Abstract
The forming of rings was a bottleneck of magnesian flux pellets in a rotary kiln, which limited production efficiency. This paper analyses how the coal ash content affects bonding strength and melting behaviour by using magnesian flux pellet powder and coal ash. Also, the mineral phase, microstructure and liquid phase composition of pellet powders that have different coal ash content are analysed in a study. The results show that when the ash content is less than 0.5%, the ash has little influence on the ring-forming material, but when the ash content is more than 0.5%, the ash significantly strengthens the bonding process of the pellet powder. That is, the ash content should not exceed 0.5%. In addition, the consolidation mechanism of the magnesium fluxes spherical ring is mainly solid-phase consolidation. Anorthite and mullite are formed in magnesian flux pellet powders when coal ash is added, resulting in a change in mineral composition. It is worth noting that anorthite exhibits high reactivity with other mineral phases, leading to eutectic reactions. When more coal ash is added, the chemical composition of the mineral phase changes in the briquettes, and the liquid phase exhibits gradual increments in SiO2, MgO and Al2O3 content. According to the phase diagram of Fe2O3-CaO-SiO2-3wt%MgO-6wt%Al2O3, the position of the silicate mineral phase shifts towards the high SiO2 region, which has the lower temperature. The liquid phase ratio of the briquette increases in this region, ultimately resulting in the formation of rings in the rotary kiln.
Published Version
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