Compaction characteristics of binary coal mixtures during binder less briquetting process

Dried coal typically had certain Particle Size Distribution (PSD) resulting from the size reduction process. Effect of PSD to the compaction phenomenon was investigated on the binary mixtures of Indonesian middle-rank coal with different mass fraction of small and large particles (%L). Compacted density of each coal mixtures was measured during uniaxial briquetting process and their compaction characteristics were analyzed with Cooper-Eaton model. It was found that Cooper-Eaton model could fit excellently (R2 > 0.99) with the experimental data. Analysis of compaction characteristics of the model (Ai and ki) and briquette density revealed that mixtures 0%L (PSD Small) and 100%L (PSD Large) were easier to compact compared to binary mixtures. Binary mixture 70%L was hardest to compact, evaluating from its lowest increase of density, from 893 to 1492 kg/m3. Relatively high coordination number at pressure 2 kPa on mixture 70%L (7.81 ± 0.20) might be the reason for high deformation difficulty. It was concluded that binary mixture of coal with the highest bulk density would results in briquette with the lowest density.