A number of brightly coloured zircon particles displayed on a black background.

The new process for treating zircon reduces radiation levels and removes impurities.

Pure zircon process provides a solution for mineral sands processors

CSIRO has developed an effective process for unlocking the value of previously unattractive zircon deposits.

  • 19 February 2007 | Updated 11 January 2013

Background

Zircon is a valuable component of most mineral sands deposits. Australia is the major producer of zircon and produces about 45 per cent of total world supplies.

The price of zircon has been increasing as the supply of zircon with low-level radioactivity diminishes. The presence of uranium and thorium make zircon radioactive. This is not considered a problem until the levels are greater than 500 parts per million (ppm).

Victoria, Australia has significant zircon deposits of fine particle size. High radiation levels, however, make these deposits unattractive for commercial production.

CSIRO’s pure zircon process  

CSIRO has developed a process which reduces the radiation level of zircons by using a heat process followed by leaching to extract the radio nuclides.

The stages involved in the Pure Zircon Process are:

  • grinding the sample to achieve a particle size of 15-20 um
  • calcining the sample with a borate mineral at 1 200 °C for four hours
  • leaching the calcine with a dilute acid solution.

The new zircon treatment process lowers radiation levels, removes impurities and protects crystal integrity.

Benefits of the process

Lab-scale testing has proved the process. The relatively low-cost process: 

  • lowers the radioactivity level
  • maintains particle size
  • removes impurities including iron, aluminium, titanium, thorium and uranium
  • avoids introducing new impurities
  • protects crystal integrity.

Major uses of zircon

Zircon is used in:

  • foundries as sand moulds
  • refractories as lining for steel ladles and furnaces
  • ceramics as glazes, pigments and enamels
  • zirconia production
  • zirconium chemicals, metals and alloys.

More than half of the commercially produced zircon is consumed in the ceramic industry as an opacifier in glazes.

Potential application for zirconia production 

The Pure Zircon Process also has the potential to be applied to the commercial synthesis of zirconia.

Zirconia is a naturally ocurring mineral that can also be synthesised from zircon. It is used in combination with other minerals, such as cobalt and iron, to produce colour pigment for use in refractories.

Zirconia made from zircon by fuming contains elevated levels of radiation compared to the feedstock zircon, but if zirconia (or other zirconium chemicals) is produced from zircons that have already been treated using CSIRO’s Pure Zircon Process, the end product could have an acceptable radiation level for commercial use.

The process could also be applied to natural zirconia to lower its natural levels of radiation.

Find out more about CSIRO's work in Mineral processing.