Preventing my next mistake

[jason_recliner]

I figure it's better to ask something stupid than do something stupid. I think I know how to best continue, but wanted to run it past the stupid filter.
I apologise if this has been well answered. I have been looking for an answer to similar questions to this all week. I've learned several other good things though.

I'm running another e-crap recovery. It's mostly pins, fingers, the odd ceramic and fibre CPU and a bunch of old Centronics connectors with heavy plating, and a few crushed RAM and old GPU chips. There's also one Pentium 4 heat spreader which when I scratched it looked like it was made of copper. I avoided everything solder as best as I could but I know there's a very small amount in there. The plan this time was to leach in AP as before, only without 1/3 H2O2 this time, so that I'd have more foils and less cement. With advice in mind that Butcher and Solar gave someone recently, I was not too worried about lead yet if boiling water washes can rid me of that. Though I'm not up to that part yet, I still have to find how to dispose of that responsibly - Lead dissolved in hot water. (The copper > iron > salt method I'm familiar with.)

I poured on some 32% HCl which within seconds went a very pale grey colour. Perhaps I may have missed the tiniest amount of thermal gunk or something. It was oh so very pale and didn't get any darker with time so whatever it was, I figured it was all taken up pretty quickly and hopefully not to worry about.

After half a day in plain HCl on the hotplate with no effect (I understand that to be perfectly normal), I also dumped in a little of some used, quite dark, AP solution from my Bluetooth antenna dissolvings. I'm not convinced in hindsight there's not iron in it as it didn't go bright green. I added a fish tank bubbler. Still not green. All day on the hotplate and with still nothing seeming to be degrading, I added just a splash of 3% peroxide and a small piece of copper. When I dipped a strip of copper foil in it for a moment, it came out "you've been dipped in acid" pink. Ok! Now we wait.

A week later and it's sort of paused. Foils are still not coming off pcb. But a lot of other stuff had degraded. But the interesting thing is the solution. There's a dark layer on top and a clear layer below. I wonder if my problem is iron. Maybe I have ferrous or ferric chloride. Googled their masses and they have a high specific gravity, so shouldn't float on top of copper chloride or hydrochloric acid, should they?

One thing is almost certain to me: that there would be zero gold in solution. Stannous chloride already says no. (Can you get false negatives caused by tin in solution? I'm now well experienced in false negatives due to excess sodium nitrate! )

If I stir the top layer, I get a nice golden foil snow dome effect that you can't see in the photo. Rather than add more acid, I believe my best step forward is to filter all solids, chuck out liquids and make up some fresh AP with copper and when it's ready, add that.

My question is: what you think is in the dark top layer? [Edit: There's actually a much more defined layer distinction than visible here. I'd run the bubbler for about 15 seconds before turning it off for a photo.]

 

[jeneje]

This may help you,,,,http://goldrefiningforum.com/phpBB3/viewtopic.php?t=20604
Ken

 

[jason_recliner]

Thanks for responding Ken.
You know what, it turns out I am kind of familiar with that thread. I wouldn't want to make the same mistake THAT guy did though. Gees, what a goose!
I'm not sure what you're trying to suggest though. That I should cement everything? Cos I wonder if that's what is going on already?

Any ideas why the dark layer is so light (in mass, not colour) compared to the clear layer, and why they separate so quickly?

 

[g_axelsson]

As long as there are undissolved base metals the solution would not turn green, any CuCl2 created is almost immediately turned into 2 CuCl. You don't need a lot to turn the solution dark brown, almost black.
A small test you can make is to pour off most of the solution into a separate container and run the bubbler for a couple of hours. That should turn it into green solution. Then pour it back again and see how fast the green color disappear, turning dark brown again.

Nitpick

- Lead dissolved in hot water. (The copper > iron > salt method I'm familiar with.)

Lead isn't dissolved in water, lead chloride is dissolved in hot water.

But the interesting thing is the solution. There's a dark layer on top and a clear layer below. I wonder if my problem is iron. Maybe I have ferrous or ferric chloride. Googled their masses and they have a high specific gravity, so shouldn't float on top of copper chloride or hydrochloric acid, should they?

No, solutions mixes and gravity can't separate them.

My question is: what you think is in the dark top layer? [Edit: There's actually a much more defined layer distinction than visible here. I'd run the bubbler for about 15 seconds before turning it off for a photo.]

A clear layer above the scrap usually means that you have too much base metals that is more reactive than copper. The copper in the CuCL cements on the scrap and Fe, Ni, Zn and other base metals goes into solution. It takes a long time and a lot of acids to dissolve the base metals under the pins. Patience is the key. Use the bubbler to agitate the solution and to convert CuCL into CuCL₂

Göran

 

[Geo]

The solution is the same color throughout. It looks clear at the bottom because the material is closer to the edge. Use a bright light and shine it through the solution to get a good idea at it's turbidity.

Iron is not your problem and it would be ferrous chloride at this point.

As long as there is base metal present, there will be no gold in solution.

Add more hcl until the solution turns lime green even if you have to remove some solution to make room.

replace the bubbler and have some patience.

 

[jason_recliner]

Thank you Göran and Geo.

I will be more patient (Mind you, there was no visible change at all in the last week). I will add more acid and bubble it up again, rather than change out my probably spent acid. If I understand you correctly, this is to keep the existing value of CuCl (or CuCl2). At this point I am not trying to dissolve any gold at all.

Point taken on the lead. I meant to say lead salts. This is still a step or two ahead of me.

It's definitely a layer separation though. When turning on the bubbler, dark clouds eddy into the clear layer. Within a minute or three it's fully mixed. Overnight it settles again. I still don't understand what's going on there. I guess I don't need to...

 

[jonn]

Let your solution settle all powder overnight. Pipette a portion out into a clean jar or beaker. Add a tiny bit of hcl. Does it turn green? if yes, add hcl to your reaction. If no, try a new sample with h2o2. Does it turn green? If yes then add h2o2 to your reaction. I'm guessing it's way to dilute. To much water, too many base metals, not enough hcl and leave you bubbler running after it turns green. Next time start a small batch with hcl and copper oxide, mix a minimal amount of pins, fingers etc to get the reaction going. Once foils are removed from base you may add hcl and more material to your reaction.

 

[jeneje]

I'm not sure what you're trying to suggest though.

Very simple Jason, you are trying to run before you can craw. You are mixing different types of material together and trying to process it all at once. This will not work. If, i may here - i would do some research on "How to properly recover my precious metals first", that means learning the different types of components, what type of pm's might be in them and separate them to each their own.

Then learn about each type by researching here or googling them. Once you are comfortable with that learn what type of refinement process you will need for the material you want to refine.

Doing it the way you are right now will get you No where.

Good luck
Ken

 

[solar_plasma]

Let us say, it makes it more difficult and it will take longer. Ken is right, better only use one type in one vessel. At least in the beginning.

 

[Geo]

I have heard of the solution stratifying into layers but I have never seen it with my own eyes. Maybe because I never have let the solution sit idle. My dad had a saying that I heard from him a thousand times " If I tell you a cockroach can pull a freight train, don't argue. Just hook it up and get out of the way".

 

[butcher]

I'm running another e-crap recovery. It's mostly pins, fingers, the odd ceramic and fibre CPU and a bunch of old Centronics connectors with heavy plating, and a few crushed RAM and old GPU chips. There's also one Pentium 4 heat spreader which when I scratched it looked like it was made of copper. I avoided everything solder as best as I could but I know there's a very small amount in there. The plan this time was to leach in AP as before, only without 1/3 H2O2 this time, so that I'd have more foils and less cement. With advice in mind that Butcher and Solar gave someone recently, I was not too worried about lead yet if boiling water washes can rid me of that. Though I'm not up to that part yet, I still have to find how to dispose of that responsibly - Lead dissolved in hot water. (The copper > iron > salt method I'm familiar with.)

Mixing many parts, with many metals involved to an acidic solution is not a good idea, the many different base metals will consume the acid, one metal may try to cement out another metal, the solution can begin to contain many different metals all competing to go into solutions as salts, free metals replacing other metals in solution and depending on which base metals are involved your solution will no longer be a copper II chloride solution...

Tin from solder is also more likely, where if gold is put into solution forms a colloidal gold in solution, along with its problems of difficulty of not being able to detect for the gold in a test with stannous chloride, or the problems of recovery of the gold from solution...

Mixing or trying to recover gold from an large assortment of electronic scrap in one pot, creates a pot full of problems, to try and overcome, especially if circuit boards are involved, this also creates a situation where electronic parts can have base metals where the acids can have a hard time reaching (like under solder mask or in between layers of the circuit board or CPU...

These base metals in tight places, can make it difficult for the acids to reach them, as the gases of the reactions try to escape the tight places, making it hard for fresh acid to get in, and if gold is put into solution with these base metals, the gold can be lost by plating onto the metal in the tight spots, or under he solder mask to remaining base metals...

As far lead chloride and its salt, Not very soluble in cold water, which is much more soluble in hot water, then when this solution is cooled or chilled most of the lead chloride becomes insoluble again, after decanting the cooled water from the lead chloride crystals, (the water can be reused by reheating to collect more lead chloride from the materials), or this water with only a tiny bit of lead salt can then go to your waste bucket, with other waste solutions, to be treated as you learned from the forum in dealing with your waste, found in the safety section. Other ways are the lead chloride can be converted to other forms of lead, like lead oxide by roasting, there are different ways you can deal with this toxic salt of lead chloride after you collect a jar full, one way is you could heat it in a solution of sulfuric acid, driving off chloride as a gas and converting the lead to lead sulfate, which could be put into an old dead car lead acid battery where the battery’s are to be recycled for there lead and sulfuric acid content, or you can save the lead salts to make litharge lead oxide, which could be used or converted back to lead, the main thing is however you deal with these salts do it with yours and others safety in mind and do it properly and responsibly...

It is also not a good idea to have to deal with these dangerous lead salts when you do not have to, if you separate the solder from you material as much as possible by other means mechanically, and do not put the lead solder or tin into the acid solutions in the first place, then you will not have that much to have to deal with later.
Keeping solder out of the recovery an refining stages, or removing them as much as possible first, helps avoid many of the dangers, and problems caused by these toxic or trouble making metals, solutions, or salts.

I poured on some 32% HCl which within seconds went a very pale grey colour. Perhaps I may have missed the tiniest amount of thermal gunk or something. It was oh so very pale and didn't get any darker with time so whatever it was, I figured it was all taken up pretty quickly and hopefully not to worry about.

If this was done to the main recovery portion, where you had the tin and base metals in solution, You already had a fairly big mess to begin with, just by dissolving all of those base metals in solution, but adding the strong oxidizer (H2O2 and dissolving the gold in this mess would have just created more problems a bigger mess, making it more difficult to recover the gold by doing this, colloidal gold (with the tin chloride in solution), or gold dissolved in with large amounts of dissolved base metals, making it very easy for you to loose your gold in the mess.
With undissolved copper or base metals also cementing out some of the gold onto the undissolved metals, what portion was not reduced in solution as colloidal gold already by tin in solution, can be cemented out in hard to get to areas, you could have gold in several different places, cemented gold, colloidal gold, and some in solution with a lot of base metals, all of which can make seeing where the gold is at with a test difficult or even impossible..

After half a day in plain HCl on the hotplate with no effect (I understand that to be perfectly normal), I also dumped in a little of some used, quite dark, AP solution from my Bluetooth antenna dissolvings. I'm not convinced in hindsight there's not iron in it as it didn't go bright green. I added a fish tank bubbler. Still not green. All day on the hotplate and with still nothing seeming to be degrading, I added just a splash of 3% peroxide and a small piece of copper. When I dipped a strip of copper foil in it for a moment, it came out "you've been dipped in acid" pink. Ok! Now we wait.

Heating solution can drive out your free HCl acid, depending how warm the solution was, and for how long it was heated or evaporated, and can also drive out water needed in the solution, as well as any oxidizer that may be needed to help oxidize base metals, if concentrated this can also convert most of the copper II chloride to copper I chloride, not to mention if there are other base metals in solution, or base metals yet to be dissolved like iron, or more reactive metals which can replace copper, or other metals from the solution...

Adding peroxide and more copper foil to a copper chloride or iron chloride solution what do you expect to happen?
Hoke's page 100 gives details of how to test for iron in solution.

week later and it's sort of paused. Foils are still not coming off pcb. But a lot of other stuff had degraded. But the interesting thing is the solution. There's a dark layer on top and a clear layer below. I wonder if my problem is iron. Maybe I have ferrous or ferric chloride. Googled their masses and they have a high specific gravity, so shouldn't float on top of copper chloride or hydrochloric acid, should they?

If I understand your post correctly, it is not a wonder you a not seeing or getting the results, you are hoping to see or get.

One thing is almost certain to me: that there would be zero gold in solution. Stannous chloride already says no. (Can you get false negatives caused by tin in solution? I'm now well experienced in false negatives due to excess sodium nitrate!

You cannot test for reduced gold, gold cemented out of solutions onto base metals, or for colloidal gold caused from having tin in solution with your gold, or gold with strong oxidizers in solution with the dissolved gold, too much base metals can also cause some problems with the tests as other metals compete with gold, you can only test for gold in solution where your stannous chloride can actually reduce the gold in that test...


If I stir the top layer, I get a nice golden foil snow dome effect that you can't see in the photo. Rather than add more acid, I believe my best step forward is to filter all solids, chuck out liquids and make up some fresh AP with copper and when it's ready, add that.

My question is: what you think is in the dark top layer?

Without knowing more, or having a better understanding of the post, It sounds like the top layer of base metal solution could have some fine foils of gold undissolved (from thinly plated layer on pins or other such materials), Which you can let settle well before decanting and filtering the solution, or the small flakes could also have been from larger foils of the original gold foils that have been dissolved down in size leaving a smaller size o gold foils, and then this gold cemented back out in other places, or some in solution as colloidal gold, the more possibilities for problems areas, the more chances for the gold to hide from you...

 

[g_axelsson]

Here is an example of cemented gold on components. There's probably some gold inside the board too. It's really easy to miss if you don' know what to look for.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

Göran

 

[jason_recliner]

Thank you guys. I truly value your correction.

If, i may here - i would do some research on "How to properly recover my precious metals first", that means learning the different types of components, what type of pm's might be in them and separate them to each their own.
I don't have much of each. A bit of this, a bit of that, and all scrap. Generally gold plated over copper on connectors. I have (mostly) kept my Bluetooth antennae separate though, because I'm not sure what inside them. I have tried to avoid all tin and steel. But I shouldn't even mix connectors, chips and fingers?
Ok then. I'm going to have really small batches, but if that's what it takes to have clean batches... Your point is well noted for the future.

Tin from solder is also more likely, where if gold is put into solution forms a colloidal gold in solution, along with its problems of difficulty of not being able to detect for the gold in a test with stannous chloride, or the problems of recovery of the gold from solution...

That's something I was trying to avoid this time. Following another thread recently (I think something Pantherlikher said) about CuClx I was originally hoping to dissolve only copper (and lower). I know I potentially blew that when I added peroxide, though I didn't use much.

Adding peroxide and more copper foil to a copper chloride or iron chloride solution what do you expect to happen?
Hoke's page 100 gives details of how to test for iron in solution.

I'm not sure whether that was a rhetorical question. But if I answer it maybe you'll understand my logic, flawed as it may be. Please understand I am not trying to justify my actions, only explain them.

In my earlier batches of HCl + H2O2 + metals, I'd see an almost instantaneous changing of colour at room temperature. This time, when I added the AP remnants from my antenna dissolvings into the HCl, I left it all day with no change on the coffee maker hotplate, which can get it about 60-80 deg C. Most concerning is that it didn't even go green, even with the bubbler (although, as Göran has since pointed out, it wouldn't work anyway while metals are still present). But this non-greening is when I started to suspect the quality of my earlier AP - that MAYBE it had lower metals in it. What I should have done in hindsight is abandon that mix, make up a fresh separate batch of HCl, copper, and a touch of H2O2 to get it started, leave it a while, then add it when the peroxide was used up.

So when I added a splash of peroxide, a few teaspoons, I was hoping to give the copper chloride a bit of a kickstart. I understood a small amount of gold could go into solution and re-cement out, but it should be very little. (???) The added copper was about a 10mm square of 0.1mm foil, just to be able to watch it for degrading. Then I thought of doing a dip-in-pull-out test, which proved copper was being eaten up.

I can say I had least read about Hoke's iron tests. But various forms of cyanide are not something I have on hand nor am prepared to handle at this point.

As for the stratification, I do mean the dark liquid layer over the clear liquid layer, that comes down to about an inch above the bottom. In the photo, which I had already disturbed, you can see how dark the yellow tube is at the surface where it's in contact with the glass, compared to the paleness at the bottom.

I added more acid yesterday and it did indeed turn a whole lot greener and paler. I could see right through it. Overnight the hotplate and bubbler are off and I came out to another dark liquid layer, over the bottom clear layer, similar to the photo. Gentle movement of the jar shows dark eddies swirling, but not something I could easily photograph any better. So perhaps the dark layer is a colloid, thanks to my tin. (I swear I did at least try to remove as much solder as possible. If that's what's responsible, it looks like it doesn't take much. All part of my learning curve.) On the other hand, could adding more HCl actually redissolve colloidal gold without free H2O2 or another oxidiser? Surely the little peroxide I added is long gone.

Right now, it's warm and bubbling away as dark olive green, and fingers that were pristine for two weeks up to yesterday, are now half degraded. Yay. I know that previously I've used too much acid. That's something I wanted to avoid and maybe I just erred the other way.

My question is: what you think is in the dark top layer?
Without knowing more, or having a better understanding of the post, It sounds like the top layer of base metal solution could have some fine foils of gold undissolved...
I'm sorry, I worded that very poorly. My precious is floating around in there for sure, and maybe some cement precious. I mean the darkness. It's most intriguing that it's lighter than the clear layer. If not colloidal gold (and I sure hope not) then this question remains. But I will start reading up on colloidal recovery.

I am really most appreciative to all of you, for the time you have taken to help me learn.
Jason

 

[Pantherlikher]

You still missed the point of not adding heat. AP with air is all that is needed. And maybe additions of HCL when it turns black and seems nothing is happening after a full day with stirring/ agitation.

The pins could have tin under the gold. Or some other parts could have tin in the make up of the part. Tin is not just in solder so you have to be careful in what materials you mix together.

Small batches at first are best. 100 pins or so would show you reactions and results.

Good luck and add allot more of the key ingredient... Patience/ time. AP takes allot of both.

B.S.

 

[jason_recliner]

I did miss that. I read Butcher's comment as excessive heat, like near boiling.
Thank you for clarifying.

 

[butcher]

Jason,
It is not that you cannot recover values, from what you have done, its that it can be very difficult even with a good understanding of what may be going on in solution, there are just so many problems that you could have, and there are just much easier and better ways that it should be done.

Next time save up your material until you get enough of it to work with, this way you will get more gold in the long run, working with a lot of small batches is a good way to loose a little bit o gold in every batch, and working with a mixed lot, and a batch of base metals and trash is a good way to loose a lot of gold in that batch.

You can do a stannous chloride test of solution in a spot plate.

After letting the insolubles settle by letting it sit overnight and decanting the solution, check and see how easily the solution will run through a filter, this will be helpful to determine if you have much tin in solution, which could have caused a problem with colloidal gold, if the solution filters easily, you most likely do not have much tin in solution, if it is hard to filter then you will surely have problems with tin.

If you suspect colloidal gold in solution you can try this, take a small sample of the solution, in the corner of the clean pyroceram dish, add a few drops of sulfuric acid, this can be done in the clean corning pyroceram dish on the hot plate...
This can be heated to help to break the colloid, but we will continue to heat to a concentrated solution so be careful here, you do not want to get even this small amount of hot acid on our skin, wear your protective gear and be cautious of how you are doing the work, lower the heat after you get it concentrated, so you can dry it out in the dish without it sputtering all over the place,(your working with very little solution so it will be faster and easier than it would be with a lot of solution covering the bottom of a dish), this small amount will not even cover the bottom of the dish, so setting one side of the hotplates feet up on small support so that it sets a bit un-level, and working with solution in one corner of your dish, dry he solution to a powder, now raise the heat to high, and let the powders smoke, when you no longer see smoke run a propane torch's flame over the small bit of powder, I would heat the whole dish evenly, although our main focus is just the small amount of powder or stain in the corner of the dish. After incineration, let the dish cool, you can then add a few drops HCl and a drop of bleach, a tiny bit of heat on the warm hot plate to vapor of the excess chlorine, and then add a drop of stannous chloride to the solution and watch for the violet color. of colloidal gold.

Most of your gold probably did not go into solution, and what did possibly was plated back out onto the remaining base metals, I also suspect your solution is mostly just base metals, from your description, but you still need to determine if gold is in solution as gold chloride or colloidal gold to determine if you will need to treat the solution to recover values.

Now level your electric hotplate, with the solid metal burners, and put the remaining materials into the pyroceram dish on the hot plate. You may need to take what is left, the undissolved the powders, metals and other junk (after decanting and testing solution), along with the pieces of circuit boards and other trash), and undissolved metals, and rinse them with a solution of NaOH dissolved in water, with just bit of heat, to convert the chlorides as much as possible to NaCl salt water which can be rinsed out with more water, this is to prevent gold from going up in smoke with the incinerating steps later.

Dry and incinerate, these powders and pieces of material, to red hot, keeping everything crushed as much as possible throughout the process, and exposing them to plenty of air, adjust temperature of the hot plate as needed, during the process of drying, lower heat when needed, and raise it to high heat as needed, or when you can without splashing or sputtering your values out of the dish, on high the salts may fuse and become a syrup and make large popping bubbles, if this happens lower heat to keep the bubbles from forming and splashing out your values, until it dries again.

When dry again you can again raise the heat, you will also have a lot of toxic smoke from the circuit board pieces, and toxic metal gases, so be sure to keep away from the smoke or keep from breathing these, crush and burn off the trash in the hot glowing red powders, with the dish on high in the hot plate, and running your torch over the powders.
A stone, or porcelain mortar can be used to crush the material,(I use an old large thick piece of rounded Pyrex type boiler sight glass, to do this with).
If you have a good fume hood great, if your doing it outside a small fan can help to keep you out of these toxic fumes, and backing away when you can.

After incineration cool the powders, and give them a wash in a boiling HCl solution, lower heat enough for the insolubles to settle (but keep it as warm as possible), decant the wash from the settled powder, if it is highly colored, repeat this until the solution does not pick up base metals indicated by the strong coloring of solution, then do the washes with boiling water, until these washes come out fairly clean.

Now after this if you still have pieces of metal or copper left in with the powders, or chunks of metal, I suspect you will still have undissolved base metals at this point, so you can use a fresh batch of copper II chloride to dissolve the copper, and continue from here...

 

[g_axelsson]

Heat or no heat doesn't matter much in the copper chloride process. The limiting factor is still oxidation of CuCl into CuCl₂, the added heat is only driving the CuCl₂ + Cu -> 2 CuCl₂ process faster.

Looking at your picture again I can see a lot of large metal pieces, a lot of exposed base metals. That is probably what killed your copper chloride. And if you don't run the bubbler all the time the copper chloride process will slow down to a crawl. It still works by air being absorbed through the surface.

The fact that you see a clear zone above the scrap when not stirring the solution with a bubbler means you have mixed in too much non-copper base metals. CuCl is green and CuCl₂ brown when in solution. A clear layer means no copper ions in solution above the scrap and without copper chloride the etching stops.
When I have tried to run the copper chloride process on pins or other massive scrap I have seen the same reaction, what is happening is a normal replacement reaction or cementation, for example CuCl₂ + Zn -> ZnCl₂ + Cu when the zinc in the brass is reacting. This depletes the copper chloride solution and you end up with a weak copper chloride solution. When this happens I let it run for a while until there is almost no copper left in solution and then decant the liquid and fill up with fresh copper chloride, repeat when needed. The spent liquid is trash and should not be mixed with the copper chloride leach. Treat as waste.

I use this process for removing pins on modern CPU:s with soldered pins, copper cements while tin goes into solution and you can just scrape off the pins. It usually takes less than an hour to process a batch.

As you now know, separate the different types of scrap and run separately until you have concentrated your gold (the recovery step) for further refining. Each type of scrap has it's own problems and solutions. With a lot of small lots you would have several small problems with specific solutions, but with everything mixed together you would have a large lot with several problems and not as easily solved.

Göran

 

[jason_recliner]

The fact that you see a clear zone above the scrap when not stirring the solution with a bubbler means you have mixed in too much non-copper base metals. CuCl is green and CuCl₂ brown when in solution. A clear layer means no copper ions in solution above the scrap and without copper chloride the etching stops.

That makes perfect sense. It also explains why it took so long for anything to happen, and why I've had more progress in the last 2 days than in 2 weeks.

.. what is happening is a normal replacement reaction or cementation, for example CuCl2 + Zn -> CuZn2 + Cu when the zinc in the brass is reacting. This depletes the copper chloride solution and you end up with a weak copper chloride solution. When this happens I let it run for a while until there is almost no copper left in solution and then decant the liquid and fill up with fresh copper chloride, repeat when needed.

Kind of like my original plan, but actually using all the acid. In other words, I've added probably now gone and added way more acid than I need. Again.
As for big metals, the chunk on the left is a graphics processor that was a bit goldy coloured on one side. I've also now fished out the P4 heat spreader which is doing me no good. There's also lots of plastic bits which would be dealt with after filtering, rinsing in NaOH, before incineration.

After letting the insolubles settle by letting it sit overnight and decanting the solution, check and see how easily the solution will run through a filter, this will be helpful to determine if you have much tin in solution, which could have caused a problem with colloidal gold, if the solution filters easily, you most likely do not have much tin in solution, if it is hard to filter then you will surely have problems with tin.

If you suspect colloidal gold in solution you can try this, ...

What an excellent, comprehensive colloidal tutorial. That ought to be sticky'd somewhere. You are very generous with your writing time.

I'm still waiting on my eBay filter papers to arrive. I really don't suspect colloidal gold for three reasons:
1: I believe I've not really added enough oxidiser to dissolve much gold in the first place.
2: Adding straight HCl made it go clear green. Unless I'm mistaken, yeah we all know how often that is, that shouldn't happen to colloidal gold without free chlorine.
3: As you pointed out, the colloid is (normally) purple. No purple here. Though I'd need to reread up on several false +/- results before dismissing it, I've just had a lightbulb moment about the mechanics of all my stannous chloride tests.
And finally, because I can't count either, 4: Göran's perfectly plausible explanation for what we see.

At the current rate of dissolution, by the time my filters arrive I should be ready. I'll see how cloggy the filter gets and if all good, that will be a good enough confirmation for me. A gorgeous display of intact gold foils are dancing around the bubbling acid. If there's a chance of a tiny loss to colloid, so be it - the price of my foolishness. I won't ditch the liquid though. I'll keep it aside and do the tests later as you describe. It will be good practice. I still need more gear yet anyway.

 

[butcher]

Good information from Göran, I would like to expand on it.

Heating, can help to speed the copper II chloride reaction, but it can also drive off needed dissolved oxygen from solution faster, too much heating or evaporation can begin to drive off needed water, further evaporation or too high of a heat can vapor off free HCl (needed to convert the copper I chloride back to copper II chloride so that we can dissolve more copper.
Without keeping these needed active components in solution, (or driving them out too fast with heat) to keep the copper II chloride solution active, and with metallic copper reacting with the copper II chloride, we convert the copper II chloride to copper I chloride which then losses its ability to dissolve copper, heating is basically a balancing act here, we can use it to help to speed the reaction, but we also must keep our oxygen, water and other active ingredients up so that we can dissolve the copper.


The copper II chloride (CuCl2) is green, as it dissolves more copper it becomes more of the copper I chloride (CuCl), the solution darkens to brown, and as it saturates with copper I chloride it will precipitate out as a white powder CuCl, at this point it will not effectively dissolve more copper and we will need to rejuvenated the CuCl back to CuCl₂ to do so.
CuCl₂ + Cu --> 2CuCl


Base metals replace (or take away) the active component of the copper II chloride leach, the copper.
The (Cu⁺)Cation with its two chloride (Cl₂^-) Anions, the base metal oxidizes into solution as Cations taking the Chloride Anions from the copper, replacing the needed copper in solution, the copper then precipitates as metal copper powder, and or plates back out of solution onto remaining base metals as a copper metal coating.
CuCl₂ + Zn --> Cu + ZnCl2
The zinc chloride (or other base metal chloride) solution becomes ineffective at dissolving more metals, or at least metals lower the in the reactivity series than zinc (or other metals than they are in the series).
Jason,
Trying to rejuvenate a base metal chloride into becoming a CuCl2 solution, again by adding concentrated H2O2 and copper metal makes no sense, and as in you’re case it can put gold in solution with the tin in solution, which can give rise to colloidal gold being trapped in your solution.


You can use copper II Chloride to dissolve many base metals, but you will have to replace the solution with fresh copper II chloride, as the solution becomes some other base metal chloride solution.
You do not normally want the gold to go into solution when doing so, by using a strong oxidizer, as this can cause problems, especially when tin is involved.

Some metals like copper, nickel, and iron, will give color to the chloride solution (they can even resemble each other in solution), many metals will not give much or any color to solution, a solution can hold several metals at once, which can also change its color.

Color can be a clue to what the solution is composed of, but it is only that, just a clue, testing is the only way to know.

Our goal in the recovery stage is to remove base metals from our gold, and remove problem causing metals, before we put gold our gold into solution later in the refining stages.

Color can be a clue, but without testing you do not know what is in solution.
We can see the colloidal gold in the stannous chloride test, as the reduced gold reflects light giving us that purple color.
But you may not see a color reflected from the colloidal gold in the larger volume of solution in your jar, the colloids are so small they are invisible, and unless the solution was extremely saturated with these colloids they would not reflect that violet light, basically again without testing you just do not know what is in solution

 

[jason_recliner]

Leaving the bubbler on has made a world of difference. Anything copper coloured seems gone, including my indicator copper foil piece.
My filters also arrived, so I decanted and filtered off some of the acid and added some new HCl just yesterday. There's still a lot a silver coloured parts that even appear intact (not corroded), and a fair bit grey coloured powder.

I've been reading about reactive series of metals. The ionic chemistry is a bit blurry, but I gleaned that if all Cu is gone into one chloride solution or another, then any Pb and Sn metal should be too. This would make my silvery stuff... Silver? [Edit: Plus PMGs - duh!] I'll leave it all a while longer anyway, to be sure. Being winter here, I really only have weekends to play with it anyway. But one of your answers on the yet untested colloids raised another question:

If you suspect colloidal gold in solution you can try this, take a small sample of the solution, in the corner of the clean pyroceram dish, add a few drops of sulfuric acid, this can be done in the clean corning pyroceram dish on the hot plate...

What does the sulphuric do? Is this for dissolving potential tin but not gold? I have some battery acid kicking around and will do it as you say, when I get to this task, but I'd like to have at least a basic feeling that I have a clue what I'm doing.