Papers by Stephen Jobson Mitchual
International journal of forestry research, Apr 8, 2024
British Journal of Applied Science and Technology, Jan 10, 2015
This study sought to determine the effect of combining sawdust of Piptadenia africana with Ceiba ... more This study sought to determine the effect of combining sawdust of Piptadenia africana with Ceiba pentandra on the physical and mechanical properties of briquettes produced at room temperature using low compacting pressure without a binder. Briquettes were produced from a mixture of sawdust of Piptadenia africana and Ceiba pentandra. Particle size of sawdust used for this study was 1mm or less. The two materials were combined at mixing proportions: 80:20, 60:40, 40:60 and 20:80 (Piptadenia africana: Ceiba pentandra). The results indicated that the relaxed density of briquettes produced from the mixed materials ranged from 534 to 766 kg/m whilst that of compressive strength in cleft ranged from 12.46 to 60.28 N/mm. At compacting pressure levels between 30 and 50 MPa, all the briquettes produced from the mixed materials had adequate compressive strength in cleft. The impact resistance index of briquettes from the mixed materials was adequate and ranged from 128 to 500%. The compressive strength in cleft and impact resistance index of all the briquettes produced from the mixed species were better than those produced from Piptadenia africana only. Additionally, at 5% level of significance, the relaxed density, compressive strength in cleft and impact resistance index of briquettes were significantly affected by the biomass raw material and compacting pressure. Thus, the addition of sawdust of Ceiba pentandra to that of Piptadenia africana could significantly improve the physical and mechanical properties of briquettes produced from sawdust of Piptadenia africana. Therefore, production of briquettes from mixed timber species should be encouraged. Original Research Article Mitchual; BJAST, 6(4): 399-407, 2015; Article no.BJAST.2015.098 400
Advances in Bamboo Science
Nativa
A critical aspect of the Sustainable Forest Management scheme is promoting lesser-used timber spe... more A critical aspect of the Sustainable Forest Management scheme is promoting lesser-used timber species in substituting the over-exploited timber species of similar technical characteristics. The study's main objective was to evaluate the technological properties within the tree height of Memecylon lateriflorum (G. Don) Bremek. They were using small clear, defect-free, straight-grained wood samples. Using standardized procedures, the samples were harvested, prepared, and conditioned from the diameter at breast height (DBH), middle, and top portion of the trees. The results indicated that the density of M. lateriflorum was 840 kg/m3, which characterizes it as a high-density wood. The study again revealed a strong correlation (83-99 %) between the woods' densities and mechanical strength characteristics. Also, the overall average tangential and radial shrinkage from green to 12 % moisture content was 9.46% and 6.57%, respectively, whereas that of longitudinal was 0.65%. The mean...
Global Journal of Engineering and Technology Advances
Keeping the workplace safe must not be the concern of only workers and companies but also nationa... more Keeping the workplace safe must not be the concern of only workers and companies but also national and global economies whose productivity and competitiveness play a major role on safe working environment. This paper investigated the impact of training on occupational health and safety of woodworkers at a wood processing village in Ghana. The study was conducted using cross-sectional design with 410 wood processing operators. Questionnaires adapted from safety management operation was used for this quantitative study. Data was analysed using descriptive and inferential statistics. All the eight (8) items under the use of personal protective equipment had their mean ratings lower than the theoretical mean of 3.0. This suggest that the woodworkers do not put on personal protective equipment during wood processing. Additionally, the study revealed that the woodworkers were not provided with personal protective equipment at work. Furthermore, the study revealed that training could signi...
Chemistry Africa, Dec 7, 2022
Sustainable Structures
This study assessed the properties of juvenile and matured glue-laminated bamboo for structural a... more This study assessed the properties of juvenile and matured glue-laminated bamboo for structural applications. Glue-laminated bamboo was produced from 2-year-old and 4-year-old culms of Bambusa vulgaris with a fast-curing polyurethane adhesive (Rapid Lion). The composites produced were assessed for their physical (moisture content, basic density, radial, longitudinal, tangential and volumetric shrinkage) and mechanical (modulus of rupture, modulus of elasticity and compressive strength parallel to grain) properties. The results show that the juvenile glue-laminated bamboo significantly shrinks about twice that of the matured glue-laminated bamboo with values of 6.32% for radial, 6.51% for tangential and 0.22% for longitudinal. It was further observed that the basic density of the matured glue-laminated bamboo was 810.56 kg/m³ which is 14.56% higher than that of the juvenile glue-laminated bamboo. The juvenile glue-laminated bamboo had MOE of 5876 MPa; MOR of 43.42 MPa and compressive...
Forests
Considering the current rate of expansion of the lumber processing industry in the world, the cur... more Considering the current rate of expansion of the lumber processing industry in the world, the current annual allowable cut of one million cubic meters of round logs is considered to be insufficient to satisfy the increasing demand of timber industries. One major area that has been highlighted in the forest policy is the introduction of lesser-used species to widen the natural resource base of the forest and to address the imbalance between supply and demand for the resources. As a contribution to addressing this problem, oil palm lumber, a lesser-used species, was subjected to different moisture content variations to determine its behavior with respect to discoloration. Specimens of oil palm trunks were extracted at Norpalm Oil Mill in the Western Region of Ghana. Oil palm lumber specimens were conditioned in a kiln to a moisture content of 15%, 20%, 25%, 30%, 40%, and 50%. The results obtained covered discoloration and mold. The effect of the extractives on the discoloration of oil...
Environmental problems associated with the rapid depletion of the tropical forest have necessitat... more Environmental problems associated with the rapid depletion of the tropical forest have necessitated the need to look for alternative sources of timber supply. Compression parallel to grain tests, three-point static bending tests, machining tests and finishing characteristics of oil palm lumber, a non-timber forest product were conducted to determine its suitability for furniture production. A compression parallel to the grain of 13 N/mm, a modulus of elasticity of 2924 N/mm, and a modulus of rupture of 25 N/mmat 12% moisture content were obtained. The lower strength properties of oil palm lumber compared to conventional lumber suggest that oil palm lumber could be used for light load bearing products such as coffee tables, center tables, ceilings and wall panels. Planing and sanding operations produced rough surfaces with sharp raised grains which had piercing effect on the fingers. However, application of sanding sealer followed by sanding operations removed all the sharp raised gr...
Journal of Sustainable Bioenergy Systems, 2014
The fuel potential of six tropical hardwood species namely: Triplochiton scleroxylon, Ceiba penta... more The fuel potential of six tropical hardwood species namely: Triplochiton scleroxylon, Ceiba pentandra, Aningeria robusta, Terminalia superba, Celtis mildbreadii and Piptadenia africana were studied. Properties studied included species density, gross calorific value, volatile matter, ash content, organic carbon and elemental composition. Fuel properties were determined using standard laboratory methods. The result indicates that the gross calorific value (GCV) of the species ranged from 20.16 to 22.22 MJ/kg and they slightly varied from each other. Additionally, the GCV of the biomass materials were higher than that of other biomass materials like; wheat straw, rice straw, maize straw and sugar cane. The ash and volatile matter content varied from 0.6075 to 5.0407%, and 75.23% to 83.70% respectively. The overall rating of the properties of the six biomass materials suggested that Piptadenia africana has the best fuel property to be used as briquettes and Aningeria robusta the worse. This study therefore suggests that a holistic assessment of a biomass material needs to be done before selecting it for fuel purpose.
International Journal of Energy and Environmental Engineering, 2013
This study examined the relationship between selected physico-mechanical properties, compact-ing ... more This study examined the relationship between selected physico-mechanical properties, compact-ing pressure and mixing proportion of briquettes produced from combination of maize cob par-ticles and sawdust of low, medium and high density timber species. Particle sizes of maize cobs and sawdust used for the study were ≤1 mm. The two materials were combined at mixing percen-tages of 90:10, 70:30 and 50:50 (Sawdust:maize cobs). Briquettes were produced at room temper-ature (28˚C) using compacting pressures 20, 30, 40 and 50 MPa. The results suggested that com-bining maize cob particles with sawdust of low, medium and high density wood species could sig-nificantly enhance the relaxed density, compressive strength in cleft and impact resistance index of briquettes produced from agricultural biomass residue like maize cobs. The results further in-dicated that the physical and mechanical characteristics of briquettes produced from combina-tions of sawdust of low density species and maize cob...
Materials Sciences and Applications
This study investigated the possible use of four agro-forest residues generated in Ghana as an al... more This study investigated the possible use of four agro-forest residues generated in Ghana as an alternative raw material for particleboard manufacture using cassava starch and urea formaldehyde as adhesives. The particle size of the materials ranged from 0.5 mm to 1.5 mm. An industrial pressing machine was used to press the homogeneous single layer particleboard. Physical and mechanical properties were determined in accordance with ASTM D 1037-06a and ASTM D 7519-11. The results indicate that the density of the particleboards produced ranged from 421 kg/m3 to 598 kg/m3. The water absorption property of the particleboards also ranged from 7.66% to 22.41% and 18.17% to 59.46% for 2-hour and 24-hour immersions respectively. Additionally, the thickness swelling of the particleboards ranged from 3.38% to 5.03% and 9.37% to 21.49% for 2-hour, and 24-hour immersions respectively. The results further indicate that the modulus of elasticity, modulus of rapture, internal bond strength and hardness of the particleboards produced for both cassava starch and urea formaldehyde were adequate. Comparatively, for all the agro-forest materials used for this study, the physical and mechanical properties of the particleboards produced using urea formaldehyde as adhesive was better than those produced using cassava starch as adhesive. It could be concluded that the particleboards produced could be used for indoor applications or interior furnishings, under dry conditions. Additionally, it is recommended that further studies that combine cassava starch and urea formaldehyde as adhesives be conducted, as well as studies on combining Plantain pseudostem and Cacao pod in particleboard production.
Journal of Environmental Science and Engineering A, Feb 28, 2016
Logging residue can be defined as any form of wood, which under the highest stage of technologica... more Logging residue can be defined as any form of wood, which under the highest stage of technological development could be used in manufacturing but is left in the forest during logging. Lumber production from logging residues of a previous logging activity by a timber firm was undertaken with the objective of determining the suitability of utilizing buttressed-stumps as raw material for the timber industry. A horizontal mobile bandsaw machine was used to process the buttressed-stumps into lumber. The machine was characterized by a thin-kerf sawing technology (kerf-width 1.6 mm) compared to the conventional bandsaw machines of kerf-widths ranging from 3.0-4.5 mm. Lumber value and volume yields, fuel consumption rate, frequency of tool replacement and lumber production rate were assessed. Results indicated that there is the potential to increase timber production from logging residues by utilizing buttressed-stumps. Lumber value and volume yields of eight timber species investigated in this study ranged from 5%-31% and 34%-54% respectively. Fuel consumption rate which increased with increasing wood density, ranged from 5-14.5 liters/m 3 of lumber produced. Frequency of saw replacement increased with increasing wood density. The number of saws required to produce one cubic meter of lumber, ranged from 1 to 7. Lumber production rate ranged from 0.10-0.38 m 3 /hour, increasing with decreasing wood density.
International Journal of Emerging Technology and Advanced Engineering, 2015
Environmental problems associated with the rapid depletion of the tropical forest have necessitat... more Environmental problems associated with the rapid depletion of the tropical forest have necessitated the need to look for alternative sources of timber supply. Compression parallel to grain tests, three-point static bending tests, machining tests and finishing characteristics of oil palm lumber, a non-timber forest product were conducted to determine its suitability for furniture production. A compression parallel to the grain of 13 N/mm2, a modulus of elasticity of 2924 N/mm2, and a modulus of rupture of 25 N/mm2at 12% moisture content were obtained. The lower strength properties of oil palm lumber compared to conventional lumber suggest that oil palm lumber could be used for light load bearing products such as coffee tables, center tables, ceilings and wall panels. Planing and sanding operations produced rough surfaces with sharp raised grains which had piercing effect on the fingers. However, application of sanding sealer followed by sanding operations removed all the sharp raised...
Advances in Research
Gmelina arborea grown in Ghana has not been promoted for its efficient use by the wood industry d... more Gmelina arborea grown in Ghana has not been promoted for its efficient use by the wood industry due to the limited technical information available and is therefore classified as a lesser-used timber species. This paper presents research findings on the planning and turning properties of Gmelina arborea cultivated in two ecological zones in Ghana. Samples of logs from six trees of the species were obtained from Daboase and Abofour in the Wet Evergreen and Dry Semi-Deciduous Forest zones of Ghana. These were crosscut into top, middle and butt sections using a chainsaw. An LT 15 Wood-Mizer bandsaw was used to saw each log into 2.6 cm-thick boards; these were then stacked for air drying. Planning and turning tests were conducted following the American Society for Testing and Materials International D1666-87-2004 method to determine the machining characteristics of Original Research Article
Biomass Conversion and Biorefinery
This study assessed the fuel characteristics of briquettes made from oil palm mesocarp fibre and ... more This study assessed the fuel characteristics of briquettes made from oil palm mesocarp fibre and sawdust of Ceiba pentandra at room temperature, using low compacting pressure without a binder. Properties of briquettes studied included stability in diameter and length, relaxed density, compressive strength, impact resistance index, gross calorific value, volatile matter, ash content and elemental composition. These properties were determined using standard laboratory methods. The results show that briquettes with better relaxed density, compressive strength and impact resistance index could be produced from a blend of C. pentandra sawdust and oil palm mesocarp fibre at low compacting pressure and room temperature without a binder. The relaxed density of briquettes produced ranged from 377 kg/m3 to 586 kg/m3 which could be classified as medium-density briquettes. The result further indicates that compacting pressure 40 MPa or more could be used to produce briquettes with adequate compressive strength in cleft and impact resistance index from the blend of C. pentandra sawdust and oil palm mesocarp fibre at low compacting pressure and room temperature without a binder. At 5% level of significance, the compacting pressure and mixing proportion had significant effect on the physical and mechanical properties of briquettes produced. The gross calorific values of Ceiba pentandra sawdust and oil palm mesocarp fibre were found to be 20.33 MJ/kg and 19.50 MJ/kg respectively. Even though most of the elemental compositions of the oil palm mesocarp fibre were not adequate, a blend with Ceiba pentandra sawdust could make it suitable to be used as an environmental friendly material for biomass briquettes production.
Open Journal of Safety Science and Technology, 2015
This paper reports the assessment of safety practices and injuries in a timber company in Ghana. ... more This paper reports the assessment of safety practices and injuries in a timber company in Ghana. A cross-sectional survey design was used for the study. Data were collected from 300 respondents at a sawmill in Ghana using a 5-point Likert-type scale questionnaire. Descriptive and inferential statistics were used for the data analyses. The result indicates that the mean rating of the respondents on their use of personal protective equipment ranged from 1.09 to 2.51. This implies that the workers of the sawmill rarely or never wear: gloves, overall, goggles, face shield, nose and mouth mask, earplugs or helmet during wood processing. Additionally, the mean ratings of the respondents regarding safety practices, machine and maintenance ranged from 2.42 to 4.03 with three out of the eight items having mean ratings higher than the theoretical mean of 3.0. The ratings of the respondents of the saw doctoring department on their practice of safety on machine and maintenance were significantly higher than those of the other departments. The result of the study further suggests that the workers of this sawmill do rarely report of: skin irritation/dermatitis, eye irritation, lack of appetite, arm/leg amputation, neck pains, hearing loss and poor eye sight problems. However, they usually report of headaches, nausea, respiratory problems, small cuts, back pains, and hip and leg pains. The outcome of this study therefore suggests that the management of the sawmill studied needs to do more to enforce practice of safety, especially the use of personal protective equipment, to reduce hazards and injuries associated with wood processing in the firm.
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Papers by Stephen Jobson Mitchual