# Corning ware pyroceram dish for calcine of Pd and Pt



## kadriver (Sep 19, 2014)

I did a small batch of Pd about a year ago - none since then.

I used a fused quartz dish to do the calcining.

The pure canary yellow Pd salt was placed in the fused quartz dish.

Then this was placed into a Corning ware casserole dish.

Finally the whole thing was place on electric burner.

The calcining went well until the very end, I had to put another Corning ware casserole dish on top of the first one to form a sort of over in order to get the very tips of the Pd salt to completely burn into sponge.

The question is; has anyone ever used just a pyroceram (Corning ware) dish to calcine Pd salt?

Is the fused quartz dish absolutely necessary?

I can buy a small Corning ware dish at the thrift store for $5 bucks.

I bought 2, four inch diameter, fused quartz dishes (one for Pt and one for Pd) and they cost a hundred dollars each.

Thanks,

kadriver


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## Harold_V (Sep 19, 2014)

kadriver said:


> The pure canary yellow Pd salt was placed in the fused quartz dish.


Was this material recovered with DMG? Palladium recovered from solution using ammonium chloride and sodium chlorate comes down red, although that result can be dissolved with ammonium hydroxide and re-precipitated with HCl. That yields a yellow powder. 



> Is the fused quartz dish absolutely necessary?


My opinion? It's highly desirable. I had a pair of Vicor dishes, but managed to fuse some platinum to the dish when heating with a torch. That was my routine after the bulk of the material had been calcined. More or less guaranteed it was all converted. 

Harold


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## kadriver (Sep 19, 2014)

Harold_V said:


> Was this material recovered with DMG? Palladium recovered from solution using ammonium chloride and sodium chlorate comes down red, although that result can be dissolved with ammonium hydroxide and re-precipitated with HCl. That yields a yellow powder.



This canary yellow Pd salt came from dissolving the brick red Pd salt in strong ammonia, filtering, then re acidifying with HCL.

I'll just stick to the fused quartz for now. 

The Corning ware material is some tough stuff.

I did have some molten gold fuse to a Corning ware dish once.

I put the Corning ware dish in the bottom of the steel pan full of tap water and poured molten gold thru the water into the Corning ware dish at the bottom.

When I recovered the pure gold one piece about the size of a dime had to be pried loose from the dish.

It took a piece of the dish with it and I had to hit it with a hammer the break the pyroceram off the gold.

kadriver


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## Irons (Sep 19, 2014)

One thing to remember is that Pyroceram has an annealing temperature of about 900*C. Once you heat it above that point, the internal crystalline structure begins to grow, making it more brittle over time. One has to be careful of cooling Pyroceram that is above the Annealing temperature, in that it is likely to shatter if cooled suddenly. Once the temperature decreases below 900*C, it can take sudden cooling without breaking. 
Fused Quartz is preferable from a safety standpoint, unless one is very careful in regulating the temperature of the furnace.


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## Lou (Sep 19, 2014)

From a purity standpoint, avoid silica with Pd and Pt if in reducing conditions.


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## Irons (Sep 19, 2014)

Pyroceram is primarily composed of Spodumene with a small amount of Titanium Dioxide to provide a seed for the crystals to grow.

Spodumene is a pyroxene mineral consisting of lithium aluminium inosilicate, LiAl(SiO3)2, and is a source of lithium. It occurs as colorless to yellowish, purplish, or lilac kunzite (see below), yellowish-green or emerald-green hiddenite, prismatic crystals, often of great size. Single crystals of 14.3 m (47 ft) in size are reported from the Black Hills of South Dakota, United States.[5]

The normal low-temperature form α-spodumene is in the monoclinic system whereas the high-temperature β-spodumene crystallizes in the tetragonal system. The normal α-spodumene converts to β-spodumene at temperatures above 900 °C.[4] Crystals are typically heavily striated parallel to the principal axis. Crystal faces are often etched and pitted with triangular markings.

https://en.wikipedia.org/wiki/Spodumene


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## kadriver (Sep 20, 2014)

Lou, I'll stick to fused quartz.

Looks like you worked at the Corning ware factory irons, that's quite a lot of info about those dishes.

They are tough and can take some heat.

I did have one shatter on me once.

I was drying some cement silver in one and it was nearly completely dry, just a little moisture left.

I cranked up the heat and got busy on something else and I heard a pop, crash like a glass being dropped on the floor.

It broke into many pieces as shards, but I was able to clean the silver up easily.

Thanks for the responses!

kadriver


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## Irons (Sep 20, 2014)

I would have loved to work at Corning. I did work as a Quality Control Tech for a supplier of Ceramic Materials many Years ago, and have since worked with them as a Hobby. I just like to research and learn how things work. 
That breaking into shards is the usual MO. When the Spodumene goes through the crystalline phase transition, there can be a lot of internal stress generated if the item is not heated or cooled slowly or evenly. I also learned the hard way, so don't feel bad. We all make mistakes.


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## Lou (Sep 20, 2014)

Quartz is fused silica (SiO2) and palladium are bad to have together.


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## Harold_V (Sep 21, 2014)

Lou said:


> Quartz is fused silica (SiO2) and palladium are bad to have together.


Interesting. What would you recommend instead, Lou? Not an issue for me any longer, but I suspect countless others will benefit from your recommendation. 

I used the Vicor dish with success, although it slowly accumulated a thin coating of oxidized palladium. Pretty colors! 

Harold


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## Lou (Sep 21, 2014)

ZrO2 or MgO.


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## kadriver (Sep 22, 2014)

Harold_V said:


> I used the Vicor dish with success
> 
> Harold



Harold,

What is the Vicor dish?

I used a fused quartz dish when I did my first Pd refining and all went well.

The metal was high purity and the fused quartz dish was spotless when I got done.

What kind of problems would be encountered using Fused quartz?

kadriver


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## Lou (Sep 22, 2014)

Vycor is intermediate between quartz and borosilicate.


The problem with fused quartz is the formation of brittle PdSi intermetallics that may contaminate the Pd and make it crack.


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## Harold_V (Sep 23, 2014)

Lou, 
Thanks for the response, and the correction of my spelling of vycor. The proper spelling had (obviously) escaped me!

Harold


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## kadriver (Sep 27, 2014)

VYCOR® glass has several exceptional properties. Since it is 96% silica, it is similar to fused quartz in its thermal properties. It may be used at much higher temperatures than PYREX Code No. 7740 borosilicate glass and will withstand considerably more thermal shock. VYCOR® products can be used continuously at 900°C and intermittently to 1200°C. Containing only five elements, it is used for very precise analytical work.

VYCOR® glass is formed as a borosilicate type glass. It is then subjected to a chemical treatment that removes most of the elements in the glass except silica (SiO2). Glass is then reheated to eliminate the microscopic holes caused by the chemical treatment. Only quartz has higher silica content.

I went to the Corning.com after doing a search.

The above information was given.

According to these folks, Vycor contains silica.

Where can I get my hands on a Vycor dish that does not contain silica?

Thank you,

kadriver


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## Irons (Sep 27, 2014)

kadriver said:


> VYCOR® glass has several exceptional properties. Since it is 96% silica, it is similar to fused quartz in its thermal properties. It may be used at much higher temperatures than PYREX Code No. 7740 borosilicate glass and will withstand considerably more thermal shock. VYCOR® products can be used continuously at 900°C and intermittently to 1200°C. Containing only five elements, it is used for very precise analytical work.
> 
> VYCOR® glass is formed as a borosilicate type glass. It is then subjected to a chemical treatment that removes most of the elements in the glass except silica (SiO2). Glass is then reheated to eliminate the microscopic holes caused by the chemical treatment. Only quartz has higher silica content.
> 
> ...



Only in your Dreams.

I think folks are getting a little too hung-up on Silica. It would be a concern for analytical work, but for practical purposes, a non issue.


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## Lou (Sep 28, 2014)

For practical purposes, an issue with Pd.


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## Irons (Sep 29, 2014)

Lou said:


> For practical purposes, an issue with Pd.



I thought this was a discussion about Calcining, not Melting.


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## Platdigger (Sep 29, 2014)

Lou said:


> ZrO2 or MgO.



This may have been discussed but, how about graphite?


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## Harold_V (Sep 30, 2014)

Platdigger said:


> Lou said:
> 
> 
> > ZrO2 or MgO.
> ...


If memory serves, carbides can form when there's carbon present, and is the reason why an oxy/acet torch is not recommended for melting the platinum metals. I suspect graphite would be a poor choice as a result. 

Harold


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## Lou (Sep 30, 2014)

I've attached this paper before.

I'm talking about calcining, specifically. You should never melt PGMs in silicaceous material (ZrO2, MgO, CaO, and less optimally, Al2O3).
So what's a chemist to do? Line your quartz boats with zirconia.

The carbide side of things is more for organics stuck in the PGM sponge (i.e. filter paper)--although if you have a mixture of graphite dust and platinum, it can carbidize the sponge.

Vycor is almost as thermally shock resistant as quartz. It's easier to work and cheaper.


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## g_axelsson (Sep 30, 2014)

The article is about PGM:s simplifies reduction of refractive oxides in reducing conditions. (hydrogen gas, CO, carbon powder in vacuum)

I've been reading it on and off for the last couple of days. Interesting reading. In the first page is this passage.


> The more stable and refractory base metal
> oxides can also react with platinum in an
> argon atmosphere, in vacuum, or even in
> air, the reactions being particularly severe
> ...


This shows that inter-metallics are formed even without a reducing atmosphere, but the marked part gives hints that oxygen suppresses creation of inter-metallic compounds.

A small disclaimer is in place here. I have no practical experience of calcining or melting PGM:s . I just enjoy discussing and learning the chemistry, so I can say some quite stupid things sometimes.

Göran


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## Lou (Sep 30, 2014)

Handling PGMs almost every day, you start see little things.


Issue is getting magnesia to stick well to silica.


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## kadriver (Sep 30, 2014)

With respect to palladium, if fused quartz is a poor choice, and Vycor is only a little better than fused quartz, then what is the better chose for reducing the metal from the salt. Instead of calcining, can the metal be rendered chemically?

kadriver


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## Platdigger (Oct 1, 2014)

I believe what they are saying here is, that it is ok to calcine in a fused quartz dish or the Vycor.

As far as rendering pd chemically Steve made this statement not long ago.
" Calcine the purified colored salt or reduce with hydrazine, formic acid, or your favorite reducing agent."
If I remember right sodium borohydride is also a good one for that.


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## kadriver (Oct 1, 2014)

Platdigger said:


> I believe what they are saying here is, that it is ok to calcine in a fused quartz dish or the Vycor.
> 
> As far as rendering pd chemically Steve made this statement not long ago.
> " Calcine the purified colored salt or reduce with hydrazine, formic acid, or your favorite reducing agent."
> If I remember right sodium borohydride is also a good one for that.



Ok, when I get the pure Pd salt then I will try this process instead of calcining. Thank you.

kadriver


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## Lou (Oct 1, 2014)

Best way to do reduction in an expedient time, say 4-5 hours, is with sodium formate with formic acid dripped in over time. At the end it may be boiled in dilute sulfuric to get heavy metallic sand. 

This doesn't work so well on Pt; hydrazine and caustic, or better yet, heat.


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