The Effect of Firing Atmosphere on Pelletizing

Abstract

The influence of firing atmosphere on phisical properties of fired iron are pellets was investigated in a bench scale.
Pellets were made from one of six kinds of natural iron ores or three kinds of artificial iron ores.
Pure nitrogen, pure oxygen, mixture of nitrogen and oxygen in various rate, and others, were used as the firing atmosphere.
The results obtained are as follows;
(1) The crushing strength of limonite pellet became weak as the oxygen content in firing atmosphere was higher. The crushing strength of magnetite pellet was low when fired in the atmosphere containing 10% oxygen, and that of hematite pellet was almost independent of firing atmosphere.
(2) Physical properties of pellets fired in atmosphere of steam, carbon dioxide or nitrogen were mostly the same.
(3) Higher oxygen content in the firing atmosphere tends to give higher porosity for all the pellets tested.
(4) When CaCO₃ was added to the ore, the bonding mechanism was seemed to be complicated.
(5) The results show that the crushing strength and chemical composition of pellets are influenced by the firing atmosphere. This indicates thavan adequate knowledge of the effect of firing atmosphere for each irono re is necessary in order to improve the pellet quality.