Abstract:
In a low pressure compaction, the use of binders is of utmost importance. However, when briquettes are compacted at too high compaction pressures, the binders are often squeezed out of the briquettes. This in turns affects the mass, shape, density and quality of the briquettes. The type of material also influences the compaction, density, calorific value and the quality of briquettes. Therefore, there is a need to study the effect of compaction pressure on different agricultural wastes mixed together at different mixing ratios. Three agricultural wastes: saw dust, rice husk and palm kernel shell were selected for this study. Cassava starch was used as binder. Three samples of homogeneous briquettes were produced from each of the selected agricultural wastes, and compacted respectively, at three different compaction pressures (294.2N/cm2, 686.5N/cm2 and 980.7N/cm2), which were selected to fall within the range of low pressure compaction. It was revealed that the respective compaction pressures at which the agricultural wastes offered good quality homogeneous briquettes were a function of the material nature of the agricultural wastes; while those of heterogeneous briquettes depended on the type of materials and on the mixing ratio. An empirical model for predicting the required compaction pressures of heterogeneous briquettes, based on the mixing ratio of the constituent materials, was developed. A multiple regression analysis of the parameters of the model revealed that mixing ratio was a significant factor in predicting the required compaction pressures of heterogeneous briquettes. Heterogeneous briquettes of sawdust/palm kernel shell, sawdust/rice husk, palm kernel shell/rice husk and sawdust/rice husk/palm kernel shell were produced and compacted at the predicted compaction pressures and also at a particular fixed compaction pressure. The result of the paired t-Test revealed that the heterogeneous briquettes offered good quality briquettes when compacted at the required compaction pressures predicted from the developed model than when compacted at a fixed compaction pressure.
