The use of coconut shell particulates to enhance the insulating refractory properties of Ukpor, Osiele and Kankara fireclays in Nigeria was studied in this paper. The chemical analysis of the raw materials was conducted using Atomic Absorption spectrometer. The samples used for different tests were prepared by mixing the clay, bentonite and coconut shell, of grain sizes of 212 -600 µm. The prepared samples were air and oven dried for 24 hours at room temperature and at 110˚C respectively. The samples were then fired at different temperatures in the range of 950˚C to 1200˚C at 50˚C interval and at 2.5˚C/min. The fired samples were investigated for their physical, insulating (thermal) and mechanical properties. Micro-structural examination was also carried out. The results indicate that clays with 25 wt% -30 wt% coconut shell and grain sizes of 212 -300 µm fired at 1150˚C -1200˚C possess enhanced mechanical, physical and insulating (thermal) properties. The SEM micrograph revealed the formation of mullite phase in the bricks fired at 1150˚C. Thus, high quality refractory bricks with enhanced insulating properties could be produced from Ukpor, Osiele and Kankara fire-clays blended with coconut shell particulates.

Lack of appropriate mix formulation has the tendency to degrade the strength of refractory bricks. This paper presents a model developed for evaluation and prediction of mix formulation for production of insulating refractory using Osiele and Ukpor fireclays blended with coconut shell particulates. The chemical compositions of the raw materials were analysed. The samples were prepared by mixing the clays and coconut shell of grain sizes 212 -600µm. Then air and oven dried for 24 hours at room temperature and at 110 o C respectively. Thereafter, sintered at temperatures between 950 to 1200 o C at 50 o C interval. The samples were tested for various properties. From the results, an Empirical Model relating the Composition and Property of the bricks was developed. 2 3 4 . The results of the model show the trend similar to experimental. Deviational analysis conducted indicates that the deviation of model-predicted data from the experimental is between 2.25 -8.9%hence, 91-97% accuracy.

In this research, kaolin, ball clay, sawdust and rice husk were used to produce insulation bricks through the solid state synthesis method. Two temperatures, 1100oC and 1200oC were used to sinter the green samples. X-ray fluorescence, scanning electron microscopy, compressive strength tests etc. were used to analyse the properties of the produced bricks. Chemical composition analysis on the starting raw materials showed that SiO2 and Al2O3 were the major constituents while Fe2O3, Na2O, K2O and TiO2 were the minor constituents. As the amounts of kaolin used in preparing the samples decrease, the bulk density, modulus of rupture and cold crushing strength of the bricks decreases while the water absorption capacity, linear shrinkage increases. The thermal analysis showed that on heating the samples, the reactions were mainly exothermic with between 8 to 10 mW/mg of heat released. The morphology of the samples showed that the pores began to collapse when the amount of kaolin present is below 70 wt. %. Sintering the samples at 1100oC and 1200oC led to slightly different values in the results and is therefore very significant. Keywords: Insulation bricks, Kaolin, sawdust, rice husk, temperature effects

In this research, Jigging, Froth Flotation and leaching have been used to beneficiate barite ore from Azara, Nasarawa State Nigeria. Chemical analysis on the ore indicates that it contains 53.09% of Ba and 11.52% S with a specific gravity value of 3.207±0.03. After the jigging operation, the specific gravity values of the underflow and overflow are 3.77±0.029 and 2.77±0.058 respectively while the Ba and S increased to 78.61% and 15.87% respectively. After the froth-flotation, the specific gravity values obtained are 3.95, 4.1 and 4.05 corresponding to pH values of 5, 7 and 9 respectively. Frothed barite with pH of 7 was leached with 0.2M HCl and a mixture of 0.2M HCl and HOCl. After leaching, the specific gravity values are 4.38±0.03 and 4.27±0.02 for HCl and HCl+HOCl respectively. The X-ray diffraction patterns show that highly crystalline peaks are obtained after froth flotation while more phases are added with leaching.

Models have been derived for assessment and computational analysis of the hardness of the heat affected zone (HAZ) in aluminum weldment. The general model; γ = 1.2714[(αβ/α + β)] was found to predict the HAZ hardness of aluminum weldment cooled in water as a function of the HAZ hardness of both mild steel and cast iron welded and cooled under the same conditions. The maximum deviations of the model-predicted HAZ hardness values γ, α and β from the corresponding experimental values γ exp, α exp and β exp were less than 0.02% respectively.