Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Bead loss in cracked cupel (1 reply)

B
benport
3 years ago
benport 3 years ago

I put a handful of buttons in a 6" cupel and placed it in the furnace.  When I checked it the cupel had cracked and the melt gone inside the cupel.  What is the best way to recover it?

J
Jorge
3 years ago
Jorge 3 years ago

First and foremost, it is important to indicate that a high capacity for absorbing is the key consideration to select a cupel because a higher absorption capacity is required for a larger sample in order to get a reliable result. It means that a larger cupel can be selected if its capillary capability is enough to get the lead oxide (formed in the process) into the cupel.

Obviously, it necessary to avoid cracks through which liquid metal could penetrate into the body of the cupel, resulting a complete or partial loss of the bead at the end of cupelling. The main aspect to keep in mind is the fabrication process and the material used to make the cupel. Sometime, the additives are of bad quality and cupel bottom cannot resist temperature changes and/or pression in the cupel body. The additives must be able to get good drying properties in the body of the cupel to eliminate the cracks.

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