Briquetting of Sawdust using Waste Paper as a Binder
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Date
2015-07
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Addis Ababa University
Abstract
This study explored the possibility of producing sawdust briquettes that could be used for energy
supply in small factories and for domestic cooking. A briquetting machine suitable for the
production of sawdust briquettes on a small scale was constructed. A portion of sawdust was
screened in to average diameter of: A (0.5mm), B (1.5mm), C (3mm), D (4.8mm), E (6.8mm)
using standard sieves of 1mm, 2mm, 4mm, 5.6mm and 8mm mesh size. The raw sawdust was
characterized for the following properties: moisture content (24.43%), density (91.34 kg/m3),
volatile matter (94.92%) and ash content (2.6%). Briquettes were produced by mixing sawdust
(both screened and raw) with waste paper in weight percentage ratios of 75:25, 70:30, 65:35,
60:40 and 55:45 respectively at three different die diameters. The computed density, porosity
index, shatter resistance, volatile matter, ash content, fixed carbon and calorific value for all
sawdust briquettes falls in the range of 218.24-322.62kg/m3, 33.97-312.4%, 98.88-99.95%,
70.24-90.56%, 2.33-7.26%, 6.7-24.26% and 14.5019-18.3832MJ/kg respectively. Further more
from the results of the Analysis of Variance (ANOVA) carried out, there were no significant
difference (p>0.05) in the quality of briquettes bonded with waste paper at different percentages
except for percentage volatile matter, ash content and heating value . The effect of die diameter
was found to be significant only on the physical properties of sawdust briquettes. A significant
effect of average particle size of sawdust was recorded in density, porosity index and volatile
matter of the briquettes. However, it was insignificant on shatter resistance, ash content and fixed
carbon of the briquettes. The optimum blend of sawdust particle size - waste paper percentage
and die diameter- waste paper percentage was assessed on the basis of the briquette properties:
density, porosity index, volatile matter, ash content and gross calorific value. The combination
of 0.5mm average particle size of sawdust and 30% waste paper gave the optimal density of
270.658kg/m3, porosity index of 29.782%, volatile matter of 86.496%, ash content of 2.829%
and gross calorific values of 16.613 MJ/kg. The optimum blend of die diameter and waste paper
was obtained at the combination of 6 cm and 25% with optimal values of density of 306.079
kg/m3, porosity index of 35.92%, volatile matter of 83.90%, ash content of 3.05% and gross
calorific value of 17.134MJ/kg. It was concluded that the calorific values of briquettes obtained
were sufficient to produce heat required for household cooking. Therefore sawdust briquettes can
be a very good alternative source of energy for domestic cooking
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Keywords
Briquetting of Sawdust