Centers for Ethio Mines Development

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Evaluation of Borax as an Alternative to Mercury in Gold Recovery: A Case Study of Benishangul Gumuz Region, Assosa Area, Western Ethiopia
(Addis Ababa University, 2025-05) Zeryihun Hailu; Bisrat Kebede (PhD); Enatfanta Melaku (Mrs.) Co- Advisor
Artisanal and small-scale gold mining (ASGM) plays a critical role in the Ethiopian economy, particularly in rural and resource-endowed regions like the Benishangul Gumuz Region, where it forms a mainstay of livelihood for many households. However, the extensive use of mercury for gold recovery in ASGM operations has raised serious environmental and public health concerns, such as soil and water contamination and toxic exposure that affect not only miners but also adjoining communities. The goal of this study was to evaluate borax as a safer and more environmentally friendly alternative to mercury in the gold extraction process, with a focus on the Assosa Zone. The study adopted comparative experimental analysis with ore samples collected from two geologically different mining areas: Agosha Kebele (quartz-vein-hosted primary ores) and Mukufute Kebele (alluvial placer deposits). Through the adoption of borax smelting and conventional mercury amalgamation techniques, the effectiveness of gold recovery was analyzed using statistical methods, including descriptive analysis, Wilcoxon Signed-Rank tests, and ANOVA. The results revealed that borax smelting yielded significantly better gold yields, with a mean recovery of 0.6125 g, compared to 0.2345 g from mercury amalgamation, while at the same time avoiding the toxic emissions and residual pollution associated with mercury. Borax also proved versatile for both ore types and showed practical advantages regarding safety, cost-effectiveness, and environmental preservation. This study confirms the technical and economic viability of introducing borax in Ethiopia’s ASGM industry and informs the wider effort towards reducing mercury use in small-scale mining. The study concludes by advocating for the adoption of borax through policy support, stakeholder training, and awareness creation, while also proposing areas of future research to determine its long-term environmental effects, socio-cultural acceptability, and potential for scalability in other mining areas.
Talc Beneficiation through Flotation Techniques in Ethiopia: A Case Study of Sidama Regional State, Hoko Woreda
(Addis Ababa University, 2025-03) Wakjira Tesfaye; Anteneh Marlign (PhD); Desisa Yadeta (PhD) Co-Advisor
Talc is a hydrated magnesium layered silicate mineral. The major uses are in the plastics industry, rubber, cosmetics, ceramics, and pharmaceuticals. Properties include increasing stiffness and resistance to heat and are suitable for talcum powder and tablet formulations since it is soft and inert. This project discusses the flotation parameters of talc beneficiation, sourced from the Sidama Regional State in Ethiopia, using high-grade and high-recovery outputs. The flotation techniques have always remained favorable for talc-beneficiating processes, especially because the process achieves gangue mineral separation. The experiments showed that under optimum conditions, the pH was 11, the collector dosage was 1.2 kg/ton, and the depressant dosage was 1.0 kg/ton, maintaining the pulp density at 200 g/l and an impeller speed of 1100 rpm. Under these conditions, the talc recovery was 74.25% in the flotation process. The chemical analysis of the resulting talc concentrate showed significant improvements: SiO₂ increased from 58.2% to 73.01%, while MgO increased from 24.22% to 24.62%. The Fe₂O₃ content decreased remarkably from 14.37% to 1.66%, reflecting a successful removal of impurities and a substantial increase in the purity of the final product. Results indicate that oleic acid and kerosene oil, with sodium hexametaphosphate as a depressant and propyl glycol as a frother, gave the best recovery with a grade improvement. Such a scheme of optimization of flotation conditions to improve talc quality is important in fulfilling these industrial applications in the industries of ceramics. This work contributes to an understanding of talc beneficiation techniques and forms the ground for further research on enhancing the talc recovery methods in Ethiopia and meeting the requirements of various industries for economic development.
Enhancing The Caloric Value of Coal Deposit Using Flotation Method in Lalo District, South-Western Ethiopia
(Addis Ababa University, 2025-02) Megersa Biratu; Melese Alemayehu (PhD); Bekele Ayele (PhD) Co-Advisor
Lalo coal reserves are mainly lignite and contain high ash coals therefore, it is important to enhance these low-quality coals. Coal applications are impacted by high ash content; hence improvements are required to lower the ash content of coal in our nation. Tests were carried out to investigate and determine the effect of parameters like particle size and collector dosage on reducing ash content from coal. The particle size observed to have the most significant role in coal ash, followed by the collector dosage. The optimum particle size and collector dosage values were -100+75μm and 7ml respectively. The results from the flotation study on a laboratory scale at optimized conditions revealed an increase in carbon content from 26.16% to 39.07%, decrease ash content and sulfur content from 25.75% to 20.09% and 0.47% to 0.21% respectively. Using a high ash content coal sample from the Lalo district coalfield, flotation is used in this study to improve the quality of coal samples to remove the ash and impurities.
Evaluation of Flotation Efficiency for Ela -Hanchano Coal in The Konta Zone, Southwestern Ethiopia Region, Ethiopia
(Addis Ababa University, 2025-02) Mebratu Menu; Melesse Alemayehu (PhD); Bekele Ayele (PhD)
The study focused on evaluating the efficiency of flotation processes in recovering coal from the Ela-Hanchano deposit in the Konta Zone of Southwestern Ethiopia. The work aims at improving recovery levels and upgrading the quality of coal by applying froth flotation, a physic-chemical method widely used for coal particles from associated impurities. This work considers critical parameters such as particle size distribution, the dosages of collector and frother, and their influence on flotation recovery, the grade of the concentrate, and the overall performance of coal beneficiation. Experimental work involved the preparation of coal samples through crushing and grinding, followed by sieving to the required particle size fractions (-500+250μm,-250+125μm and -75μm). Flotation tests were conducted using a laboratory flotation cell with kerosene as a collector and n-octanol as a frother. Recovery efficiency was evaluated at different reagent dosages and particle sizes. Proximate analyses were carried out to establish the physio-chemical characteristics of the treated coal, including moisture content, ash content, volatile matter, fixed carbon, sulfur content, and calorific value. Results showed that finer particle sizes significantly improved flotation recovery, and the highest efficiency was obtained as 87.58% for particles of under 75μm. The optimum collector (5ml) and frother (4ml) dosages improved the flotation process in terms of enhancing coal concentrate quality. Treated coal showed a reduction in ash content from 12.90% to 10.95%, a decrease in moisture content from 21.54% to 2.60%, and an increase in fixed carbon from 34.14% to 46.41%. The calorific value of the coal improved remarkably from 4,804.07 Cal/g (8,647.33 Btu/lb.) for raw coal and 6,418.15 Cal/g (11,552.67 Btu/lb.) for treated coal. This research underlines the importance of flotation parameters in the optimization of coal beneficiation and presents a framework that will help to improve the exploitation of Ethiopia’s coal resources.
Categorization of Coal Based on Composition and Mineralogical Analysis for Evaluation of Quality Indicators; A Case Study of the Botor Tolay Area, Jimma, Southwestern Ethiopia
(Addis Ababa University, 2025-05) Likasa Bakala; Kebede Gamo (PhD); Bekele Ayele (PhD) Co Advisor
The classification of the coal's composition from the Botor Tolay deposit and its implications for coal quality indicators are the main goals of this study. The project research employs analysis of coal samples collected from five points within the studied area, utilizing techniques such as proximate, calorific value, sulfur content, XRD, XRF, and FTIR analysis methods to determine key compositional elements. The results reveal distinct categories of coal based on their calorific value, sulfur presence, moisture content, ash content, volatile matter, fixed carbon, and fuel ratio. Accordingly, calorific value ranged from (7,406.54 to 9,783.46Btu/lb), sulfur content (0.17 to 0.21%), moisture content (1.12 to 1.46%), ash content (33.99 to 48.52%), volatile matter (19.13-21.94%), fixed carbon (30.84 to 42.88%) and fuel ratio (1.61 to 1.95%). Hence, all the studied coal samples fall within the sub-bituminous coal category based on calorific value categorization. One of the coals sample BT-1 has the highest percentage of fixed carbon (42.88%), which made it to have a high fuel ratio, enabling it to be more combustible. Major element analysis of the coal sample indicates it contains the maximum amount of SiO2 (67.668% by wt.), and Al2O3 (24.194% by wt.) followed by Fe2O3 (4.472% by wt.) and (TiO2 (1.296% by wt.). Functional group analysis indicated the presence of the peak of the -OH stretching vibration group and the peak in the spectra of coal found between 1100 and 400 cm−1, which are assigned to clay minerals such as quartz, kaolinite, and illite. The Crystal chemistry structure analysis of the coal sample revealed the presence of silicon dioxide (SiO2) and pyrite (FeS2), which may contribute to increased ash content.
Process Enhancement of Sapphire Gemstone from Borena Zone, Oromia Region, Southern Ethiopia
(Addis Ababa University, 2025-04) Kibirite Mokonen; Mulugeta Sisay (PhD); Aselefech Mitiku (Mrs.) Co-Advisor
The Borena Zone in the Oromia Region of Southern Ethiopia has recently emerged as a significant source of sapphires. Despite the region's potential, local processing methods remain rudimentary, often relying on manual labor and traditional techniques that limit the quality and market value of the gemstones. This study explores the current state of sapphire processing in the Borena Zone and proposes technological enhancements to improve the efficiency and quality of the final product. From Mining Engineering point of view, integrating advanced processing techniques, such as cabochon style and Faceting, the sapphire industry in this region can significantly elevate its quality of the mineral; Sapphire. Successful case studies from other regions, including Sri Lanka and Madagascar, highlight the transformative impact of modern processing technologies. Implementing these advancements in the Borena Zone has the potential to not only increase the value of Ethiopian sapphires but also foster the quality. and strengthen the local gemstone industry's global competitiveness. This project work underscores the critical need for technological investment and skill development to achieve substantial process enhancements in the Ethiopian gemstone sector.
Beneficiation of Blended Coal by Froth flotation Technique, In The case of Kripto Coal Mining and Chemicals PLC Elasanchano Woreda Konta Zone South West Region of Ethiopia
(Addis Ababa University, 2025-03) Ewunetu Mitku; Mulugeta Sisay (PhD); Mamaru Genetu (Mr.) Co-Advisor
Beneficiation of blended coal in the case of Kripto coal mining and chemicals plc located Elasanchano woreda konta zone, south western part of Ethiopia using kerosene as a collector n-octanol as afrother sodium silicate as a depressant with aeration speed of 1850 r/pm to facilitate the formation of small bubble enhance the calorific value of blended coal in the three flotation parameters studied in this project. which is particle size, frother dosage and flotation time is investigated. The optimal particle size we get maximum combustible recovery and quality is +125+-250 μm particle size which have 35.699% recovery and its heating value measured in boom calorimeter is 6,047.5781Ca/gram. The optimal frother dosage we get maximum recovery and grade is 6ml of n-octanol which have 65.157% recovery and its heating value is 6,412.7735 Ca/gram. The optimal flotation time we get high combustible recovery and quality of coal is 10 minute which have 70.426% of recovery and its calorific value is 5,894.4779 Cal/gram. Generally, froth flotation technique is good for environmentally friend method for the reduction of sulfur content in coal which reduce the release of SO2 gas cause for the formation of acid rain and health risks including lung cancer in humans. This project reduces the sulfur content of blended coal 0.68% to 0.44%. So, froth flotation is an appropriate method for the enhancement of heating value and proximate and ultimate characteristics of coal by removing the impurities from coal.
Mineralogical characterization of Bikilal Iron ore of Western Wollega, Gimbi, Ethiopia
(Addis Ababa University, 2024-09) Jebessa Mammo; Melesse Alemayehu (PhD)
The Bikilal Iron Deposit is located in Gimbi, West Wollega zone of Oromia National Regional State, 440 kilometers west of Addis Ababa and is found at 25 kilometers northeast of Gimbi town. Its iron ore deposit is a Kiruna-type magnetite – ilmenite deposit that consists of magnetite, ilmenite, hematite, sulphides, and apatite. The principal ore minerals are magnetite and ilmenite. Bikilal iron ore with 57 million tons of magmatic origin. Its iron ore accounts 23.3% magnetic iron content and with 41% total iron. The main objective of the project is to characterize the mineralogy of Bikilal iron ore so as to identify the main valuable minerals, gangue minerals, and their relationships, as well as the grain size in the various ore phases.To study the mineralogy of Bikilal Iron Ore secondary data were collected. Primary data were gained from laboratory analysis for thin section and polish section (One sample each) done at Ethiopian Geological Survey of Ethiopia, X-Ray Diffraction analysis done at Adama Science and Technology University Laboratory. The Polish section analysis indicates that mineral compositions were 10% Pyrite, 15% Ilmenite, 20% Magnetite and 1% Chalcopyrite with xenoblastic texture and 54% gangue. Thin section analysis also indicate that the description of the ore were dark gray in color and fine to coarse grained in texture and its mineral compositions were 62% plagioclase, 30% hornblende, 5% Opaque, and 3% Biotite.. Six Chemical composition analysis by atomic absorption Spectrophotometry (AAS) were taken from secondary data (Zewdneh Tassew, 1990) and (Debebe Tafesse, 1995) to analyze the major oxides present in the ore and their average results were 48.55% SiO2, 0.85% TiO2, 9.47% Fe2O3, 17.08% Al2O3, 8.68% MgO, 10.53% CaO, 2.35% Na2O, and 0.308% P2O5. Additionally, Seven X-ray florescence (XRF) results were taken from (tesfa Lemu, 2013) and the average results were 47.97% SiO2, 0.91%TiO2,17.52%Al2O, 9.65%Fe2O3, 0.13%MnO, 8.58%MgO, 12.03%CaO, 2,52%Na2O, 0.09%K2O, and 0.312%P2O5. Three samples were analyzed by the X-ray diffraction (XRD) on the Bikilal iron Ore at Adama Science and Technology University Laboratory. The phases were identified as 52.2% Hornblende, 1.2%Biotite, 27.8% Actinolite, 6.3% Titanomagnetite, and 12.6% amphibole. The elemental composition of the XRD analysis were O, Si, Fe, Ca, Mg, Al, K,Ti with negligible amount of F and V. From analysis results above SiO2, TiO2, and Al2O3 make up the majority of the gangue minerals in Bikilal iron ore, with an unacceptably high concentration of the harmful element phosphorus. One explanation for the indication of a decrement in the amount of the key mineral in the ore (Fe2O3) is the relatively high silica content of the Bikilal iron ore, even when compared to the iron mineral hematite. This indicates the amount of the gangue is very high that exceeds the amount of the important mineral present in the ore. Others impurities found in the ore include MgO, CaO, Na2O, K2O, TiO2 and albeit in smaller amounts. The commercial ore should contain fewer than 6% and 4% of silica and alumina, respectively (Joan J. Kiptarus et al., 2015) but the Bikilal iron ore SiO2 and Al2O3 average content are 36.2% and 6.4% respectively, that is very big difference in respect to gangue contents. Alumina is a particular target during the beneficiation of iron ore and is a representation of pollution in the steel-making process. As a result, the Bikilal iron ore deposit's average quality is below the needed requirement, which is less than 40%, and is not comparable to the top iron ore nations, leading to the low-grade ores. The deposit of the ore can be exploited for multiple sources of different valuable commodities in addition to iron ore like phosphorus, Gold, Aluminium and Titanium.
Flowsheet Development Studies for Lega Dembi Gold Process Plant
(Addis Ababa University, 2023-09) Adinew Abebe; Abubeker Yimam (PhD)
This flowsheet advancement of Legadambi processes for gold plant contain different unit operation and unit process. Legadambi gold process plant use different beneficiation mechanism to extract and recover the valuable metal or element of interst from associated mineral or gangue. The process consists seven consecutive and interdependent but segregated unit operating process and unit process. Process those implmented in Legadembi were comminution (crushing and grinding), Thickening and reagent leaching (Extraction), both adsorption and Desorption (stripping), Electrowinninng and gold Smelting,Tailing dam and Detoxification plant. The flowsheet consists two crushing circuits each consists a primary, secondary and tertiary stage crusher that produces a crushed ore product, which is then conveyed to feed the grinding unit. Grinding unit is configured in two single stage mills with cyclone classification to confine the particle size reduction within requirement range. Grinding unit consist circuit discharges ore slurry through desanding screen to thickening unit; screen removes trash material from overflow slurry. Flowsheet of thickener and reagent unit utilizes flocculent chemicals to increase/enhances settling rate of solid in grounded ore slurry for gold and silver leaching process. Leaching circuit uses sodium cyanide to extract gold. In the pulp procedure, activated carbon and gold from the ore are utilized to adsorb the recovered gold from solution in carbon. The carbon is gathered and processed in the elution circuit, which separates the carbon and gold, after the CIP circuit. While the gold is extracted from solution during the electrowinning process, the carbon is renewed and utilized again in the CIP circuit. To create gold Dore bars, the stripped and electrowonted gold is melted in a gold chamber. For the purposes of final deposition, recovering decant water, and the detoxifying process, process tailg ravitate to a tailing storage facility. Process tails solution detoxified in cyanide destruction plant before being discharged to the environment. Finally, Production process of each unit described with block and process flowsheet.
Grindability and Comminution Energy Consumption in Case of Midroc (Lega Dembi and Sakaro) Gold Ore
(Addis Ababa University, 2023-09) Yonas Hordofa; Bogale Tadasse (PhD)
The purpose of this study was to investigate the impact of mill speed and grinding time on the grindability and comminution of gold ores from the Lega Dembi and Sakaro deposits. A batch mill internal diameter of 200 mm and volume (5 dm3) was used for the experiment. The study employed a two-factor approach, considering different grinding times (10 and 15 minutes) and three fractions of mill critical speed (40%, 50%, and 60%).The experiment involved dividing the feed into five equal portions across eleven size class fractions ranging from 4mm to -75μm, with a √2-series interval. A total of ten kilograms of material, divided into one-kilogram portions, were used for the experiment. The objective of maintaining a critical speed below or equal to 50% was to minimize energy consumption during the milling process. The study aimed to assess both the grindability and energy consumption of the two deposits. The results of the study indicated that the rate of breakage increased with grinding time rather than mill speed. For the Lega Dembi deposit, at 40%, 50%, 60% speed and 15 minutes grinding time, the amounts of desired particle size classes produced were 251.7 grams, 264 grams, and 263 grams for the different mill speeds. Similarly, for the Sakaro deposit, the amounts produced were 251.7 grams, 232.6 grams, and 256 grams for the respective mill speeds. Based on the obtained results, the study concluded that mill speed had no significant effect on the grindability of the gold ores from both mining sites, as grinding times.
Grindibility and breakage characteristics of Sekota iron ore deposit in Wag-Himra Zone, Northern Ethiopia
(Addis Ababa University, 2023-06) Yohanes Belachew; Bogale Tadesse (PhD); Birtukan Yenealem (Co-Advisor)
In this study, the influence of mill rotation speed and grinding time were investigated on Sekota iron ore grinding process in a batch mill with length 150 mm and inner diameter 150 mm. The particle size distribution of the feed was carried out by an electric sieve and the bulk feed was classified into three samples to perform the grinding test. Three distinct iron ore feed size fractions between -335mm to +0.71mm, -0.71mm to +0.15mm and -3.35 to -0.075mm separated by a series of √2 gaps were prepared. The fractions were milled at different grinding times (5, 15, 25, 35, 45 and 60 min) at 450 rpm and at different mill rotational speeds (250, 300, 350, 450 and 550 rpm) at 25 min. The mill rotation speed and grinding time affect the energy consumption, the desired grind size and the P80 of the feed size fraction. When grinding time increased from 5 to 60 min, the percentage of cumulative mass of target size increased from 8.5 to 31.1%, from 7.1 to 22.8% and from 10.6 to 26% for coarse, fine and mixed iron ore size fractions, respectively. Likewise, a significant amount of the desired grind size is produced as the grinding speed increases until the maximum critical speed is reached. For all feed size fractions, the required grind size amount (-0.075 mm) is not achieved at grinding times from 5 min to 60 min and at maximum mill rotation speed (450 rpm). The product size distribution of the three iron ore feed size fractions were also affected as the grinding time and the mill rotation speed increased from 5 to 60 min and 250 rpm to the maximum speed (450 rpm). The P80 values of all feed size fraction generally decreased both milling time and mill speed are increased from 5 to 60min and 250 to 450 rpm respectively. Unlike the P80, the energy consumption of the ball mill increases significantly as the mill speed and grinding time increase from 250 to 450 rpm and from 5 to 60 minutes respectively.
Evaluation of the Nature of Porosity in Carbonate Rock Of Hamanlei Formation, Ogaden Basin, Ethiopia: Implications For Prediction of Reservoir Quality
(Addis Ababa University, 2023-06) Yimam Ali; Solomon Kassa (PhD)
The Ogaden basin is the largest sedimentary basin in Ethiopia having 350,000 km2 areal coverage. It is also the most studied sedimentary basin in Ethiopia. Nonetheless, the amount of data gathered from this baisn is not enough to better comprehend the petroleum system of the basin. The Hamanlei carbonate rock in the basin makes good reservoir rock. The nature of this reservoir rock is complex owing to various factors. Despite detail studies were conducted to understand the reservoir property, particularly core and wireline log study, further studies are needed for better characterization of this reservoir rock. To further characterize the reservoir property, i.e. porosity, of this rock and prediction for reservoir quality, petrographic and image analysis were performed. The outcome of this study provides valuable insights into the mineralogy and texture of the studied rocks. Furthermore, it highlights the importance of understanding the different pore types that enables to better interpret the reservoir quality and potential flow characteristics of the studied rocks. Generally, the porosity value of the reservoir rock is too small which is caused by the dominant proportion of matrix and cement
Process Mineralogy of Laga Dambi Gold Ore, Oromiya, Southern Ethiopia
(2023-09) Walkite Alemayehu; Bogale Tadesse (PhD)
To understand gold ore processing, the important mineralogical properties of Laga Dambi gold ore was described qualitatively and quantitatively. This is required to determine the parameters of gold ore grade, ore composition (elemental and mineralogical), and concentration of any valuable minerals, nature and concentration of minerals detrimental to the processing. One 75mm x50mm size polished thin section was supplied from each sample and was examined by conventional transmitted and reflected light polarizing microscope to determine the distribution of gold in the samples. Sub samples (500g) of each ore type were ground to 1mm and the heavy minerals concentrated using gold pan. The concentrates were submitted for mineralogical analysis to determine the distribution and particle size of gold in the samples. XRD, XRF and Geochemical analysis was carried out for gold mineralogical characterization and its concentration determination. From the data obtained it can be concluded that, gold is the most valuable element in the ore. The samples are all well graded and show excellent liberation. Sulphide mineralization is coarse within all the samples The pyrrhotite is the most abundant sulphide in all the samples, with the exception of Mse T5 where it is second in abundance to pyrite.Samples OP T1 and MSe T5 containing the highest concentrations of sulphide minerals. The gangue in the samples is dominated by crystalline quartz and mica (muscovite, biotite and phlogopite). Gold was identified in all but the Op T1 head sample. Pyrroyite, pyrite, and chalcopyrite are the most frequent interfering minerals that either consume cyanide or oxygen, or both, and adversely affect the rate or extent of gold leaching. From mineralogical point of view liberation size of gold can be determined to be120μm. from XRD and XRF techniques quartz was predominant gangue minerals in all types. Ankerite, dolomite and plagioclase feldspar were also present in minor constituent. All samples contained low levels of base metals, with the possible exception of OP T3, which are not likely to hinder processing mechanism.
Application of Lapidary Technology for Sustainable Gemstone Resource Development In Ethiopia
(2023-09) Tsion Shumalem; Abubeker Yimam (PhD); Aselefech Mitiku (Ms.)(Co-Advisor)
Ethiopia is renowned for its mineral abundance and more than 40 varieties of gemstone resources. With the artisanal and small scale miners controlling the production, the phase of the gemstone path abruptly came to a halt, with just a few rough dealers and a few gem cutters remaining, resulting in a very low economic benefit from the sector. The purpose of this study is to look into the function of lapidary technology for sustainable gemstone resource development in Ethiopia. The paper focuses on identifying the country‘s gemstone resource development challenges, the stages of the lapidary process and colored gemstone value chains, lapidary technology and the economic and social importance of lapidary technology in creating various jewelry and decorations using the new technology. In this study, interviews, literature reviews, lapidary work on a selected sample (gemstone from Wegel Tena, Amhara Regional State, Ethiopia), and an economic analysis of rough and value-added gems are conducted to analyze the role of lapidary technology on the industry. Furthermore, it is designed to comprehend the stages of the supply process and gem value chain, as well as to investigate the economic and social ramifications of modern lapidary technology on the development of sustainable gemstone resources. The impact of lapidary on increasing the value of rough gemstones is enormous. An economic analysis made of agate, crystal quartz, obsidian, jasper, and opal found that there is an increase between 400 and 70,000 folds due to the effect of lapidary technology and value added on the rough gemstone. The study’s findings revealed that the fragmented character of the gemstone business attributed to its lag behind other mining industries. Moreover, the study indicated that the gemstone industry in Ethiopia lacks technology, finance, lapidary expertise and a controlled market system. Enabling legislation should be put in place to ensure that the necessary economic return from gemstone resources is attained in order to protect the business and support a successful gemstone cutting and polishing industry.
Effect of Particle Size on Coal Cleaning by Froth Flotation Method in Didaye Woreda, Wolaita Zone
(2023-06) Tiruye Kassaw; Bogale Tadesse (PhD); Guta Legesse (PhD) (Co-Advisor)
The aim of this study is to investigate the effect of particle size on the efficiency of coal cleaning process by froth flotation. Coal cleaning is an important process, which involves removing ash, and other impurities from coal to improve its quality for energy and industrial use. Froth flotation is a widely used method for coal cleaning, which relies on the difference in surface properties between the coal particles and the mineral matter. However, the efficiency of froth flotation is greatly affected by the size of coal particles. In this study, four different sizes range of coal particles (-500μm+350πm, -350μm+225μm, -225μm+180μm and-180mμ+100μm) were tested for their ability to float in the froth flotation process. Results showed that the efficiency of coal cleaning was highest for particles ranging from at this particle size -350μm+225μm, while particles above +350μm showed the poorest performance. The results suggest that particle size is a critical factor in the success of coal cleaning by froth flotation, and -350μm+225μm coal particles are more amenable to this process. The findings of this study will help in optimizing the coal cleaning process to improve its efficiency index, combustible recovery and ash rejection.
Reverse Flotation as a Method for Beneficiation of Sekota Iron Ore
(Addis Ababa University, 2023-06) Temesgen Demissie; Abubeker Yimam (PhD)
Upgrading low grade Sekota iron ore to reduce the unwanted minerals and improve the quality is necessary to address these issues, in order to produce an acceptable feed for a steel production facility. The primary aim was to use reverse flotation as a beneficiation method for Sekota iron ore, in order to get a last flotation that meets the desired specifications. This process was divided into three stages: crushing, grinding, and flotation. For each of these stages, such as grinding, dosage of collectors, flotation duration, and procedures were determined. In the laboratory, where the samples were obtained, the ore was ground in a size of -0.074mm, using 250 grams of ore, with varying amounts of anionic oleic acid as the collector, 5mg/ton of activator and 5mg/ton of depressant, and floated with 2.0 g/ton of ethanol frother. The slurry was maintained at 10.5 using NaOH throughout the process. Before conducting any optimization tests on the iron ore flotation process, a laboratory procedure was developed to carry out the reverse flotation of the iron ore. The results showed that following these parameters, the flotation process achieved a final concentrate with a grade of 39.16% iron and an iron recovery of 41.29%. In this study, with varying duration of flotation, the iron grade ranged from 40-45% with an iron recovery of approximately 42%.
Flotation Response of the Kindo Didaye Coal Deposit, Wolaita Zone
(Addis Ababa University, 2023-06) Temesgen Ayisa; Mulugeta Sisay (PhD)
The main objective of the project was to investigate the optimum flotation behavior of the coal.Flotation is an important process, which involves removing ash, and other impurities from coal to improve its quality for energy and industrial use. Froth flotation is a widely used method for coal cleaning, which relies on the difference in surface properties between the coal particles and the mineral matter.However, the efficiency of froth flotation is greatly affected by the size of coal particles. The bulk sample from jaw crusher was milled by cross-bitter miller and coal sample was ready for separation in arranged sieve shakers based on their size. Then,fine powder coal samples were prepared by using different size of sieve shaker arranged as and measured the mass of the feeds of each particle size before the starting of flotation processes.In this study, four different sizes range of coal particles (-500 to +250 μm, -250 to +150 μm,-150 to +125 μm,-125μm to +75μm and -75 μm) were tested for their ability to float in the froth flotation process. Because of natural hydrophobicity of coal, there are a range of chemicals used to further enhance the floatability of coal particles.Results showed that the optimum flotation was highest for particle size und.75μm, while particles above +250μm showed the poorest performance and the same result was seen by the increase of kerosene amount at the same particle size. The results suggest that particle size and the over use of reagents are critical factors in the success of flotation response. The findings of this study will help in optimizing the coal cleaning by flotation increasing the heat value of the coal by avoiding the impurities. So in this flotation experiment the calorific value increases.
Reverse Anionic Flotation for Potential Beneficiation of Sekota Iron Ore, Northern Ethiopia
(Addis Ababa University, 2023-09) Tarekegn Dure; Abubeker Yimam (PhD)
In this project study, hematite ore sample obtained from Sekota area, Northern Ethiopia was used. Main objective of the study is to obtain iron concentrate at possible maximum grade and recovery by using reverse anionic flotation beneficiation method. The effect of oleic acid collector dosage and sieve size fractions were studied and optimized. The chemical and mineralogical characterization of the ore was also determined. Results of chemical analysis using atomic absorption spectroscopy (AAS) showed that the iron ore contains 65.12% Fe2O3 (45.57% Fe). Major gangue minerals were SiO2 (20.62%) and Al2O3 (8.86%) while all other minerals were reported at <1%. Mineralogical descriptions using the X-ray diffraction (XRD) and QEMSCAN BMA showed predominantly hematite and goethite with quartz, kaolinite and clay as gangue minerals while others P and S are in lower amounts. The concentrate 62.96% Fe2O3 with highest grade of 44.07% Fe was obtained with 43.4% Fe recovery in the feed size fraction (−63 μm) adding 3g/t of oleic acid collector. Based on the results obtained from the flotation tests conducted, Sekota iron ore at a sieve size of -75μm and -63μm were able to enhancing both grade and recovery.
Identification of Reservoir Rocks, Properties and Structural Mapping of the Abay Basin in Viewing of Petroleum Exploration
(Addis Ababa University, 2023-06) Seid Endrie; Ketsela Tadesse (PhD); Bisrat Kebede (PhD) (Co-Advisor)
The basins has unique geological characteristics and holds different types of sedimentary rocks, such as sandstones, shales, carbonates, and volcanic rocks. The Abay (Blue Nile) Basin is located in the northwestern part of the country and covers an area of over 63,000 square kilometers. The Abay Basins covers a sizable area of the country. It includes Were Ilu, Mechale, and Legehida, which have notable oil seep exhibits. The contribution of the Upper Sandstone reservoir rock data is gathered from prior researchers and written materials in order to develop a relevant relationship between the types of reservoir rocks and structural mapping of the study area. In order to undertake the experimental tests for this study, samples are gathered from the field and sent to laboratory centers. In the laboratory, the chemical composition, porosity and permeability values of the reservoir rocks are determined using a representative sample that was collected from the study area. Based on the results of the experiments, the reservoir rock for the Abay (Blue Nile) Basin formation is an Upper Sandstone reservoir rock with relatively good porosity and excellent permeability. The Upper Sandstone rocks in the Abay basin have porosity values that range from 32.31 to 34.35% and permeability values that range from 1766 to 2350 mD, which suggests that the reservoir quality is generally very good (porosity)and excellent (permeability). During field work, it was discovered that the following fault systems were dominate in the study area. These includes; east-west (E-W) trending faults, northeast-southwest (NE-SW) trending faults, and northwest-southeast (NW-SE) trending faults. The oil and natural gas can be gathered and stored in reservoirs, the geological features called hydrocarbon traps. The presence of a petroleum system in the Abay Basin is strongly supported by the oil seepage at Were Ilu. The study area is characterized by rough structures, so airborne geophysical surveys are advised rather than ground geophysical surveys; seismic lines are needed for the study of the Abay Basin in order to delineate structural traps, stratigraphic traps, and indicate active faulting in the areas where it is possible for seismic line surveys; the basin requires further study regarding the main hydrocarbon fluids reservoir rocks, the total organic carbon contents of the source rocks and the carbonate reservoir rocks.
Reverse Flotation Potential of Bikilal Iron Ore Deposit: A Project Work on Wollega Area Western Ethiopia
(Addis Ababa University, 2023-06) Samuel Getaneh; Mulugeta Sisay (PhD); Guta Legesse (PhD) (Co-Advisor)
Iron is one of the most abundant rock forming elements, constituting about 5% of the earth’s crust. It is the fourth most abundant element next to oxygen, silicon and aluminum and after aluminum, the most abundant and widely distributed metal. Iron is extracted primarily from iron ores. The iron ores mainly include oxides and hydroxides such as magnetite (Fe3O4), hematite [Fe2O3], goethite [FeO(OH)], and limonite [FeO(OH)_nH2O].The primary gangue mineral in iron ores is quartz. The main problem regarding to beneficiate the Bikilal iron ore deposit are the presence of some deleterious gangue minerals such as Phosphorous, Alumina and silica and lack of advanced separation equipment. The aim of this project work is to indicate that the Bikilal iron ore deposit has naturally low grade iron content which is 41.2%Fe and it can be improved by anionic reverse flotation. The method used to upgrade this ore is first the qualitative and quantitative mineralogical analysis has been determined by atomic absorption spectroscopy (AAS) to know the initial amount of iron in the ore. Based on this information reverse anionic flotation has conducted in a batch flotation cell in two size classes at 75μm and 63μm. Oleic acid has been used as a collector whereas Ethanol used as a Frother. Modifiers such as activators, depressants and pH regulators have also used to promote the efficiency of flotation process. The concentrate of flotation has been analyzed again by (AAS) to evaluate the performance of the selected method. The amount from the concentrate has significantly increased from 41.2%Fe average grade to 62%Fe grade. The recovery of iron have been calculated as 65% for under 63μm and 74.4% for under 75μm.The amount of the concentrate for 63μm was 215g and that of 75μm was 250g. Therefore the recovery of iron from 215g under 63 μm is 65.5%Fe which is better than the recovery from 250g under 75μm that is 74.4%Fe. This project work mainly conducted based on (AAS) analysis results but it is not suffifeint to judge the general mineralogical composition and beneficiation process that should be applied in the Bikilal iron ore deposit. Therefore additional investigations and laboratory analysis such as (XRD), (SEM) and (XRF) are recommended to come up with a more tangible and realistic data. This paper have also discusses in detail about the factors that can affect the flotation performance of the ore and the alternative chemical reagents that can go through the mineralogy of Bikilal iron ore deposit.

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