Cupellation / Assaying  

Cupellation is a metallurgical process used to refine noble metals like silver and gold. The process involves heating ores or alloyed metals in a cupel—a porous container able to absorb lead oxides and other impurities. When the ore or alloy is heated to high temperatures in the presence of lead, the base metals oxidize and are absorbed by the cupel, leaving behind the pure noble metal.

The CF cupellation furnaces are designed for the cupellation, or fire assay test, of precious metals, which is a standard test method used to determine their purity. The furnaces meet the Hallmarking requirements specified by the Convention on the Control and Marking of Articles of Precious Metals (known also as “Precious Metals Convention”, “Hallmarking Convention” or “Vienna Convention”). The test method produces hazardous vapours. When used within a suitable fume management system, the cupellation furnaces are designed to handle the vapours without exposing the operator to these hazards. The design of the cupellation furnace range ensures protection from the corrosive environment which would damage a conventional furnace. Carbolite Gero also offers a range of smelting/melting furnaces.