Fire Assay Crucibles

Product Overview

Fire assay crucibles (also known as ceramic refractory crucibles) play a crucial role in the fire assaying of precious metals. Crushed ore samples are mixed with fluxes, a carbon source and powdered lead oxide in a refractory crucible. The crucible and mixture will then be placed inside a furnace and heated to around 1150°C (2100°F). A series of chemical reactions will separate the metal from its impurities, allowing it and its impurities to be measured and its purity to be calculated.

Fire Assaying is done by assay houses (otherwise known as assay offices), organisations dedicated to testing the purity of precious metals (such as gold, silver, and the platinum group metals (PGMs)), ensuring that products conform to legal requirements for purity, and issuing relevant hallmarks. Fire assay crucibles and the fire assaying process are also often used by the mining industry to scientifically analyse material samples.

IPS Ceramics supply refractory crucibles to assay houses worldwide, plus many companies recovering precious metals from electronic waste and other waste streams. Made from cordierite, they easily stand the temperatures required for assaying. They are available in a wide range of shapes and sizes, ensuring they fit your particular setup perfectly.

For our full list of available sizes, please see our datasheet. If a suitable size isn’t available, please contact our sales team with your requirements.

Technical Information

Products	Pouring Cups
Composition
Minerology	Cordierite Mullite
Al₂O₃	28%
SiO₂	67%
Fe₂O₃	1.5%
Other	3.5%
Properties
Max. Service Temp.	1150°C / 2100°F
Bulk Density	1.95 g/cm³
Open Porosity	23%
Modulus of Rupture (room temp.)	20 MPa
Modulus of Rupture (1250°C / 2280°F)	15 MPa
Thermal Expansion (20-1000°C / 70-1830°F)	3.2 x10⁻⁶/K
Specific Heat Capacity	1.0 kJ/kg.K
Thermal Conductivity	1 W/mK