Tin Recovery From E-Waste part 1: Viewer Request Special
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- Опубліковано 26 вер 2024
- In this video I tackle an often asked question from viewers: How to recover the tin from E-Waste? Here I show one way to do it. I show a method for recovering tin from depopulated circuit boards. In future videos we may explore other ways. Please visit the Urban Gold Mining section of my web site at mdpub.com/Urban... for more information.
My other channels: @electrogeek6437 Electronics & Retro-Computers
@MikesLapidaryFossils Rockhounding and Fossil Hunting.
Chemicals used in these videos:
Muriatic Acid, 1 gal amzn.to/3ENdTvs
Pure Lye 99% Pure Sodium Hydroxide Beads amzn.to/3LrK9b2
Sulfuric Acid Drain Opener, 32 fl oz (2) amzn.to/3iX7Hpc
Coconut Shell Activated Charcoal Carbon - 2.2 Lb (1 Kg) amzn.to/3sSbnB9
Nitric Acid: xelexo.net/ind...
Sodium Nitrate 99+% Pure 5lbs amzn.to/3EG5PfX
Custom Building Products Sulfamic Acid amzn.to/3lc3aSy
Hi-Yield Iron Sulfate (4 lbs.) amzn.to/3p788RA
Bonide 1-Pound Granules Stump-Out, 4 Pack amzn.to/2Vlty1y
Tin Shot (1 Pound | 99.9+% Pure) Raw Tin Metalamzn.to/3fclLKl
Easy Peasy Urea Fertilizer amzn.to/38q5Xjx
Equipment and supplies used in these videos:
Dual Powered Digital Pocket Scale 200g x 0.01g amzn.to/3GJC8vR
3pcs Glass Graduated Beaker Set 500ml, 1000ml, 2000ml amzn.to/3faaHO3
12PK Watch Glasses, 6" (15cm) - Cover Lids for Beakers & Flasks amzn.to/3j5MHMS
Filtering Flask, 1000ml - Borosilicate Glass - Conical Shape, with Integral Side Arm www.amazon.com...
United Scientific Supplies JBF1150 Buchner Funnel, 1150 ml, Diameter 150 mm amzn.to/2WAamh7
1 Stage HVAC Vacuum Pump 4.5cfm 1/3hp 110V amzn.to/3Sip451
Aroma Housewares AHP-303 Single Burner Hot Plate, Black amzn.to/378jL1p
Plastic Strainer 6-Inch, Black amzn.to/3DU9Ywe
Plastic Squeeze Bottle - 2Pcs Wash Bottle 500ml amzn.to/3KE1HQI
300PCS 3ML Plastic Transfer Pipettes amzn.to/3f9JQ4B
Nitrile-Vinyl Blend Exam Gloves, X-Large 100 amzn.to/3swI0EZ
Refining Precious Metal Wastes by C. M Hoke amzn.to/45X5Wiu
Your final procedure when processing Printed Circuit Board (PCBs) is actually my initial procedure.
Removal of solder (tin recovery) liberates all electronic components from PCBs, making it so easy to sort out the loose components for further processing; hence it's always done before attempting to recover gold, silver, copper, or any other values. Remember: Tin is worth around 5 times more than Copper!
Most backyard refiners refuse to accept that time is their best friend. They want "results" here and now. Contrary, it's much more profitable to use less acids, use methods that enables you to recover spent acids and chemicals, use procedures that demands the least physical attention, and instead let the time work for you. Your fear of getting iron in the solution is founded in the fact that your HCl is far too concentrated for solder removal. Very weak HCl will dissolve most of the tin, some of the lead, an insignificant amount of iron, and won't touch silver. It just takes a little longer.
Tin behaves odd in many ways. One of them is if tin solder has been in contact with copper (or gold), a phenomenon called metal diffusion have occurred. It's best illustrated if you use a cheap soldering iron with a copper tip. Over time the tip inevitably becomes shorter and shorter as the tin solder absorbs a tiny part of the copper tip every time you use it. Therefore, dissolved solder from fully gold plated pins do contain gold! Metal diffusion is one of the reasons why a two-step process is needed for complete removal of solder from PCBs. A small part of the solder is encapsulated in the diffusion layer of tin/copper. HCl cannot dissolve copper unless an oxidizer is present, but HNO3 can. Caution: Don't try to remove solder solely with nitric acid as the first step, unless you love to fight with that slimy goo called metastannic tin.
Be aware there are two types of solder. The old type (commonly 63% tin + 37% lead), and the new lead free type (at least 90% tin + around 5% copper + 1 to 4% silver + around 1% other metals, usually bismuth). The two types behave different during dissolving and must be processed accordingly.
Very weak HCl, between 4 to 6,5% is ideal for solder removal. Reaction time is up to 6 hours for old PCBs with thick tin/lead soldering, around half the time for PCBs with lead free soldering, and around one third of the time for newer PCBs (surface mounted components) having thin soldering.
Heating speeds up chemical processes. It has been common practise to heat the HCl solution to 80 C (some even say 90 C but it's around the boiling point of 6.5% HCl, and too near the boiling point of 4% HCl). An annoying side effect occurs when lead is exposed to HCl: Lead develops a passivation layer! That's why HCl can't remove more than around half of the lead from the old type solder, but removes 90 to 95% of the tin (5 to 10% is trapped under the lead passivation layer). Regarding the lead free solder, HCl removes around 98% of the tin (2% is trapped in the metal diffusion layer), but none of the copper and silver alloys from the solder. The thickness of the passivation layer is not linear proportional to the temperature, at higher temperatures just a slight increase in the temperature causes the layer to double in thickness. The latest scientific research has shown that the heating temperature must not exceed 75 C to keep the passivation layer at a manageable level. At 60 C the layer will be rather thin, although this temperature prolongs the dissolving process. Nevertheless, 60 C is the optimal temperature.
If this method is used for a combination of depopulation and at the same time solder recovery, it's important not to submerge the PCBs in the acid. Weak HCl dissolves some other metals too, though rather slowly. However, aluminium parts will not only be lost, but also immediately consume the HCl, and worse the acid solution will be contaminated with aluminium causing nothing but problems later on. To avoid that, I use several flatbottomed 90 liter rectangular plastic tubs. The PCBs are placed in a single layer and weak HCl is poured slowly into the tub to a level of maximum 5 mm. This way none of the components comes in contact with the acid, only the legs/pins. Due to the low quantity of acid in the tub, already at the next batch a few ml of full strength HCl must be added when the reaction slows down. Be careful not to add too much HCl in order to keep the acid concentration below a maximum of 6.5%.
You added H2SO4 before filtering to create lead sulfate. If you had filtered the solution prior to addition of H2SO4, you could have removed the lead chloride; which is easy to recover metallic lead from by electrowinning. Such process has the added bonus of recovering all of your spent HCl for reuse to dissolve more solder = free HCl acid! Tin is a heavy acid consumer.
Prior to the second step in solder removal a thorough cleaning of the PCBs must be done to eliminate all traces of HCl. Either by dipping them shortly in boiling water, or better by pouring boiling water on them. Avoid any extended contact with boiling water as some electronic components, like aluminium cased electrolytic capacitors, poses a risk of exploding if heated.
HCL is very effective for dissolving tin but struggles with lead. HNO3 will finish the process, now that almost all tin is gone.
Weak HNO3, between 6 to 9% maximum, will dissolve all the remaining tin, lead and/or silver/copper present in the solder; both from the lead passivation layer and from the metal diffusion layer. Heat to under 75 C (60 C is optimal). Reaction time is pretty fast. Thin solder residue is removed in 10 minutes, remaining thicker solder layers take more than ½ an hour. Never leave the PCBs in this solution for more than 1 hour as nitric attacks most other metals too, thus damaging components if you use this method for depopulation. If solely bare boards (without any components) are treated, you can leave them for as long as needed for full recovery of all exposed copper on the boards. Notice: If the concentration of HNO3 is kept at a maximum of 6.5% no metastannic tin is formed!
Lately I've found that a large fine-mesh plastic net/sheet is excellent for lifting up the PCBs and all liberated components from the acid solution in one go. It's placed in the tub before any PCBs are spread out on the bottom.
The bare boards are then processed for recovery of Gold (even the thin ENIG Gold-plating), and later further processed for Bromine extraction and pyrolyzed, yielding Raw Pyrolysis Oil. Warning: In the '70s and '80s lots of PCBs were made of various fiber material impregnated with resins containing formaldehyde. When such boards are heated they'll give off dangerous fumes which will contaminate the pyrolysis oil, requiring purification because it's illegal to use as is. After purification I run this Raw Pyrolysis Oil through another unit, cracking it to Petrol/Gasoline, Diesel, and Fuel Oil.
Last step is separating out the copper layers. What remains is solely the glass fibers, which are only profitable to sell in shipments of 10 tons or more. Luckily, a glass recycler passes by to pick up all types of glass for free so at least I have no expenses for disposal.
All electronic components are processed hydrometallurgically for full recovery of Precious Metals as well as all Base Metals; nothing is lost.
I process all high/medium/low grade PCBs at home for recovery of virtually every bit of value from both the boards, as well as all the individual electronic components. I never waste time manually depopulating any kind of Printed Circuit Boards!
Thanks for all the good advice.
Thank you for your comment it's very informative
What's your pyrolysis setup look like?
@@petevenuti7355. I have four pyrolysis units. Each is built for handling only one of four different ways of pyrolysis, depending on the type of feed material. One of them is made entirely of acid resistant stainless steel.
All are constructed with the same basic fire chamber (rocket stove), and interchangeable reaction vessels. I can quickly swap reaction vessel, even when the fire chamber is burning red hot. I have nine reaction vessels; and one extra for water distillation. The latter provides me with distilled water at no cost (raw material is waste water from chemical reactions and refining). I can do many pyrolysis runs a day, but every reaction vessel must cool down until next day to avoid self ignition of the carbon remains.
A fifth one is on the drawing board. It'll be a very large one, capable of handling things like refrigerators (compressor removed) or whole car doors/hatches, and similar larger objects.
What would you specifically like to know about pyrolysis units?
Could you make a video series about recovering everything from pcbs, you obviously know a lot and i wanna see your setup if you dont mind 🤔
Your making more work for me. I was about to scrap a bunch of boards. But now i have to keep them. Thanks
Just started processing floor sweeps after a lot of de-populating. I was planning on doing electrolysis to my HCL boils to recover tin. Your timing of this video is perfect for me. I was curious if there was another method for recovering tin that would be more efficient for me.
Thanks for your time and effort. Looking forward to part 2.
thank you very nice formula tinclorite to tin metalics very beautiful
Very cool
Mike that was an AWESOME explanation of the process I truly appreciate it
Thank you for uploading. Was curious how to recover tin
That was a great explanation on how to do this. I cringe at all the tin I have discarded
Thank you
The bathtub ring will come off with isopropyl alcohol. I boil my memory chips in Muriatic acid to remove the solder before I incinerate them. I don't want tin in my aqua regia when I extract the gold from them. I always assumed that the ring was from the adhesive that was under all the stickers on the chips, But that stuff keeps forming on the glass. I have found that pouring a little isopropyl alcohol in the glass and wiping it down with a napkin really gets it off easily.
thanks for the valuable experiment, it helped me a lot to get the tin chloride from the soldering wire
A thought on the waste boards, stripping the solder mask with Sodium Hydroxide the putting the exposed copper clad boards into Sulfuric acid to get copper sulfate, then electroplating the copper back out to reuse the acid in a cycle?
Also wondering about tin recovery, from AP solution heavy with copper and tin I would imagine ... Thank you 😊😊 always good stuff 👍
separating the copper and tin would be a problem.
@@omegageek64 so just selling it as bronze would be ok .. best case use the alloy to make "love knots"
If you ever see a circuit board with the letters sn ag cu silkscreened on it, you're looking at a board that uses lead-free solder. The Sn is TIN, Ag for Silver and the Cu is for copper. There may be Silver in that Tin you're extracting from those circuit boards.
Theres lots of palladium on those ram sticks. Prolly some gold traces. Id use heat to get the tin and ap to get the gold
That heavy sediment you had before you added the sulfuric acid was likely gold. I hope you didn't throw away that filter paper.
The sediment you’re talking about is almost likely silver as the gold foils “should” be visible unless you’re talking about the precipitate which would most likely be lead sulphate
@@redbaronrefining5322 Silver, gold and whatever else is present after you subtract the tin
Not gold without dissolving copper.
What did you do with the lead sulfate. Same compound found in lead acid batteries...
Did you rinse off the depleted RAM sticks before tossing them in the trash. One to neutralize the acid and two to get all the tin solution included in your recovery process?
Electrolysis is the way to go for recovery of tin
That may make an appearance in a future video.
Where is the video?
Mike I recently did the AP method on my boards and I was wondering how do I collect the lead and tin out of the solution if you get a chance to do a video on that I would really love it
Okay.. might have wanted to filter before & after sulfuric acid... 🤔🤔
Black dust from the first filtration may contain silver and gold. Silver from the solder and gold from the connector on the chips.
Hi Mike, Fascinating! I think I'll wait until you do part 2 to see the other options. Since I have 5 - 60 gallon drums full of boards - I'll have to think about this! One question - would aluminum capacitors cause any problems being left on the boards? ooppss - one more....would the exothermal heat get hot enough to distort or damage a 25 gallon plastic drum? See what you've done!! Now my brain hurts! Thanks for all your R&D to educate us! Thumbs up! Stay safe. Jim
Part 2 is going to be about ways of converting the tin oxide back to tin metal. Sometime in the indefinite future I'll look at other ways of getting the tin out of solution. Going to be a while though. As usual, I'm heading out of town for a couple weeks.
@omegageek64 I look forward to it. I just checked and tin is $11.80ish per pound. Curious to see your yield
@Respawncomedy where? I am paying 25 bucks for .9985+ I could use some 12 dollar tin.
@@ManMountainMetals don't know. I looked up tin metal values
this is good stuff mate
I skipped to the end so maybe you already mentioned this, but if you just soaked the entire ram sticks in hcl then you'd probably recover more tin, and also that would remove the chips from the pcbs. Two birds with one stone.
It would also dissolve iron from the steel legs of some ram chips. Iron and tin are notoriously hard to separate. My way the tin is iron free.
@omegageek64 oh weird I hadn't known there were chips with steel legs. Nickel yes, but iron? Those must be some really cheap chips.
Save and send them to Jason so he can get the copper out
Hi Mike could you have use baking soda (cheaper) SnCl2 + 2NaHCO3 → SnO + 2NaCl + H2O + 2CO2
One word: foaming. Ammonia and/or lye are more expensive, but there is no foam over.
Just save up the boards and give them to the scrapyard for free along with stuff you're already turning in for money. Even if they wouldn't want to pay for them, the copper is still in there and it's better to let them have it to recover than sending it to a landfill.
Wouldn't there be copper in this - dissolved by the hydrochloric acid ?
Not much. Hydrochloric acid doesn't readily dissolve copper. plus it will preferentially attack the tin since it is a more reactive metal. I pulled the boards out when the tin reaction seemed to be done. The lack of green color in the solution shows that there is little if any copper present.
Is there any gold under the solder mask? Was wondering if I should save those ram boards.
Nope two thin pieces of copper foil with fiberglass in between is all that is left.
OK so I tried this with all the lose solder I had from de-populating stuff. After I added sulfuric acid filtered the HCL it was clear but then it sat for a week and the top few inches turned yellow. so a put a few tin balls in and they started to react. the next day some metal (I think the metal that made your solution purple) fell out, I filtered it and slowly added lye crystals straight into it. The tin fell out of a clear solution. the waste solution I heated a little and added some hcl and lead crystals(i think) fell out . I did it several times and once it changed to a white powder I know was lead. so check your waste maybe?...Fixed..... in the end I added HCL when it should have been sulfuric acid. warm the solution and add sulfuric acid and the lead will come out of solution. it also come out if you just leave the solution about a week.
Nice video
Sulphuric acid is conc or diluted
Mike I've seen you use PH test strips before (with the colour comparison chart). Why use litmus paper this time?
Those test strips only measure a narrow range around neutral. I don't need precision for this operation.
This tin will be very dirty with copper etc
So.. why dilute the HCL? Couldn't you dissolve more RAM sticks and do it faster if you hadn't diluted it?
it's seems no one removed tin from soldered board then recovery gold from soldered gold plate pad.😢
Stannous chloride is not a reactive test to detect gold in solution?
ahhhh, I could have ran those through my granulator... 😞
Sorry I didn't think to ask you about that. does your granulator do a good job of separating the copper from PC boards? If so, I can send you some from a future batch.
I did a small test run, It was about 50 percent clean coming out, lot of it was the mask still stuck to it. When I get some time I am going to run a batch after I put it in a lye bath. Maybe that will loosen up the mask so when it is hit by the blades it will separate better. Over all it does a good job. Better than fine braided wire. The copper bits are bigger.
Hi Tim. Would you be willing to make a video about your granulator? How it works?
The factories that make them have some videos on UA-cam. What would you be looking for on operations?@@ttutone1
I am thinking of doing this but wondering if adding sulphuric acid from a car battery will still precipitate the lead sulphide or would the sulphic acid already be loaded with lead as it came from a lead acid battery?
Are you going to melt or smelt the tin into a solid metal??
Going to try a couple of different methods.
@@omegageek64 Very Cool
Hcl will stay active until you neutralize it.
The cost of acids and electricity and time is not worth the price of the end result. The chemistry is cool though
I buy tin in the form of lead free fishing weights from Wally World. This is a good chemistry experiment, but in no way profitable.
Truly painfull to watch. With all the constant blathering I couldn't finish the video. So I still don't know how to get the tin out.
Lie is a good word...
For this ? Video ?
OOOOOPS -
I meant lye.
Let's spend 30 dollars and a bunch of time to recoup maybe 5 dollars
Not worth the time and cost but the chemistry is cool if you just want to explore the chemistry
The first part with hcl is useless.
Melt the copper out
A copper II chloride leech will take the copper plating off the boards before you pitch them. You can easily recover that with a little bit of aluminum tossed into the copper II chloride. And as you know the copper II chloride is essentially self regenerating. You just got to refresh it every once in a while with some HCL and its cheap enough that you're going to be losing money by throwing your copper away like that. I mean this is about recycling isn't it? this whole thing?
Another way of extracting the tin is via electrolysis... Save you the cost of the lye
i just need to know how to convert lead sulfate back into Metallic lead please now
Heat above 1000 C to convert it to lead oxide. Reduce to lead with charcoal.
Have you tried freezing them : tin became dust with cold
Mike, question for you. I used vinegar-salt-h202 to free gold foils from random boards. There is a bark grey sludge forming. Presuming it is coming from the solder. Will H2SO4 release it from the gold foils, or do I go a different direction.
How is it acidic if your ph was above 7 in the first place