Carbonate Freezing

Description

• Removes impurites from cyanide baths
• Precipitates carbonate salts by reducing the bath temperature. For sodium salts, the temperature must drop to around 26oF.
• Source of carbonates in plating solutions
  • breakdown of cyanide (particularly at high temperatures)
  • excessive anode current densities
  • adsorption of carbon dioxide into the solution from the air

Advantages / Limitations

• Carbonates effect on plating
• low plating densities
• decrease plating efficiency
• deposits will be rough
• Can NOT be preformed in-line

Resource

• Cushnie, George C. Jr. Pollution Prevention and Control Technology for Plating Operations. National Center for Manufacturing Sciences, Ann Arbor, MI, 1994.