Fundamental Design of Steelmaking Refractories

1 Heat and Mass Transfer

1.1 Introduction

Commercial grade raw material calcination in a rotary kiln is common to make an economical product. The end product feeding regions are divided into several segments to achieve calcined outcomes like dolomite, spinel, mag-chrome, bauxite, etc. Ineffective heat distribution and mass-transfer during rotation result in an immature and uncalcined product that eventually reduces the properties of the refractories. While considering the nonuniform heat distribution in a kiln, there is always a chance to form a premature uncalcined product with a moisture-absorbing tendency; dolomite is an excellent example. Similarly, incomplete spinel conversion from a mixture of MgO and Al₂O₃ in synthetic raw materials eventually enhances the volume expansion in spinel-based refractory, as well as the improper calcination of natural bauxite facilitates forming a porous mass that absorbs more water during the castable casting results in premature failure.

Organic binder essentially develops a polymeric network and binding refractory grains, but a gradual formation of ceramic bonding requires a predefined temperature in the firing. Tunnel or batch kilns are used in the refractory industry to achieve prerequisite temperatures for high-performance working lining, backup lining, and continuous casting refractories. A highly efficient kiln may provide uniform heat distribution all along the sides from top to bottom, sidewall burner zone to opposite side wall ...