Possibilities of Graphitization of Unburned Carbon from Coal Fly Ash

Abstract

The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.