Our Gold Recovery & Refining Project -- Begging for... "Assay"

LT_golden

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Hello, GRF,


I’m new here, and my friend and I are electrical engineers in the consumer electronics industry. We recently cleaned out the EE lab at the office and were allowed to keep any of the electronics garbage that we wanted. So we spent a couple of weeks’ time, off-and-on, to pull out pins, cut out gold fingers, and desolder what components we could off the PCBs that were gold plated, for our gold recovery and refining project.

The lab has exhaust pipes with hoods to draw away the fumes from soldering, and so we’ll be using doing all of the chemistry underneath those.

We are not pressed for time or anything (this is a personal project, after all, probably once-in-a-lifetime-only), but we would like to be as safe and yet as efficient (in terms of gold recovered & purity achieved) as we can, all the while learning and having fun.

Toward those ends, I have drafted up the following procedure based on what we could understand from our research. The point of this post was to sum up our knowledge into a procedure we can safely follow to achieve our desired results, and to beg for your review and evaluation of it. Before that, here are a few side notes.

* I happen to have a reverse osmosis (RO) system at home so we’ll be using RO water throughout the entire process.

* When heating water, we would use a microwave, with the water inside a glass container that has been cleaned inside and out with soap, and nothing else would touch the inside of the container. When not in use, the container would be placed up-side-down on a rack.

* We are unable to obtain hydrochloric acid where we live, so we’ll just use the vinegar + table salt (iodine-free) + hydrogen peroxide (peracetic acid?) method. However, for simplicity’s sake, I’ll just refer to it as HCl (or hydrochloric acid).

* We also can’t obtain nitric acid, so no aqua regia for us; nor concentrated sulfuric acid, so we have to make our own from battery acid; we aren’t even going to consider cyanide due to the dangers associated with it; and we wanted to do something completely different from our work, so no reverse-electroplating.

* Thank you, Harold_V, for your multiple-washing instructions for gold powder. As well, thank you, Harold_V, Geo, Butcher, lasersteve, FrugalRefiner, 4metals, and all the experts whose names I have forgotten, for all your valuable info.


And now, on to the procedure that we have written up. The gold recovery process is already in progress and


Recover the Gold
a) Soak the electronics parts in a white vinegar, salt, and hydrogen peroxide solution for ~3 days and, with an old toothbrush, brush off all gold plating that hasn’t yet fallen off. I’m using an air bubbler, with a knot tied at the end of the tube but with holes poked through it with a sewing needle, to reduce the bubble sizes. This was used during my aquarium days and was great for injecting CO2 into the fish tank without having to deal with air stones with lousy suction cups and needing to be cleaned in bleach once in a while due to algae growth, etc.
b) Rinse gold flakes from larger components (eg. PCBs) with water into the metal solution.
c) Filter the solution using a plastic kitchen strainer to eliminate larger pieces while keeping the gold foils in the solution.
d) Rinse the larger pieces for final gold flakes. Use the toothbrush if needed.
e) Filter the gold flakes with 2 stacked coffee filters. Using a wash bottle, wash the gold flakes to the center of the filter.


Prepare Concentrated HCl for Dissolving, Washing and Purifying Gold
a) Place white vinegar in refrigerator (4 deg. C) for a couple of hours.
b) Filter for the solids formed (concentrated acetic acid).
c) Dissolve salt until saturated.
d) Filter out salt that was not dissolved.


Dissolve the Gold
a) Place entire filter paper with the gold flakes inside, into a glass container.
b) Add the concentrated HCl into the container with the filter paper + gold flakes.
b) Gently heat to keep mixture at ~65 deg. C.
c) Slowly add bleach, stir, until all gold dissolves.
d) Cover and allow to settle for half an hour. If more gold particles remain, reheat and add more bleach.
e) Repeat d) until all gold is dissolved.


Precipitate Platinum and Palladium
a) Saturate hot water with ammonium chloride.
b) Use filter paper to filter out trash.
c) Add to metal solution and stir.
d) Using excessive ammonium chloride may be helpful in precipitating all the Platinum and Palladium.
Q.: Harold_V has said that Platinum-group metals do not precipitate from dilute solutions, so I’m not sure about this step. Could I skip this step without the risk of contaminating the gold with the Platinum-group metals?


Precipitate Lead
a) Around here, I can only get 1:1.28 strength battery acid. Concentrated sulfuric acid is out of the question.
b) Boil battery acid to remove water. Place inverted funnel on top to reduce splashing.
c) I would stop the heat once the boiling slows down to minimize dangers associated with overheating very concentrated sulfuric acid (hopefully this concentration is enough to precipitate all of the lead in the metal solution).
e) Allow both the concentrated sulfuric acid and the metal solution to cool to ambient temperature.
f) Drip sulfuric acid into the metal solution to precipitate lead, until no more lead sulfate forms with any additional sulfuric acid.
g) Add ice cubes to metal solution + lead to cool before filtering out lead sulfate and other particles.


Precipitate Gold
a) Heat metal solution to ~50 deg. C.
b) Sprinkle Sodium Metabisulfite (SMB) into metal solution and stir.
c) If Stannous Chloride test shows positive for gold, then sprinkle more SMB.
d) After Stannous Chloride test shows negative for gold in the metal solution, filter for the gold precipitate.
NOTE: Thanks in advance to lasersteve for his reply at Small precip particals. Good to know to avoid precipitating ultra-fine gold particles that pass right through the filter paper!


Wash and Re-Purify Gold
a) Hot water wash until the mixture becomes clear.
b) Into gold powder, add concentrated HCl prepared previously, and water. Boil mixture for about an hour.
d) Add water to cool, allow gold to settle, then decant.
e) Add 10% ammonium chloride solution (the best that I could get here), twirl to allow ammonium chloride solution to wash powder more thoroughly, then boil until ammonium is gone.
f) Add water to cool, allow gold to settle, then decant.
g) Wash with hot water, add water to cool, allow gold to settle, then decant.
h) Repeat through a) to g).
Q.: By Hoke (pg. 73, section entitled "Some Special Cases"), this should be enough to get rid of most of the tin, iron, copper, lead sulfate. However, she used aqua regia (which we can’t obtain because we can’t obtain nitric acid here, but tin would be dissolved by HCl anyway, so we believe that this process would still help). Is this correct?


Re-Dissolve and Re-Precipitate Gold
a) Into mixture, add concentrated HCl prepared earlier.
b) Gently heat to keep mixture at 65 deg. C.
c) Slowly add bleach, stir, until all gold dissolves.
d) Allow to settle for an hour. If more gold particles remain, reheat and add more bleach.
e) Repeat d) until all gold is dissolved.
f) Precipitate gold, using oxalic acid (Hoke said that this was good if the gold to be precipitated is already pretty pure, which we are hoping that this would be the case at this stage; Harold_V said that he never used 2 different precipitants and still got good results), which is available here as a bathroom and porcelain tile cleaner.
g) Filter gold powder, wash thoroughly with hot water while in filter.
Q.: Is this a bad idea, using a bathroom and porcelain tile cleaner containing oxalic acid to precipitate the gold?


Prepare Gold for Melting
a) Crunch filter-paper-with-gold into a ball, and gently blow-dry.
b) Wet ball with alcohol and allow to dry.
NOTE: This is so that I do not blow off any gold powder during the melting process. I don’t have the experience or the confidence to do it correctly (elevating the torch to 12+ inches initially, heating from the edges, etc.), and I don’t have the resources to practice with. Additionally, we have limited access to the torch.


Melt Gold
a) I’ll be using a newly-purchased ceramic melt dish, washed with soap and water. I will also abrasively clean the inside and outside of the torch head, as well as wiping it clean.
b) Heat with torch, sprinkling Borax powder now and then to see if it melts right away.
c) When Borax melts easily, cover lightly with Borax, and then place the filter paper ball inside, then sprinkle some more Borax over the ball.
d) Heat the ball, until all paper burns away and gold melts into a bead.
e) Very, very slowly lift the torch (taking eg. 5-10 minutes to get to a far-enough distance where the heat from the torch is no longer sufficient to keep the gold glowing-hot). The purpose of this is to see if I could make the gold form into crystals.
f) Allow gold and melting dish to cool completely, then add water to dissolve the Borax and retrieve the gold.
Q.: How could I make sure that the gold does not attach itself to the melt dish?
Q.: if the gold does get attached to the dish, would I be able to just break the dish to get the gold bead without damaging its surface? Hoke said to just break the dish (actually she used a crucible), but didn’t mention whether this would damage the gold bead’s surface.


Waste Solution
Q.: I’d like to grow cupric acetate crystals from the waste solution. Could I use a similar method to growing salt crystals? I’d probably add copper wires pieces to the solution until no more would dissolve (saturate), then using a long copper wire instead of the fishing line in the solution, then add small pieces of aluminum foil to the solution and let the cupric acetate form crystals on the copper wire? Would the cupric acetate precipitate too quickly for crystals to form on the wire, even if I add ~1cm^2 of aluminum foil at a time?
Q.: After growing the cupric acetate crystal to the size I’m happy with, we would first continue adding aluminum foil until it no longer dissolves. Then we’d slowly add lots of baking soda (slowly, so that the reaction isn’t so fast that the liquid spills) to neutralize the acid (and do a pH test). Then we’d filter the particles to seal in a transparent resin to serve as a record of this event (also for safety reasons). Afterwards, would the solution be safe to be poured down the drain? Would the sodium bicarbonate be enough to cement out the aluminum? By the reactivity series, it should... Right? We don’t have the sodium hydroxide or the magnesium hydroxide that 4metals mentioned in his waste treatment reply.
NOTE: Thank you to 4metals for his reply about waste treatment here.
NOTE: After I get the crystal, I would then cover it with a nice thick coat of clear nail polish to preserve it.


Additional Questions
Q.: How could I have recovered more gold, eg. from the waste solution?
Q.: How high could I expect the purity of the gold bead to be if I follow this process?
Q.: What steps did I miss? I’m sure I forgot something... What could I do better? Which steps may be unnecessary and could be skipped without affecting gold purity? Looking for an education here!
Q.: Are there any safety-related issues you see with this process? What could I do to further reduce damage to myself and my friend, and to the environment?


Thank you so very much for having read this far, and we really appreciate any comments, questions, what-ifs, and/or concerns that you might have for us!
 

butcher

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LT_golden,
Your first post shows you have done much of your homework.

I cannot help you with the question of the use of vinegar, Using an organic acid substitute for Mineral acids or inorganic acids as I would not try it myself, I do not understand the organic or carbon-based chemistry or its dangers.

Freezing out acetic acid, which has a melting point of 17 ∘C . freezer around −10 ∘C.
filtering the solid acetic acid should give you very concentrated acetic acid, which could be a safety hazard.
https://en.wikipedia.org/wiki/Acetic_acid#Health_effects_and_safety
http://www.sciencelab.com/msds.php?msdsId=9922769

waste treatment, all acetates are soluble, many many metals will form acetates, Many more will form acetates with oxidizers in the acid, many of which are very toxic, I have not studied all of their dangers, or how one would deal with these carbon-based waste solutions.

Personally, I would concentrate my effort on obtaining or making the mineral acids, and forget the idea of using vinegar.
 

LT_golden

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First of all, thank you to butcher who replied with your info and experience. It's difficult to post at GRF where we live, probably due to the national firewall here. It took almost a week for me to successfully save my first post above!

Mineral acids are "hidden" in other products where we live and are therefore time-consuming to find. Nitric acid and nitrates are completely out of the question. Eventually, empty vinegar bottles piled up, and due to the vinegar being only 3% (cheaper) to 8.5% (twice as expensive) they needed to be replenished over the long spans of time we needed to dissolve all the materials. So we broke down and did some market research and eventually found some ~35% HCl (more expensive) and some ~20% HCl (less expensive). These did noticeably accelerate the process as well as reduce the amount of solutions needed. But we are still working on concentrating sulfuric acid from battery acid.

Side note: We were unable to concentrate our vinegar. Putting into the fridge (~4 deg. C) or the 0 deg. C cabinet did not produce any solids to filter out. But when placed into the -17 deg. C freezer, either the entire bottle froze up, or there was no freezing until the vinegar was agitated, at which point, the entire bottle quickly froze up. Letting the ice melt at room temperature and collecting half of the original volume in run-off also produced no appreciable color difference between the two, when tested with litmus paper. Maybe the vinegar contains something that we're not aware of.


On to our findings and thoughts so far.


On Processing Materials with Tin

When reading up on Hoke's advice on processing materials with tin, we thought, okay, HCl (which we eventually found) will take care of the tin solder, but since the goal is to dissolve all base metals anyway, let's just soak everything in the HCl + H2O2. This resulted in a thick layer of fine solids/paste that covered everything and very little gold foils had come free. We wasted a lot of time, thinking that the reaction was just slow. Indeed, the vinegar + salt solution actually stopped working after dissolving most (but not all) of the solder on the PCBs.

And because the HCl we found needed to be shipped with 3-day delivery, we tried to save our acids by not adding to the mixes.

Fortunately, at least HCl does take care of the pale paste/powder.

Subsequently, all newer batches were all soaked in HCl for a day before soaking in etching solutions. Actually just hours of soaking a BGA removed all the solder balls and dislodged the caps and resistors on the package. A quick rinse with our RO water cleaned off the dissolved solder slag, and the BGAs are ready for etching. This seemed to "tidy up" the process, allowing the etchant to work on the copper/nickel right away rather than wasting time and effort on the solder first (and possibly expending itself).


On Using an Air Bubbler

We only have 1 air bubbler and didn't think to get another. But from another point of view, this was also educational. We were able to observe that the vinegar and salt solution (with air bubbler) slowly albeit steadily continued to etch the PCBs (previously cleaned of solder by HCl) over a couple of weeks, while the beaker with the large amount of connectors and pins would seem to stall after about 3-4 days (with no air bubbler), unless a little more hydrogen peroxide was added. Sure, both solutions needed acid top-ups once in a while, but with an air bubbler, there seemed to be no need for additional hydrogen peroxide.

We've finished etching the PCBs for their gold foils, and the air bubbler is now in the beaker with all the pins and whatnot.


On Pulling Out the Pins from the Connectors

From our experience so far, pulling out the pins from the connectors whenever possible serves the purpose of reducing the total volume of materials to process, and, thereby, less volume of chemicals needed to reach all the materials.


On Recovery

So far, it seems that the recovery process can be quite varied and time- and energy-consuming due to the different kinds of materials to be processed: sulfuric acid (which we still have yet to distill a usable amount) wet ashing for the black-capped ICs and some plastics, incineration for other plastics (which we are thinking of just using sulfuric if possible; still trying), removing pins from connectors, solder removal, evaporating down solutions for easier management, repeated filtering in some cases, etc., etc.

Most of our difficulty is due us basically second-guessing ourselves at every step: Do I really need to pull out these pins, or would it really matter? Do I take out these half-dissolved base metal chunks or just wait for the acids to dissolve them all? Do I use the air bubbler in this container or that one? Should I first soak in HCl first to remove tin or boil in aqueous sodium hydroxide to remove contaminants first? It's been a lot of hard-work and guess-work, but it also continues to be fun and rewarding.

While we have not yet embarked on the refining process, from what we've seen in our research, refining appears to be more about being scrupulously clean, washing diligently, and to be patient for reactions to occur and for sediments to fully settle.


Next Steps for Recovery

* We have a last batch of pins just starting the soak in HCl + H2O2, with the air bubbler helping it along. Wait for days, monitor progress, add HCl as needed.
* We have a bunch of small connectors which look like they have a good coat of gold foils all the way, but the pins are very difficult to remove and so we think we will just etch directly.
* We have a bunch of larger connectors which need to be thoroughly washed of foils. The first wash for this will probably be done with a very dilute water + HCl solution to dislodge the foils from the connectors' plastic parts.
* We have a batch of low-value connectors, but we aren't sure whether it's worth processing these, since their pins are somewhat difficult to remove.
* We got ourselves 2L of 1:1.28 battery acid, and working on concentrating it safely based on catfish's post.
* We have a bunch of CPUs, PCHs, RAM ICs, etc., to be first boiled in sodium hydroxide, and then to soak in HCl to remove tin, and then to wet ash with sulfuric acid.


Looks like we have our work cut out for us. Thank you for having read thus far; apologies for the occasional incoherence, due to my tiredness while writing this update. I'll keep reporting as we progress (though, likely due to the exceedingly long first post, not many people were able fully read/respond). As always, any comments, suggestions, queries, constructive criticism, are all welcome.
 

butcher

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The idea of wet ashing besides being dangerous does not sound like a good idea to me.
I would look into using fire to do the work (incinerating the CPUs, PCHs, RAM ICs, etc...) instead of using acid.

I would also look into using some methods or processes, such as the concentrated sulfuric acid cell for gold recovery and other processes where your reagents are reusable or can process more materials, where most of the material is copper, smelting copper into high copper anodes and using electrolysis...
 

LT_golden

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Hi butcher,

Thank you for your reply.

For the black cap stuff... with incineration and then crushing, wouldn’t a lot of the gold bonding wires be trapped inside the package particles, and be very difficult for the acids to reach? I don’t have a steady source of these materials for processing, this is why I’m trying to recover as much gold as possible this one time, and from what we’ve seen in our research, I couldn’t do better than wet ashing, or could I?

As for reverse electroplating... Letting the pins sit in acid and just waiting it out isn’t a big deal, just needing patience and the occasional stirring (and even stirring isn’t needed now with the air bubbler) and replenishing the acids. What we would like to improve on is getting at the connectors with lots and lots of pins which are difficult to pull out, like older DIMM connectors which have a slightly thicker and more complete gold plating than the newer ones, as well as power connectors with the thick pins that are pretty much embedded inside the plastic and would need to be cut out individually. Reverse electroplating wouldn’t seem to help here, since it’s really difficult to get all metal in contact with the wire mesh of the electrode, right? Or am I just too lacking in imagination in this...?

Thanks very much for your help.
 

butcher

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LT_golden,
My advice is to keep looking for the reagents you may need.
Keep up with the study of the different processes used that are known to work.
Focus on mechanical separation of the materials and metals, different types of scrap may need different processes.
You will process more gold with your education than you can from trial and error with half-educated guesses and through blind experimentation.

I can see you are educating yourself well, but I feel you are trying to jump right in the middle of it all and tackle it all at once while trying to reinvent some of the wheels before understanding how they actually work.
 

LT_golden

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butcher said:
LT_golden,
My advice is to keep looking for the reagents you may need.
Keep up with the study of the different processes used that are known to work.
Focus on mechanical separation of the materials and metals, different types of scrap may need different processes.
You will process more gold with your education than you can from trial and error with half-educated guesses and through blind experimentation.

I can see you are educating yourself well, but I feel you are trying to jump right in the middle of it all and tackle it all at once while trying to reinvent some of the wheels before understanding how they actually work.

Hi butcher,

Thanks for the reply.

Yeah... you’re right about us doing some trial and error... the thing is, our main difficulty we think lies with the ICs.

For connectors, we’ve pulled out the pins we could. The connectors we have remaining don’t really have that much gold on them anyways, and we’ve considered just giving up on them since their pins are very difficult to pull out without breaking (mainly notebook computer SO-DIMM connectors). You kindly mentioned using reverse electroplating, and this gave me an idea, partly based on this discussion. I came home and mixed a small amount (~50mL) of vinegar and salt, grabbed an old cup, and also dug up the USB salt water metal etcher I made a while ago (basically just a couple of cables wired up to a USB connector and bundled up nicely. I attached it to an iPad charger, took some pins with gold on them still, and in a few seconds each, I was able to de-plate the gold on the pins. It was windy out, and I detected no fumes, but did see some bubbling on both terminals inside the solution, which by my understanding from your replies in that discussion, should be chlorine and hydrogen gases? I didn’t dissolve in HCl + bleach and test with Stannous Chloride, but from what I’ve read, that should have been gold.

My idea was that there was a piece of a sort of “breadboard” (sort of a practice circuit board, if you will) which is basically a thin sheet of copper. The SO-DIMM connectors could be laid against this sheet so that all pins are in contact with the sheet, submerged in the vinegar + salt, and reverse electroplated that way.

We are nervous about working with concentrated sulfuric acid. So would this be a reasonably safer way to deal with this kind of connectors whose pins are difficult to remove?

Though I did mention wet ashing, we are still very unsure about considering it a possibility (since we’re so nervous about sulfuric acid). We only looked at it because where we live, it’s easy to detect if your neighbor is burning something, and if it isn’t a barbeque... But inside his little workshop, we just might carry out wet ashing. At this point, we are still looking for ways to process these black cap ICs... we don’t have any kind of crusher, we can’t burn, we are scared about using concentrated sulfuric... while I continue searching, any direction you could kindly point us in would be greatly appreciated...

Incidentally, you mentioned reagents. Did you mean those used in recovery? HCl, nitric acid, and the like? Unfortunately, we are unable to acquire any nitric acid here without applying for permits and us and our families being closely scrutinized by the government here for the rest of our lives. Neither are we able to outright make nitric acid, as instant freeze packs here are all made with urea and fertilizers non-nitrate-based. Or did you mean chemicals like SMB, ammonium chloride, stannius chloride, oxalis acid, and the like? Those were easier to come by.

Thank you for your help thus far, butcher. I know I can be rather long-winded, so I especially appreciate your replies. This long-winded-ness is unfortunate, because while I try to learn and get help, I see a lot of posts made by people who obviously have not done as much research as we did, and yet they receive many more replies than I seem to be getting. I don’t blame anybody, because we all have lives and don’t want to spend a half hour reading through this kind of really long crap which doesn’t contain anything new to help them out. I have only myself to blame.

So, thank you again, butcher. Will report back when we think of a better idea of what to do next.
 

g_axelsson

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Are you doing this for fun or for profit?

How much gold do you think there are on SO-DIMM connectors?

Before collecting kilos of material you can do a small assay to see if the connectors are worth your time.
Here is a thread about pins from laptops... http://goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=27268#p288661

A test tube sized experiment could be all you need to find out how much gold you have in a circuit board or a component.
In this thread I extracted the gold from one circuit board (10 mg), http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=23737
or from a single IC (50 mg), http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=7056

Göran
 

butcher

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Because you have done a lot of homework, I find it is hard to give an answer, your post does cover a lot of territories making it harder to pin down on one subject or answer...

You can make many things you may need, even some reagents, although finding them locally would simplify matters considerably, there are also other ways you could do reactions which may not be common and may not be as efficient or as easy.

At this point, you have a good start in educating yourself but I feel you have much more to learn even before using reagents if you could find them.

I also suggest focussing on one type of material, one process, or discussion of processes.

Vinegar and salt is not a subject or a process I would even consider even if I lived in a cave, so discussing it is not something I find very interesting.
 

LT_golden

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Hi Göran and butcher,

Thank you for your replies.


Göran,

g_axelsson said:
Are you doing this for fun or for profit?

How much gold do you think there are on SO-DIMM connectors?

Before collecting kilos of material you can do a small assay to see if the connectors are worth your time.
Here is a thread about pins from laptops... http://goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=27268#p288661

A test tube sized experiment could be all you need to find out how much gold you have in a circuit board or a component.
In this thread I extracted the gold from one circuit board (10 mg), http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=23737
or from a single IC (50 mg), http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=7056

Göran


Yeah... definitely doing this just for fun, and for a learning experience for something else different that I’m working on, the possibility of autonomously manufacturing with self-replicating machines out in space. Because some of the most common, non-inert elements in the universe are hydrogen, oxygen, and carbon, any self-replicating machine capable of traveling any significant distance needs to be able to work with those to obtain fuel/energy, so that it could build more of itself and then moving on to building things like solar panels and microwave lasers for larger-scale power generation and delivery and other things. I’m also following some research on making conductive material from organic compounds.

I suppose I should have started with organic chemistry, but as I’ve never been deeply interested in chemistry beyond the surface and its potentials, I’ve decided to start with something that could produce a pretty and lasting result. Truthfully I could have started anywhere but due to input from my friend and the garbage just sitting around our office lab, I’ve decided to start by working with my friend on this little project. This gold recovery & refining endeavor is likely going to be just a once-in-a-lifetime thing (though my friend may do more), and I have done enough reading to be aware that any risks we take above being as humanly safe and careful as possible may also result in physical and property damage to last a lifetime.

But, sorry, I digress.

Thanks very much for the links you provided! Refining gold from a single small board? A single IC? Dang... talk about taking it to the next level!

To answer your question... We do not expect much gold from the SO-DIMM connectors. We basically just want to do it so that we could say that we did it. :p We also don’t have kilograms of material as you said... I haven’t added up the numbers yet, but including circuit boards, memory modules, IC, pins, connectors etc. we picked out, we probably have around 5 kgs of material, which is not going to produce any real appreciable amount of gold. Whatever we do get, we’ll likely just hammer it flat, etch a stamp in steel, stamp the gold, and cast it in some transparent epoxy for, you know, the record.

I would’ve loved to see the pictures in the posts you provided, unfortunately it appears that I do not have the privileges to view the images in those posts.

At this point, we are unsure of what to do with the so-called black capped ICs. We have a dozen of those or so, and we couldnincinerate it or do the infamous and dangerous wet ashing method to process it. We are scared of using such concentrated sulfuric acid, but we can’t realistically incinerate things due to where we live... So we are still looking for ways to process these. Would you happen to have any pointers for us?


Butcher,

butcher said:
I also suggest focussing on one type of material, one process, or discussion of processes.

Yes, definitely. From now on, this is what I’ll be doing. In retrospect, being so long-winded and posting sort of a progress report without posing specific questions was somewhat inconsiderate on my part.

Incidentally, and to start off, could you please help me understand why you (and, seemingly, many of the more senior forum members) seem to be uninterested in using salt water or vinegar + salt for reverse electroplating?


Thank you both for your help. I do appreciate each and every comment, even if it’s just a reality check on our mindset and status.
 

g_axelsson

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LT_golden said:
I would’ve loved to see the pictures in the posts you provided, unfortunately it appears that I do not have the privileges to view the images in those posts.

Probably just a question about www in front of the link or not, either try to fix the link by adding the missing www like this...
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=27268#p288661
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=23737
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=7056
or log in again when you don't see the pictures. There are no hidden areas or restricted images on GRF (with the sole exception of the admin board).

LT_golden said:
At this point, we are unsure of what to do with the so-called black capped ICs. We have a dozen of those or so, and we could incinerate it or do the infamous and dangerous wet ashing method to process it. We are scared of using such concentrated sulfuric acid, but we can’t realistically incinerate things due to where we live... So we are still looking for ways to process these. Would you happen to have any pointers for us?
I would definitely go with just incinerate the black top and then wash the bond wires from the ash. It definitely is the safe process here. Wet ashing scares the shit out of me, the liquid would literary eat the flesh of your bones if you got it on you. Accidents happens even in the safest environments, the more safety the longer between accidents.

Göran
 

LT_golden

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Hi Göran,

g_axelsson said:
Probably just a question about www in front of the link or not, either try to fix the link by adding the missing www like this...
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=7056
or log in again when you don't see the pictures. There are no hidden areas or restricted images on GRF (with the sole exception of the admin board).

WOW! That is tiny and AWESOME! So easy to lose, though. That's like, roughly the size of a 0603 resistor... ridiculous. A good sneeze and...

Turns out, I wasn't able to view the images because I was logged out. On my phone, I seem to get logged out each time I open a link to another topic. I'll keep an eye out for the "Login" button in the future.


g_axelsson said:
I would definitely go with just incinerate the black top and then wash the bond wires from the ash. It definitely is the safe process here. Wet ashing scares the crap out of me, the liquid would literary eat the flesh of your bones if you got it on you. Accidents happens even in the safest environments, the more safety the longer between accidents.

I see. I'll see if we couldn't drive out to a less populated area over the weekend or something. A couple of questions though if you please...

From what I've seen on YouTube (yeah, YouTube again, I know, but please bear with me...) and patnor’s post incinerating seems to produce whitish-grey chips that need to be further crushed. They appear far easier to crush, but still, particles remain. Even after filtering through a collander, wouldn't the bond wires, being embedded in the plastic in the first place, still be trapped inside the particles, and might be difficult for HCl + bleach to reach, thereby possibly leading to losses?

Also, after the incineration and crushing/powdering, the next steps generally seem to look like magnetically separating some of the unwanted metals, then mixing with detergent+water into mud, and blu-bowling or sluicing to separate the ash, is this correct?

Or, is it possible to burn long enough that the plastic turns crumbly (for lack of a better word that I can think of right now; English isn't my first language :p) enough that the die+wires+pads can basically come out intact?

I know I'm just being nit-picky... but even though I get that 100% recovery is never possible (with whatever method including wet ashing), we would like to try and get all that we can, given our limited amount of input materials right now.


Thanks very much for your help.
 

g_axelsson

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The ash after incinerating IC:s is made up of the filler, silicon dioxide, ie fine sand. It is quite crumbly and you can often crush it between your fingers unless you overheat or not burn out all the carbon residues. When breaking an incinerated IC in two parts you can see how far the carbon have been burned off, it's often a quite distinct border between the white ash and the black carbon residue. If you burn it too hot or too long time the silicon dioxide will start to fuse together into a more solid mass.

Here are a few pictures of a chip I incinerated. I put it on a firebrick and used a small hand torch, just went out on the balcony for a few minutes. Then I used ultrasonic to break down the ash without breaking the rest of the chip.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=11827&p=161648#p161576

You don't need a big bonfire to incinerate a few chips. Heat and air is the most important thing when incinerating, too little air and you don't burn off the carbon, no matter how hot you get it.

Göran
 

LT_golden

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Hi Göran,

g_axelsson said:
The ash after incinerating IC:s is made up of the filler, silicon dioxide, ie fine sand. It is quite crumbly and you can often crush it between your fingers unless you overheat or not burn out all the carbon residues. When breaking an incinerated IC in two parts you can see how far the carbon have been burned off, it's often a quite distinct border between the white ash and the black carbon residue. If you burn it too hot or too long time the silicon dioxide will start to fuse together into a more solid mass.

Here are a few pictures of a chip I incinerated. I put it on a firebrick and used a small hand torch, just went out on the balcony for a few minutes. Then I used ultrasonic to break down the ash without breaking the rest of the chip.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=11827&p=161648#p161576

You don't need a big bonfire to incinerate a few chips. Heat and air is the most important thing when incinerating, too little air and you don't burn off the carbon, no matter how hot you get it.

Göran

You know, I was on page 3 of that discussion that you linked for me when I received your reply.

Ultrasonic... dang, I seem to have read that somewhere (maybe it was something written by you?). Would something used to clean glasses work? I saw what you wrote, smacked my forehead, and went to an online store... ultrasonic glasses cleaners are being sold at around USD$10! Is there a frequency range you tend to go for or does it not seem to really matter?

Also, you said that incineration temperature and duration are both important... since we’ll be driving out, I was thinking using a hand-held, battery-powered fan (usually used by people to cool their faces during summers, here) for providing air to the burning charcoal. Do you think this would be enough?

Thanks a LOT for this tip! You’ve given me new hope.
 

g_axelsson

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The ultrasonic bath was just a test, nothing that I have tested on more than a few ic:s at a time. It worked like a charm to expose any carbon without crushing it as you could see on the pictures.

I have no idea if the fan you are talking about would work or even do something good for you. There are a number of different styles of incineration here on the forum, some people just burn it to a crisp and then use a ball mill to break them up into powder afterwards.

Try to keep it simple and start with small tests to see what works or not. Putting IC:s on top of burning coals would probably create an atmosphere with very little oxygen so it might take quite a while to burn off all the carbon in the plastic. If you go for a crisp only and not care about the carbon then it might be less of a problem.

Göran
 

LT_golden

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Hi Göran,

g_axelsson said:
The ultrasonic bath was just a test, nothing that I have tested on more than a few ic:s at a time. It worked like a charm to expose any carbon without crushing it as you could see on the pictures.

I have no idea if the fan you are talking about would work or even do something good for you. There are a number of different styles of incineration here on the forum, some people just burn it to a crisp and then use a ball mill to break them up into powder afterwards.

Try to keep it simple and start with small tests to see what works or not. Putting IC:s on top of burning coals would probably create an atmosphere with very little oxygen so it might take quite a while to burn off all the carbon in the plastic. If you go for a crisp only and not care about the carbon then it might be less of a problem.

Göran

Thanks. The ultrasonic sounds like a fantastic idea and since the cleaner I saw was so cheap (and battery powered, LOL) I think I’ll give it a try. Seems to save quite a bit of water... just hold the incinerated chip in tweezers and hold it aloft in the water to be cleaned... theoretically anyway. The murky water would then of course have to be checked for escaped gold.

We’ve never heated anything just to burn it to a crisp through and through... this will be interesting.

We don’t have a mill or grinder or anything of the sort so if this works it definitely should minimize mess.

We’ll give this a shot and I’ll report back. Thanks again!
 

g_axelsson

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LT_golden said:
Thanks. The ultrasonic sounds like a fantastic idea and since the cleaner I saw was so cheap (and battery powered, LOL) I think I’ll give it a try. Seems to save quite a bit of water... just hold the incinerated chip in tweezers and hold it aloft in the water to be cleaned... theoretically anyway. The murky water would then of course have to be checked for escaped gold.
You are overthinking this, battery powered... that's probably a quite weak unit. You will loose money on batteries only. Just take some metal object, a spoon for example (don't use it ever for food if you use a spoon), and crush the chip to powders, it will be faster as well as cheaper.

There are so much free stuff that you can use for a quick test. You don't need to have anything fancy, the chips can be crushed between your fingers if you are lucky with the incineration.

Göran
 

LT_golden

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g_axelsson said:
You are overthinking this, battery powered... that's probably a quite weak unit. You will loose money on batteries only. Just take some metal object, a spoon for example (don't use it ever for food if you use a spoon), and crush the chip to powders, it will be faster as well as cheaper.

Heh, I do see your point, and it is something I’ve considered. Also we might have a few tricks to boost the power of the thing as well as make it no longer battery powered. In any case, because of many senior members’ advice and also our fear of concentrated sulfuric acid, we as well as our inexperience with chemistry, we have pretty much sworn off wet ashing. Though take a look at this...


009129F6-CE6B-490A-BFC9-2B654477FF20.jpeg


Now, isn’t that just beautiful?! 😍

Sure, the team did it with wet ashing with sulfuric acid, but still, it would be so nice if we could replicate the result with incineration. Additionally there’s the advantage of less loss to worry about due to the gold binding wires being pulverized to specks that get lost easily or are hardly visible.

We aren’t trying to “reinvent the wheel” or anything so to speak, and we won’t be obstinate about it either; if it really comes down to pulverizing and breaking some wires, so be it. But it wouldn’t hurt to aim, right?

Meanwhile, it’s sort of a min-maxing kinda thing, as in RPGs where you can adjust your stats... if you know what I mean. :p
 

Smack

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Using incineration: http://www.goldrefiningforum.com/phpBB3/viewtopic.php?t=11827
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?t=22951
 

LT_golden

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Hi Smack,

Thanks for your reply! And, man, nice name. :wink:

Thanks for the links you provided. I’ve actually read those two multiple times and have them bookmarked for quick reference.

However I’m really looking for something else. But I appreciate your input.
 

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