# Dissolving CPU Ceramics



## Anonymous (Oct 17, 2009)

I may have stumbled onto to something, before I left on my Saskatchewan trip I had a bucket of crushed cpu's waiting for to be smelted. 

The bucket was loaded with flux Borax/Soda Ash/Sodium Nitrate left by the furnace on my return some water. On stirring it looks like the cpu ceramics the small bits that do not crush are completely dissolved into a mud.

I'm going to add some complete cpu's and see what happens, an will post the results when I know them.

Best Regards
G


----------



## Irons (Oct 17, 2009)

That sounds very useful. It would save a lot of labor. :idea:


----------



## Oz (Oct 17, 2009)

That would be fantastic if reproducible. What ratio were the dry ingredients in? It sounds as though water was added, just enough to cover the solids?




gustavus said:


> I may have stumbled onto to something, before I left on my Saskatchewan trip I had a bucket of crushed cpu's waiting for to be smelted.
> 
> The bucket was loaded with flux Borax/Soda Ash/Sodium Nitrate left by the furnace on my return some water. On stirring it looks like the cpu ceramics the small bits that do not crush are completely dissolved into a mud.
> 
> ...


----------



## Anonymous (Oct 17, 2009)

Oz said:


> That would be fantastic if reproducible. What ratio were the dry ingredients in? It sounds as though water was added, just enough to cover the solids?



Mother nature added the water and yes just enough to cover the material, which sat for a week in my absence. I do not have time to reproduce the experiment but will sift the material looking for some of the larger chunks I know were in there.

I'll post my findings along with the flux recipe later this afternoon.

Manitoba winters are cold and long, the wife does not want a repeat from last year garden hose wrapped up in the snow blower. God I hate common sense anyhow I gave in todays the day for putting everything in it's place.

ttys
G


----------



## goldsilverpro (Oct 17, 2009)

No offense, but this all sounds very weird. I have fire assayed many crushed alumina CPU packages, using those same chemicals - at about 1900F. The ceramic was untouched, as far as I could tell, and whole pieces floated on top of the slag. Maybe your parts weren't alumina, but I doubt it. I'll be interested in seeing the results of a more controlled experiment.


----------



## Anonymous (Oct 17, 2009)

goldsilverpro said:


> No offense, but this all sounds very weird. I have fire assayed many crushed alumina CPU packages, using those same chemicals - at about 1900F. The ceramic was untouched, as far as I could tell, and whole pieces floated on top of the slag. Maybe your parts weren't alumina, but I doubt it. I'll be interested in seeing the results of a more controlled experiment.



GSP I think your right, I rinsed the mud with warm water, and there's still chunks in the bottom of the bucket. No doubt about it the flux had no effect of the ceramic. Some green colored lumps that are easy to break up though so something took place.


----------



## 4metals (Oct 18, 2009)

Back in the '80's I went up to Sabin Metals in Rochester NY with a 55 gallon drum of ceramic multi layered hybrids. Normally we granulated this stuff and digested it in aqua regia. The problem was the un-dissolved residues of the ceramics were always payable so they had to be refined anyway. Sabin's salesman, actually a saleswoman, guaranteed they could smelt the ceramics and I could watch the whole thing. 

They fluxed the mix with cryolite (sodium aluminum flouride) and added about 200 pounds of copper. The melt took over 8 hours, I remember sitting watching the melt through a shift change and into more coffee than you could imagine, but when it came time to pour, the slag came off the top smooth as silk and the ladled samples poured as shot from the beginning of the metal flow, the middle of the flow, and the end of the flow, all assayed very close. 

So she was right, the ceramics did melt, not quick and I believe the crucible was only good for I melt, but it was a good melt.


----------



## Harold_V (Oct 18, 2009)

4metals said:


> So she was right, the ceramics did melt, not quick and I believe the crucible was only good for I melt, but it was a good melt.


I'm inclined to think that the refractory materials (the ceramics) were dissolved by the flux, not melted. That would be especially true when you consider the melting point of alumina. It would be much the same as silica being dissolved in soda ash, yielding glass. 

Interesting! I can well imagine that the crucible was good for one heat, and one heat only. My tilting furnace was lined with a 94% alumina refractory. You could see the damage caused by a day's worth of run time. My flux included soda ash and fluorspar, each of which tend to raise hell with refractories. 

Harold


----------



## Irons (Oct 18, 2009)

Cryolyte makes sense. Aluminum is produced that way. Refined Bauxite (crude Aluminum Oxide) is mixed with Cryolyte and melted in an arc furnace.
That might be a good way to process Cats.


----------



## qst42know (Oct 18, 2009)

The right type and proportion of fluxes make ceramics possible. The right amount promotes fusion or vitrification. A surplus of the right type flux actually lowers the melt temperature of refractories.

http://www.azom.com/Details.asp?ArticleID=3507


----------



## 4metals (Oct 18, 2009)

A liquid free flowing flux which can dissolve the ceramic is only one part of a successful smelt, albeit a big part. The parts I had smelted had visible gold and PGM's layered throughout. Converter cores have extremely small particle size PGM's.

The second trick in a successful smelt is collecting the metals, in the melt I witnessed the added copper was the collector and the metals were heavy enough to be collected. The question of collecting metals from converters, considering their small particle size, may be an issue. 

I have successfully melted prepared jewelry sweeps in a rotary furnace using a standard soda ash, borax, and silica flux and copper as a collector. In that case the small particle size was collected by the action of the rotating charge in the furnace. 

Unfortunately replacing the refractory in a rotary melter is an involved and costly process, cryolite would eat it up pretty quickly if used to melt ceramics regularly.


----------



## T3sl4 (Oct 19, 2009)

And in contrast, you need something to resist it. Some of the more exotic materials are good for this: as I recall, there is a brick made (not sintered, but *cast*!) from zircona, alumina and silica, used for glass manufacture, which is specified as something like zero wear for 15 years continuous operation. No flaking, little dissolution.

Zirconia is a bit more robust than alumina, but it probably dissolves just as well in cryolite. (Cryolite contains aluminum complexed with fluoride, as AlF6 groups, which will gladly give up a few fluorides of their own to dissolve any other aluminum nearby. Zirconium and silicon both form identical complexes.) Magnesium oxide may stand better.

Something completely different, like silicon carbide or graphite, cannot react in the same way. But the problem with these becomes porosity; salt (used for fluxing aluminum) simply drains out of a commercial SiC crucible. It's very hard to make nonporous >99% density SiC. And you still have to keep it away from oxygen, otherwise the carbon burns up and the silica dissolves like everything else (SiC is great in air without flux, because the silicon oxidizes, passivating the surface).

Metals are also a possibility, but most will react with the metal content (wouldn't want your values uselessly brazed to the bottom of your brand new molybdenum crucible), and most are still vulnerable to oxidation (basically except iridium, which is just a little expensive).

So ultimately I guess the question becomes, can you afford a sacrificial one-time crucible, or can you find nonporous SiC and make it last?

Tim


----------



## Palladium (Oct 19, 2009)

Irons said:


> Cryolyte makes sense. Aluminum is produced that way. Refined Bauxite (crude Aluminum Oxide) is mixed with Cryolyte and melted in an arc furnace.
> That might be a good way to process Cats.



I think that's how the big boy's do it now ain't it ?

I think they melt the cats in a plasma arc furnace and add something like lime to solidify the slag ? The precious metals which are about the only other heavier thing in the mix settles to the bottom as a button or plug which can then be refined.

Not quite sure if that's how it's done, but i think it's something like that.

Anyone ?


----------



## Platdigger (Oct 19, 2009)

I have read that with a plasma or carbon arc, they throw the cats in whole and the iron from the cans themselves becomes the "collecter" of the pms.


----------



## 4metals (Oct 19, 2009)

All of the commercial cat "refiners" here de-can the converters before they ship to a refiner. The scrap steel value offsets the de-canning cost and the refiner stream samples the innards before processing. Steel as a collector would cause more problems, most prefer copper.


----------



## markqf1 (Oct 19, 2009)

On another thread, our friend Arthur posted a flux recipe for converter material.
I believe it was borax, soda ash, and about 10 percent copper.
He said that the slag was assayed afterward and it showed that they were getting all the good stuff out.
I haven't tried it ,...yet. :lol: 

Mark


----------



## Iridium chaser (Jan 6, 2019)

Well,I consider only two ways of dealing with ceramics of all sorts:the first one being molten NaOH for more multiple material and for more precise stuff I use either 70% HF or the same with adding sulfuric acid!And the more cruel and devastating way being molten oxone:there are some disadvantages of the last method like that nothing is capable of handling it so the only way not to demolish the vessel is not to let the molten oxone reach the vessel since it easily and surely defeat such things like fused thoria,any fused oxide and fluoride,and even the allmighty iridium metal can not survive mauling by molten oxone!


----------

