CARBONIZATION OF WET AND PREHEATED COAL - EFFECT ON COKE QUALITY AND ITS RELATION WITH TEXTURAL PROPERTIES

The effects of coal preheating on the quality, textural and surface pr operties of the coke were assessed in comparison with the conventional wet charging system using a Spanish hvb coal. Coal was flash dried an d preheated in a 2 t h(-1) Precarbon pilot plant. Carbonization tests on the wet and preheated coals were carried out in a semi-industrial s cale oven of 6 tonne capacity. Because textural and surface properties have an important effect on coke quality, an exhaustive characterizat ion of the resultant cokes was made. Cokes were characterized by using microscopic image analysis, mercury porosimetry, density measurements , optical and scanning electron microscopy (SEM) of surfaces. Mechanic al strength and reactivity towards CO2 were also studied. Surface area s were determined by N-2 adsorption at 77 K using the Brunauer-Emmett- Teller (BET) equation and CO2 adsorption at 273 K using the Dubinin-Ra dushkevich (DR) equation. Coal preheating improved coke mechanical str ength considerably but at the same time increased the reactivity of th e cokes. The higher reactivity could be due to the increase in micropo rosity and CO2 surface area.