An efficient MgAl 2O 4 spinel additive for improved slag erosion and penetration resistance of high-Al 2O 3 and MgO–C refractories

• Published in: Ceramics international Vol. 28; no. 3; pp. 245 - 253
• Main Authors: Ganesh, I., Bhattacharjee, S., Saha, B.P., Johnson, R., Rajeshwari, K., Sengupta, R., Ramana Rao, M.V., Mahajan, Y.R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2002
• Subjects: AlCl 3; EPMA; High Al 2O 3; MgAl 2O 4; MgO–C; Permanent linear change; Slag erosion; Slag penetration; Slag erosion; MgAl 2O 4; MgO–C; High Al 2O 3; Slag penetration; AlCl 3; Permanent linear change; EPMA
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/S0272-8842(01)00086-4

A stoichiometric dense MgAl 2O 4 spinel has been prepared according to a conventional double stage firing process using AlCl 3 as a sintering aid. A stoichiometric mixture of aluminum trihydroxide and caustic MgO was calcined at 1300 °C for 1 h in order to achieve a desired degree of spinelization. AlCl 3 in different amounts, i.e. 0.911, 1.822 and 2.733 wt.%, was coated on spinelized powder using wet-impregnation technique and sintered at different temperatures ranging from 1500 to 1600 °C for 1 h. Among the spinels sintered at 1550 °C for 1 h, spinel incorporated with 2.733 wt% AlCl 3 has exhibited superior properties in terms of bulk density, apparent porosity and water absorption. Further, this sintered stoichiometric spinel incorporated with 2.733 wt.% AlCl 3 was characterized by means of scanning electron microscopy (SEM), energy dispersive analysis with X-rays (EDAX) and electron probe microanalysis (EPMA). EDAX analysis revealed that AlCl 3 as a sintering aid helps in reducing the Na 2O present in the raw materials composition after sintering. EPMA studies revealed that spinel prepared in this study is well comparable with the commercial spinel (Alcoa, AR-78, USA). Finally, 20 wt.% of the stoichiometric spinel incorporated with 2.733 wt.% AlCl 3 prior to sintering was added to high-Al 2O 3 and MgO–C refractories to evaluate its effect on slag erosion and penetration resistance as well as on repeated permanent linear change (PLC) of these bricks. By the addition of stoichiometric MgAl 2O 4 spinel, the slag erosion and penetration resistance of high Al 2O 3 and MgO–C refractories was improved remarkably, and their PLCs exhibited more steady and stable positive values after spinel addition.