CHANGING BULK DENSITY IN CARBONISATION BLENDS

摘要

Bulk density in coal blends is often associated with moisture content. However, moisture is not the only factor affecting charge density. Investigations of single coal and blend crushing and screening, with crushing of oversize only, have demonstrated that the crushing regime affects coal particle size distribution. Oven charge density also benefits from oil addition to coal blends, with some oil types being more effective than others. Optimising particle packing improves charge density in coke ovens and is beneficial because it decreases shrinkage and increases coke strength. Potential packing densities of blends have been assessed by calculating the skewness and kurtosis of the particle size distributions. Research has shown that optimum crushing for top charged blends requires a size distribution with 71-73% <2 mm and 38-40% <0.5 mm, with such blends producing similar coke quality to oiled blends that have undergone standard industrial crushing. The greatest benefits are obtained from optimising both crushing and oiling, which have the potential to improve coke yield and coke quality. Increasing charge density can be used either to increase coke oven yield or to maintain coke quality when increased proportions of poorer coals are included in cheaper blend formulations. Size distribution, moisture, oiling and blend composition all affect coal blend density.