Step by step instructions for AP processing circuit boards

[ssmontecarlo]

While this is true, if you have any concerns about re-using your AP solutions processing them separately can make a difference. This was pointed out in this thread.

I am hoping this thread will continue on to re-using and recovery of AP wastes.

Question. I re-used the AP solution two days ago. The AP solution I re-used was used on magnetic gold pins prior. I put the solution on more magnetic pins. I had the other pins in a bucket, still just covered with the " magnetic AP solution ". They still had some gold on them. They also were turning black. The new batch of pins, I filtered the gold off them.
I combined the two buckets of pins into one bucket.
Got the bucket of pins that was still submerged in the magnetic AP solution. Placed a large plastic strainer on top of bucket with a large coffee filter. Poured the solution from the bucket containing the pins into the filter.
Caught the solution, transfered it back into bucket with pins. Stirred it, swirled the solution over pins. Well more gold was floating in solution. So I poured it back through the same filter. Caught the solution, poured it back into the bucket with pins.
I did this for 10- 15 min. Well I was also catching in my filter some type of black material.
Washed the gold out of filter. Used regular city water. The solution in my beaker contain gold and a blackish reddish color. The mystery material was lighter than the gold. It settled above the gold.
I removed the water and added Hcl to the beaker. Thinking the Hcl would dissolve the mystery material into solution leaving gold...no. I still have what is remaining of the pins in a bucket. I still have all the filters too. They contain very small particles of gold in them. I will process them later. But not the filters containing this black red looking mystery material.
Anyhow...if you could, direct me to a forum to read, give advice, criticism, etc. I would be Thankful. Yes I did read over the link you provided again. And I've searched the forums looking for answers. I've found one that speaks of a similar situation.
I might should have mentioned this earlier. This was 3rd time using the same solution on gold pins. First and second time..I had no issues. Recovering and then refining the gold. Everything went great. I doing 200 grams of gold pins each time. Just regular pins from boards.
Thank You and Be safe

 

[Martijn]

If you put magnetic pins in AP, the dissolved copper will cement out on it and it will be red or black when oxidized. I think that's what happened here.
Just keep it in AP without any ferrous metals and the 'mystery metals' will dissolve.
HCL does not dissolve Copper. With air it does and then it turns into AP.
AP does not really go bad, it only get more and more by adding HCl and copper until it's polluted with an excess of other base metals like zinc, tin, nickel, etc. Iron does not mater that much, since that forms an oxidizer like Copper Chloride.

 

[anachronism]

If you put magnetic pins in AP, the dissolved copper will cement out on it and it will be red or black when oxidized. I think that's what happened here.
Just keep it in AP without any ferrous metals and the 'mystery metals' will dissolve.
HCL does not dissolve Copper. With air it does and then it turns into AP.
AP does not really go bad, it only get more and more by adding HCl and copper until it's polluted with an excess of other base metals like zinc, tin, nickel, etc. Iron does not mater that much, since that forms an oxidizer like Copper Chloride.

Mostly true- ultimately you can make Ferric leach if the Iron content gets too high. This is one of the issues with using Iron to cement out the Copper if you are going to re-use the solution.

 

[snoman701]

My biggest problem with AP is when it's running whole boards. Think HP or Textronix. I end up with a saturated solution with white precipitate as well as a lot of lead/tin from the solder.

RIght now I have two five gallon buckets of what I thought was AR waste that I use as AP. Turns out it still had nitric in it. No gold to start....plenty of gold now. Cementing gold out of AR in quantity isn't quite as easy as it seems it should be.

 

[Yggdrasil]

My biggest problem with AP is when it's running whole boards. Think HP or Textronix. I end up with a saturated solution with white precipitate as well as a lot of lead/tin from the solder.

RIght now I have two five gallon buckets of what I thought was AR waste that I use as AP. Turns out it still had nitric in it. No gold to start....plenty of gold now. Cementing gold out of AR in quantity isn't quite as easy as it seems it should be.

Something is off here, no Nitric in AP and usually no unidentified scrap solutions either.

 

[ssmontecarlo]

If you put magnetic pins in AP, the dissolved copper will cement out on it and it will be red or black when oxidized. I think that's what happened here.
Just keep it in AP without any ferrous metals and the 'mystery metals' will dissolve.
HCL does not dissolve Copper. With air it does and then it turns into AP.
AP does not really go bad, it only get more and more by adding HCl and copper until it's polluted with an excess of other base metals like zinc, tin, nickel, etc. Iron does not mater that much, since that forms an oxidizer like Copper Chloride.

Ten 4

Edit by Moderator, removed extra quotes.

 

[snoman701]

Something is off here, no Nitric in AP and usually no unidentified scrap solutions either.

I didn't realize there was nitric in it. But re-using acid that still has life is quite common for recovery purposes. It's just important to make sure you aren't using high ORP waste.

 

[Yggdrasil]

I didn't realize there was nitric in it. But re-using acid that still has life is quite common for recovery purposes. It's just important to make sure you aren't using high ORP waste.

Yes, true but this whole thread is about AP

 

[Shark]

My issue with pins in AP has been volume. Putting a couple hundred grams in it wasn’t much problem at all. Putting 2-3 pounds in it was always a pain. They tend to bond together in a lump and cement the copper out of the solution, even when I used two to three gallons of AP on them. Like snowman mentioned I started using AR waste on them in an air lift assisted bucket. That rig worked well for AP as well but can easily cause copper to drop out as the white crystal copper (I think this is (CuCl) that easily dissolves HCl. Or just save them and run them in a cell.
I have also used AP by just adding small volumes of pins, a few grams at a time, to a bucket full of AP and running them as I would larger boards, leave them how ever long it takes and come back to them when they are done. I still prefer the cell but some low grade pins float in sulfuric cells.

 

[ssmontecarlo]

Ten 4

Edit by Moderator, removed extra quotes.

Thank you..I honestly don't know what I did to cause that issue.

 

[snoman701]

Exactly Shark...for fingers, it works fine. For pins, it's a waste of good copper. Even for fingers, I find it meticulous to dig all the circuit board material out. It's taken me many years and much waste to learn that sometimes it's better to just let someone else make money off your material while you get out and work a little harder to repeat the process. I hate to think the damage I've done to my lungs trying to chase grams of gold from just fugitive fumes, let alone the flat out mistakes I've made.

I've used all the recovery methods. For the hobbiest, AP works. For the person trying to earn a living, but without an industrial facility...sending off for surface leaching or melt / assay is unfortunately the best option.

 

[BShan]

I started my AP with no peroxide and it took a while to start up, but it did eventually start. From reading, I understood that AP was a slow process, so I didn't care about adding another few weeks.

I did one more test batch, but for that one I just grabbed some old solution and mixed it with some more muriatic acid, and it started much more quickly.

 

[Martijn]

Exactly Shark...for fingers, it works fine. For pins, it's a waste of good copper. Even for fingers, I find it meticulous to dig all the circuit board material out. It's taken me many years and much waste to learn that sometimes it's better to just let someone else make money off your material while you get out and work a little harder to repeat the process. I hate to think the damage I've done to my lungs trying to chase grams of gold from just fugitive fumes, let alone the flat out mistakes I've made.

I've used all the recovery methods. For the hobbiest, AP works. For the person trying to earn a living, but without an industrial facility...sending off for surface leaching or melt / assay is unfortunately the best option.

I used a set of buckets for that.
One smaller or tight fitting the other. The top one drilled a lot of 3 mm holes in the bottom and around the bottom side and by simply lifting the bucket, you rinse the foils down leaving the boards in the top bucket. Like a strainer. Pick out the stripped ones and add more fingers.
You can also perforate smaller plastic containers and put them besides each other in the AP.
Air hose can be put under the material.
Back on subject of reuse of AP: I still have a 25 Liter jerry can of AP stored. Its not waste.

 

[Shark]

I used a set of buckets for that.
One smaller or tight fitting the other. The top one drilled a lot of 3 mm holes in the bottom and around the bottom side and by simply lifting the bucket, you rinse the foils down leaving the boards in the top bucket. Like a strainer. Pick out the stripped ones and add more fingers.
You can also perforate smaller plastic containers and put them besides each other in the AP.
Air hose can be put under the material.
Back on subject of reuse of AP: I still have a 25 Liter jerry can of AP stored. Its not waste.

All but one of my larger systems worked on the same principle. It was different system that I targeted pins and larger copper pieces with. I am still arguing with my self over rehashing how it worked yet. I know I should but…….

 

[4metals]

If the copper based pins or fingers were processed in a slow rotating polypropylene cement mixer would if be better and more efficient?

 

[Yggdrasil]

If the copper based pins or fingers were processed in a slow rotating polypropylene cement mixer would if be better and more efficient?

I believe so, both agitation and air bubbling should help.
I was looking into making something smaller, but found no good base so I settled for traditional bubbling.

 

[4metals]

Here in the US a company called Harbor Freight (which ironically sells mostly Chinese manufactured goods) makes this small cement mixer. I have seen refiners remove the top half and mount a 5 gallon bucket in there. They use it for small CN strips but it should work equally well for AP to keep the load tumbling.

 

[Yggdrasil]

Here in the US a company called Harbor Freight (which ironically sells mostly Chinese manufactured goods) makes this small cement mixer. I have seen refiners remove the top half and mount a 5 gallon bucket in there. They use it for small CN strips but it should work equally well for AP to keep the load tumbling.

The link do not function here, but I expect it would be good.
My problem was that I could not find anything local in my country.
I could have searched the eBay or alibaba, but assumed the freight would be too much, so I used what I had on hand.

 

[Shark]

I think it might work for those few who can or will run low grade pins by multiple pound lots. The only downside is that large bunch’s of pins in AP can very often cement the copper out of the solution. A pound or two in a five gallon bucket, even if it held 3-4 gallons is a problem. The addition of physically tumbling the pins with a good air supply may well be the answer. This needs some further thought.

 

[4metals]

The only downside is that large bunch’s of pins in AP can very often cement the copper out of the solution.

Copper won't cement copper out of solution, are you referring to mixed pins with some magnetic and some not? Iron will cement copper, possibly another benefit of separating the magnetics from the non magnetic.

In my mind, any way I could concentrate "low grade" materials is a win. If tumbling pins separates the gold plating and at the same time drops some finely divided copper is that so bad? Sure clean foils are nice but it can be hard to collect all of the foils. If one started with 5 pounds of pins and after the foils are loose you filter and collect maybe 4 ounces of foils, and precipitated copper, you have done a good job of concentrating the material because the mass of the pins did not dissolve so you do not need to waste acid dissolving them because you got the gold and a little copper with it. From there a much smaller aqua regia dissolve will separate your values with considerably much less waste.

Again this is just my perspective because I have only seen huge quantities of this material which takes an entirely different approach.