisulfate with the exact same results with one small exception I can see really tiny gold flakes on the surface of the liquid against the beaker. There isn't alot but it definetly looks like gold. I can't fool myself though as some leaf or piece may not have dissolved and somehow made it past my paper filter. (a properly folded one too thanks to hokes
I am stuck thinking three things. Either I simply haven't broke enough gold down to see any results, I haven't gotten rid of all the nitric acid or I am simply using the wrong precipitant. I was thinking of using some copper wire to cement it out and then us nitric to get rid of the copper but before I did anything else I feel I need some advice or guidance. Please be brutal if you need to as I really want to get this perfected.
On to the point.I have A LOT of gold leads, pins, connectors, ect from several years of saving off PC's. All leads of RAM and cards are broken off to only have the PCB with the visible gold on it. (Rest of PCB gets recycled at our electronic scrap dealer) There are also hundreds of CPU's from all eras and manufacturers thrown into the mix. Altogether I have about 20 kilos of gold scrap. (obviously much less in actual gold weight) So after reading through these forums and playing around with different scrap methods such as electroplating to reclaim copper, zinc, tin ect I decided to opt for AR to start on my gold.
I currently have two batches of approx. 500ml each Both batches have about 40 grams of scrap dissolved in them. I did not weight the scrap after the metal was eaten off as I didn't see the point. (please tell me if I am wrong)
The first batch I admit I was a little heavy handed on the nitric acid putting 150ml to about 350ml of hydrochloric acid. As expected a good reaction ensued and soon all metal was dissolved and the reaction stopped. I filtered off the solution (dark green at this point) and proceeded to add enough water to rinse the scrap and filter to top it off at about 500ml of total AR solution. Stannous chloride test shows the presence of gold but took about 45 seconds to do anything at all. Since this is my first time I am unsure as if this is good or bad. Either way at this point I decided to opt for the boil method to get rid of the nitric acid. Not to mention since I was heavy with the nitric I figured it would be the best way to do so. About 4 hours of medium heat and never bringing the solution to a rolling boil eventually yielded about 220ml of liquid. At his point I was thinking that there was no nitric acid left. Due to the lack of testing material I held a piece of gold leaf in the solution with no reaction so I am hoping this means that there is no nitric left. Precipitating the gold out is where I am stuck and I think it is because of what I am using. I bought 500ml of sodioum bisulfate but when it shows up in the mail it says sodium bisulfate monohydrate. I am unsure if the two are truly the same and after reading further and seeing that others use sodium metabisulfite I am unsure if it will even do anything. When I put the sodium bisulfate in nothing happens but that is what I was expecting. A slow process of letting it sit. I waited overnight and nothing but a very light grey dust on the bottom. I then poured it off to find that there is not brown mud
I decided to make a second batch and change a few things around this time. Stannous chloride also had about the same result. Unfortunatly this is the where I used the last of it though and can no longer test. I used approx all the same measurements as before but instead of boiling the nitric out i used urea. I added pinch by pinch until there was no fizzing or fuming left. I then added my sodium bisulfate with the exact same results with one small exception I can see really tiny gold flakes on the surface of the liquid against the beaker. There isn't alot but it definetly looks like gold. I can't fool myself though as some leaf or piece may not have dissolved and somehow made it past my paper filter. (a properly folded one too thanks to hokes
I am stuck thinking three things. Either I simply haven't broke enough gold down to see any results, I haven't gotten rid of all the nitric acid or I am simply using the wrong precipitant. I was thinking of using some copper wire to cement it out and then us nitric to get rid of the copper but before I did anything else I feel I need some advice or guidance. Please be brutal if you need to as I really want to get this perfected.
