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Search Results: 1 - 10 of 148869 matches for " Joseph K. Byaruhanga "
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Application of Different Models for the Prediction of the Kinetics of Direct Reduction of Natural Iron Ores  [PDF]
Abraham J. B. Muwanguzi, Aliaksandr Alevanau, Joseph K. Byaruhanga
Geomaterials (GM) , 2017, DOI: 10.4236/gm.2017.74009
Abstract: Simulation of the direct reduction conditions was performed in a laboratory furnace. Lump samples from natural hematite iron ore were reduced by a gas mixture of H2 and CO (H2/CO =1.5) at temperatures of 700°C, 800°C and 900°C. The effect of reduction temperature on the reduction degree, reduction rate of samples and carbon deposition were investigated and discussed in this study. The thermo-gravimetric data obtained from the reduction experiments was run in a programme that calculates the solid conversion rate. Also, three models: 1) Grain Model (GM), 2) Volumetric Model (VM), and 3) the Random Pore Model (RPM), were used to estimate the reduction kinetics of natural iron ores. It was found that the RPM model result agreed best with the obtained experimental results. Furthermore, it gave better predictions of the natural iron oxide conversion and thereby the reduction kinetics.
Characterization of Chemical Composition and Microstructure of Natural Iron Ore from Muko Deposits
Abraham J. B. Muwanguzi,Andrey V. Karasev,Joseph K. Byaruhanga,P?r G. J?nsson
ISRN Materials Science , 2012, DOI: 10.5402/2012/174803
Abstract: The study aimed at investigating the chemical composition and microstructure of raw iron ore from the deposits in Muko area (south-western Uganda). The quality of this iron ore was evaluated to establish its suitability to serve as a raw material for iron production. Samples were taken from the six hills of Muko ore deposits and tests carried out to establish their composition and properties. X-ray diffraction and scanning electron microscopy were employed in the investigation and chemical analysis performed to determine the compounds constituting the ore. The quality of this ore was compared to generalized world market standards and ores from other nations. It was found that Muko ore is a rich hematite grade with Fe content above 65%. It has little gangue (<6% SiO2 and 3-4% Al2O3) and low contents of the deleterious elements ( % and %), which correspond to acceptable levels for commercial iron ores. 1. Introduction The most commonly used iron-bearing minerals contain iron compounds as follows: hematite, Fe2O3 (70% Fe); magnetite, Fe3O4 (72.4% Fe) and of much less importance are: limonite, 2Fe2O3·3H2O (60% Fe); siderite, FeCO3 (48.3% Fe); pyrite, FeS2 (46.6% Fe) [1]. These iron percentages are in their pure states. In ores, the Fe content is lowered according to the amount of impurities present. Overall, the quality of iron ore is mainly judged based on the Fe content. More specifically, ores with Fe contents above 65% are regarded as high-grade ores; 62–64% medium- (or average) grade ores and those below 58% Fe are considered as low-grade ores [2–5]. Iron ore consumption for steelmaking was standing at 850 million tonnes at the end of the twentieth century and was estimated to reach more than 1.3 billion tonnes over the first quarter of the century [6]. The known world resources of crude iron ores are approximately 800 billion tonnes containing about 230 billion tonnes of Fe [7]. It is apparent that most of the known deposits contain low-grade ores with iron contents less than 30%. By contemporary growth of the world consumption of iron ores (about 10% per year), the known resources of iron ores could run out within the next 64 years [8]. It is thus imperative to find new sources of iron ore to supplement the existing sources, in order to meet the growing demand. Therefore, revealing and exploiting new deposits of iron ores, particularly of high-grade, is very important. Iron ore deposits have been known to occur in the Muko area in south-western Uganda (430?km from the capital city Kampala) since the 1920s. However, they still lay unexploited and
Characterisation of the Physical and Metallurgical Properties of Natural Iron Ore for Iron Production
Abraham J. B. Muwanguzi,Andrey V. Karasev,Joseph K. Byaruhanga,P?r G. J?nsson
ISRN Materials Science , 2012, DOI: 10.5402/2012/147420
Abstract: The blast furnace is still the dominant form of iron production, but over the years, direct reduction methods have increased due to a number of reasons. Overall, iron production methods have optimal requirements with respect to the feed materials especially iron ore. In this study, tests were carried out on Muko iron ore from Uganda to analyse its suitability to meet the feed requirements of today's dominant iron production methods. More specifically, the Tumbler, Abrasion, and Shatter Indices of the ore were determined. In addition, porosity, thermoanalysis, and reducibility tests were performed. Overall, the Muko ore was found to have good mechanical properties exemplified with tumble and shatter index data >89.0?wt% and <2.5?wt%, respectively. Furthermore, its reducibility at 0.87%/min is within the acceptable range as a natural material feed for blast furnace and direct reduction furnaces. Also, the energy requirement for heating the ore to 1100°C was found to be higher in the samples containing a wider size range of irregular grains and the largest contaminations. In summary, it is concluded that the Muko iron ore has good physical and metallurgical properties to serve as a natural material for the blast furnace and direct reduction furnaces. 1. Introduction Iron, along with its generic products, is currently the most widely utilised metal in the various sectors of the world’s economy. Many factors contribute to this, ranging from the good mechanical properties it possesses to the low cost associated with its production. Iron is mainly produced through two methods; the blast furnace, BF, route (pig iron), and the direct reduction, DR, route (sponge iron). According to the World Steel Association, 2011 [1], crude steel production was standing at 1.4 billion tonnes by the end of 2010. Of these, 70% was produced via the basic oxygen furnace (BOF), which uses pig iron from the blast furnace, and 28% via the electric arc furnace (EAF), which uses sponge iron and scrap [1]. Iron ore can be used directly in its natural form as a raw material for processing iron or it can be upgraded through beneficiation before it’s charged into the BF or DR furnaces. The feedstock is evaluated for physical and metallurgical properties [2]. Physical properties give an indication of the material behaviour during handling and descent in the furnace. Metallurgical properties on the other hand indicate the materials’ behaviour during the reduction process. In selecting iron ore for iron and steel industries, some of the properties which need to be considered include (i)
Characterisation of the Physical and Metallurgical Properties of Natural Iron Ore for Iron Production
Abraham J. B. Muwanguzi,Andrey V. Karasev,Joseph K. Byaruhanga,Pär G. Jönsson
ISRN Materials Science , 2012, DOI: 10.5402/2012/147420
Abstract:
Characterization of Chemical Composition and Microstructure of Natural Iron Ore from Muko Deposits
Abraham J. B. Muwanguzi,Andrey V. Karasev,Joseph K. Byaruhanga,Pär G. Jönsson
ISRN Materials Science , 2012, DOI: 10.5402/2012/174803
Abstract:
Lipid Lowering Potential of Malakwang (Hibiscus) Species Leaf Extract in Hyperlipidaemia-Induced Rats  [PDF]
Gertrude M. Alal Ojera, Yusuf B. Byaruhanga, Christine Magala-Nyago, Charles M. B. K. Muyanja
Food and Nutrition Sciences (FNS) , 2018, DOI: 10.4236/fns.2018.92012
Abstract:
Malakwang (Hibiscus species) is a common vegetable regularly used in the diet and traditional health care support in Uganda. In this study, the efficacy of malakwang leaf extract as a potential regulator of serum lipids, urea and creatinine was investigated in hyperlipidemic rats. Forty two albino rats were arranged randomly into seven groups of six and fed with diets. Four experimental and three control groups were considered in the design. The rats in the experimental groups were fed on high fat diets containing different amounts of leaf extract from red and white malakwang variants. Control groups were fed on diets devoid of malakwang: a basic standard rat diet; high fat diet; and high fat with atorvastatin. The diets were administered daily and rat weight determined. On the last day, blood was drawn from the rats and the serum analysed for lipids, creatinine and urea using spectrophotometric techniques. Statistical analysis was used to estimate mean differences in weight and concentration of the biochemical parameters between experimental and control groups. Results indicated a decrease in weight gained up to the fourth week in rats fed on the high fat diet with malakwang leaf extract. There was a significant difference in the levels of low density lipoprotein cholesterol (p < 0.05), with lower levels in rats fed on 200 mg/kg red and 400 mg/kg white malakwang leaf extract. No significant change was noted in total cholesterol and triglycerides. Whereas there was a higher level of serum creatinine with the two malakwang variants (p < 0.05), serum urea levels were significantly lower. Leaf extracts of both red and white malakwang (Hibiscus) exhibited capacity to reduce low density lipoprotein cholesterol, maintained serum urea but not creatinine. This may offer prospects for using malakwang in the dietary approaches to address public health concerns linked to high level of cholesterols.
Risk Factors and Co-Existence of Infectious Causes of Reproductive Failures in Selected Uganda Cattle and Goats: A Brucella spps-Toxoplasma gondii Study  [PDF]
Steven Kakooza, Maria Tumwebaze, Esther Nabatta, Joseph Byaruhanga, Dickson Stuart Tayebwa, Edward Wampande
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104502
Abstract:
Reproductive diseases are one of the most significant challenges in livestock breeding and production. The present study was done to determine the 1) sero-prevalence of Brucella spps and Toxoplasma gondii in bovine and caprine samples, 2) risk factors associated with sero-positivity, 3) occurrence of Brucella-T. gondii co-existence with emphasis on samples with a history of reproductive failure. To fulfill the stated objectives, a retrospective study was carried out in May, 2015 on livestock blood samples received by Central Diagnostic Laboratory for the period of February, 2014 to January, 2015. A total of 279 serum samples from livestock were submitted by farmers and veterinary practitioners for serological diagnostic tests. Of the total (279), 59 blood samples had sufficient bio-data crucial for their inclusion in the study and were screened for antibodies against Brucella spps using Standard Rose Bengal Antigen. Toxoplasma gondii infection was also confirmed by using multi species indirect ELISA Test kit. The overall Brucella and T. gondii serological prevalence derived from the samples was 49.2% and 3.4% respectively. A significant association was found between animal species (X2 = 3.836, P = 0.049), breed (X2 = 0.279, P = 0.041) and occurrence of Brucellosis. An overall prevalence of 3.8% mixed infection to Brucella spps and T. gondii in bovine samples was obtained where 2 animals which had previous occurrence of abortion were found positive. Information obtained from the study will add on already existing one in attempt to build a fulcrum for taming livestock reproductive failures a step to boosting productivity.
Gas Phase Activation of Methane Molecule with Lead Benzene Dication Complex Ion, [Pb(Benzene)2]2+  [PDF]
Joseph K. Koka
Materials Sciences and Applications (MSA) , 2019, DOI: 10.4236/msa.2019.102009
Abstract: Motivated by the search for ways of a more efficient usage of the ubiquitous, and unexploited resources of methane, recent progress in the gas-phase activation of methane by metal dication complex ion is discussed. The gas phase theoretical and experimental analysis on [Pb(Benzene)2]2+ was conducted. The [Pb(Benzene)2]2+ complex ions were prepared using a combination of the pick-up technique and high energy electron impact, and then held in a cold ion trap. Excitation with tuneable UV radiation resulted in the formation of [Pb(Benzene)2(H2O)]2+, [Pb(Benzene)2(H2O)2]2+, [Pb(Benzene)]+, Pb+ and Benzene+ ions when the experimental results were analysed. The two optimised geometries of [Pb(Benzene)2]2+ namely the C2V eclipse and C2 staggered were observed. Methane activation of [Pb(Benzene)2]2+ complex ion yielded [Pb(Benzene)2(Me)]2+. [Pb(Benzene)2(H2O)(Me)2]2+,? [Pb(Benzene)2(H2O)(Me)]2+, [PbBenzene(Me)3]2+ and [Pb(Benzene)(Me)]2+. The PEC calculated binding energy of methane to lead benzene dication complex ion was approximately 25.45% higher than the value recorded on DFT calculation. This difference was due to the charge differences on the lead metal centre. While the actual calculated charge on the Pb metal in the optimised geometry was 1.68 the charge of +2 on the Pb metal was considered in the PEC calculation.
The Distribution of the Time of Ruin, the Surplus Immediately before Ruin and Deficit at Ruin under Two Sided Risk Renewal Process  [PDF]
Joseph Justin Rebello, K. K. Thampi
Journal of Mathematical Finance (JMF) , 2017, DOI: 10.4236/jmf.2017.73032
Abstract: In the renewal risk theory, the study of two sided jumps has been attracted by many researchers since its introduction. After the development of the distribution of modified inter time claim occurrence, the explicit expressions for ruin theory components in the literature under some assumptions, in this work, we examine probability density of the time of ruin, surplus immediately before ruin and deficit at ruin respectively under two sided risk process using some basic assumptions. Explicit expressions for distribution of interest are being derived.
Potential Use of Selected Sweetpotato (Ipomea batatas Lam) Varieties as Defined by Chemical and Flour Pasting Characteristics  [PDF]
Agnes Nabubuya, Agnes Namutebi, Yusuf Byaruhanga, Judith Narvhus, Trude Wicklund
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.37118
Abstract: Chemical and functional properties of ten sweetpotato varieties were investigated. The sweetpotato were of various flesh colours which included orange, yellow, cream and white with dry matter content ranging from 30.2% - 39.2%. The sweetpotato varieties varied significantly (p < 0.05) in total amylase activity, total starch and amylose content whose value ranges were 0.256 - 0.570 mg/ml/min 68.4% - 73.6%, 16.2% - 23.4% respectively. The pH of flours from the different sweetpotato varieties ranged from 6.01 - 6.64. The pasting behaviours of the sweetpotato flours also showed significant differences (p < 0.05) in the individual parameters (peak time, pasting temperature, peak viscosity, trough viscosity, final viscosity, breakdown and setback) among the different varieties. The results revealed the influence of variety on the chemical composition of sweetpotato and their pasting properties. Correlations were also revealed among different components of the sweetpotatoes which would be a basis in selection of the varieties for processing into different products.
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