| Title | THE ROLES OF MATRIX ALUMINAS ON THE PROPERTIES OF HIGH PERFORMAING CASTABLES |
| Thematic area | Monolithics for Various Applications |
| Presenter | Dr. ARUP KUMAR SAMANTA |
| Authors | Dr. ARUP KUMAR SAMANTA, TRL KROSAKI REFRACTORIES LIMITED, JHARSUGUDA - INDIA Mrs. SMITA SATPATHY, TRL KROSAKI REFRACTORIES LIMITED, JHARSUGUDA - INDIA Mr. E ARIMITSU, TRL KROSAKI REFRACTORIES LIMITED, JHARSUGUDA - INDIA Mr. K TSUYUGUCHI, TRL KROSAKI REFRACTORIES LIMITED, JHARSUGUDA - INDIA Mr. P B PANDA, TRL KROSAKI REFRACTORIES LIMITED, JHARSUGUDA - INDIA Mr. SHANKHA CHATTERJEE, ALMATIS ALUMINA PVT. LIMITED, KOLKATA - INDIA |
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Abstract
Decades back only ground calcined alumina was the choice of high-alumina matrix products that were used in castable formulations. At that time the flow properties of castables were enhanced by the use of silica fume. However, silica fume, later was avoided in high performing castables because of inferior high temperature thermo-mechanical properties above 1400ºC. Then the development of new generation castables came by using fully ground reactive aluminas for high temperature applications such as steel ladle well blocks, seating blocks, RH snorkel or porous plugs etc. It is well established before many a times that high alumina castables (such as medium/ low/ ultralow cement castables) containing higher Na2O, especially in matrix ingredients, show inferior high temperature properties in Al2O3 – Na2O - CaO system. So, the choice of those reactive aluminas or matrix aluminas in new generation high performing castables are certainly not limited to chemical purity but mainly to the physical properties such as specific surface area (BET) and particle size distribution (PSD). A wide range of bi-modal and multi-modal reactive aluminas of different specific surface areas were selected to observe their effects on the rheology, workability, volume & structural stability and cold and hot strengths of high alumina low cement castable. The optimum choice of such matrix formulation provides easy castable mixing and placement conditions as well as excellent mechanical and physical properties to support the demands of high temperature applications. In this present work four different kind of matrix aluminas were selected on the basis of d50 and surface areas. Rheological study, water demand, flowability along with all common properties like AP, BD, CCS, volume stability etc. were studied. Different mineralogical phases were identified by XRD and microstructure analysis was carried out by SEM for some specific samples to understand the properties after firing at different temperatures. |
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