Figure 1. Illustration of a grate-kiln system

Modelling of failure in Rotary-kiln systems

Published: 16 October 2012

One challenge met in many industrial processes is degradation of materials. LKAB as one of the world’s leading producers of the upgraded iron-ore products experiences varied degradation conditions during the processing of their products. Iron ore pellets are the main product of LKAB. Pellets come in different types depending on the requirement of the customer. Before transportation to customers the pellets are sintered in a rotary-kiln system to have full strength. The sintering process of pellets is central and highly important for the quality of LKAB’s products. Grate-kiln systems are used in order to oxidize and sinter pellets at temperatures up to 1400 °C. Unexpected failures of such systems are highly costly and causes production discontinue.

The work is focused on the rotary-kilns at LKAB and theirs functionalities and robustness. Rotary-kilns are large cylindrical constructions, measuring up to 7.5×40 m. The cylinder is made of steel and because of the high temperatures it has an insulating lining consisting of bricks. The bricks are exposed to very tough conditions: high temperatures, temperature variations, chemical degradation, wear, load oscillation (rotation of the kiln in combination with the weight of the brick layer itself and the load of pellets) and more. Commonly high-alumina brick are used for this application.

To study the process in detail, numerical modelling and simulations will be used. The idea is to work both on a global and a local level to study the behaviour of the furnace during operation. The main purpose of this work is to create numerical models to predict the influence of mechanical and thermo-mechanical effects on the entire furnace system for predicting errors and improve service life.

The project is funded by LKAB.

Project participants:Dmitrij Ramanenka, Pär Jonsén, Kjell Eriksson, Gustaf Gustafsson, Solid Mechanics LTU