The Effects of Some Processing Parameters on Physical and Densification Characteristics of Corncob Briquettes

Abstract

Corncobs are generated from maize (Zea mays). The residue is usually dumped and flared on the farms, where it constitutes fire, environmental and health hazards. Corncobs are potential feedstock for energy generation. This work investigated densification characteristics of corncobs. Corncobs were collected from farm dump at a moisture content of 10.96 dry bases, reduced and sieved into three particle sizes S1, S2; and S3. Starch mutillage of 20, 25, and 30 % by weight of the residue was added as binder. The briquettes were produced using briquetting machine at pressures of 2.1, 4.2 and 6.6 MPa. The ASAE standard methods were used to determine the moisture contents and densities of the milled residues and briquettes. The compaction, density and relaxation ratios as well as percentage expansion of the briquettes were determined using ASAE standard methods. The mean moisture content of the corncob residue was 9.64 %, while that of relaxed briquettes was 7.46%. The value of bulk densities of the residue materials was 50.32 kg/m3. The initial, maximum and relaxed densities ranged from 151-235 kg/m3; 533-981kg/m3 and 307-417kg/m3 respectively. The compaction ratio ranged from 2.27 to 6.50. The maximum percentage volume reduction was 626%, while the axial and lateral relaxations were in the range of 0.62-9.85% and 0.64-3.63 respectively. The briquettes were stable up to six months. For the three processing parameters examined, binder ratio B1, particle size S3 and pressure P3 exhibited most positive attributes.