Adição de óleo para aumento da densidade de carga de carvões na coqueria

Abstract

The techniques that aim the bulk density of coals mix increase for use in the coking plants contribute to the reduction of coals blend cost, since they enable the use of poor caking coals and lower price. In addition, they can improve the coke strength, which contributes to the coke rate reduction in the blast furnace. The oil addition in the coal mix increases the bulk density by reducing the surface tension of water and allowing a better approximation between the coal particles, favoring the effective contact during the plastic phase and producing a more resistant coke. This work presents a study of the oil addition effect on the bulk density under different coal particle size and moisture. The oil addition influence on coke quality and coking time in the pilot coke oven was also evaluated. Bulk density tests were performed at three levels of oil addition (1.0 l/t, 1.5 l/t and 2.0 l/t), moisture (8%, 10% and 12%) and particle size (82%, 85% and 88% < 2.83mm). Subsequently, on pilot-scale, coke was produced and submitted to reactivity and mechanical resistance tests. The coking time was measured through a thermocouple installed in the coal center during the entire coking process. The results showed that the gradual oil addition promoted an increase on bulk density while rising coal moisture and reducing particle size caused its decrease. The highest bulk density value was obtained with moisture 8%, particle size 82% <2.83mm and oil addition of 2.0 l/t. The coke strength (DI and CSR) was improved with the bulk density increase, showing the feasibility of this technique. However, with increasing bulk density, longer coking times were observed.