Studies of slag infiltration on fire proof insulation in grate kiln owen

LKAB Contact Lars-Olof Nordin, Bo Lindblom    LTU Contact John Ion
Posted in Smart pellets

Iron ore pellets are a prepared burden material for ironmaking. Rotary kilns are commonly used to sinter such pellets. The mullite based lining material in these kilns, are bricks that needs to be replaced regularly due to degradation caused by a slag. The aim of this project is to reach higher knowledge about the different wear mechanisms that degrades this refractory lining during production, in order to avoid them for an improved lifetime of the lining.

Many steps are included in the extraction from iron ore to metallic iron, where the processes vary between different producers. Iron ore pellets are a prepared burden material for ironmaking, in a blast furnace or by direct reduction. Rotary kilns are commonly used to sinter such pellets, especially in the case when the predominant ore is magnetite. These kilns are usually lined with mullite containing bricks, which needs to be replaced regularly due to depletion caused by a slag and thermomechanical strains. The slag present in the kiln consists of ~95 % hematite, alkali-, alkaline earth- and other oxides; mainly from pellets that have disintegrated and from fly-ash from coal burned to heat the kiln, and it adheres in chunks on the lining.

 

This study focuses on the interaction between refractories and slags that occurs in the kilns during the sintering process in the iron ore pellet production, and the aim is to reach higher knowledge about the different mechanisms that degrades the refractory lining during production, in order to avoid them for an improved lifetime of the lining. The study been carried out both on lab scale basis, and on samples collected in industrial furnaces under production stops, as well as in-situ during drift.