Handling and Thermal Characteristics of Briquettes made from Fonio Husk
Bisu, D. Y., Y. H. Kwala and S. I. Ige
Department of Mechanical Engineering Technology
Federal Polytechnic, Bauchi, Nigeria
Email: danladibisu@fptb.edu.ng
Corresponding Author: Bisu, D. Y.
ABSTRACT
This study attempted to convert fonio husk, an agricultural waste into a fuel for cooking in households, making its disposal sustainable. Samples of fonio husk and wild acacia nilotica fruits were acquired from dehusking mills in Tafawa Balewa and Muda Lawan market respectively. The fonio husk and gum extracted from the dry acacia fruit were characterized using standard procedures such as ASTM E870 – 82(2013) for proximate analysis, BS 1377 – 2:9.2, 9.3, 9.4 for particle size determination and ASTM D2015-00 for calorific values. Briquettes were produced from mixtures of fonio husk and various concentrations of wild Acacia nilotica fruit gum (15 %, 25 % and 35 %) at 3 different compaction pressures (2 MPa, 4 MPa and 6 MPa) using a cylindrical mould (with piston) of 41 mm depth and 37.5 mm inner diameter at a moisture content of 15 %, using a local fabricated machine fitted with a pressure gauge. The briquettes were sun dried for 14 days and subjected to durability test using ASTM D440 – 86 standard procedures for drop shatter for coal, and water absorption test. The moisture content and bulk density of unprocessed fonio husk were determined as 5.81 % and 195.32 kg/m3 respectively, while those of the relaxed briquettes were (5.09 – 5.65 %) and 223.90 – 425.08 kg/m3 respectively, with volume reduction of 144.63 – 217.63 %. The relaxed densities decreased with increase in binder concentration and compaction pressure. The maximum densities of the briquettes increased with increase in binder concentration and compaction pressure ranging from 565.75 – 823.05 kg/m3. The impact resistance index of the briquettes ranged from 143 – 333, as against the minimum acceptable value of 1000. The briquettes absorbed 83.33 – 223.08 % water within 5 seconds, beyond which it dispersed. The ignition time and burning rate of the briquettes ranged from 25 – 60 seconds and 10.20 – 22.80g/min respectively. This study concludes that fonio husk is a good briquette material with good densification characteristics and ignition time, but has poor handling characteristics and burning rate. Further study is recommended on other binder materials and processing conditions to improve handling characteristics and burning rate.
Keywords: Acacia nilotica, Briquettes, Fonio husk, Waste disposal
