New Additive Package for Microsilica Gel-bonded MgO Castables

Bjørn Myhre, Hong Peng

Elkem Silicon Materials, 4675 Kristiansand/Norway

Revision

Volume 5, Issue 4, Pages 83 - 88

Abstract

The use of high-performance basic refractory castables is essential in state-of-the-art steel-making and clean steel production. However, self-flowing magnesia castables have not been widely used until now. A major challenge is that during the hydration process brucite is formed which causes volume expansion and subsequent cracking. The objective of this paper is to present a new Elkem specialty product (SioxX-Mag), which has been developed for gel-bonded MgO castables based on MgO-SiO2-H2O bond. It contributes to better workability and setting behaviour while hot-properties remain unchanged. When SioxX-Mag replaces other dispersants in MgO castables, self-flow is more than doubled in our test system. Using SioxXMag, cracking caused by brucite formation is suppressed and crackfree dried samples are made. It is also observed that the explosion resistance during firing has been significantly improved making fast firing feasible.

Keywords

MgO castables, additives, self-flowing, microsilica, gel-bond

References

[1] Watanabe, Y.; Ono, T.; Yukinawa, T.; Sakamoto, S.: Development and Application of Monolithic Refractory Containing Magnesia Clinker. Proc. 2nd Int. Conf. Refr. Tokyo, Japan. 494–506 (1987) [2] Sandberg, B.; Mosberg, T.: Use of microsilica in binder systems for ultra-low cement castables and basic, "cement-free" castables. Advances in Refractories Technology, Vol. 4 (1989) 245–258 [3] Myhre, B.: Cement-free castables in the system MgO-SiO2: The effect of bond phase modifiers on strength. Proc. 93rd Annual Meeting. Amer. Ceram. Soc. (1991) [4] Odegard, C.; Feldborg, H.; Myhre, B.: Magnesiasilica- hydrate bonded MgO castables. Proc. UNITECR' 01, Mexico, 4–8 Nov. 2001 [5] Odegard, C.; et al.: MgO-SiO2-H2O bonded MgO castables. Part 1: Effect on flow, set and hot properties when substituting microsilica with alumina in pumpable MgO castables. 4th Int. Symposium on Refractories, Dalian, China, March 2003, 148–156 [6] Ghanbari Ahari, K.; Sharp, J.H.; Lee, W.E.: Hydration of refractory oxides in castable bond systems II: alumina–silica and magnesia–silica mixtures. J. Eur. Cer. Soc. 23 (2003) [16] 3071–3077 [7] Salomão, R.; Bittencourt, L.R.M.; Pandolfelli, V.C.: A novel approach for magnesia hydration assessment in refractory castables. Ceram. Inter. 33 (2007) [5] 803–810 [8] Souza, T.M.; Braulio, M.A.L.; Luz, A.P.; Bonadia, P.; Pandolfelli, V.C.: Systemic analysis of MgO hydration effects on alumina–magnesia refractory castables. Ceram. Inter. 38 (2012) [5] 3969–3976 [9] Sako, E.Y.; Braulio, M.A.L.; Pandolfelli, V.C.: Microstructural evolution of magnesia-based castables containing microsilica. Ceram. Inter. 38 (2012) [7] 6027–6033 [10] Peng, H.; Myhre, B.; Luo, M.: New additive pakkages for self-flowing high-alumina and MgO based refractory castables. Proc. ALAFAR 2012, Cancun, Mexico, 5–8 Nov. 2012 [11] Myhre, B.; Peng, H.; Luo, M.: Cement free MgO castables Part I, flow, setting and slaking. Proc. UNITCER’ 13, Canada, Sept. 2013 [12] EMMA (Elkem Materials – Mixture Analyzer) software, free download at: http://www.materials.elkem.com/

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