Design and Fabrication of a Combined Charcoal Grinding and Moulding Machine

Abstract

The design and fabrication of an affordable biomass processing equipment remain essential for improving small-scale charcoal briquette production in developing regions. This study presents the development and performance evaluation of a combined charcoal grinding, mixing, and moulding machine that integrates size reduction, binder mixing, and compaction into a single system to improve process efficiency and reduce losses. The machine was constructed primarily from mild steel and powered by a 2.2 kW electric motor. Design analyses were carried out to determine the power requirement, shaft dimensions, and mixing chamber capacity. Performance testing was carried out using 10 kg batches of dried charcoal and grinding times used ranged from 11.8 to 12.4 min. The results showed that the total power required by the machine was 1.185 kW, the calculated shaft diameter was 15 mm, while the mixing chamber capacity was 12.1 kg of charcoal mixture. Throughputs between 46.9 and 48.8 kg/h was obtained along with an average of 48.0 kg/h, corresponding to a capacity efficiency of 96.1% relative to the 50 kg/h design target. The moulding unit produced briquettes with uniform dimensions, having an average diameter of 40 mm, height of 35 mm, and mass of 85 g, indicating consistent compaction. Durability evaluation produced an average shatter index of 6.93%, indicating good resistance to breakage during handling and transportation, while combustion testing gave an average ignition rate of 8.04 mm/min, indicating stable flame propagation suitable for domestic cooking applications. The close agreement between experimental and design values demonstrates that the integrated machine operates efficiently and reliably. The developed system offers a simple and effective solution for small-scale conversion of charcoal fines and agricultural residues into densified solid fuel.