NEW COAL BLENDING TECHNIQUE FOR CONTROLLING COAL COMPATIBILITY BASED ON SURFACE TENSION OF SEMI-COKE

摘要

For more precise anticipation of coke strength, we focused on adhesion phenomena between coal particles, which is influenced by surface tension difference of softening coals. To evaluate surface tension of coals, we devised a method that measures surface tension of semi-cokes obtained by heat treatment of coals at 500°C as a substitute for softening coals.First, we investigated the effect of surface tension difference between two coals on interfacial structure and coke strength. As a result, wettability or adhesion between two coals was bad when surface tension difference was large, and coke strength was deteriorated. Next, the finding was extended to multi-coal blend by introducing standard deviation of surface tensions of coals as a blending index. The strength of coke was deteriorated with an increase in standard deviation of surface tension.The blending technique based on surface tension enables us to evaluate more precisely the coal compatibility and to select the good combination of coals, which can contribute to the production of high strength coke and effective usage of coking coal resources.