Centers for Ethio Mines Development

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Analyzing the Effect of Operational Parameters on the Breakage Mechanisms of Spodumene Mineral to Optimize the Comminution Processes of Lithium Bearing Pegmatite in Kenticha, Ethiopia
(Addis Ababa University, 2023-06) Abdu Ebrahim; Alberto Velazquez Del Rosario (Prof); Ijara Tesfaye (Mr.0
This study is aimed to investigate the optimal operational conditions for breaking down the Kenticha, Ethiopia Li-pegmatite,which contains lithium minerals, particularly spodumene. The goal is to produce high-quality spodumene concentrate by achieving the desired particle size, particle distribution, which are crucial for efficient separation during the physical separation and subsequent froth flotation steps. To achieve this, one sample from Kenticha Li-pegmatite replicated four times were characterized using X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS) techniques for mineralogical and geochemical analysis respectively. XRD analysis confirmed that the ore was predominantly composed of spodumene, with minor amounts of quartz, mica and feldspar. AAS analysis showed that the ore contained a moderately high level of lithium (approximately 2.5%) as well as other trace elements such as iron, and very low amount manganese and phosphorus. The results indicated that the ore had the potential to be a valuable source of lithium for industrial purposes. The sample then were crushed using a Laboratory Jaw Crusher in primary step and the study was conducted for different conditions parameters of grinding as a secondary step using a Laboratory Ball Mill. Optimal breakage mechanism was determined to achieve the desired spodumene concentrate.The results showed that the optimal conditions under the experimental analysis identified as milling power: 41 W, amount of feed: 250 g and the milling speed: 500 rpm, could produce narrow size distribution and the desired particle size for high spodumene concentration. This research has significant implications in the field of lithium mineral processing, providing important insights into the operational parameters that can achieve high-quality spodumene concentrate.
Applicability of Gravity Separation Method on The Ashashire Gold Ore Deposit from Benishangul Gumuz Region, Ethiopia
(Addis Ababa University, 2023-06) Misganu Kabeta; Mulugeta Sisay (PhD); Abaynesh Mitiku (Mr.) (Co-Advisor)
The current Project of applicability of gravity separation method for gold ore deposit was conducted in Ashashire locality of Benishangul gumuz region, North western Ethiopia. The purpose of this project is beneficiating the Ashashire gold ore deposit by applying the gravity separation. The Ashashire composites were produced to provide sufficient mass for this study and experiment includes sample preparation, head assay analysis of gold and multi-element, gravity concentration and mineralogical analysis. The study conducted to determine the applicability of gravity separation method by using KC on the Ashashire gold ore deposit. The samples were moderately ground to the standard grind size of P80 - passing 106, 75, 53 μm and this nominal size was selected for the preliminary assessment for Concentration optimization. During the study, a grind optimization was conducted on the composites sample with varying grind size to evaluate the effect of grind size on gold recovery. The gravity testing comprised three-stage concentration by centrifugal knelson concentrator to produce gravity concentrate. High recovery of gold from the gravity concentrates was achieved from the second gravity concentration. Based on the results from laboratory experiments, a grind size of P80 75 μm is selected as optimal size for the ashashire deposit using KC gravity methods. Increasing the grind size from P80 of 75 μm to106 μm decrease recovery rate from 75 % to 54 % or decreasing the grind size from P80 of 75 to 53 μm decrease gold recovery rate to 37%. It was observed that repeat gold head assays varied, indicating the presence of coarse gold particles and uneven gold particle distribution. The native gold grain in the ores is mostly associated with quartz and Fine gold is closely associated with pyrite, forming inclusions and dispersed within pyrite. According to the fire assay, chemical, and mineralogical analyzes data, only gold and telluride is commercially valuable component in the ores. Presence of 2.13 ppm Te was detected in the composite sample during head assay analysis. The differences between assayed head grades and calculated head grades would indicate that the gold is not evenly distributed within the ore and occurs as localised spots. Gold was identified to occur predominantly in the native form and as Au-Te. The sample subjected to gravity separation assayed about 2.6 g/t Au.
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.
Application of Montmorillonite Type Bentonite Clay From Chacha Area as Alternative for Local Construction Material
(Addis Ababa University, 2023-06) Addisu Misgana; Abubeker Yimam (PhD); Enatfanta Melaku (Mr.)
Hollow concrete block are produced from derbanPozolana Portland Cement (PPC), pumice and other aggregates (sand, scoria, gravel and clay). Mixing ratio and composition for HCBs although depend on the availability of materials. It is widely varying among the producers of cottage and industrial scale. However, all producers apply cement as a major constituent for binding. The demand of cement for HCBs and other construction materials is very high while the cement supply is very low. As a result, cost of production and sell price in the market is expensive and becoming not affordable for end users. The objective of this study is to investigate and evaluate the effect in using relatively cheaper bentoniteas cement replacement in HCBs production. Bentonite is available in a bulk when compared to cement. In the process focushas been given for curing and compressive strengthof HCB by varying the amount of cement and bentonite as major constituents in three ways (10kg bentonite replacing 10kg cement, 15 kg bentonite replacing 15 kg cement and 20 kg bentonite replacing 20 kg cement for a single batch /64 HCBs). All HCB samples were produced using 0.84 m3 pumice, 40 liters’ water. In addition silicate analysis (chemical composition) and physical properties (bulk density, moisture content and free swell test) of Chacha clay. Standard Compressive strength tests using (CES24:2013) method for HCBs of six sample replicates with average result on a total of 54 samples tests were made for 14, 21 and 28 age of curing time. For 28days’ age the average compressive strength (N/mm2) of 1.43, 1.27 and 1.23 were achieved by 10%, 15% and 20% bentonite replacement respectively. The compressive strength of HCBs is found to increase with increase of curing age and decreases with increase of the bentonite loading ratio. Generally, replacing of cement with bentonite at 28 days, a 10% bentonite replacement obtained the highest strength value, followed by a 15% bentonite loading ratio and a 20% bentonite loading ratio.
Beneficiation and Upgrading of Coal Via Dense Media Separation (DMS) In Ankober Woreda, North Shewa Zone
(2023-06) Gizachew Ayu; Bogale Tadesse (PhD); Henok Tamirat (Mr.)(Co-Advisor)
Coal is a type of fossil fuel and a combustible black or brownish-black sedimentary rock, formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years as rock strata and used as a fuel for energy resource. But, coal is usually formed associated with gang mineral (ash) those can decrease combustibility of coal. Thus, to utilize this resource safely and efficiently, coal separation and concentration is required. Density-based rejection of ash is an effective method to remove gangue before the process of coal combustion for the purpose of improving the quality of coal. By using a uniform crushed particle size of coal sample (-4.75+4.5 mm) in different specific gravities of heavy medium (1.4, 1.6, and 1.6), the specific gravity of 1.4 was found to be the optimum parameters to successfully upgrade the coal and improve its calorific value. Based on the results of the float product of 32.8% of concentrated coal and 24% upgraded coal obtained with reduced ash content of 60.72% and 21.79% increase of fixed carbon at specific gravity 1.4 and also it was found that upgrading, floating, fixed carbon as well as ash reduction subsequently decreases in floats as the specific gravity increases unlike volatile matter. From this work, it can be concluded that beneficiation and upgrading of coal by dense media separation method is good technique to produce improved and safely used coal as an energy source for coal-fired utilization.
Biostratigraphy, Burial History and Thermal History of Gambella Basin, Ethiopia; Implications for Source-Reservoir Interaction and Hydrocarbon Generative Potential
(2023-06) Changkuoth Dhan; Samuel Getnet (PhD)
The Gambella Basin, located in southwestern Ethiopia, near the Sudan border, covers an area of about 15,350 sq.km. It has a NW-SE elongated outline, and it is presumed to be the southeastern extension of the Melut Basin of South Sudan. Geological data review indicates that sedimentation in the interior Basins of the South Sudan is controlled by intermittent rifting phases that continued up to Mid Miocene. Biostratigraphy, Burial history and Thermal history evaluation of Gambella area, analysis include the Palynological and Paleoenvironment analysis on 104 cuttings samples and 16 sidewall cores from the interval of 60-3500 mKB in Jekow well and carried out on seventy 70 ditch cuttings from the interval 745-3250 in Jacaranda well (PCOB report, 2007 ). The exploration wells, Jekow (in the East) and Jacaranda (in the West) Gambella, Ethiopia which have penetrated the target zone of Sothern Melut Basin extension of the South Sudanese rift Basin. The source rock screening, Thermal Maturity, zonal layer, geologic section, the vitrinite reflectance and the age have target the interest of burial history and the hydrocarbon generative of the Basin. A one-dimensional modeling of Burial history and Thermal history was performed in Jekow and Jacaranda locations using one PetroMod 1-Dimensional modeling of Integrated Exploration Systems of Gesellschaft mit beschränkter Haftung, (GmbH-IES), Germany. However, due to unsuccessful exploration campaign in South Melut Basin where Gambella Basin is extended and in addition to the poor quality seismic data implied that the risk for the petroleum system in the West Gambella Sub-basin is still very high.
Characterization of Coal Composition of Shela Area, Wolayita Zone, Southern Ethiopia, Implication
(Addis Ababa University, 2023-06) Abinet Markos; Sofiya Abdulkadir (PhD)
The present study focused on the mineral characterization of Kindo-Didaye coal by adiabatic Calorie Metter, Gravimetric, hard groove index and proximate techniques. The result showed that coal quality ranged between (2475.79-10931.96Btu/lb); Sulphur (<0.02 % to 2.93%), moisture (1.21 to 1.99 %), volatile matter (15.45 to 26.37%), ash content (28.19 to 71.26%) and fixed carbon (11.21 to 44.23%). The majority of the Coal samples fall within lignite “B”, subbituminous “B” and sub-bituminous “C” ranks and none agglomerating. The grindablity index of the majority of the coal samples has the range (56.2-66), which HGI values of the Shela area coal samples indicate that most of the samples can be characterized as lignite and are also extremely challenging to grind.
Characterization of Ore and Gangue Mineralogy at The Ashashire Gold Deposit, Benishangul- Gumz Region, Western Ethiopia
(Addis Ababa University, 2023-06) Getnet Belachew; Melesse Alemayehu (PhD); Basalifew Zenebe (Mr.) (Co-Advisor)
Gold is a precious metal that is highly prized and has been significant throughout human history. It has been used as money and for ornamental purposes. It is a crucial component in electronics, medical equipment, and other industrial uses. Around the world, mining operations have sprung up in response to the demand for gold, and efficient extraction and processing depend on an understanding of the mineralogy of gold deposits. This study aimed to characterize the mineralogy of the Ashashire gold deposit located in the Benishangul Gumuz Regional State, Western Ethiopia. Six representative mineralized core samples were analyzed using fire assay with atomic absorption spectroscopy (AAS), inductively coupled plasma (ICP), quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) and X-ray diffraction (XRD). The study found that the gold in the deposit occurs primarily as native gold and gold-telluride, with a strong association with tellurium and often found as free particles or in association with gangue minerals such as quartz and pyrite. Pyrite is the dominant sulfide mineral detected in all core samples, with only trace amounts of chalcopyrite detected. The gangue minerals present in the deposit are mainly quartz, ankerite-dolomite, muscovite, chlorite, and albite, with lower levels of paragonite, rutile, magnetite, and calcite. The presence of tellurium suggests that specialized processing techniques may be required to liberate the gold from the tellurides. The degree of liberation, liberation sizes, and recovery of gold are all impacted by the texture of the ore. The gangue mineral composition of the ore can also impact gold processing in several ways, including cyanide consumption, clay coating and gold adsorption, ore hardness, mineralogical complexity, and processing costs. The mineralogical data can be used to develop a suitable processing route, taking into account the ore texture, gold mineralogy, and gangue mineral composition. A combination of techniques such as gravity separation, flotation, cyanide leaching, pressure oxidation, and CIL/CIP could be employed to maximize gold recovery and minimize environmental impact. Further metallurgical testing and optimization are necessary to fully understand and optimize gold recovery from this deposit.
Characterization of Permian to Triassic Formation Within Ogaden Reservoir Ethiopia, Implication of Source Reservoir Interaction
(2023-06) Eshetu Lema; Samuel Getnet (PhD)
The Ogaden region is located on the Somali Plateau, in southeast Ethiopia. Originally a clanbased term, the Ogaden is now commonly used for the entire region below about 1,500 m a.s. l., an area of some 350,000 km2 that encompasses most of the Somali Regional State and includes the southwest portion of Oromia. The Northern Ogaden Basin is underlain by Precambrian basement rocks and Phanerozoic rocks consist of Paleozoic – Mesozoic sedimentary rocks and Cenozoic volcanic and cover rocks. The Phanerozoic of northern Ogaden Basin is formed on an exhumed rift-related, NW-to WNW trending basin that formed as a result of the NE-SW extension that began in Paleozoic. The oldest rocks in the basin are represented by the deposition of Paleozoic-Early Jurassic succession, which is made of continental clastic sediments (Wayu Sandstone and Adigrat Sandstone). They are deposited within grabens bounded by NW-trending and northeast-and southwest-dipping normal faults, which are developed above a top-to-northeast detachment fault. They are un conformably overlain by Middle – Late Jurassic sediments comprised of mainly limestone with minor interbeds of shale and marls (Hamanlei, Urandab and Gabredarre Formation) that pass upward into the Garbeharre Formation, which consists of sandstone, mudstone, shale with minor interbeds of limestone at the base of the succession. The climate is hot, arid to semiarid, corresponding to the Ethiopian bereha and kolla climatic zones. Three basic physiographic provinces are recognized: the Genale and Shebele drainage basins and the Eastern Slope and Plains. The two drainage basins include spectacular upstream canyons that witness the vertical movements that have accompanied the succession of rifting events in the Ethiopian Rift, Afar, and the Gulf of Aden. In strong contrast, the Eastern Slopes and Plains is dipping less than 0.4° on average over hundreds of kilometers to the southeast and is mantled by red sands. Several remarkable Oagden landforms are described and analyzed, including volcanic, fluvial, and gravitational features, some having few equivalents in other areas on Earth.
Characterizing the Ore Mineralogy of Kenticha Pegmatite for Lithium Beneficiation, Southern Ethiopia
(Addis Ababa University, 2023-06) Gutema Mekonen; Alberto Velazquez (Prof.); Kaleb Gebreyes (Mr.) (Co-Advisor)
Lithium is a highly sought-after resource crucial for rechargeable batteries, and the Kenticha pegmatite ore deposit in Ethiopia holds potential as a source of this valuable element. The focus of this study was to investigate the mineralization of Kenticha, specifically the spodumene ore, and its suitability for beneficiation processes. Through XRD, AAS, and petrographic microscope analysis, the study identified the minerals present in the spodumene pegmatite ore, their average composition, and mineral texture for spodumene concentrate liberation. Spodumene was found to be the most abundant mineral, but its low degree of liberation from other minerals required additional processing steps for high yield. Weathering significantly impacted mineral identification and quantification, affecting diverse mineral morphology and liberation. The study's findings have implications for mining operations, exploration, and processing strategies, suggesting additional processing steps for spodumene recovery and highlighting the impact of weathering on mineral characterization. The study provides valuable information on mineral texture and liberation for selecting processing methods for beneficiation, contributing to a better understanding of the Kenticha pegmatite ore deposit's mineralization potential for lithium extraction.
Comminution circuit flow sheet Development for Optimum Performance of Iron Ore Processing, in the Case of Sekota, Wagehimra, Northern Ethiopia
(Addis Ababa University, 2023-06) Ephrem Tialhun; Abubeker Yimam (PhD); Megeressa Bedo (Mr.) (Co-Advisor)
Sekota Iron Ore aims to contribute to the economic development of Ethiopia by exploiting and producing high-quality iron ore for both domestic and international markets. The company expects to create employment opportunities and generate revenue for the government, which can be used to invest in other developmental projects. Besides, the establishment of Sekota Iron Ore could also help to reduce the country's reliance on imported iron and steel products, promote local industries and contribute to the growth of the mining sector. Most of the minerals extracted in the nature are founded disseminated with the gangue, this creates a necessity to liberate these particles and reduce the size for principally reach a big concentration of the desired material. As the comminution is by far the largest energy consumer in most mine sites, the study of the mineral processing try to conduct this size reduction with the bigger efficiency possible. comminution flowsheet design is a critical process in the production of iron ore. In this study, the flow rate was fixed at 150t/h with the Crusher specification of a Cedarapids JC24x36 jaw crusher model and a Nordberg Hp 300 S/M cone crusher. Based on the mineralogical information and ore properties provided the AggFlow Version 460.22 software is used to conduct, a comprehensive comminution flowsheet design to achieve the desired particle size distribution and mineral liberation. In the communition of primary crusher stage Iron ore at top size of 42 inches or (1066.8mm) generates 5 different ranges of materials, the first is at a size of 45mm, the second at 10mm, and the third is at 8mm, between 15 and 8mm and between 23.5 and 15mm. The primary crusher, a Cedarapids JC2436 Model Jaw crusher, was required to reduce the feed size with closed side setting of 69.85 mm to a manageable size of end product 21Mtph for further processing. The Nordberg Hp 300 S/M cone crusher was used as a secondary crusher with closed side setting (CSS) of 28mm to further reduce the particle size to 26Mtph. To complete the task several choices analyzed and as final design used 1 jaw crusher Cedarapids Jc 2436, and two cone crushers Nordberg HP 300 S/M. some screening and conveyors placed in the design to increase the reduction ratio of the equipment.
Determination Of Work Index of Spodumene from Kenticha Ore, Southern Ethiopia
(Addis Ababa University, 2023-06) Anuwar Mama; Bisrat Kebede (PhD)
From Kenticha, Southern Ethiopia, granite and kenticha spodumene ore were collected and used separately as reference ores. Each test ore was weighed at 2000 grams, and the reference ore was weighed at 500 grams, and all were ground in a lab ball mill under the same conditions. Size analysis of the feed to the ball mill and the output from the ball mill was performed on both the test ore and the reference ore, with the results properly tabulated. The feed and discharge particle sizes for the samples going into the ball mill were calculated using the Gaudian Schumann formula to ensure an 80% passing rate. The work index of the Kenticha spodumene ore was then calculated using Bond's equation, and it was discovered to be 11.391 kWh/t.
Determining The Liberation Size of Mekaneselam Iron Ore Southern Wollo Zone, Northern Ethiopia: Implication for Beneficiation
(Addis Ababa University, 2023-06) Getahun Meseret; Dejene Hailemariam. (PhD); Belayneh Digafe (Mr.) (Co -Advisor)
Iron is one of the most important types of ferrous metals that extracted from ore minerals of iron, like magnetite, hematite and others. Ethiopia has a lot of iron ore resources which are located in different parts of the country. Among this, Mekane Selam iron mineralization, which is located in south Wollo zone, Northern Ethiopia, is the target area of this project work. The main objective of this project work was to determine the liberation size of the target iron-bearing ore mineral through mineralogical identification, chemical composition analysis, and examination of the particle size distribution. Atomic absorption spectrometry (AAS), X-ray florescence (X-RF), X-ray diffraction (X-RD) analysis, and sieve analysis, were widely used methods for this project work. The chemical composition of Mekaneselam iron ore consists of 16.55–77.59 % Fe2O3, 7.31–59.02% SiO2, and 1.44–17.38% Al2O3. With an average weight percentage of 48.34%,48.96% of Fe2O3, 34.7%,31.8 % of SiO2, 8.2%,10.68% of Al2O3, and 0.018% , 0.19 % of P2O5 and other minor compositions that resulted from X-RF and AAS compositional analysis respectively. The mineralogical results generated from X-ray diffraction showed that Mekaneselam iron ore consists of major iron-bearing ore minerals of 40–60% hematite, 8–59% goethite, with an average value of 49.13% hematite and 27.85% goethite. The dominant associated gangue minerals are 1–21% quartz with an average value of 11.5% and 1–23.5% kaolinite with a mean value of 8.6%. The examination of the particle size distribution of sizing curves shows that 80 percent passing (P80) of the grinded ore sample is 1100μm. The size-wise chemical compositional analysis of AAS revealed that a higher weight percentage of the target ore mineral was recorded under a sieve size range of (-250μm + 180 μm). This implies that the appropriate liberation size of the target iron-bearing ore mineral is found between (-250μm and +180μm) sieve size ranges. This liberation size range shows a cumulative passing of 38% total particles. The chemical and mineralogical results of Mekaneselam iron ore indicate that the ore is very low grade and can be upgraded to commercial values by using gravity concentration followed by a high-intensity magnetic separator. In addition, it can be upgraded by magnetic reduction roasting (MRR), followed by a low-intensity magnetic separator.
Effect of Clay Slimes on Flotation in Case of Dado Coal Deposit, Jimma, South Western Ethiopia
(Addis Ababa University, 2023-09) Abraham Feyisa; Melesse Alemayehu (PhD); Ijara Tesfaye (Mr.) (Co-Advisor)
In Ethiopia, coal mining is a significant economic activity. The existence of clay slimes, which have an impact on the quality and amount of coal, is just one of many difficulties that coal mining activities must overcome. These problems regarding the impact of clay slime on coal flotation were the focus of this study project. Using flotation mixtures containing slime particles and coal particles in the 0.5-0.25 mm, 0.25-0.125 mm, and 0.125-0.063 mm size ranges, batch flotation and flotation rate tests were conducted with the primary goal of examining the impact of slimes on the recovery of coal particles by flotation. The findings of this study suggest that the content of slime particles and coal particle size had a bearing on the influence of sludge particles on the coal flotation recovery. Recovery of coal ash by flotation in all size fractions in the mixed flotation was larger than that of coal granules in each flotation cell when the mass proportion of the slime particles was below 20%. However, when the particle mass ratio of the slime exceeded 20%, the former was lower than the latter. Additionally, as the percentage of slime particles increased, coal particle recovery using flotation across all size fractions dropped. Additionally, it was easier to see how slime particles affected the Recovery via flotation of coarse coal particles.
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.
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
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.
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.

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