Zircon Industry Association, 24 Old Bond Street, Mayfair, London W1S 4AP, UK
 

Foundry Sands & Coatings

Zircon is widely used in the foundry industry, mostly in the form of SAND and FLOUR (milled sand) for casting and refractory applications.
Zircon’s properties make it ideal as a moulding base material for sand casting and investment casting, in addition to use as mould coating in die casting and in refractory paints and washes to reduce the wettability of other foundry sands.

Why is zircon used for casting in foundries?

The following properties make zircon an excellent material for sand casting, investment casting, and die casting:

  • Low acidity: its pH varies between neutral to slightly acid
  • Clean and round grains allow the material to be easily bonded together
  • Consistent fineness and ability to form fine grains
  • High ability to bind with all organic and inorganic sand binders
  • Low thermal expansion coefficient and high spatial stability at increased temperatures
  • High melting point (2,100 – 2,300℃)
  • High thermal conductivity
  • Chemical stability at high temperatures
  • Low wettability by molten metal
  • Good recyclability
Foundry Sands and Coatings

What are the advantages of using zircon in foundry processes?

The advantages of using zircon sand and zircon flour in these foundry processes are:

  • Zircon’s low wettability, consistent grain fineness and ability to form fine grains allows the creation of high precision castings with good surface finish, prevents the mineral from sticking to the cast metal and avoids metal penetration into the mould
  • Its high thermal conductivity allows higher cooling rates than other mould materials, which also results in a better surface finish
  • The higher dimensional accuracy and better surface finish achieved through the use of zircon minimises post-casting operations such as machining and cleaning of the cast part
  • Zircon’s low wettability by molten metal increases the recoverable sand and hence the recyclability of the material
  • Its chemical stability ensures uniform results when using recycled sand
Foundry Sands and Coatings

Applications

Zircon and its derivatives have a vast array of applications. The largest market for zircon is the ceramics industry. Approximately 54% of zircon that is produced is used in finely ground form in the ceramics industry. 14% goes is used by the foundry industry, and approximately 11 - 14% is used in refractory applications.

A growing portion of the zircon mined worldwide is used for the extraction of the metals zirconium and hafnium or their further processing to produce zirconium chemicals. There is a considerable number of further uses and it is clear from emerging research and development that zircon will continue to play an even greater role in the technological advances of the modern era.