Production and Characterisation of Refractory Bricks for Cement Kiln Burning Zone Application

Abstract

Cement clinker is produced in a rotary kiln at a sintering temperature of 1450°C. Because of this temperature, the kiln body is lined with refractory bricks. The failure of these refractory bricks is a challenge to cement producers because of its high impact on production and cost. Today, Nigerian cement factories depend on expensive imported refractories to survive. This work addresses this challenge by producing quality and less expensive refractory from locally sourced materials. The refractory materials were selected based on the thermal load for kiln burning zone, the material composition, particle size distribution and purity and refractory properties following ASTM C133 standard. The bricks were produced using compression moulding techniques at 125 MPa. The results showed that the thermal load for the kiln burning zone is 14.43 GJ/m<sup>2</sup>hr. Dolomite and zirconia material characterized using XRF and SEM-EDX reveals that its composition, particle size distribution and purity meet the requirement for cement kiln burning zone refractory material. The absence of K<sub>2</sub>O, SO<sub>3</sub> and Na<sub>2</sub>O in the composition makes it suitable for cement kiln refractory application. The properties of the refractory analysed based on ASTM C133 standard showed that the optimum value for apparent porosity, bulk density, cold crushing strength, modulus of rupture, thermal conductivity, refractoriness and refractoriness under load were 16%, 3.42g/cm<sup>3</sup>, 95.89 MPa, 15.14 MPa, 1.56 W/mK, 1800°C and 1648°C respectively. Thermal shock resistance of 30 cycles at 1500°C and 1600°C. These properties were better off compared to the commercial refractories with the following properties apparent porosity, bulk density, cold crushing strength, modulus of rupture, thermal conductivity, refractoriness and refractoriness under load were 17%, 3.2g/cm<sup>3</sup>, 90.0 MPa, 14 MPa, 2.1 W/mK, 1800°C, 1350°C and 30 cycles at 1500°C. This means they have better performance and longer service life. The incorporation of zirconia in the bricks increases its wear resistance, stability at high temperature and better coating index. This concludes that the locally produced refractory addresses the concern of cement producers and presents a good opportunity for investors in the area of refractory bricks production in Nigeria.