Keyboard mylar processing

[kjavanb123]

All,

After taking over the abandoned refinery plant, I have almost 400 lbs of keyboards, which i dismanlted one of them to get the mylar and dump the little boards into another bucket, tried to burn the mylar using a torch and it made into this

This is the 150 lbs of keyboard being moved to weighing station,


Also more keyboards on shelves to be processed later


I will use the shredder there with one mylar to see the result will post them, also would it be possible to shredd the entire keyboard and acid wash in a SS tank there to remove the silver. Will post pics soon.

Since i am getting these e waste almost free and GRF has been the main education I got for refinery any proceed from refining and profits some of it will be donated to this awesome site as a way of getting back to all who have helped me learn so far.

Regards
Kevin

 

[Claudie]

There are a lot of metal screws and sometimes a metal plate inside the keyboards, that may make shredding a problem and possibly mix other metals with the Silver making it harder to process.

EDIT: It looks like you have a lot of work ahead of you, have fun!

 

[Smack]

Don't shred anything, not even the mylars. The mylars are as small as they are going to get, shredding them will only make them take up more space. Read the post by lazersteve on the topic.

 

[kjavanb123]

I read the Steve post on it snd first picture showed the result of that test, so I need to go to dilute nitric stripping for these, but using the shallow dish of dilute nitric and put the mylars one by one is very time consuming for the load we have, I used the shredding the x-ray films and boil them on oxalic acid.

Regards
Kevin

 

[Pantherlikher]

Nice...
Looks like you gots alot of work just waitin for ya...
Buy a good screw gun and bits and remove any and all screws you find... and the good stuff will just fall out on you.
I believe GEO? has a nice long thread on keyboards. Do a mylar search and read some.
Good luck and have fun...
B.S.
If only my piles of crap smelled as good...

 

[kjavanb123]

All,

Thanks for your input, please find the following data for this 110 kg load of keyboards,

Total keyboard weight: 110 kg = 242 lbs
Net mylar weight: 2.3 kg = 5 lbs
Will post the weight on PCBs and ICs recovered from them tommrow.

Mylars


A cool method I have found by accident in order to remove the mylar and small PCBs inside the keyboard, is the have a metallic cart like the one in the picture, preferly with solid sides, then wear eye protection glasses and gloves plus an air mask, then smash the keyboards side way to the edge of the kart, untill it breaks which is pretty fast, once you did this with both ends of keyboard, mylar will be detached without any effort, plus the keys and plastic will end up in the cart, sometimes the PCBs end up attached in the plastic and in the cart which you can remove later.
I did the unscrew using a battery charged screwdriver it is neat but very time consunming, so try this method instead you can 100 keyboards in 30 mins or so.

A fast scrapping method for keyboards


More photos and update tommorow.

Regards
Kevin

 

[Smack]

I wouldn't trust that scale lol poor thing looks like it got run over by a bulldozer.

P.S. Rotate pictures please.

 

[kjavanb123]

All,

Some updates on the project, I used some of the polypropylen tanks available on site, filled it with 50 hno3 and 50 water to almost 2 inches. I could lay 6 to 7 sheets per batch, this speed things up down side larger acid volume used, also places a rinse bucket nearby so after the sheets were stripped I would spray them to the rinse bucket with distilled water.

I still think about a paper shredder would be beneficial and speed things up even faster. Will try that tommorow.
Pictured of mylar stripping tanks before and after



After putting mylars in




Regards
Kevin

 

[jmdlcar]

kjavanb123,

When you take apart the keyboards that little board inside are you going to keep them? If not PM me what you may want for them.

Thanks
Jack

 

[kjavanb123]

Yes I save the small boards inside them, few of them are one side gold plated, there are some ICs which I removed and saved to further processing.

Regards
Kevin

 

[jmdlcar]

Thanks I glad you know about the gold and they are not going to scrap yard.

Jack

 

[kjavanb123]

Jack

Thanks for that info, yes I will process those boards separately and post the result.

On the mylar project, I filtered the silver nitrate solution, dropped a small clean copper sheet to it, and lots of gray powder started to form, but I put in a big slap of copper which was used before to plate copper out of solution by the previous company who was working here, and silver nitrate solution turned milky, as yo can see in the following, I expect the copper chloride left on the copper sheet somehow replsced the silver nitrate with silver chloride, ouch, I removed the dirty coppper sheet and let the solution to settle and will check it tommorow.

Silver nitrate solution after stripping 2 lbs of mylars,


After putting a copper sheet that I suspect was copper chloride


Now I will check the forum to find a method to clean up the mess,

Regards
Kevin

 

[butcher]

As you know now the copper should be clean as possible, I would cut that piece of copper down to a piece that would fit your bucket better, the silver can try to plate to the copper, while you are trying to cement it out of solution, and with that large of a piece of copper you will have a hard time cleaning off the silver and recovering it.

Ideally You want a thick piece of clean copper, the thickness of the copper can help insure only the surface is attacked and the copper metal does not dissolve and fall apart into your solution as undissolved copper flakes, with thin sheets the surface area of the copper is not attacked evenly, so as the copper dissolves you can have small pieces of copper falling off into your silver cement, with is hard to remove, and can contaminate the other wise fairly pure silver with much more copper.

The copper buss bar used to cement should only be used for that purpose, and as you have learned you should not use it on both chloride and nitrate solutions, as you can introduce salts from a previous use, the buss bar should also be cleaned and rinsed after use, and dried and stored to keep it clean, sealing it in a plastic bag can help to keep it clean and keep it from oxidizing with copper salts that are not very acid soluble, the used buss bar will have some values plated to it, and with reuse you will recover these values.

You can let your solution sit, the silver in solution will form silver chloride and eventually settle out of solution as white silver chloride powders, as long as you have more silver nitrate in solution than you do chlorides, the silver will remove all chloride from your nitric (silver nitrate solution), as AgCl. this will clear your solution which you could then decant the clean silver nitrate from the powders and proceed to cement silver metal from with a clean piece of copper.

You will most likely want to keep silver chloride separate from your silver cement, and treat them separately, converting the silver chloride to metal before melting.

Or you could just go ahead and finish this batch cleaning off your copper into solution, and adding NaCl sodium chloride (table) salt to the remaining solution and treat the lot as AgCl.

 

[g_axelsson]

I would continue cementing on a clean piece of copper, then decant most of the solution, leaving silver and silver chloride mix in the bottom. Then mix some sodium hydroxide and pour in, this will convert the silver chloride into silver oxide.
From here you could either treat it with caro's syrup (or similar sugar) or just melt it, the silver oxide will decompose into silver and oxygen at 280 °C.

You might lose some unconverted silver chloride into the flux or going off as smoke. But if you try to do this on a commercial scale you need to know when recovery is good enough and not hunt for that last percent.

Göran

 

[kjavanb123]

Butcher and Goran

Thanks a lot for your advise, sadly I got it after I dried the mixed silver powder, here are the photos of what I did since thie morning 24 hrs after I left the milky solution,

Solution after 24 hrs, with some whitish gray color powder at the bottom,


After decanting the light blue solution, droppped the samecopper sheet and it produced some gray powder but after few minutes it started to dissolving the copper as the color of solution was going to darker blue, so removed the copper sheet,
And let the powder on the bottom of red bucket under the sun to dry


Aft 3 hrs it was completey dry, so I scraped it off the red bucket and weighed it that was 4.25 grams.


After it was melted the button weighed 2.2 grams. This was from a 700 gram mylar. This was my very first time so I must have messed up.

On the other hand, while scrapping 100 kg keyboards, I saved the plated boards, the gold plated one that are only plated on one side weight 15 grams


Here are some ICs which seem low yield for gold from 100 kg keyboards


So i have almost 1600 grams of mylars to process using a paper shredder and clean copper slab per instructions, while I was going through some of the telephones we recieved for free, and discovered under the dialing patch there is also a mylar with similar silver, which I will test tommorow.

Thanks all for your help
Kevin

 

[jmdlcar]

Most of them have gold under the green solder mask. Just make a mark with a knife on the green solder mask but not to hard and you will see it or not. The only thing hard to do is the parts and the solder on each board. Every keyboard has gold but one so that not to bad.

Jack

EDIT for spelling

 

[Smack]

There should have been more silver from 2lbs. of mylars. Just my opinion from doing them. Did you test the solution with HCL after cementing? I'm guessing you had free Nitric left, next time have a measured amount of silver to put in your solution to use up the Nitric acid before you put the copper in to cement the silver. Or don't cement your silver out of solution, put it in a container and wait till you have more mylars to run and use more of the Nitric in your solution that way before cementing.

 

[kjavanb123]

Jack,

No I haven't tested the left over solution with HCL will do this and will let you know.

Regards
Kevin

 

[kjavanb123]

Update status on this project, I took suggestions from you guys, dropped hcl to the left over solution and got this white cloud forming, as you can see below


This is the silver chloride after decanting the solution


Also cut the fingers from the boards scrapped from the keyboards, here is the weight ratio of board weight to the finger weights.

And the fingers from the boards



Regards
Kevin

 

[Smack]

Kevin I said test the solution with HCL, all you need is one drop and it will tell you if there is still silver in solution or not. If you get any white when the drop hits the solution, you need to put the copper back in. You could have just left the copper in overnight the first time around. Better yet, do like Kadriver and cement the bulk of your silver, decant then leave your copper in overnight. There is a lot of info on this subject here and has been for quite some time if you catch my drift.