Dilatation/contraction measurement of briquette during carbonization

Measurements of dilatation and contraction of a briquette were carried out in order to develop the new cokemaking process which can use non- or slightly caking coals. The briquette was composed of coals (caking coal and non- or slightly caking coals) and additives (soft pitch) as a binder. After these components were mixed at various ratios and stirred at 373 K, they were molded to the rod-shaped briquette (Φ 9 mm × 30 mm, apparent density : 1200 kg/m³) by a uniaxial compression briquetting machine. The briquette was carbonized in an infrared image furnace at various heating rates and dilatation and contraction of the briquette were measured. The result showed that the true dilatation of the briquette was irrelevant to the heating rate and the binder content and was about 20%. The contraction coefficient of the briquette had two peaks as well as caking coal. The first peak of them was caused by the release of the volatile matter and the second peak was caused by an increase in the carbon orientation with hydrogen release. Because the binder reacted as a volatile matter in the briquette, the first peak of the contraction coefficient depended on the binder content of the briquette. The additive property was verified by the measured contraction coefficient of the briquette with varying the binder content.