Modelling the effect of compaction pressure on the densification of agricultural waste briquettes

An empirical model for predicting the required compaction pressure of heterogeneous briquettes was developed in this study. The study was based on low-pressure compaction, where the used of binders is paramount. Three agricultural wastes: sawdust, rice husk, and palm kernel shell were used in the study. The material type was a key factor of influence on the briquette samples produced. The optimum compaction pressures of the homogeneous briquettes were 686.5, 981, and 981 N/cm2, for sawdust, rice husk, and palm kernel shell, respectively. The predicted required compaction pressures of the heterogeneous briquettes, as predicted from the model, ranged from 715 N/cm2 to 950 N/cm2 for sawdust/palm kernel shell briquettes, 710 N/cm2 to 906 N/cm2 for sawdust/rice husk briquettes, and 936 N/cm2 to 975 N/cm2 for palm kernel shell/rice husk briquettes. The heterogeneous briquette samples compacted at the predicted required compaction pressures offered better quality briquettes in terms of density and calorific value than those compacted at a fixed compaction pressure of 1177 N/cm2. It was established that the developed model offered ease of compaction and effective utilization of materials and will be of great use in the design of variable pressure briquetting machines.