Reactions between Mullite based Refractories and Slag at Elevated Temperatures
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
In the iron ore pelletizing, the sintering of the pellets takes place in a rotary kiln which is lined with refractory bricks. During the process, deposited materials such as iron ore slag, additives, binders and fly ash stick on the surface of the lining, and with time, by infiltration and diffusion, a corroded layer is formed. Some of the reactions occurred in that layer are promoted by the presence of alkalis. Refractory/deposited materials reactions and infiltration of deposited materials were studied at laboratory scale. In this study, techniques such as differential scanning calorimetry (DSC), x-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used. Reaction temperatures, phase transformations and infiltration depth of deposited materials were determinated. Additions of alkalis into the materials involved were used to enhance the reactions between them. Using powder mixtures the results of DSC show that in addition of K2CO3 the reaction temperature range is 850-950°C showing formation of new phases around 850°C with kalsilite and around 950°C with leucite; in addition of the mixture Na2CO3 and K2CO3, there is a broader temperature interval of 600-925°C with formation of kalsilite at lower temperatures and nepheline at higher temperatures. In the characterization of the infiltration of deposited materials into the brick it was observed that nepheline was formed mainly in the corroded brick layer but K feldespathoids (leucite, kalsilite, kaliophilite) were formed beneath the corroded brick layer.
Place, publisher, year, edition, pages
2011. , 57 p.
Technology, refractories, mullite, slag, alkalis
IdentifiersURN: urn:nbn:se:ltu:diva-48107Local ID: 5962bbe0-727d-4e0e-82e5-fe30a056eda8OAI: oai:DiVA.org:ltu-48107DiVA: diva2:1021445
Subject / course
Student thesis, at least 30 credits
Materials Engineering, master's level
Validerat; 20110705 (anonymous)2016-10-042016-10-042016-10-17Bibliographically approved