Evaluation of refractory castables and coatings used in pre-heat zone of grate-kiln for iron ore pellet production

AbstractIron ore pellets are a prepared burden material for ironmaking that are commonly sintered in a grate kiln furnace system. Deposited material can adhere in chunks to localised regions of the lining of such furnaces, causing lining depletion. Such deposits consist mainly of iron oxides, but alkali, alkaline earth and other oxides formed from disintegrated pellets and fly ash may also be present. In order to investigate methods of preventing such formations, tests have been performed using several different castables and coatings. Samples of liner castables with and without coatings, installed in an industrial furnace, were collected after 6 and 24 months in production use, and characterised using scanning electron microscopy to identify the materials, characterise morphological changes at the deposit-coating-lining interface, and to determine the active chemical reactions. An Al2O3 based coating applied to one of the fields was found to be in good condition after 6 months in use, but no traces of th...