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- Kasedde, Hillary, et al.
(författare)
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Characterization of brines and evaporites of Lake Katwe, Uganda
- 2014
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Ingår i: Journal of African Earth Sciences. - : Elsevier BV. - 0899-5362 .- 1464-343X. ; 91, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- Lake Katwe brines and evaporites were investigated to determine their chemical, mineralogical and morphological composition. 30 brine samples and 3 solid salt samples (evaporites) were collected from different locations of the lake deposit. Several analytical techniques were used to determine the chemical composition of the samples including Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS), ion chromatography, and potentiometric titration. The mineralogical composition and morphology of the evaporites was determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Physical parameters of the lake brines such as density, electrical conductivity, pH, and salinity were also studied. The results show that the lake brines are highly alkaline and rich in Na+, Cl-, CO32-, SO42-, and HCO3- with lesser amounts of K+, Mg2+, Ca2+, Br-, and F- ions. The brines show an intermediate transition between Na-Cl and Na-HCO3 water types. Among the trace metals, the lake brines were found to be enriched in B, I, Sr, Fe, Mo, Ba, and Mn. The solid salts are composed of halite mixed with other salts such as hanksite, burkeite and trona. It was also observed that the composition of the salts varies considerably even within the same grades.
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| 3. |
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| 4. |
- Kasedde, Hillary, et al.
(författare)
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Mineral recovery from Lake Katwe brines using isothermal evaporation
- 2013
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Ingår i: International Mine Water Association Annual Conference 2013. - : IMWA International Mine Water Association. - 9780615793856 ; , s. 855-860
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Konferensbidrag (refereegranskat)abstract
- Lake Katwe is a saline lake within the East African Rift system in Western Uganda, with a rich source of mineral salts. The present work aims at evaluating possibilities of future salt extraction from the lake deposit. An isothermal evaporation experiment was conducted on the lake brines. The precipitated salts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. Various economic salts such as thenardite, gypsum, mirabilite, burkeite, hanksite, anhydrite, trona, halite, nahcolite, thermonatrite, and soda ash precipitate from the lake brines. The experiments also reveal the sequence of mineral salt precipitation in the order sulfates→chlorides→carbonates.
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| 7. |
- Kirabira, John Baptist
(författare)
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Characterisation of Ugandan raw-minerals for firebricks -before and after sintering.
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Development of products which can be produced from acountry's natural resources is very important as far as theindustrialization of a nation and saving foreign exchange isconcerned. Presently, industries in Uganda and the other statesin the Lake Victoria region import allrefractory-related-consumables, as the demand cannot be metlocally. Based on the abundance of ceramic raw materials forhigh temperature applications in the region and the demand forrefractories by industries it is pertinent to develop andmanufacture firebricks by exploiting the locally available rawmaterials.This thesis thus, concerns the characterisation of ceramicraw mineral powders from in the Lake Victoria region, moreparticularly, Uganda, with the aim of developing firebrickrefractories from the minerals. Two main deposits of kaolin anda fireclay deposit, located in the Lake Victoria Region,Uganda, were investigated to assess their potential in themanufacture of refractory bricks. Raw- and processed samplepowders were investigated by means of x-ray diffraction (XRD),thermal analysis (DTA-TG) and Scanning Electron Microscopy(SEM). In addition, the chemical composition, particle sizedistribution, density, and surface area of the powders weredetermined.A general production process scheme for manufacture offirebricks starting with raw powder minerals (Mutaka kaolin andMukono ball clay) was used to make six groups of samplefirebrick. Experimental results from the characterization offormulated sample bricks indeed reveal the viability ofmanufacturing firebricks from the raw minerals.Characterization of the sample bricks has been done fordetermination of physical and mechanical properties; density,shrinkage, porosity, water absorption, and phaseidentification. Formation of mullite, which is a principalcompound for aluminous refractories, is evidenced in thepowders with DTA tests and for the fired samples with XRD; thefired samples are dominated by mullite peaks.Keywords: kaolin; clay; powders characterization; ceramics;mullite; Lake Victoria region;
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| 8. |
- Kirabira, John Baptist, et al.
(författare)
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Fireclay refractories from Ugandan kaolinitic minerals
- 2006
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 77:8, s. 531-536
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, two deposits, one of kaolin and the other of ball clay, located in Uganda were investigated for the possibility of manufacturing fireclay refractories. Kaolin from the Mutaka deposit was used as the main source of alumina while ball clay from Mukono was the main plasticizer and binder material. The formulated green body was consolidated by wet pressing and fired at 1350 degrees C in a tunnel kiln. Characterization of the sintered articles was done by X-ray diffraction, scanning electron microscopy, and chemical composition (ICP-AES). In addition, technological properties related to thermal conductivity, thermal shock, alkali resistance, water absorption, porosity, shrinkage, permanent linear change, linear thermal expansion, refractoriness under load, and cold crushing strength were determined. The properties of the articles manufactured from these naturally occurring raw minerals reveal that they compare favorably with those of parallel types. Thus, the raw materials can be exploited for industrial production.
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| 9. |
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| 10. |
- Kirabira, John Baptist, et al.
(författare)
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Powder characterization of high temperature ceramic raw materials in the Lake Victoria Region.
- 2005
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Ingår i: Silicates industriels. - 0037-5225. ; 70:10-sep, s. 127-134
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Tidskriftsartikel (refereegranskat)abstract
- Two main deposits of kaolin and one of fireclay, located in the Lake Victoria Region, Uganda, were investigated to assess their potential in the manufacture of refractory bricks. Raw- and processed sample powders were investigated by means of x-ray diffraction (XRD), thermal analysis (DTA-TG) and Scanning Electron Microscopy (SEM). In addition, the chemical composition, particle size distribution, density, and surface area of the powders were determined.
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| 11. |
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| 12. |
- Kirabira, John Baptist, 1979-
(författare)
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Properties of Ugandan minerals and fireclay refractories
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Development of products which can be produced from a country’s natural resources is very important as far as the industrialization of a nation and saving foreign exchange is concerned. Presently, industries in Uganda and the other states in the Lake Victoria region import all refractory-related-consumables, as the demand cannot be met locally. Based on the abundance of ceramic raw materials for high temperature applications in the region and the demand for refractories by industries it is pertinent to develop and manufacture firebricks by exploiting the locally available raw materials. This thesis thus, concerns the characterisation of ceramic raw mineral powders from the Lake Victoria region, more particularly, Uganda, with the aim of developing firebrick refractories from the minerals. Two main deposits of kaolin and a ball clay deposit were investigated to assess their potential in the manufacture of refractory bricks. Raw- and processed sample powders were investigated by means of X-ray diffraction (XRD), thermal analysis (DTA-TG) and Scanning Electron Microscopy (SEM). In addition, the chemical composition, particle size distribution, density, and surface area of the powders were determined. A comprehensive study on beneficiation of Mutaka kaolin was carried out using mechanical segregation of particles. The aim of the study was to explore other potential applications like in paper filling and coating. The beneficiation process improves the chemical composition of kaolin to almost pure, the major impurity being iron oxide. A general production process scheme for manufacturing fireclay bricks starting with raw powder minerals (Mutaka kaolin and Mukono ball clay) was used to make six groups of sample fireclay brick. Experimental results from the characterization of formulated sample bricks indeed revealed the viability of manufacturing fireclay bricks from the raw minerals. Based on these results, industrial samples were formulated and manufactured at Höganäs Bjuf AB, Sweden. Kaolin from the Mutaka deposit was used as the main source of alumina while ball clay from Mukono was the main plasticizer and binder material. The formulated green body was consolidated by wet pressing and fired at 1350°C in a tunnel kiln. Characterization of the sintered articles was done by X-ray diffraction, scanning electron microscopy, and chemical composition (ICP-AES). In addition, technological properties related to thermal conductivity, thermal shock, alkali resistance, water absorption, porosity, shrinkage, permanent linear change (PLC), linear thermal expansion, refractoriness under load (RUL), and cold crushing strength were determined. The properties of the articles manufactured from the selected naturally occurring raw minerals reveal that the produced articles compare favourably with those of parallel types. Thus, the raw materials can be exploited for industrial production.
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| 13. |
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| 14. |
- Kirabira, John Baptist, et al.
(författare)
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Towards the improvement of salt extraction at Lake Katwe, Uganda
- 2013
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Ingår i: International Journal of Scientific and Technology Research. - 2277-8616. ; 2:1, s. 76-81
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of Lake Katwe salt deposit in Western Uganda is well-known through the East African region. Production of salt from this saline lake has been practiced for decades following traditional methods; however the quality and yield of the products are poor. There are also risks of burns, as the workers get into direct contact with the brine. Detail assessment and evaluation of the mine has been done through field studies, raw sample materials analysis. Results indicate that the raw brine from the lake is rich in sodium, chloride, potassium, carbonates, sulphate ions with traces of calcium, magnesium, and bicarbonate ions. This motivates the aspiration to properly extract salts from such a rich source. The lake brines contain impurities such as organic matter and suspended solids. With increasing demand for usage of sustainable technologies for saltextraction, the present study calls for the improvement of salt extraction at Lake Katwe through optimizing the use of the current solar evaporation technique while integrating it with a mechanized chemical separation process. This would ensure better recovery and process efficiencies, low costs and simple brine pre-treatment procedures.
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