BEWILDERED

[Cleon]

Hello GRF members,
I am very new to this venture. I have a large amount of E waste that to me looks rich with foil.( photo below). I'm not new to refining plasser gold, for I have been prospecting for over 40yrs. But the process ,or processes for E waste is a different venture. My stock pile of the E waste pictured below is in excess of 100 lbs of trimmed PCB's plus bare pins and the like. I would like to process it properly so as not to waste it....Thoughts????

 

[Golddigger76]

You could process these boards several different ways but start with a small amount as a test until you get a proper technique figured out because if you end up making a mess a small mess is easier to fix than a huge mess.

First question:
Is there gold plating under the solder mask ?
If no then that will narrow down the process for you.

Second question :
Is there any solder or components on the boards?
If yes you need to remove everything you can as far as components, even little mlcc's.
If they have solder on the boards and you being new, then you should take the simplest route.

Before you start have all of the protective equipment to keep you safe like nitrile gloves, safety glasses ect., do this outdoors and where children and animals can not get ahold of it.
Do it where the wind blows the acid fumes away from you if you do not have a fume hood.

My opinion is that first you need to soak them in hydrochloric acid to remove as much solder possible if they do have solder.

Once you have the solder leached off and you rinse the boards very well you can go to the next step.

I would just put them directly into a large beaker with dilute nitric(50/50) to quickly remove the gold plating but if you are brand new to refining I would not recommend it because if you do this process wrong you will have a nasty tin nitrate in with your gold foils and it is a giant pain to deal with if you don't know how.

I think for you if brand new to working with acids you should just get a aquarium air bubbler and put the hose and bubbler stone in the bottom of a one gallon bucket, fill up the bucket with boards maybe to about the half gallon point and then pour in enough hydrochloric acid to cover the boards about a inch or two over the boards.
You can drill a hole into the bucket lid that's the same size or a little bit smaller than the hose so the hose fits through but the fumes from the acid will not escape, give yourself plenty of hose inside the bucket to open the lid without pulling the bubbler stone out of the bottom of the bucket.
Your aquarium air pump can sit on top of the bucket lid and you can pull off the hose when you want to open up the bucket to check on the progress.

The hydrochloric acid will start turning green from copper going into solution, this copper is copper chloride and is what will be doing the work of dissolving the base metals that the gold plating is plated to and the oxygen from the aquarium pump is what will help the process along.

Without the air bubbler it will take forever but will get your gold foils released.

When the acid is almost black in color you need to pour out about 9/10th's of the acid and replace it with new acid.

You can process several boards with the same solution, just remove the boards that have the gold plating stripped and rinsed off, then put in more boards.

Once you decide to stop the process you can remove and rinse the boards, filter out the gold foils, wash them well with water and refine them with aqua regia or the hydrochloric and bleach method.

Before you start anything search the forum and study all of the steps including dealing with the waste.

Become very familiar and confident about the whole process long before you start and it will go smoothly.

It is not a fast process but it is simple, cheap, and effective.

For us who are very experienced refining and handling all of the chemicals and chemistry, we may use other methods that are faster but more dangerous.

There's several routes that you can go but start small and keep it simple !!!!
Other forum members will chime in and probably add to what I have said or maybe even give you a different process that they think will be a better fit for you, seriously consider the methods that are given and decide which one works best for you.

 

[Cleon]

Golddigger76...
I want to thank you for your quick response and advice that you gave. I am very excited and anxious to get started now. I do have all the safety equipment that I need including a fume hood. I have refined plasser gold that I have prospected for either by panning or detecting, so that I could pour into my ingot mold and have a 999 ingot and sell them. That part I have down. It's the E waste that is intiming to me because of so many other metals that you have to deal with, and all in the same solution .
When refining my nuggets and flakes that I prospected for...I need very little AG to solidify the gold. I'm starting out with product that is between 21k and 23k gold and little if any other metals.
With the E waste I'm having to deal with many other metals in different quantities that all want to either stay with the gold through the solution process (if not done correctly) or just be a nuisance.
Right now I have three different AG solutions with three different colors. One is bright blue, one is dark green....both of them are very clear. The third solution is so milky white with a slight blue tent and concentrated that you can't begin to see though it.
I know by testing the solutions that the gold is fully suspended in each...but accompanied by what else...I do not know.

 

[Golddigger76]

Golddigger76...
I want to thank you for your quick response and advice that you gave. I am very excited and anxious to get started now. I do have all the safety equipment that I need including a fume hood. I have refined plasser gold that I have prospected for either by panning or detecting, so that I could pour into my ingot mold and have a 999 ingot and sell them. That part I have down. It's the E waste that is intiming to me because of so many other metals that you have to deal with, and all in the same solution .
When refining my nuggets and flakes that I prospected for...I need very little AG to solidify the gold. I'm starting out with product that is between 21k and 23k gold and little if any other metals.
With the E waste I'm having to deal with many other metals in different quantities that all want to either stay with the gold through the solution process (if not done correctly) or just be a nuisance.
Right now I have three different AG solutions with three different colors. One is bright blue, one is dark green....both of them are very clear. The third solution is so milky white with a slight blue tent and concentrated that you can't begin to see though it.
I know by testing the solutions that the gold is fully suspended in each...but accompanied by what else...I do not know.

Just remember that when it comes to boards Tin is your nemesis !!
Eliminate the tin as much as possible

 

[Golddigger76]

Also keep in mind that even though you see a lot of gold on your boards there's most likely less than you think.

Depending on how new or old the boards you have are makes a difference on the amount of gold that you will get out of refining them.
Older boards, military boards, testing equipment boards, medical equipment, and communications boards, probably others will generally have thicker gold plating.

Around the year 2000 the amount of gold, and silver that is used in electronics other than the boards I listed above started becoming less and less.
I do my best to stay away from refining newer consumer electronic boards because on the scale that I refine, it's just not worth it.

I don't mind refining ram boards but the older ones almost always have more gold.
What are your boards from and what time era are they from ?

 

[Cleon]

Again I want to thank you for your quick response and insightful information about the boards.
Most of the boards I have are used in plasma cutting machines ( of a world-leading manufacturer of plasma cutters).
The company that I got the boards from is used to test all the boards for quality control so that the manufacturer only receives approved components. I was told by one of the engineers at this company that the gold foil used is minimal 30mic and quite often 50mic.
I also have over five pounds of bare pins and buttons ( as seen in the photo below).
Much thanks
Cleon

 

[Shark]

Strong nitric does not play well with nitrile.

 

[Golddigger76]

Cleon,
These gold plated buttons, would they happen to be electrical contacts by any chance ?
Nice looking pins as well !!

 

[Cleon]

Thanks...the pins are heavy coated (50mic) over a thin copper wire. The buttons are just that....they are connected to the PCB by silver solder and then a flexible push button on the outside of the component makes the contact. These I'm told are 30mic foiled.
But 5lbs of them should refine well.

 

[nickvc]

I would recommend that you separate the items and process them that way , if one item causes problems then it saves all the material been in a mess .

 

[Cleon]

Thank you...
That is exactly what I plan on doing. I have done three other small batches of lesser quality, in hopes of working out a good process and minimal waste...with three different outcomes??? The first two I think I can handle ok,( green solution and blue solution, both very clear) the third came out very milky, non transparent and seams on the thick side compared to the first two.???

I'm guessing that the first two are because of various amounts of tin and copper. I have no idea about the third.
I would like to solve the issues with these three test before I continue with more. I'm on my second reading of her book to glean more insight now that I have product in front of me. But I am more than happy to receive assistance from those that already have the experience and knowledge to help me push through these test.

Thank you for commenting on my post. It's always nice to hear from others. Look forward to hearing from you again.
Cleon.

 

[Yggdrasil]

Thank you...
That is exactly what I plan on doing. I have done three other small batches of lesser quality, in hopes of working out a good process and minimal waste...with three different outcomes??? The first two I think I can handle ok,( green solution and blue solution, both very clear) the third came out very milky, non transparent and seams on the thick side compared to the first two.???

I'm guessing that the first two are because of various amounts of tin and copper. I have no idea about the third.
I would like to solve the issues with these three test before I continue with more. I'm on my second reading of her book to glean more insight now that I have product in front of me. But I am more than happy to receive assistance from those that already have the experience and knowledge to help me push through these test.

Thank you for commenting on my post. It's always nice to hear from others. Look forward to hearing from you again.
Cleon.

How do you process them?

 

[Cleon]

Well...when it comes to the PCB's....like in the photo, I first get them all to "about " the same size. Then I have a large basket sieve that I put them in and then dunk them in boiling water for about 30 seconds to remove excess fibers from trimming them to size, and hopefully remove any oils that might be present. I then use compressed air to blow them off and dry them in a pre. heated kitchen oven at 175 degrees. ( spare oven in my shop for such things)
I then put them in a glass beaker and cover them with straight nitric and bubbler...or hydrochloric acid and peroxide and bubbler to remove the foils. Then I filter out the foils,rinse with hydrochloric then with hot water before putting them in the AR solution.

 

[Yggdrasil]

Well...when it comes to the PCB's....like in the photo, I first get them all to "about " the same size. Then I have a large basket sieve that I put them in and then dunk them in boiling water for about 30 seconds to remove excess fibers from trimming them to size, and hopefully remove any oils that might be present. I then use compressed air to blow them off and dry them in a pre. heated kitchen oven at 175 degrees. ( spare oven in my shop for such things)
I then put them in a glass beaker and cover them with straight nitric and bubbler...or hydrochloric acid and peroxide and bubbler to remove the foils. Then I filter out the foils,rinse with hydrochloric then with hot water before putting them in the AR solution.

Then I guess the murky one was in Nitric, right?

 

[Cleon]

No....in fact it was the only one I did in hydrochloric and peroxide???

 

[Cleon]

I will post a picture of the solution and the boards when I get home.

 

[Cleon]

So, I put the solution in a couple of jars to free up my beakers....it has been sitting for several days now and still very milky. There is signs of it separating, probably do to me adding water to the solution. As you see the boards are even covered with the film, that since they have dried is chalky to the touch.
The gold and other metals are gone. Im wondering if it is coming from the boards, but I can't say.

 

[Yggdrasil]

So, I put the solution in a couple of jars to free up my beakers....it has been sitting for several days now and still very milky. There is signs of it separating, probably do to me adding water to the solution. As you see the boards are even covered with the film, that since they have dried is chalky to the touch.
The gold and other metals are gone. Im wondering if it is coming from the boards, but I can't say.

The reason I thought about Nitric is that it could be Metastannic acid, but it could also be Copper Chloride.
Add a bit more HCl and see if it cleans up with air bubbling.

 

[Cleon]

Thank you so much for the suggestion. I will definitely try it and keep you posted. I truly appreciate all the help you and others. The support I have received from this awesome forum is impressive. Everyone has been very helpful, courteous and respectful, even with me being such a novice.
Cleon Lambert

 

[Cleon]

ok...I did add HCL and Wow...almost instantly clear. Amazing...but why???