ISO 4698:1994

Iron ore pellets — Determination of relative free-swelling index

The principle of the method specified is determination of swelling of fired iron ore pellets of a specified size range under isothermal reduction, determination of the volume of pellets before and after reduction at a temperature of 900 °C, using a reducing gas consisting of carbon monoxide and nitrogen, calculation of the free-swelling index, expressed as a percentage, using the difference between the two volumes.