Harddrives - what can be harvested - and what it contains ?

[carasoph]

Hiya all,

As my first post here, after reading mostly ANYTHING around here, I must say that I have a very good idea of what and where thing are going/doing....
and I must take my hat down to all of you here....
If I only knew of this community 2 months ago, I wouldn't have thrown away those 500+ computers I had in my brother's garage....

BUT... I must say that I'm still confused!
I recently got a bunch of 150+ Hard drives (free) and I want to know if they are worth the trouble of tearing them apart, and if they are, what exactly should I take out of them ???

I have done that barbaric, though - VERY clean, action on 1 of them just to see what is in it, and here is what I have found:

2 Somewhat magnetic Gold colored main discs.
1 VERY shiny silver colored engine complex
4 VERY strong magnets at the base of the needle
1 WORTHLESS writing needle (except for the $0.02 copper worth at its base)

My questions are:
1. is there any value to those parts?
2. What would I expect to get from what parts ?


Thanks...

Caramon Majer

 

[lazersteve]

Welcome to the forum Carasoph,

The platters (silver discs) are where the Platinum is in hard drives.

The casing is typically aluminum or magnesium (rarely).

The head armature is aluminum with a small amount of copper.

The screws are usually iron or steel alloys.

The platter spacers are aluminum alloys.

The spindle motor has an aluminum housing with copper stator wrapped on an insulated iron core.

The circuit board is loaded with tidbits of monolitihic capacitors which typically contain nickel, tin, palladium, and sometimes even silver, gold, or platinum. The circuit board headers are of course gold plated over copper or brass.

The magnets are usually nickel plated neodymium types and sometimes samarium-cobalt . Other types of magnets may also be used.

If you haven't checked out my website http://www.goldrecovery.us , you should. I'm working on a new PGM Processing DVD which will include an entire section on processing hard disc platters.

Here's the forum 10 cent Guided Tour link :

Guided Tour

Enjoy,

Steve

 

[carasoph]

Steve,

That is the most detailed and concrete answer I ever got over the net on ANYTHING... :lol:

Thank you for the details, it really helped me a lot...

Hopefully, I will not be a noob for long... :lol:

CaraSoph

 

[carasoph]

Any1 knows what is the yield from those platters ?

 

[Lou]

Well Johnson Matthey (a major refiner themselves) says that they contain on average 35% platinum. Whether that's by mass of the whole disk, or by mass of that particular component, I do not know. I do know that my friend has several hundred of these, but I'm not keen to do anything with them unless I can find a reliable report on them.


source: http://www.platinum.matthey.com/applications/harddisk.html

 

[lazersteve]

Lou,

Welcome to the forum.

Several links referring to the content of Hard Disk platters have been posted, including the one you have posted. Here's a few threads relating to platters:
Platters 1

Platters 2

Platters 3

Platters 4

These are just a few of the platter posts.

Steve

 

[Lou]

Thank you very much sir. I'd already started to look into some of your (and others') work, and I appreciate the links!

Personally, I would probably burn off as much as the organics as possible, and then dissolve the residues in lead, add zinc, stir, and try the Parks process. Wouldn't want to cupel. Either that or I'd dissolve all in copper, electrolyze the copper from the crude anode, and collect the sludge and do wet chem on that.

Platinum is really inert stuff, so the residues from burned hard drives should be a mixed bag of lesser metal oxides, with the platinum metal being unoxidized (it doesn't oxidize even when molten). This metallic ash of sorts ought to dissolve nicely with say, sulfuric acid or hydrochloric acid. That would remove the base metals, and leave the platinum residue behind, which could be treated with AR, or done via gas phase haloextraction (personally, I think a viable option for catalytic converters...)


Regards,
Lou

 

[Platdigger]

Lou, welcome to the forum.
Can not seem to send you a PM......

 

[goldsilverpro]

The Parkes process has always seemed quite dangerous to me. First off, there would be molten lead, which always sends off fumes. Then, the Parkes way to remove the zinc from the PM is to evaporate it off.

There was an old gov BOM report that used aluminum instead of zinc. I've always found that separating Al from PM is difficult though.

Electrolytic copper is theoretical but impractical, unless you use a membrane. With only a few ppm of impurities, the copper deposit at the cathode would soon be so fluffy and non-adherent that it would be impossible to work with.

In any of these processes, I feel that you should first consider the negatives.

That's a pretty good idea on the catalytic converters, Lou. Using chlorine gas is dangerous but could be easily made safe. Cl2 would probably get the Rh, also. Wouldn't the PGM end up in a liquid form? May have rinsing issues, especially with hydrocarbons present. The alumina may be quite absorbent, also. May be able to put catalyst in boiling water to rinse or, maybe, use ultrasonic rinsing. Cats could make a fortune for somebody that could come up with a process that is fast, efficient, cheap, simple, and safe. Interesting idea.

 

[aflacglobal]

Lou, welcome to the forum. Now i got another brain to pick. :wink:
Chris, lou, or anyone. Why is the RH so darn hard to break down. I mean what is it that won't let it dissolve in the acid. I guess what i am try to say is the problem with electron acceptance, rejection, or something totally different? Is their something needed or missing ?

:?:

 

[goldsilverpro]

Hey, Ralph.

The Rh thing has mainly to do with strong bonding, I would guess.

To dissolve any metal, you need two things: an oxidizer and something for it to combine with. Rh will combine with many things to form compounds: sulfates, chlorides, and phosphates, etc., all in various oxidation states. Therefore, the oxidizer is possibly the problem. Nothing common is strong enough to oxidize the Rh and, therefore, it won't dissolve.

Probably, though, the lattice bonding in the solid Rh is too strong to be overcome by common acid(s). The only formulas that even barely touch the Rh involve concentrated sulfuric acid, which is the strongest common acid. Also, conc. H2SO4 is a powerful oxidizing agent.

Could be both of the above. Maybe, they're both the same phenomenon.

 

[Lou]

Thank you very much all. The forum is actually acting pretty buggy, it doesn't forward me to my posts after I post them, it says ''debug error encountered'' or something of the like. I am not surprised that I can't get any PMs (damn!). Edit: I can Private Messages.

Ok, with respect to the Parks process. I've done it before on a small scale and I can say temperature control is important, less temperature equals less oxidation (which means better absorption of metal values), and more importantly, less metal vapor pressure for both the Pb and the Zn. I did not distill off the zinc because it would be a pain in the butt to do, instead, I dissolved in HCl which worked a treat!

Second, in defense of copper, which also I have done. It is only really good with low concentration materials that have a lot of burnables. I used a pure piece of copper sheet as the cathode, and my anode was about 97% copper. I forget the exact molar composition of the bath, but it was your basic copper (II) sulfate and sulfuric acid, but to ensure that I got a clean plating (not the fluffy stuff you had), I cleaned the copper cathode with concentrated HCl, then fine sand paper, that helps a good deposition. The biggest secret to getting a shiny copper deposit (and not fouling up your precious metal mud concentrate) is to add a few tablespoons of thiourea--you will get a very nice shiny copper plate, not the dull stuff that's easily scraped off. This adheres.

On to the catalytics...I have actually done some small (as in 1 honeycomb) tests with this gas phase transport and it works well, very well, and is very clean. The downsides are that you have to use a gaseous halogen, high temperature, and for this you need expensive materials, like quartz, SS 316, or monel. I am doing active research in this area, and will be glad to let out some details, but for now, I kind of want to keep it proprietary like. My method is different than the autoclave+H2SO4+NH4Cl method from the South Dakota School of Mines Patent, and it affords an almost quantitative yield based on what I've seen so far.


On the topic of rhodium, that's really something you usually don't see outside of a very specialized industry, I've probably seen and been able to buy more rhodium in the past few months (several ounces of the metal) than ever before in my life. It's expensive but it's easy enough to refine.

Hot aqua regia does attack rhodium, and so does concentrated, 18M sulfuric at a very high temperature (literally high enough to make the H2SO4 start to decompose into SO3, which is very very nasty) with the formation of a brown solution. Iridium is much harder to deal with than rhodium, which for me has been just as bad as platinum for dissolving big pieces (though powdered Pt goes faster). I have a picture of me dissolving some rhodium sponge that a friend sent me (to confirm if it was Rh) using the sulfuric. It was a qualitative test, as I didn't feel the need to fire up the AA to do it, but rhodium won't dissolve in nitric like palladium, or in HCl, but it will dissolve in sulfuric acid, something which its PGM sisters will not do sans palladium (which is ruled out by the nitric test).

What determines the corrosion resistance of a particular metal depends on a variety of factors, and the chemical reasons behind it are very complex. Some of it does have to do with how easily its valence electrons can be lost or added to, but there are also nuclear effects at work as well. Transition metal chemistry can be very complex (pun intended hahah )

 

[Harold_V]

Electrolytic copper is theoretical but impractical, unless you use a membrane. With only a few ppm of impurities, the copper deposit at the cathode would soon be so fluffy and non-adherent that it would be impossible to work with.

Indeed!

I could write a book on that one!

I tried that process, when I first started refining, in hopes of avoiding the inquartation process.

Please-------don't get me started! :wink:

Harold

 

[Lou]

Really? Is it that problematic for you? What current densities, what electrolyte(s) and concentration, how much agitation, what temperature, and how pure was your anode?

 

[Harold_V]

Chuckle!

My negative experience goes back to the early 70's. At this point I have no recollection of any of the details, but I would have been working with little in the way of equipment at that time. I was still in the very early phase of learning to refine, and was hoping to circumvent what looked like a difficult process, inquartation.

I got off on the wrong foot when I made my vat from stoneware, which promptly broke while in operation. Couple gallons of copper sulfate and sulfuric acid spilled on the floor in the garage.

I have no doubt that the system works, it's just that I am not a chemist, and have a limited bag of tricks. I got exactly what GSP described-----a fluffy deposition, which readily contaminated the sludge.

There isn't a doubt in my mind, one of my problems was the fact that I had low grade copper, contaminated with far too many elements in higher than acceptable proportions. Sort of brings to mind a gold or silver cell. A waste of time unless the feed is already of high quality.

Harold

 

[Lou]

I see. You know what they say, garbage in, garbage out.

Electrolysis can be useful, but it does need a certain degree of babying. If the nitric acid is cheap, then I'd just say to add as much pins and circuit boards to a big crucible of copper, and saturate it with gold, silver, platinum, and all the rest and burn away all the plastic and gangue. Then just dissolve as much away in nitric, drop out the silver with chloride, spot test for Pd.

Then some cold AR on the gold and Pt powder should separate them nicely.

 

[Harold_V]

I'd have to agree, assuming nitric is readily available.

I was fortunate. While I played around a little with electronic scrap early on, it wasn't long until my hobby was inundated with high grade wastes from the jeweler's bench. While I was very capable of running the low grade stuff, and did it pretty much as described, I moved away from it and never really looked back. I was too busy refining better materials and didn't have the time to waste. In a sense, my success played a big role in my limited knowledge. I got very good at doing certain things, but didn't experiment as much as I might have liked. Stripping with a sulfuric cell, for example, never got past the building the cell, which was never put in operation. Same goes for a gold parting cell. It was completed, and anodes even cast, but by then I was so well entrenched in my customary procedures, all of which yielded excellent quality products, that I simply never looked back.

To be honest, when it went from hobby to a living, a lot of the fun went with it.

No regrets, but it's nice if you can keep your hobby just that-----a hobby.

I am slowly returning to machining as my hobby. It's taken years to get past the burnout I experienced, which may explain my eagerness to turn refining into a livelihood, even when it was never intended to be one.

I envy you your chemical education. While I got very good at refining, I was (and am still) often at a loss to explain why things work as they do. I am not educated beyond high school. I was very good at following the recipe, however, so coupled with good guidance from books, I managed to conquer the challenges to my satisfaction.

Harold

 

[goldsilverpro]

Lou,

Your experiments with electrolytic copper must have been brief. Unless zero base metals were being added to the copper, the deposit would, over time, become unmanageable. Since it would be foolish to do this on a one-shot basis, you would need a system that could be used over and over

Let's say your bars are 98% copper/2% base metals. At first, the Cu in solution is much higher than the base metals (BM) and the cathode deposit will be smooth and adherent. The rate at which the various metals deposit is mainly dependent on their concentration and their individual electrical characteristics. Therefore, at first, there is very little deposition of the base metals. They build up and their deposition rate increases. At some point, the deposit turns to crap, no matter how much grain refiner (thiourea; iron-free molasses, etc.) is used. For a 30% base metal, copper alloy, the deposit may turn to crap in only 5 minutes. The number one problem in electrolytic refining systems is to maintain a sound, manageable, cathode deposit. You can't do that when base metals reach a certain level in the solution. You can only delay it, briefly, through the use of additives.

I see no gain though the melting of PM scrap into copper. At best, you would convert solids to a powder, for easier dissolving.

Electrolysis can be useful, but it does need a certain degree of babying. If the nitric acid is cheap, then I'd just say to add as much pins and circuit boards to a big crucible of copper, and saturate it with gold, silver, platinum, and all the rest and burn away all the plastic and gangue. Then just dissolve as much away in nitric, drop out the silver with chloride, spot test for Pd.

This doesn't make any sense to me, at all. It takes 1/2 gallon of nitric to dissolve a pound of copper. There is already plenty of copper in the items mentioned to be able to use nitric. Why waste extra copper and nitric and produce unneeded waste? Also, with the method you suggest, you would have lots of un-oxidized, PM containing, carbon floating on top.

 

[Lou]

Yes, fouling of the electrolyte is a problem and as you alluded to, it's an equilibrium problem, as more copper is removed from the system, the amount of impurities in the anode rises and they start to dissolve as well. The problems begin when the amount of copper reducing is more than the amount being oxidized into solution to replenish that which is deposited. I will grant you that I've only done the method on the small scale (i.e. <kilogram range) and it worked reasonably well, how it goes with larger runs, I cannot say. I will also admit that I did not run it to until the anode was gone (I'd have to look in my notes for the actual weight).

It seems you have experience with doing it industrially. I would be glad to hear about it.



"This doesn't make any sense to me, at all. It takes 1/2 gallon of nitric to dissolve a pound of copper. There is already plenty of copper in the items mentioned to be able to use nitric. Why waste extra copper and nitric and produce unneeded waste? Also, with the method you suggest, you would have lots of un-oxidized, PM containing, carbon floating on top."

You're right if that is how you understood me. When I say burn it all and let it dissolve in copper, I mean burn off all of the plastics. It's been my experience with nitric acid and various plastics that it can makes these plastics very gummy and encapsulate your metal values. I don't like to dissolve metal off of any polymer save fluorinated ones if I can at all help it. Also, I don't understand what you mean by ''carbon floating on top''. If it is incinerated properly with excess oxygen, there will be no carbon. There will be metal oxides, but no carbon.

I say to dissolve it in copper because the resultant alloy is much easier to deal with, and I suppose it can be likened to inquartation. As I recall, many electrical solders have tin mixed in, and tin is bothersome to deal with when doing a straight nitric acid digestion. That is my rationale for me saying that. Aside from that, I do agree, just burn it all to oxides, let the silver, lead, and copper oxidize then part the unoxidized gold and any platinum from the rest with nitric. However, you say that there is already sufficient copper in there that it is alloyed down and can be dissolved with nitric as is. If that's so, then I owe you a big favor as this might save mea lot of time if I were to refine computer parts in mass. I never said I've done this with CPU material, just what I'd do if I had a bunch to handle. I've done it with other things, but never computer parts. I tend to stay away from them because I dislike the plastic components.

Thanks for your replies.

 

[goldsilverpro]

I surely misunderstood. It sounded like you were burning the boards in molten copper in a crucible. In which case, I can easily visualize unoxidized black carbon floating on top

About the only modern plastic I've found on boards that won't stand up to hot strong nitric is nylon. It gets sticky and expands. Some of the older plastics tended to form a hard powdery skin of the surface in the presence of strong hot oxidizing acids.

The point is that, due to the inherent problems of electrolytic copper, I chose to not do it industrially, except when using a membrane to prevent any deposition. I did happen to be a plating engineer, for about 10 years, and I owned two plating shops in L.A.

You mentioned earlier that you formulated plating solutions. May I ask what gold compound you're using for the gold solution? Is the solution alkaline or acidic?