Gas Evolution during Mechanical Milling of Hematite-Graphite Mixture

• Published in: ISIJ International 2004/12/15, Vol.44(12), pp.1970-1974
• Main Authors: Kashiwaya, Yoshiaki, Suzuki, Hiroshi, Ishii, Kuniyoshi
• Format: Article
• Language: English
• Subjects: ball milling; carbothermic reduction; composite pellet; gas evolution; mechanical milling; reduction
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.44.1970

In previous studies, the reactivity of hematite-graphite mixture obtained by the mechanical milling was investigated. The rate of reaction has remarkably increased and the starting temperature of reaction decreased with the milling time. Understanding the phenomena and its mechanism occurring in the milling would contribute to develop the new feeding material for ironmaking process. In this study, milling of hematite and graphite mixture was carried out with the same procedure. Gas analysis by QMS was performed to clarify the evolved gas during milling qualitatively and quantitatively. Gas evolution from graphite was mainly CO gas. CO2 gas also evolved in the early stage of milling. These gases would be related to the adsorbed gases before milling. When the sample exposed to air in the course of milling, much gas adsorbed on the surface of milled graphite, which increased with the increasing milling time. When the hematite and graphite mixture was milled under argon atmosphere, mainly CO gas evolved owing to the reduction reaction. From these results of gas analysis, the mechanisms for the gas evolution during the milling were proposed.