A cupel is an essential refractory product used for the separation of gold and silver and the absorption of lead melt. Its primary function is to absorb molten lead and its oxide (PbO) at high temperatures, thereby collecting precious metals such as gold and silver on the surface of the cupel. The cupel is an irreplaceable consumable in precious metal analysis and testing. The product operates at temperatures between 900°C and 1050°C, featuring high absorption capacity, excellent refractory properties, superior oxygen affinity, uniform pore structure, and relatively high chemical purity.
1. Technical Parameters of Cupel
|
MgO, % |
≥89 |
|
Cao, % |
2.10 |
|
SiO2, % |
2.3 |
|
Al2O3, % |
1.7 |
|
Fe2O3, % |
0.72 |
|
BaO, % |
0.2 |
|
Na2O, % |
0.2 |
|
Density, g/cm3 |
2.8 |
|
Cold Crushing Strength, MPa |
30 |
|
Alumina absorption rate, % |
70-75% of the weight of the ash dish |
|
Precious metal recovery rate, % |
99.5 |
|
Particle size distribution, mesh |
190-220 |
2. Product Description
Cupels are primarily made by pressing and sintering bone ash or magnesia-based raw materials. They possess a highly absorbent porous structure, along with good refractory properties and oxygen affinity. They absorb molten lead and lead oxide (PbO) at high temperatures, thereby enriching precious metals like gold and silver on their surface for analysis. Magnesia-based cupels offer more stable structure and higher mechanical strength, suitable for use at temperatures of 900°C to 1050°C. Under high-temperature oxidizing conditions, cupels can withstand prolonged operation without softening or collapsing.
Cupels can rapidly absorb large amounts of PbO, leaving the precious metals on the surface. With their uniform pore structure, high chemical purity, and excellent oxygen affinity, they are commonly used for the analysis and detection of precious metals such as gold, silver, and platinum, composition analysis of alloy materials, and high-temperature oxidation absorption tests in research institutions.
3. Main Performance Characteristics of Cupels
1) High Absorption Capacity: Capable of rapidly absorbing large amounts of PbO, leaving precious metals on the surface.
2) Good Refractory Properties: Structure remains stable at high temperatures.
3) Excellent Oxygen Affinity: Promotes the oxidation reaction of lead, improving separation efficiency.
4) Uniform Pore Structure: Ensures consistent absorption rate and prevents cracking due to excessively rapid absorption.
5) High Chemical Purity: Minimizes interference in precious metal analysis.
4. Main Applications
Cupels are commonly used for:
Content detection of precious metals such as gold, silver, and platinum.
Laboratories in the mineral products and metallurgical industries.
Composition analysis of alloy materials.
5. Precautions
1) Cupels should be dried or preheated at low temperature before use to avoid cracking due to moisture.
2) After loading lead-containing beads, the temperature should be gradually increased to the cupellation temperature according to the process curve.
3) A "white core" or "halo" appearing in the cupel after lead absorption is a normal phenomenon.
4) After absorption is complete, the gold and silver beads will remain on the surface of the cupel.
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