X-ray phase analysis of open hearths

Conclusions

After current and capital repairs, the basic phase in the hearths is periclase. Apart from periclase there is also magnesioferrite, monticellite and forsterite.

Hearths surfaced with nine layers of a mixture of magnesite and scale and three layers of pure magnesite with slagging of the scale after capital repairs hardly differ at all in phase composition. When surfacing with nine layers, there is a considerably greater amount of forsterite.

The basic laws governing the variation in phase composition according to window and layer are manifested both in the hearth surfaced with nine layers of magnesite and scale, as well as in the ones surfaced in three layers with pure magnesite and slagged with scale.

During current repairs, the phase composition of the hearth is basically no different from the phase composition which is obtained during capital repairs. Since there is no substantial difference in the phase composition of the hearth surfaced by the high-speed or conventional methods, the strength of the hearth during high-speed surfacing is not inferior.

The composition of the hearths after service is characterized by magnesioferrite, periclase, a solid solution of magnesioferrite in periclase, monticellite, forsterite, merwinite, complex spinel MgO·Al₂O₃, dicalcium silicate and braunmillerite.

Typical of the phase distribution and lattice parameter of the periclase according to the level of the hearth is a parallel variation in the content of the periclase and monticellite as well as an inverse relationship between the amount of periclase and its lattice parameter.