Investigation of Two-stage, Closed-circuit Crushing System (CPC Process) for Size Control of Coal Charge

Abstract

The crushing conditions of coal in a closed circuit with a vertical centrifugal screen and the effect of this closed-circuit crushing were studied, and the CPC process was newly proposed. To commercially apply the CPC process, the vertical centrifugal screen was improved for screening a large amount of wet coal, and test operations with an actual coke oven were conducted to examine the effectiveness of this process by the use of the improved screen. The following practical effects of the CPC process were confirmed.(1) As coke quality indices, DI15015and CSR can be respectively improved by 1 to 2 and 1 to 4.(2) The coke breeze yield can be reduced by 2%.(3) About 10% American hard-coking coal can be replaced by Australian soft-coking coal.(4) About 5-10% noncaking and poorly caking coals can be used in the coal blend.The mechanism for the improvement of coke strength by this process was also investigated. Lastly, it is also mentioned that the CPC process can be assessed as basic coal preparation technique, on the basis of the experimental data in comparison with other technologies and the combination of the CPC process with the other pretreating techniques (coking process with briquette-blend and process with the addition of caking substance).