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Adeleke A.A.,Obafemi Awolowo University | Ibitoye S.A.,Obafemi Awolowo University | Afonja A.A.,Obafemi Awolowo University | Chagga M.M.,National Metallurgical Development Center
Petroleum and Coal | Year: 2014

Fractions of Okaba coal OK±250 ground to pass the 250μm sieve in three stages were subjected to proximate/ash composition analyses, hot aqueous leaching de-ashing with sodium carbonate and water (at atmospheric pressure) in multiple stages and in a Na2CO3-H2O- H2O sequence. The results obtained indicate that the ash contents percent of Okaba fractions OK-250(1), OK-250(2) and OK+250(2) were further reduced below the upper limit of 10 by 1.9, 2.2 and 1.8, respectively. These reductions translate to an average overall ash decrease percent of 12.57, while the volatile reduced by 9.85 and fixed carbon increased by 18.65. The ash content of the concentrates blend at 8% is lower than 10% required for coal blends for standard coking practice. The light transmission microscopy of the coal fractions showed that the chemical leaching process produced finer coal particles and caused a decrease in the ash content of the coal fractions. The reduction in ash content obtained at the atmospheric pressure treatment of Okaba coal will further enhance its participation in blend formulation for cokemaking. Source


Ihom P.A.,National Metallurgical Development Center | Agunsoye J.,University of Lagos | Ogbodo J.,Scientific Equipment Development Institute
Leonardo Electronic Journal of Practices and Technologies | Year: 2011

The effect of moisture content of Yola natural sand has been studied. The moisture content was varied from 1 to 9%. The effect of the moisture content on the green compression strength, green permeability and bulk density was investigated. Particle size distribution of the natural sand, the grain fineness number, average grain size, grain shape and the clay content of the natural sand were also studied. 5% moisture gave the optimum green compression strength of 118.6KN/m2. The dry compression strength increased with moisture content, an optimum value of 4000KN/m2 was obtained at 9% moisture. The Yola natural sand had a grain fineness number of 88.05AFS, average grain size of 335.78 microns and a clay content of 26%. A sand mixture containing 5% moisture was prepared and used to produce a test casting with aluminium scraps, the test casting was sound. Source


Ihom P.A.,National Metallurgical Development Center | Abella A.S.,Metallurgical Training Institute Onitsha | Ogbodo J.,Scientific Equipment Development Institute Enugu
Leonardo Electronic Journal of Practices and Technologies | Year: 2011

The use of Kruskal-Wallis test as an analytical tool for the key components of a newly developed core mixture was studied. The study showed that Kruskal- Wallis test can be use to analyze a core mixture using data collected on the properties of the core mixture. In this work the data used was the dry compression strength of cores produced using the core mixture. The key components of the core mixture; the binders and the sands were analyzed. The result showed that the dry compression strength values of the core mixture depend on the type of sand and on the nature of the binder used. This analysis agreed with previous works carried out by several other authors using conventional methods for analysis of core mixtures. Source


Mohammed R.A.,Ahmadu Bello University | Abdulwahab M.,Ahmadu Bello University | Abdulwahab M.,Tshwane University of Technology | Madugu I.A.,National Metallurgical Development Center | And 2 more authors.
Journal of Materials and Environmental Science | Year: 2013

The effect of Cyperus esculentus L. oil as a corrosion inhibitor on the corrosion rate of A356.0-type Al-Si-Mg alloy in simulated seawater environment was investigated using gravimetric method. The corrosion rates were studied in different concentrations of Cyperus esculentus L. oil (0.2, 0.4, 0.6, and 0.8g/v) at temperatures of 30, 50, and 70°C. The results revealed that Cyperus esculentus L. oil in 3.5% NaCl-aluminium environment decreased the corrosion rate at various concentrations considered. Results also showed that Cyperus esculentus L. oil decreased the corrosion rate of Al-Si-Mg alloy immersion time considered. The minimum inhibition efficiency was obtained at 70°C while the maximum inhibition efficiency of 69.97% was achieved with 0.8g/v inhibitor concentration at 30°C. Cyperus esculentus L. oil acted as an effective corrosion inhibitor for Al-Si-Mg alloy within the temperature and concentration range studied. The results demonstrated that Cyperus esculentus L. oil adsorbed on the surface of Al-Si-Mg alloy and obeyed Langmuir adsorption isotherm. Source


Adeleke A.A.,Obafemi Awolowo University | Ibitoye S.A.,Obafemi Awolowo University | Afonja A.A.,Obafemi Awolowo University | Chagga M.M.,National Metallurgical Development Center
Petroleum and Coal | Year: 2011

Fractions of the high ash Nigerian Lafia-Obi coal L±250 ground to pass the 250 μm sieve in three stages were subjected to proximate/ash composition analyses, hot aqueous leaching de-ashing with water and sodium carbonate in multiple stages and in a H2O-Na2CO3-H2O sequence (with initial solution homogenization). The results obtained showed that ash contents percent of 24.60, 14.70 and 24.07 were obtained for fractions L-250(1), L-250(2) and L+250(2); respectively as against 32.55% in the as-received coal. The ash reductions obtained translate to overall average ash removal of about 38.66% at the 19.90% ash content of the concentrates blend at a good 1:20 ratio of reagent to coal. The study also showed that a three stage leaching in the sequence H2ONa2CO3- H2O (HSH) produced a higher leaching rate than Na2CO3-H2O-H2O (SHH). The ash content of the concentrates blend at 19.90% is lower than 23.80% required for coal blends for Indian standard coking practice, but higher than the maximum of 10% upper limit for the conventional cokemaking practice. The reduction in ash content obtained at the atmospheric pressure treatment of Lafia-Obi coal was found to compare favourably with that of a high pressure elevated temperature autoclave leaching of an Illinois coal. Binary blend formulation between the prime coking western Canada coal and Lafia-Obi coal as-leached showed that inclusion of 16.63% of the latter was probable and this translates to reduction in cost per ton of about $23.67. A successful upgrade of the leaching route derived to industrial scale will make Lafia-Obi coal available as a blend component for economical cokemaking. Source

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