Influence of draff as coking additive on the quality of lump coke using non-baking coals

For the production of high-strength lump coke from non-baking coals the processing, agglomeration and gentle coking of the agglomerates are essential steps. In previous studies the influence of the processing regime and the briquetting and coking parameters were systematically analysed. The current investigations combined the intensive processing of German and Indonesian brown coals in a twin-screw extruder and a swing mill with the addition of 5 wt% draff as a coking additive. Briquetting the mixture of coal and draff leads to an increasing briquette compressive strength. This binding capability of the draff is probably caused by the denaturation of protein during the processing in the twin-screw extruder and the swing mill. The produced coke as well offers a high mechanical strength. During the coking process the protein and cellulose material could be partially converted to solid bridges between the particles causing a higher coke compressive strength.