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Search Results: 1 - 10 of 553843 matches for " A.B. Adahama "
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Effects of Stamped Charging on the Strength of Coke from the Weakly Caking Australian Agro-Allied Coal Blend Mixed with Coke Breeze  [PDF]
A.B. Adahama, A.O Adeleke, A.O. Olulana, S.A. Ibitoye
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.74027
Abstract: The weakly caking Australian Agro-Allied coal sample mixed with 7% un-reactive coke breeze was subjected to stamped charging prior to carbonization for 22 hours in a 250kg pilot plant to improve the resulting coke strength. The coal was carbonized with a bulk density of 1,000kg/m3 and heating flue temperature of 1,340℃. The screen distribution analysis and the micum tests conducted on the coke gave M10 and M40 of 15.90% and 73.20%, respectively. These results show that the Agro-Allied coke produced is inferior to the coke from a normal top charged counterpart with M10 and M40 indices of 15.40% and 78.20%, respectively and do not satisfy the requirements for the blast furnace ironmaking process. These results thus suggest that the stamped charging coking improvement method designed for high caking, high volatile coals may not be able to improve the strength of coke resulting from a weakly caking, medium volatile coal mixed with coke breeze.
Study on the Reliability of Coke Research Establishment Micum 40 Formula to Predict Coke Micum 40 Strength at The Ajaokuta Steel Plant, Nigeria  [PDF]
A.O. Adeleke, A.O. Olulana, A.B. Adahama, R.S Makan, S.A. Ibitoye
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2007, DOI: 10.4236/jmmce.2007.62011
Abstract: G-values of 0.97, 0.93, 0.94 and 1.01 were determined for Polish Bellview blend 1 (BV1), Polish Bellview blend 2 (BV2), Australian Agro-Allied blend (AA) and American Carbon Energy blend (CE), respectively. The coking duration of 18 hours, 17 hours, 16 hours and 22.5 hours, respectively were used to carbonize the coals each having volatiles 31.8%, 31.3%, 30.22%, and 21.90%, respectively. The Coke Research Establishment (CRE) formula predicted M40 micum strength of 77.98%, 77.12%, 77.55% and 92.05% for BV1, BV2, AA and CE blends, respectively. These predicted values were found to deviate from the experimentally determined M40 indices of 77.80%, 70.80%, 78.20% and 64.16% determined for BV1, BV2, AA and CE respectively by 0.18 units, 6.32 units, -0.65 units, and 27.89 units respectively. Thus, the best M40 index predicted was determined for BV1 blend with 0.97 G-value and 18 hours coking time with only a small allowable deviation of 0.18 units. The CRE formula has therefore been shown to be valid to predict M40 index of coke produced from coal blends with G-value of about 0.97 and carbonized at a moderate coking time of 18 hours. It has also been shown that the coking conditions that produce the best M40 index also produced the best M10 index.
EFFECTS OF PRE-HEATING ON THE MICUM STRENGTH OF COKE FROM A COAL BLEND INCLUDING 5% OF NON-CAKING NIGERIAN OKABA COAL
A.O. Olulana,A.A. Adeleke,A.B. Adahama,S.A. Ibitoye
Petroleum and Coal , 2011,
Abstract: A coal blend consisting of 95% Australian Agro-Allied coal and 5% Nigerian non-caking Okaba coal wascarbonized in a 250 kg capacity coke oven at a flue temperature of 1,250oC by normal wet and preheatedcharging for 18 and 15 hours, respectively. Screen distribution analysis and micum drum tests on thecoke products gave M10 of 24.60% and 9.5% and M40 of 67% and 76.2%, for normal and preheatedcharge, respectively. These results showed that the coke produced from the preheated charge has abetter resistance to abrasion (M10) and fragmentation (M40) and the micum indices obtained are similarto the micum characteristics of cokes produced in coke ovens in some other countries. Furthermore,the coke micum 10 and micum 40 strength are very close to the M10 and M40 specifications for coketo be used for blast furnace operations at the Ajaokuta Steel Plant, Nigeria.
PILOT SCALE CARBONIZATION STUDIES ON POLISH BELLVIEW COALS FOR METALLURGICAL COKEMAKING
A.O. OLULANA,A.B. ADAHAMA,A.O. ADELEKE,S.A. IBITOYE
Petroleum and Coal , 2009,
Abstract: The pilot scale carbonization of the normally charged bituminous Polish Bellview coal blends wasconducted in a 250kg capacity coke oven with a bulk density of 800kg/m3, flue temperature of 1250°Cand coking time of 18 to 20 hours. The micum drum test conducted on Bellview A and B cokes gaveM10 abrasion resistance of 11.40% and 15.40% and M40 resistance to fragmentation of 77.80% and70.80% for Bellview coke A and B, respectively. The results of this study showed that Bellview A coalblend is of a higher bituminous grade than Bellview blend B, though its micum indices do not meet thespecification of 9% (maximum) M10 and 78% (minimum) M40 for blast furnace ironmaking at theNigerian Ajaokuta steel plant. It is however expected that the small deviations of +2.4% and -0.2%,in the M10 and M40 of Bellview B coke may be eliminated during industrial scale cokemaking under ahigher static load and the application of coking improvement techniques such as pre-heating andstamp charging .
Employee`s Perception of Women Leaders in Nigeria Private and Public Organisation
A.B. Owolabi
The Social Sciences , 2013,
Abstract: Despite the constraints and the negative worldview about women, the world today is witnessing an upsurge of feminine power, influence and productivity. Significant changes have therefore occurred in gender-role and gender based division of labour. This paper examined employees` perception of women leaders in Nigeria private and public organizations. A total of two hundred and fifty participants were used for the study (125 workers from public and 125 workers from private sector). An attitude towards women leader scale was administered into them and scores were analysed using the independent t-test and 2 2 Analysis of variance. Results show that there are negative attitude towards women leaders but there are no significant difference in the attitude of private and public employees towards women leaders. Sex and marital status also predict employees` attitude towards female leaders, with males and married people having a favourable attitude towards women leaders. Findings were discussed in the light of previous findings in the literature
High trypanosome infections in Glossina palpalis palpalis Robineau-Desvoidy 1830 in southern Kaduna state, Nigeria
A.B Ahmed
Science World Journal , 2007,
Abstract: A survey was undertaken to determine the prevalence of trypanosome infection in Glossina species in Kaura Local Government Area (LGA) of Kaduna State, Southern Guinea Savanna, Nigeria, aimed at identifying areas to be prioritized for area-wide tsetse eradication. The flies were trapped from a relic forest and also from 22 locations spread within the LGA and dissected to determine infection rates and infection types. Glossina palpalis palpalis Robineau-Desvoidy 1830 was the only tsetse species encountered both within the relic forest and the 22 locations sampled; its distribution was strictly riverine. Out of the 409 non-teneral flies dissected in the relic forest, 18.1 ± 0.02%, were infected with trypanosomes, with infections of the vivax-group dominating (76.92%) over the congolensegroup (23.01%). Of the 690 flies caught from 22 locations, 9.9 ± 1.0% were infected, 69.12% with vivax-group and 30.88% with congolense-group. Infections of the brucei-group were not encountered throughout the investigation period. The high prevalent figure of 12.64% recorded in the flies from both the relic forest and other locations portray the area as highly risky, with Bondong, Manchok and Kadarko districts being highly endemic, followed by a region of medium prevalence at Kukum district and a region of low endemicity within the mountain ranges of Zankan district. A well articulated vector eradication programme that will target G. p. palpalis and the various species of other biting dipterans is recommended as the solution to the recurring nagana problem in the area.
Breeding of the Hooded Vulture Necrosyrtes monachus in the Kruger National Park
A.B Daneel
Koedoe : African Protected Area Conservation and Science , 1984, DOI: 10.4102/koedoe.v27i1.558
Abstract: Mundy (1982, The comparative biology of southern African Vultures, Vulture Study Group, Johannesburg.) states that records exist for only 22 nests of the Hooded Vulture Necrosyrtes monachus in Rhodesia, of which he visited 15, while in only three nests were the eggs measured. He makes no specific mention of egg measurements from nests south of the Limpopo River, although the average of 10 "Southern African" eggs is given as 74,72 (Range 68,7 - 78,1) by 55,89 (Range 54,0 - 57,8) mm. Nevertheless, five South African breeding records exist, all from the Kruger.
Effect of Delayed Bleeding on Carcass and Eating Qualities of Rabbit Meat
A.B. Omojola
Pakistan Journal of Nutrition , 2007,
Abstract: A total of forty eight matured New Zealand rabbits with an average weight of 2.06±0.45 kg were used to evaluate the effect of delayed bleeding on carcass and organoleptic characteristics of rabbit meat. The rabbits were fed concentrate diet containing 19.11% Crude Protein (CP) and 2514.3 Kcal/kg Metabolizable Energy (ME) for a period of thirty five days. The rabbits were randomly assigned to four treatment groups in a completely randomized design. Each treatment was replicated thrice with each replicate consisting of four rabbits. Treatment one served as control where the 12 rabbits were bled immediately after stunning while treatments 2, 3 and 4 comprised of rabbits that were bled 5, 10 15 minutes after stunning. After proper bleeding, the rabbits were skinned, washed and eviscerated and cut into primal cuts. Samples for sensory evaluations were taken from the thigh muscle and the remaining carcasses were aged at 4°C for 24 and 72 hours. The result showed that the dressing percentage, chilled carcass weight and the pH were not affected (p>0.05) by delayed bleeding while the volume of blood drained decreased (p<0.05) as the period between stunning and bleeding increased. The drip loss and cooking loss increased as the time between stunning and bleeding increased while the Water Holding Capacity (WHC) decreased. The effect of delayed bleeding on shear force, WHC, drip loss and cooking loss became more pronounced with ageing. Apart from the colour and juiciness rating that significantly (p<0.05) decreased, the other eating qualities were not affected (p>0.05) by delayed bleedin
The role of karst in the genesis of sulphur deposits, Pre-Carpathian region, Ukraine
Klimchouk,A.B.
Speleogenesis and Evolution of Karst Aquifers , 2005,
Abstract: Most of exogenous epigenetic sulphur deposits are clearly associated with intensely karstified carbonate and sulphate rocks. This paper demonstrates, using the Pre-Carpathian region as an example, that karstification is one of the most important processes guiding the formation of sulphur deposits. This is determined by a coincidence of some major prerequisites of these two processes. In the Podol'sky and Bukovinsky regions the Miocene aquifer system is well drained by erosion valleys; the giant network caves known here in gypsum formed under past artesian conditions. In the region of sulphur deposits, associated with the same karstified gypsum strata, true artesian conditions still prevail. Hydrogeologic data show that abundant cavities detected in the vicinity of sulphur deposits can be interpreted as having the same origin as the relict caves of the Podol'sky and Bukovinsky regions. The widespread belief that the gypsum/anhydrite bed in the region is an aquifuge separating the Miocene aquifers is inadequate. This belief caused much controversy with regard to the genetic interpretations of sulphur deposits in the region. Cave systems formed by the upward water flow through the gypsum/anhydrite bed govern the water exchange between the aquifers within the aquifer system. A new karst model for the formation of sulphur deposits is suggested. It agrees well with the hydrogeological features of the Miocene sequence and with biogeochemical mechanisms of sulphur origin in low-temperature diagenetic environments.
Conceptualisation of speleogenesis in multi-storey artesian systems: a model of transverse speleogenesis
Klimchouk, A.B.
Speleogenesis and Evolution of Karst Aquifers , 2007,
Abstract: Conceptual and respective quantitative models of speleogenesis/karstification developed for unconfined aquifers do not adequately represent speleogenesis in confined settings. A conceptual model for speleogenesis in confined settings is suggested, based on views about hydraulic continuity in artesian basins and close cross-formation communication between aquifers in multi-storey artesian systems. Soluble units sandwiched between insoluble porous/fissured formations (common aquifers) initially serve as low permeability beds separating aquifers in a confined system. Conduits evolve as result of vertical hydraulic communication between aquifers across the soluble bed ("transverse speleogenesis"). Recharge from the adjacent aquifer is dispersed and uniform, and flow paths across the soluble bed are rather short. There is a specific hydrogeologic mechanism inherent in artesian transverse speleogenesis (restricted input/output) that suppresses the positive flow-dissolution feedback and hence speleogenetic competition in fissure networks, and accounts for the development of more pervasive channelling in confined settings, of maze patterns where appropriate structural prerequisites exist. This is the fundamental cause for the distinctions between cave morphologies evolving in unconfined and confined aquifers and for eventual distinctions of karstic permeability, storage characteristics and flow system behaviour between the two types of aquifers. Passage network density (the ratio of the cave length to the area of the cave field, km/km2) and cave porosity (a fraction of the volume of a cave block, occupied by mapped cavities) are roughly one order of magnitude greater in confined settings than in unconfined. Average areal coverage (a fraction of the area of the cave field occupied by passages in a plan view) is about 5 times greater in confined settings. Conduit permeability in unconfined settings tends to be highly heterogeneous, whereas it is more homogeneous in confined settings. The storage characteristics of confined karstified aquifers are much greater. Recognition of the differences between origin, organisation and behaviour of karst systems evolved in unconfined and confined settings can improve efficiency of exploration and management of various resources in karst regions and adequacy of assessment of karst-related hazards.
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