Cryolite usage

[kjavanb123]

All,

I am preparing to lead smelt my first ceramiv catalytic converter.

I read attached article, about cryolite usage in alumina smelting, I can't make up what it says about ration of cryolite to alumina.



If someone gets it please share with us.

Best regards
Kj

 

[cuchugold]

89% pure cryolite. 11% alumina, for the lowest melting point (eutectic). To lower melting point more, add more AlF3.

 

[kjavanb123]

Let's say the weight of ceramic catalytic converter is 1000 grams, which most of its weight consists of alumina.

To dissolve that much alumina based on your suggestion, it would need 8090 grams of cryolite as flux?

Seems very high.

Thanks
Kj

 

[cuchugold]

I only translated the document you posted. It seems right. Usually one uses a lot more flux in weight than charge. I never used the process described, but I saw the electrolytic cells in action, and they use a lot of flux. I don't know if they re-cycled it somehow. Catalytic ceramic balls are sintered alumina. I doubt they will just dissolve. You probably need to crush them to dust.

 

[kjavanb123]

Hi,

Milling the ceramic cats is first step, finding the right ratio of flux to material is the second step.

I have tried this using copper and an ounce of cryolite for each lb of material, but some copper got oxidized and lost in slag.

That formula is mentioned in Hook's book on page 228, although instead of cryolite she mentioned using flourite to melt sand and old crucible.

This time I will be using lead oxide.

Regards
Kj

 

[cuchugold]

Litharge (lead oxide) does the job. With regular adds of fine carbon (or wheat flour), or sodium carbonate, or whatever reducing material you have. Silver chloride with sodium carbonate is great too. It looks like chicken soup, except for the fumes. You can suck all the fumes with a vacuum cleaner that has a water filter. Perfect for small scale, even indoors operations.

 

[g_axelsson]

The flux mix mentioned at the top of the thread is for an aluminium electrolytic cell. In that case the consumption of cryolite is minute and new alumina and carbon anode is added continuously while molten aluminium is tapped off at the bottom. In that case the amount of cryolite is of minor concern. Cryolite in an aluminium cell is like water in a silver nitrate cell, it just dissolves the part we are most interested in and doesn't play a part except as a solvent.

Göran

 

[kjavanb123]

Thanks all. I am planning to use flux formula on her book on page 228.

2 parts stock flux and an ounce of flourite for each lbs of milled ceramic catalytic converters.

Cryolite I got the price locally seems high for my operation.

I will keep you posted.

 

[cuchugold]

What type and size of furnace are you using ?.

 

[kjavanb123]

Hi

Sorry for my late respond. I use a graphite crucible 3-kg. Use a 4-liter paint can with kaewool blanket.

I have not done this project yet. Once I do I eill post result.