Beginner questions and mistakes

[solar_plasma]

One way to avoid problems can be to start with dissolving only copper with HCl and a little H2O2 without gold bearing material. Let it dissolve until the liquid discolors from a beautiful emerald green (just like you see it in Geo's picture) to a dark green brown almost black. Then activate it only with HCl and air at room temperature.

 

[Grelko]

When running pins in copper chloride the zinc can cement out the copper and make it a zinc chloride solution and that's not working. If you have enough copper chloride or oxidizer from the start it won't be any problem, but without that it can take some time for a new batch to start working.
This isn't the same problem when running fingers, as circuit board traces are made from pure copper.

Göran

This may be the problem. As I was saying, I added around a cup of peroxide and the solution changed color, but after a day, it went back to clear/cloudy. I'm not sure what color zinc chloride is, but since zinc would cement out the copper, the green color would go with it.

I've added another cup and a half and it went right back to the dark yellow/greenish brown just like it did the first time. Except this time I made sure to mix it up very well also, instead of just letting the pump do its job. I'll have to keep an eye on it for a couple days to see if it goes clear again.

One way to avoid problems can be to start with dissolving only copper with HCl and a little H2O2 without gold bearing material. Let it dissolve until the liquid discolors from a beautiful emerald green (just like you see it in Geo's picture) to a dark green brown almost black. Then activate it only with HCl and air at room temperature.

I may have to try this since I tend to over do it on the peroxide still. If I use the pre-made copper chloride instead of peroxide, I shouldn't really have to worry about dissolving gold into solution much. "I'd still test it anyways to be sure"


A while back I was processing fingers and a few other small plated pieces I had. The flakes/powder came out to 0.8g. It is still dirty with a good bit of green solder mask in it, but it's a start

 

[g_axelsson]

Zinc chloride is colorless so it fits in perfectly with your description. Pins are often made of brass and contains around 30-40% zinc.

Save your old copper chloride solutions and use that to start the next batch. The way you are doing it is fine, add some more peroxide if the color disappears, the copper is exposed and the cemented copper often covers the gold so it will dissolve before the gold is attacked. Any dissolved gold will cement out on the remaining pins.
Just recover all sediments as cemented gold could be very fine.

Göran

 

[jason_recliner]

In other words, once you start your copper chloride solution, you should never need peroxide again. Which serves to highlight how poor a choice of name "AP" or acid/peroxide really is.

 

[solar_plasma]

In other words, once you start your copper chloride solution, you should never need peroxide again. Which serves to highlight how poor a choice of name "AP" or acid/peroxide really is.

What's about:
Copper catalyzed acid leach CCAL
Copper catalyzed acid reaction CCAR or just CAR
Copper catalyzed acid reaction leach CCARL or just CARL

:mrgreen: :mrgreen: :mrgreen: Let CARL do the job! Or, hey, just put it back into your CAR!

 

[jason_recliner]

Let me see... Reuse spent acids in your CAR. Nope, I can't see that ever being misunderstood.

 

[g_axelsson]

If you have too much pins and too little old copper chloride it still will turn into zinc chloride solution by cementation.

The name AP is a sad mistake as it isn't even necessary to use peroxide in the start. It will just take a while but oxygen from the atmosphere will work it's way into the solution and slowly start it up. I used peroxide seven years ago and managed to dissolve a lot of gold at the end. This was just before it was revealed on the forum that the peroxide could dissolve gold.
I've never used peroxide since then for the copper chloride process. That's why I always write copper chloride instead of AP to try to get into peoples minds that it is a bad name.

For a test, put some contact fingers in a jar, add HCl and water and put somewhere safe outside, far from things that could rust (or in a fume hood) and leave it for a month. Add water and HCl if it evaporates too much. You'll see that a month is about what it takes to run fingers that way. A bubbler makes it go so much faster but the principle is the same.

CARL or CAR was a good try, in the industry the process is known as "ammoniacal copper chloride etch" or just "copper chloride etch". It's commonly used with ammonium for complexing the CuCl to make it soluble, we use HCl for the same purpose and it also helps regenerate the leach as a source of chloride ions to form the CuCl₂.
http://www.www.journalamme.org/papers_amme03/1229.pdf

Göran

 

[Geo]

The main reaction is increasing the oxidation of the target metal. The metal will oxidize and then the metal oxide is dissolved in solution using an acid. The same thing happens to gold when we dissolve it. The gold oxidizes to gold(III) oxide (Au2O3) which is soluble in HCl and nitric acid. To the naked eye, You just see the reaction and the gold going into solution. The same happens to copper. HCl alone will not dissolve copper metal. There needs to be a small amount of copper oxide to put the copper into solution. Copper oxide is stable and can be stored easily. It can be made by exposing copper dust to the atmosphere. Green copper oxide will form and will not decompose. Adding copper oxide to HCl creates copper(II) chloride instantly.

 

[Grelko]

The solution went back to clear/cloudy once again, it must be zinc chloride. I was going to give it another day or two, and if it doesn't start turning more green by then, I was thinking about siphoning about half of the solution out (which should take a good portion of the zinc chloride with it) and add fresh HCL to it.

I do happen have about half a gallon of used AP that was left over from fingers and a couple other pieces that I was getting ready to dispose of. So far all I've done to the used AP was add clean copper wire since I didn't have any bus bars at the time. It's nice and green.

Actually, now that I think about it, a better idea would be to filter the used AP, siphon half a gallon from the bucket and just add the used AP to it.

 

[g_axelsson]

Now you get it! 8)

Göran

 

[Grelko]

Also saves me a couple dollars, since I won't have to buy more HCL yet

 

[Geo]

It seems that the pins may be some proprietary metal. Take a small amount from your AP bucket and try them in hot HCl and see if you can see the reaction. If you can see the reaction with just HCl, you may be able to dissolve most of the base metal in just HCl before moving it to the AP bucket.

 

[Grelko]

It seems that the pins may be some proprietary metal. Take a small amount from your AP bucket and try them in hot HCl and see if you can see the reaction. If you can see the reaction with just HCl, you may be able to dissolve most of the base metal in just HCl before moving it to the AP bucket.

Thanks for the info, I'll have to try that soon as I get a chance.

About a week ago, I took out half a gallon of solution from the bucket and added some of my used AP "filtered it first". So far the solution in the bucket is staying nice and green.

I've been seperating the pins, that I have been slowly gathering up for the next batch once this is finished. Full plated, partial, magnetic or non. This should help ALOT next time because, the ones in the bucket are around 3.5 lbs of every type mixed together.

 

[solar_plasma]

On the long run you might want to read about the sulfuric cell. Even I tried it myself I can't see any meaning in dissolving pins, while there is a so much more cost effective method with actually no waste.

 

[solar_plasma]

It would be nice to sticky a list of acceptable videos, along with titles and links and, maybe a few comments.

I started on such a list on my wiki, http://goldrefiningwiki.com/mediawiki/index.php/YouTube

So far it's only links to a few of our members...
* https://www.youtube.com/user/sreetips/videos Videos by kadriver, contains a lot about silver and gold but also palladium and platinum.
* https://www.youtube.com/channel/UC7MJW65g2CFT9wr0eUx4msg Videos by Palladium, mostly silver related videos but also how to glaze a dish.
* https://www.youtube.com/user/metalicmario/videos Videos by '''goldenchild''', silver chloride, reverse electroplating, seasoning a dish, melting gold and silver, shotting, fume hood.

I have added Geo to that list now.

Göran

Thanks, Göran, just the thread I thought of. Yes, Palladium, that's just why I thought that thread.

From the last nitric thread Making nitric acid failed

https://www.youtube.com/channel/UCIgKGGJkt1MrNmhq3vRibYA Nurdrage, maybe not a member, but informative

 

[Grelko]

I've come into another snag in the process. I believe that the solution is dissolving the iron in some of the pins because, the solution has turned a dark brown/red and it seems like alot of the pins/powder in the bottom of the bucket have solidified. I can still break it apart with the plastic dowel rod that I use to mix it with but, it doesn't seem that anymore is going to dissolve.

I'll try to get a picture up one of these days, but the way I can explain it, is that the solution looks almost like a reddish chocolate milk in color and thickness.

I figure the solution is full and I should filter what I can, then recharge, or replace it with fresh.

The last time I filtered about half a gallon, the dried powder had gold flakes but the rest was red/brown with green in it.

I still need to do washes for the powder because the green is indicating copper and the red "rust color" should indicate iron.

Either way, after everything is dissolved, I was going to take all of the powder and redo it again as much as needed until all I have left is the gold. I'm just taking my time since this is my first try on a batch of pins.

It seems like more than half of the pins have been dissolved so that part is working, even though it is very slow, even with the pump.

Next time I try to remove plating from the gold pins, I'll definately be looking into a sulfuric cell, since I still can't find any nitric in my area.

 

[Geo]

You don't have enough solution for the amount of metal you are trying to dissolve. The color of the solution is a good indication of copper(I) oxide.

 

[Grelko]

I had a feeling that would be my main problem seeing that I had approximately 3.5 lbs of material and only 3 gallons of HCL to use when I started "plus water and peroxide". I was going to decant/filter most of the solution and add fresh to it.

I may need to do this a couple more times to get everything dissolved, possibly around 8-10 gallons of HCL for the 3.5 lbs of material. "I'm using a four gallon bucket"

A sulfuric cell is definately going to be alot easier and MUCH faster for pins next time I do this. Reading that there is very little/no waste produced with it, is great to know, because doing this with HCL, there is alot to dispose of when I do get finished.

I didn't want to mess around with electric and sulfuric acid at first, but the more I learn about it, the easier it will be when I go that route.

 

[Grelko]

Not having enough solution was definately the problem. I decanted/filtered about 75% of the entire bucket, then added 1.5 gallons of fresh HCL to it. I thought I still had around half of the pins left to dissolve, but it turned out that nearly all of the material, that was solidified at the bottom, was powder. Also, it must have been mostly copper or zinc, because there's barely any powder at the bottom now.

There is probably 1/2 an ounce of pins left to dissolve from the 3.5 pounds of material, then I can filter the entire thing, and put what's left into a mason jar for further cleaning.

I started evaporating some of the used solution that I will be disposing of. It came out to being approximately 6 gallons total for the 3.5 pounds of materials. 4 gallons of HCL, 2 gallons of water, and a bit of peroxide.

 

[FrugalRefiner]

Be sure to check all solutions with stannous chloride before treating them for waste prior to disposal.

Dave