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 is the main product of LKAB. Pellets come in different types depending on the requirement of the customer. Before transportation to customers pellets is 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, see figure, 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. Failure of the brick lining is common - leading to very costly production stops.
To study the rotary-kiln in detail, numerical modelling and simulations are used. The idea is to work both on a global and a local level to. The main purpose of this work is to create numerical models to predict the influence of mechanical and thermo-mechanical effects (direct or indirect) on the lining. With the increased knowledge can e.g. management of the kiln be improved (e.g. heating procedure), different material choice or geometry be suggested. In the end, life of the brick lining could be increased.