Sciencemadness Discussion Board

Dissolving unknown metal that may have PGM's

RogueRose - 28-8-2018 at 23:56

So I'm going to try to put some assumptions and or myths to rest about what hard drive platters are coated with I've heard everything from polished micro iron/chrome/nickel to platinum, rutherium, palladium and silver and even simply polished aluminum with an invisible carbon coating (diamond like finish). Some say only old HD's have PM's, while others say only newer one's have them - so it seems a real BS fest among some people.

What I will say is that I remember asking my metal recycling center about this some time ago and they said "just aluminum" and they were asked all the time, and I dumped about 10-15 years of platters on them (while working as a tech, that is a few liquor boxes of platters) and a washing machine or two in volume of aluminum bodies. So I'd like to see what the deal is finally.

I'm going to run about 6-8 tests on platters from different hard drives produced from 2001 to 2014 and I figure I'll cut a quarter out of a platter and dissolve it.

I thought I'd start with HCl to get rid of the Al, then filter, rinse then either use HCl or H2SO4 w/ H2O2 to dissolve the Ni, Fe, Co and Cr - if it is in there.

I would assume that if there is anything left it would be a PM of some kind I can't think they would dissolve with this method.

Can anyone see any problems with this process or suggestion on a different method? ..

pure speculation :

Sulaiman - 29-8-2018 at 00:54

I suspect that treatment with HCl will give a pink solution due to Co

I would also try NaOH as a first 'solvent' as it will dissolve Al quite quickly
then nitric acid should get everything else except PGMs ... if any are present

I have no Pt chemistry experience, but based on Au recovery:
Originally I used to dissolve everything in Aqua Regia (AR) then try to selectively precipitate gold.
It works, but it can get messy and it uses a lot of AR, and makes a lot of NO2.
I found it better to try to dissolve away all non-gold metals first,
leaving a small volume of stuff to process with AR etc.
The important thing with Au is that you know that it is in one of the vessels that you are using,
it cannot change into a different element,
so no matter what mistakes you make - it is in there somewhere.
(do not dispose of anything until you are certain that it contains nothing of value to you)
The key is being able to determine in which vessel is the valuable metal,
this is where SnCl2 helps.
So your first task is to make/get some Pt indicator,
I believe SnCl2 also works for Pt and Pd.

With gold recovery one important step is separating liquids and solids,
filtering looses significant quantities of product.
Due to the density of PGMs they settle really quickly,
so rather than filtration use patience + decantation.

personally,
I hope that there is no significant PGM content
as I have had the opportunity to collect hundreds of platters :P

[Edited on 29-8-2018 by Sulaiman]

DJF90 - 29-8-2018 at 02:49

It would be advantageous to take a small sample of each platter, dissolve in whatever affords a homogeneous solution (Aqua regia is the most likely candidate) and then use spot tests to determine which, if any, contain metals of interest. From there you can then process the appropriate platters, taking notes and recording masses to determine quantity of contained/recovered PGMs

wg48 - 29-8-2018 at 02:53

You should watch this video https://www.youtube.com/watch?v=L0bcNm1gfpU from Nurdrage.

RogueRose - 29-8-2018 at 15:27

I watched that Nurdrage video before and watched it again, but it shows different results from another video (2 part) of an eastern european guy trying to extract platinum from platters, but his video showed that no platinum was present but the test showed other PM possibly palladium or ruthenium amd he got a small bead (about 2x size of a .177" BB from about 10 platters. The metal was only able to be melted by an oxyacetelene tourch or an arc welder, so that seems to suggests a PM since it didn't dissolve with HCl and HCl/H2O2 mix - which should dissolve cobalt, chromium and Nickel.

Sulaiman - I kind of agree with you about hoping there is no PGM's in there b/c I gave up well over 2,000 platters at aluminum prices.. I am also kind of suspicious about this b/c there could be people benefiting from people not knowing there are PGM's and selling them at scrap Al prices..

RogueRose - 31-8-2018 at 02:07

So I have run some tests with HCl, HCl + H2O2 and NaOH and I would have to strongly suggest HCl if you are in a hurry and want it as simple as possible. The sodium aluminate causes the liquid to thicken and get cloudy while the HCl is crystal clear, which is pretty odd considering I've made aluminum chloride before with supposedly pure Al foil, and it turned black, grey and yellow where this only turned grey when an excess of Al was added to 31% HCl and there wasn't enough water to make the salts IMO.

So I dissolved 3 platters, 2 from 2.5" and 1 from a 3.5", the 2.5" was an expensive SAS and the 3.5 was a "newer" (300-500GB platter) cheap SATA (low end of the drive series) but all dissolved the same, leaving the same material behind. So I have a decent amount of foil from these and I'm trying to figure out what to do if there is cobalt, chromium, nickel, etc in it, I thought about using H2SO4 + H2O2 and seeing if there is anything dissolved with that I'm not going to AR until I've tried removing everything possible with single acids. I'm just wondering if I can make a sulfate of cobalt or chromium with H2SO4 + H2O2.

From my experiements with 75%Cu 25% Ni I dissolved the Ni in HCl + H2O2 easily but IDK if that could have been because the Cu/ CuCl was in solution? Is that possible or should my same HCl + H2O2 be able to dissolve the Nickel in this foil lining? I didn't see any color in any of these reactions except the aluminate get grey/maroonish at on point were it was very concentrated, adding water made it white to light grey. I'm impresses how clean the HCl solution looks.

unionised - 31-8-2018 at 02:36

I thought I'd have a play with this idea.
So far I have a bunch of black sludge . :-)
However I thought you might be interested to hear about an observation I made.
I heated the platters with a blow torch and the Al melted and ran out leaving the coating (and much less Al) behind.
I probably won't bother doing anything with the aluminium but, I now only have about 6 grams of metal (some Al + whaterv the coating is) to dissolve, rather than 30.

RogueRose - 31-8-2018 at 07:32

Quote: Originally posted by unionised  
I thought I'd have a play with this idea.
So far I have a bunch of black sludge . :-)
However I thought you might be interested to hear about an observation I made.
I heated the platters with a blow torch and the Al melted and ran out leaving the coating (and much less Al) behind.
I probably won't bother doing anything with the aluminium but, I now only have about 6 grams of metal (some Al + whaterv the coating is) to dissolve, rather than 30.


So what made the black sludge?

That is a good idea with the blow torch. I did that a long time back with a few platters, when I just wanted to see if they were Al or glass and I found that they seemed to have a much higher MP than standard Al, it took much more heat than I thought it would and melted much later than larger pieces of Al. I'm wondering if the coating is the reason for this, probably reflected much of the heat? How did you heat, direct flame to the platter surface or to a cut edge?

How many platters did you have (were they 2.5" or 3.5")? I didn't weigh anything before starting b/c my scale wasn't accessible (PSU missing)..

I'm surprised at how thick these foil layers seem to be, much thicker than what I was led to believe and it seems to be a very dense material and very tough metal, so I have some hopes it may be some PM's but we shall see.

unionised - 31-8-2018 at 07:45

When the Aluminum dissolves I will pour of that solution add more acid and an oxidant to get the black sludge into solution so I can find out. Interestingly, it doesn't seem strongly magnetic.

Now you mention it, the melting did seem slow. Mainly I heated the shiny surface- some bits it blackened more than others. The molten metal didn't seem particularly bright red.
They were 3.5 inch platters.
Glass ones would be good- no pesky Al in the mix.

RogueRose - 31-8-2018 at 08:15

Quote: Originally posted by unionised  
When the Aluminum dissolves I will pour of that solution add more acid and an oxidant to get the black sludge into solution so I can find out. Interestingly, it doesn't seem strongly magnetic.

Now you mention it, the melting did seem slow. Mainly I heated the shiny surface- some bits it blackened more than others. The molten metal didn't seem particularly bright red.
They were 3.5 inch platters.
Glass ones would be good- no pesky Al in the mix.


A funny thing happened to me when trying to melt them the first time. I had a charcoal forge and had about 12+lbs of molten Al in a crucible and the platters were in the with everything else, after everything melted and it was glowing bright red, the platters were still not even soft so I figured that they were glass. I took them out and let them cool and later used a grinder on them and found that they were indeed Al. So the coating must have some massive heat reflection capabilities which I think Pt is known for though IDK for certain.

[Edited on 8-31-2018 by RogueRose]

unionised - 31-8-2018 at 09:08

I may have a brief look at the alloy. The interesting point is that adding elements to Al will usually lower the MP rather than raising it.
Also, if they were glowing then they were that hot.
The coating seems to do a remarkable job of holding stuff together.

RogueRose - 31-8-2018 at 12:01

I don't remember if the platters were red hot, but the rest of the molten aluminum was. They did remain solid as I used pliers to remove them from the melt.

I washed all the "foil" to remove the HCl and NaOH (and the salts) and put them in small vials and washed 2x each again. I decided to try dissolving with H2SO4 and H2O2 so I added the H2O2 first and in 3 of them I got instant catalyzation (slow but steady bubbles, I think it is from the edges of the cut foil (they are about 1/2cm^2 pieces) having some kind of metal exposed that catalyzes H2O2 which I think Pt and Pd do.

I added some H2SO4 and in 2 vials I got a faint green color and in all of them the bubbling increases a lot or started, the foil started rising to the top and falling, but then after about 90 mins much of bubbling stopped and all was still pretty clear (no more green after about first minute) so it seems nothing is going to dissolve that didn't dissolve in HCl or NaOH, which is promising. I am going to try again with a higher concentration of H2SO4 , H2O2 and heat, I didn't use heat now except for that produced by the acid (which was about 150F)..

RogueRose - 31-8-2018 at 16:57

I tried a 70% H2SO4 15% H2O2 15% water concentration and heated and got bubbling and a slight green color but it doesn't dissolve the metal. I thought it might have been forming a passivation layer, so added water slowly and still no luck.

So this metal foil won't dissolve in either HCl or H2SO4 with H2O2, both with heat, so IDK what metal that isn't a PM that this could be. I didn't want to use nitric (b/c I have to make it with salts) or AR but I guess I need to try nitric before trying AR.?

After looking at some more videos, I keep hearing that there aren't PM's on these and one video says the layer is cobalt and that seems like it might be difficult to dissolve. Does anyone have any experience with making cobalt salts? Does HCl or H2SO4 usually do the trick? I thought HCl usually dissolved tool steel which has cobalt or is tipped or something. Any suggestions on this?

AJKOER - 4-9-2018 at 05:22

A simple galvanic cell constructed of chlorine bleach (NaOCl) to which you add the mystery metal mix as one electrode and say, one selects the more noble metal electrode (to be verified) as Silver (which should have much more surface area than the other electrode).

If the Ag is attacked (this would be is visibly determined), there could be more noble metals present than Silver, even if their respective concentrations are very small.

Reference: As an example, see my thread https://www.sciencemadness.org/whisper/viewthread.php?tid=84... .

[Edited on 4-9-2018 by AJKOER]