# Corningware dish for Calcining



## kadriver (Dec 26, 2011)

I bought a DVD for recovering and refining platinum and palladium from lazersteve.

In this video, a fused quartz dish is used for calcining the platinum.

I have searched for this type of dish (fused quartz) on the web and found a source, but they are about $40 each.

I have several white corningware casserole dishes. They are about 4 inches square with 1.5 inch tall sides. These dishes can take lots of abuse and still shine.

I was wondering if these corningware casserole dishes ($3 at the thrift store) could be used for calcining the platinum instead of an expensive ($40 apiece) fused quartz dish?

Thanks - kadriver


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## glondor (Dec 26, 2011)

If you have some original corningware you may be ok. Newer corning is not the same. Butcher uses corningware for incinerating wastes on a hotplate with a torch. New corningware will break. Not the same type of glass as the old.


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## qst42know (Dec 26, 2011)

I have had the right type of these hot enough to oxidize carbon soot till gone over a gas flame. But I don't know how they will react to the platinum group salts.

The mark I have seen most on the right type is "Range-Oven-Microwave safe" in an ink stamp. Sometimes this ink stamp is worn off.


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## lazersteve (Dec 26, 2011)

I would be very careful when heating and cooling any type of corningware. Change the temeprature gradually and you should be ok, heat or cool too rapidly and you will end up with a shattered dish and perhaps lost PGMs. 

The reason I use quartz in the video is because fused quartz can be heated to nearly 1600C and immeadiately dipped in cold water and it will not break. The quartz can survive this type of abuse because of it's low coefficient of thermal expansion, meaning it does not expand and contract very much when heated and cooled rapidly. This is one of the properties of fused quartz that makes it great for use in the lab, espeically when working with PMs.

Steve


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## kadriver (Dec 26, 2011)

Thanks Steve.

I may just go ahead and get the fused quartz to be safe.

Can you suggest a source for these dishes?

kadriver


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## slickdogg (Dec 26, 2011)

Have you checked these guys out 
http://www.technicalglass.com/product_pages/fused_quartz_labware/labware/fused_quartz_labware.html


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## kadriver (Dec 26, 2011)

slickdogg, I just completed ordering two fused quartz dishes from them - Thanks!

kadriver


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## slickdogg (Dec 26, 2011)

your welcome. 
They got some good stuff as well as there prices, they ship pretty fast too.


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## glondor (Dec 26, 2011)

Which one did you get Driver? was it this style?? http://www.technicalglass.com/product_pages/opaque/rectangular_trays.html


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## kadriver (Dec 27, 2011)

I orderd two RD75 - 75ml - 89mm round.

They were $53 each, plus tax & shipping.

It will probably be $130 when its all said and done.

But I am happy with the purchase.


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## samuel-a (Dec 27, 2011)

Good choice Kev.

It is well worth investment.

I'm using regular (german made - "schott") borosilicate evap' dish for Pd.
And for Pt, an alumina sample holder (crucible design) for Pt.

On the hot plate, I heat the Pd salts to 450-500C, so not to form oxides. This produce a reletivly convenient sponge to melt with a torch.
The Pt salts are heated to well above 750C in my fat boy furnace to form a tightly adhered sponge.

I didn't heat Pd salts before to above 750C, since i'm thinking (maybe wrong) the oxides formation will Infringement the sponge and it will blow away with the flame.

Sadly, i have no other way for metling other then a oxy /propane torch at the moment..
(i'm drooling on induction rig with a chamber for inert atmosphere/vacuum)


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## kadriver (Dec 27, 2011)

All I have is an oxy/acet rig. I read in Hoke that acetylene is not a good gas to use to melt platinum:

"Acetylene with oxygen provides enough heat...but because of its tendency to form the brittle platinum carbide...the oxy-acetylene flame is not often used in this work." Hoke, page 294. 3rd sentence.

I see that you use propane. Hoke states that "city gas, in combination with oxygen from a cylinder" is suitable as long as the flame is properly set. By city gas, I concluded that she was refering to natural gas.

It appears that you are getting good results using oxy-propane to melt your platinum. I have seen you do it in your video.

After melting the platinum, do you "prove" the metal by striking it with a hammer on an anvil?

Hoke states that if the metal splits at the edges under the hammer, then it is impure. The platinum bead is hammered while still hot - Hoke, page 296, last paragraph.

kadriver


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## lazersteve (Dec 27, 2011)

I buy all of my fused quartz glass from TGP. They are the best.

The best choice fused quartz dish for open air calcining of small samples of sponge would be the flat round petri type dishes from TGP. The low profile and wide base allow for the ammonium chloride to off gas easily.

Since the DVD was filmed I quit using calcining as a conversion method. There are much quicker and 'more pleasant' methods that can be used. The primary ways I convert the ammonium salt now is via hydrazine and ammonium hydroxide with acid and zinc as a secondary method for smaller batches or potassium PGM salts. Hydrazine and ammonium hydroxide requires some skill and extra safety, but is very quick. Zinc and acid is by far the best of all worlds, fast, safe, and easy. The zinc method requires a final acid wash when the reaction is complete. Performed properly both zinc and hydrazine form beautifully coherent heavy sponge (I affectionally call them 'gray matter' because of their brain-like appearance) which handles, washes, and melts like a dream.

I ran two batches of the ammonium chloride with my tube furnace and the result was a very nice fluffy gray sponge, but the reaction was not very fast. Another side effect of tube furnace calcining is scrubbing the off gases.

Steve


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## kadriver (Dec 27, 2011)

lazersteve said:


> Zinc and acid is by far the best of all worlds, fast, safe, and easy. The zinc method requires a final acid wash when the reaction is complete. Performed properly both zinc and hydrazine form beautifully coherent heavy sponge (I affectionally call them 'gray matter' because of their brain-like appearance) which handles, washes, and melts like a dream.



Steve, the zinc and acid you mentioned above, is it described in Hoke?

If not, then could you describe the process or point out a reference on the forum?

I have done a search with negative results.

Thank you - kadriver


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## lazersteve (Dec 27, 2011)

Check item number 16 on the General Reactions List in the Guided Tour Link below.

Steve


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## kadriver (Dec 27, 2011)

I found a description of the zinc and dilute HCl method:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9521&hilit=zinc+platinum

It gives a detailed description with photos.

I have some zinc powder, but I am not sure of its purity.

Since your zinc turnings are of known purity, I am going to get some from you.

I will check the reference you posted about item 16 in guided tour.

Thank you - kadriver


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## kadriver (Dec 27, 2011)

I found the procedure in step by step format here (item 16 in guided tour):

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=8416&start=20

Thank you. I want to try both calcining and the zinc acid methods when I get to that point.

I am reading and studying all I can before I even begin to process any material.

Thank you for pointing me in the right direction - kadriver


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