Home built centrifuge - gold concenrates from IC's

[rusty]

When the tantalum mud is wet bottom picture resembles chocolate powder, now that it dry has taken on its traditional color - blue gray.

Top picture is at 200 mesh.

Tantalum is also used in resistors as well surface mount capacitors.

I estimate that I'll have 3 or 4 pounds of tantalum to recover from my cons.

Where are our tantalum buyers on the forum, if anyone is interested in purchasing shoot me a PM.

 

[Marcel]

Sorry, I missed that step somehow.
Did you mill tantalum capacitors here?
Tantalum is usually coated with an oxydationlayer immediatly. I have Ta powder and sponge here. It is all black because of that TaO. Pure Ta is very rare and very expensive compared to the (usual) mix of Ta and TaO that you find in the capacitor. Ta is not a noblemetal, it oxidizes with minimal energy. So I would not susspect too much pure Ta in such a mix. TaO is also very very hard, tools are made of it. I doubt that it can be milled by steel.
Dont want to be counterproductive, but I guess it will be very difficult to extract the Ta from such a mix mit our household means. I would rather try to isolate it as much as possible and then sell the mud to a pro.
Will be interesting to see how your story will go on... Good luck.

 

[rusty]

Sorry, I missed that step somehow.
Did you mill tantalum capacitors here?
Tantalum is usually coated with an oxydationlayer immediatly. I have Ta powder and sponge here. It is all black because of that TaO. Pure Ta is very rare and very expensive compared to the (usual) mix of Ta and TaO that you find in the capacitor. Ta is not a noblemetal, it oxidizes with minimal energy. So I would not susspect too much pure Ta in such a mix. TaO is also very very hard, tools are made of it. I doubt that it can be milled by steel.
Dont want to be counterproductive, but I guess it will be very difficult to extract the Ta from such a mix mit our household means. I would rather try to isolate it as much as possible and then sell the mud to a pro.
Will be interesting to see how your story will go on... Good luck.

I milled everything except the kitchen sink, anything a magnet would grab was removed.

I'm going to hunt up my twin carbon arc torch then melt some of this powder. This project will have to wait until the weekend as I do not have any carbon rods on hand, I'll phone Russ in the morning and get him to bring me a few carbon rods.

That carbon arc torch has no trouble reaching the required melting point of tantalum.

http://www.teledyneleemanlabs.com/r...lysis_of_Trace_Elements_in_Tantalum_Oxide.pdf

Tantalum is a blue gray metal with a melting point of 3017ºC, the fifth highest behind tungsten,
rhenium, osmium and carbon. Tantalum is found in the Earth’s crust at concentrations between 1
and 2 μg g-1 by weight and naturally occurs in minerals such as betafite, columbite, simpsonite and
tantalite. As a pure metal, tantalum is used to produce capacitors and resistors that are found in
computers, DVD players, automotive electronics and portable telephones.

 

[rusty]

I'm not expecting any great wonder in my attempt to melt a small sample of tantalum powder, from what I've read it's melted under vacuum with an inert gas cover.

The best I have for a gas cover is CO2 i think argon is preferred, or perhaps I could use a crude flux cover.

The carbon arc torch below is a bit of interesting history, can reach temperatures beyond 3000ºC. and will sunburn exposed body parts in seconds. You need a decent shade of glass in your helmet or suffer flash.

 

[rusty]

I'm coming up with some very interesting information on tantalum, actually I'm very curious as to how I ended up with so much of it.

http://www.commerceresources.com/s/AboutTantalum.asp

Uses for Tantalum

About half of the tantalum consumed each year is used in the electronics industry, mainly as powder and wire for capacitors, owing to tantalum's particular ability to store and release electrical energy. This allows components to be exceptionally small and they are therefore favored in space-sensitive high-end applications in telecommunications, data storage and implantable medical devices. Tantalum is also used for electronic sound filters and as a barrier against copper diffusion in semi-conductors. Tantalum carbide's hardness makes it ideal for cutting tools.

 

[Marcel]

@rusty:
The capacitors dielectric is made from pure tantalum, but this Ta is then converted into a mix of more or less Ta + Ta2O5

Dielectric
The dielectric is then formed over all the tantalum particle surfaces by the electrochemical process of anodization. To achieve this, the “pellet” is submerged into a very weak solution of acid and DC voltage is applied. The total dielectric thickness is determined by the final voltage applied during the forming process. Initially the power supply is kept in a constant current mode until the correct voltage (i.e. dielectric thickness) has been reached; it then holds this voltage and the current decays to close to zero to provide a uniform thickness throughout the device and production lot. The chemical equations describing the dielectric formation process at the anode are as follows:

2 Ta → 2 Ta5+ + 10 e−
2 Ta5+ + 10 OH− → Ta2O5 + 5 H2O

The oxide forms on the surface of the tantalum but it also grows into the material. For each unit of oxide, one third grows out and two thirds grows in. It is for this reason that there is a limit on the maximum voltage rating of tantalum oxide for each of the presently available tantalum powders.
Source:
http://en.wikipedia.org/wiki/Tantalum_capacitor

The black color that I have here may be the carbon powder that is also used in the construction. If I clean them, they are still very dark with a very deep blue teint.
I just want to point in that direction, since I would expect to meet mostly Ta2O5 and not pure Ta, which would mean that it is refined and treated in a different way to purify it.

Tantalum pentoxide is a highly robust material, decomposing thermally above 1470 °C.

Chlorination of Ta2O5 with carbon tetrachloride affords tantalum pentachloride:

Ta2O5 + 5 CCl4 → 2 TaCl5 + 5 COCl2

Ta2O5 can be reduced several different ways, including the use of metallic reductants such as calcium and aluminum.

Ta2O5 + 2 Al → Al2O3 + TaO2 + Ta
Ta2O5 + Ca → CaO + 2 TaO2

These reactions can be further modified to yield pure tantalum via stoichiometry, thermal control and electrolysis.
Source:
http://en.wikipedia.org/wiki/Ta2O5

So you may only need to reach 1500°C instead of 3000°. That would be much easier.
Hope this helps..

 

[etack]

Gill I doubt what you have is all Tantalum. you would need on the realm of 15# of caps to get that much powder. also as we know with gold the powder is not the same color as the melted bar.

Also most of the Tantalum would have been removed with your magnetic separation. Tantalum is not magnetic but the CuFe or Ni leads are. they are not always easy to separate.

an interesting test for you would be to press it into a pill and run some DC current through it to see if it changes color.

I ran some quick numbers and think it might be possible to account for about 2# but highly unlikely for any more.

Older MB had more Ta caps and most are on the graphic sound cards. on 1.2 tons that would be close to 4-6kilos @ 20% return on SMDs thats in the 1-2# range. not all SMDs have a 20% return that is the average low end.
There is no way of knowing what you have until you get it tested.

Eric

 

[rusty]

@rusty:
The capacitors dielectric is made from pure tantalum, but this Ta is then converted into a mix of more or less Ta + Ta2O5

Dielectric
The dielectric is then formed over all the tantalum particle surfaces by the electrochemical process of anodization. To achieve this, the “pellet” is submerged into a very weak solution of acid and DC voltage is applied. The total dielectric thickness is determined by the final voltage applied during the forming process. Initially the power supply is kept in a constant current mode until the correct voltage (i.e. dielectric thickness) has been reached; it then holds this voltage and the current decays to close to zero to provide a uniform thickness throughout the device and production lot. The chemical equations describing the dielectric formation process at the anode are as follows:

2 Ta → 2 Ta5+ + 10 e−
2 Ta5+ + 10 OH− → Ta2O5 + 5 H2O

The oxide forms on the surface of the tantalum but it also grows into the material. For each unit of oxide, one third grows out and two thirds grows in. It is for this reason that there is a limit on the maximum voltage rating of tantalum oxide for each of the presently available tantalum powders.
Source:
http://en.wikipedia.org/wiki/Tantalum_capacitor

The black color that I have here may be the carbon powder that is also used in the construction. If I clean them, they are still very dark with a very deep blue teint.
I just want to point in that direction, since I would expect to meet mostly Ta2O5 and not pure Ta, which would mean that it is refined and treated in a different way to purify it.

Tantalum pentoxide is a highly robust material, decomposing thermally above 1470 °C.

Chlorination of Ta2O5 with carbon tetrachloride affords tantalum pentachloride:

Ta2O5 + 5 CCl4 → 2 TaCl5 + 5 COCl2

Ta2O5 can be reduced several different ways, including the use of metallic reductants such as calcium and aluminum.

Ta2O5 + 2 Al → Al2O3 + TaO2 + Ta
Ta2O5 + Ca → CaO + 2 TaO2

These reactions can be further modified to yield pure tantalum via stoichiometry, thermal control and electrolysis.
Source:
http://en.wikipedia.org/wiki/Ta2O5

So you may only need to reach 1500°C instead of 3000°. That would be much easier.
Hope this helps..

Marcel thank you for the great info, I doubt that I'll ever try to process the ta, but sell the powder to those who are better equipped to handle it.

My excitement lies in the fact that I've been able to recover it as an added value to the scrap I'm able to process myself.

 

[etack]

Refining and melting Tantalum is just a waste of time. I have quite a bit of it in Ta caps and wouldn't get a good price on it if it was all pure. its sold and dealt with in the tons not the pounds. I am the only person that will buy Ta caps or small amounts of Tantalum at any sort of decent price. If you have over 250# of caps some people will talk to you. If you have 100# of 99% tantalum you can get an ok price but still under half of its price. Most scrap yards won't take it unless they are in a part of the country that deals in this scrap from hi temp application some refractories and jet engines or chemical application.

3-4# of Ta powder or even anodes will and is hard to sell.

Eric

 

[rusty]

Gill I doubt what you have is all Tantalum. you would need on the realm of 15# of caps to get that much powder. also as we know with gold the powder is not the same color as the melted bar.

Also most of the Tantalum would have been removed with your magnetic separation. Tantalum is not magnetic but the CuFe or Ni leads are. they are not always easy to separate.

an interesting test for you would be to press it into a pill and run some DC current through it to see if it changes color.

I ran some quick numbers and think it might be possible to account for about 2# but highly unlikely for any more.

Older MB had more Ta caps and most are on the graphic sound cards. on 1.2 tons that would be close to 4-6kilos @ 20% return on SMDs thats in the 1-2# range. not all SMDs have a 20% return that is the average low end.
There is no way of knowing what you have until you get it tested.

Eric

The majority of the boards were hybrid and I remember them well as the chips on-board had a thick layer of clear epoxy poured over them, some larger IC's with metal backing had the backing soldered to the board. They were a nightmare to shear off the chips.

I had first incinerated the chips before milling, the magnetics removed afterwards, of late I've been milling my chips without incinerating.

Pressing the powder into a pill and running DC current sounds more interesting than trying to melt the powder, this test batch I have on hand was not washed all that well a hint of purple showed on drying so we know there was still some gold chloride present.

I agree there is more than just tantalum present, from the layer left behind after decanting the leach,

Uppermost top layer is reddish brown, then we have the tantalum, then a grainy material under the Tantalum a layer impregnated with white specks, looks like a shovel full of beach sand full of broken sea shells.

Then on the very bottom I still have some precious metals once exposed reacting with the leach, when it had been inactive for days.

The layer under the tantalum is very compacted, I can easily pour off the upper layers leaving the compacted layers untouched. I really have to dig to remove that bottom layer then it comes out in large clumps and sheets.

I have my suspicions that the brown powder is a rare earth with a specific gravity between copper and tantalum, with the following property's, reddish brown in color, used in electronics, non magnetic and non reactive to acids.

Now it would be cool to have a laboratory centrifuge using Pyrex vials where one could visually see the layers of separation.

There are seventeen rare earths, http://en.wikipedia.org/wiki/Rare_earth_element

21 Sc Scandium Light aluminium-scandium alloy for aerospace components, additive in Mercury-vapor lamps.[4]

39 Y Yttrium Yttrium aluminium garnet (YAG) laser, yttrium vanadate (YVO4) as host for europium in TV red phosphor, YBCO high-temperature superconductors, Yttria-stabilized zirconia (YSZ), yttrium iron garnet (YIG) microwave filters,[4] energy-efficient light bulbs[5]

57 La Lanthanum High refractive index glass, flint, hydrogen storage, battery-electrodes, camera lenses, fluid catalytic cracking catalyst for oil refineries

58 Ce Cerium Chemical oxidizing agent, polishing powder, yellow colors in glass and ceramics, catalyst for self-cleaning ovens, fluid catalytic cracking catalyst for oil refineries, ferrocerium flints for lighters

59 Pr Praseodymium Rare-earth magnets, lasers, core material for carbon arc lighting, colorant in glasses and enamels, additive in didymium glass used in welding goggles,[4] ferrocerium firesteel (flint) products.

60 Nd Neodymium Rare-earth magnets, lasers, violet colors in glass and ceramics, ceramic capacitors

61 Pm Promethium Nuclear batteries

62 Sm Samarium Rare-earth magnets, lasers, neutron capture, masers

63 Eu Europium Red and blue phosphors, lasers, mercury-vapor lamps, NMR relaxation agent

64 Gd Gadolinium Rare-earth magnets, high refractive index glass or garnets, lasers, X-ray tubes, computer memories, neutron capture, MRI contrast agent, NMR relaxation agent

65 Tb Terbium Green phosphors, lasers, fluorescent lamps

66 Dy Dysprosium Rare-earth magnets, lasers

67 Ho Holmium Lasers

68 Er Erbium Lasers, vanadium steel

69 Tm Thulium Portable X-ray machines

70 Yb Ytterbium Infrared lasers, chemical reducing agent

71 Lu Lutetium Positron emission tomography - PET Scan detectors, high refractive index glass - Leds

 

[rusty]

To avoid cross contamination I've ordered a few new vacuum filter flasks along with some other odd bits of glassware. Once this arrives we'll all have a chance to see how much gold was recovered from that big lot of concentrates.

A few minutes ago unloaded the ball mill, what I would like to show is how well the gold braze has been abraded from these CPU lids during their time spent in the mill. The lids were still attached to the cpu's before going into the mill, they're history.

The resin from the chips is very abrasive and it does a very good job of wearing away at the gold brazes and plated material.

On a side note, I mailed off a sample of the gray powder to have it read from an XRF, hopefully we'll have some information within the next couple of weeks.

 

[rusty]

A small sample of todays run through the centrifuge, judging from the flame during incineration process there's not very much copper in my cons.

After incineration I mortared the lumps, if you enlarge the picture you will see bright specs of which reflected the camera flash, I suspect this to be silver which beaded up during incineration.

The chips processed were from random lots recently purchased off ebay.

 

[rusty]

I've altered my process, eliminating a few steps.

1. Raw un incinerated chips straight to the ball mill, screened out pins sending the remaining mud to the centrifuge.

2. Incinerated small centrifuge sample - pictures above.

3. Concentrates from centrifuge straight to 50/50 nitric, the filtered liquor has a hint of green - no copper. Addition of HCL produced silver chloride.

4. The insolubles from the nitric leach will be incinerated, possibly an HCL leach with a few drops of sulfuric acid before proceeding to gold using an acid / bleach leach.

Top picture filter full of brown mud, I suspect the orange floater is possibly a rare earth.

 

[g_axelsson]

Why do you think you have rare earth in chips? If there are some it is as doping in the silicon die, it would be in such minute amounts and mixed into the silicon.
I think your orange floaters is of a quite more mundane origin, iron hydroxide, or as most people calls it, rust.

Göran

 

[rusty]

Why do you think you have rare earth in chips? If there are some it is as doping in the silicon die, it would be in such minute amounts and mixed into the silicon.
I think your orange floaters is of a quite more mundane origin, iron hydroxide, or as most people calls it, rust.

Göran

After doing a color comparison I agree with Göran the orange residue is iron hydroxide.

For the time being I've concluded my input to this thread, to satisfy the skeptics will report our findings from the sample of gray powder sent out for analysis. Until then I turn this thread over to you for debate and discussion.

The pros and the cons of the centrifuge.

 

[rusty]

A sample of the gold chloride from my concentrates.

 

[srlaulis]

I can't wait to see the final product! :mrgreen:

 

[butcher]

Is that real sunshine in that picture :lol:

 

[rusty]

Is that real sunshine in that picture :lol:

360 days, a rain storm is a 10 minute torrent. Wanna talk about snow.

 

[rusty]

The results from an XRF reading on the gray powder, percentages only in precious metals mode.

Silver less than 2%
Platinum 1%
CR, Chromium
TA, Tantalum
ZR, Zirconium
SR, Strontium
PB, lead
BR, Bromine
HG, Mercury
FR, Francium
AS, Arsenic
ZN, Zinc
RE, Rhenium
FE, Iron
MN, Manganese
NI, Nickel