Mineralogical Characterization of Okote Gold Ore Deposit, Oromia Region, Southern Ethiopia: Implication to Gold Processing
| dc.contributor.advisor | Worash Getaneh | |
| dc.contributor.author | Ebisa Dugasa Kitata | |
| dc.date.accessioned | 2026-06-29T12:41:09Z | |
| dc.date.available | 2026-06-29T12:41:09Z | |
| dc.date.issued | 2026-01-01 | |
| dc.description.abstract | Gold, the yellow metal possesses unique physical and chemical properties, attractive in color and brightness, durability, resistant to corrosion and oxidation, made it valued mainly for jewelry and other adornments. Gold has been known and valued for a long period since ancient time and its demand and price has been increasing from time to time. Processing of gold that involve liberation through comminution, concentration using flotation, gravity and cyanidation or combination of these require mineralogical understanding of the gold ore deposit for acceptable gold recovery. The current study, mineralogical characterization of Okote gold ore deposit, aim at identification of gold ore and associated minerals, grain size distribution, and understand their impacts on gold processing; that help for selection of gold processing methods for appropriate gold recovery in the feasibility study and plant design of Okote gold deposit. The study approach involved chemical analysis for major, minor and trace elements using AAS, ICP-OES and ICP- MS and mineralogical analysis using optical microscopy, XRD and electron microprobe analyzer (EMPA). The ore minerals identified is exclusively native gold, with trace amounts of electrum, and telluride mineral-petzite. Associated minerals: pyrite (dominant), pyrrhotie, chalcopyrite, covellite sphalerite, rutile, tannantite, goethite, limonite, hematite, and magnetite. Gangue minerals are dominated by quartz (49.34%) and calcite (19.4%), followed by mica + illite (9.3%), chlorite (8.0%), amphibole-hornblende (3.86%), dolomite (2.28%), and others such as feldspars and tourmaline (7.82%). Grain size distribution of gold is as follows: 15.59% >74 µm, 40.07% between 74 µm and 37 µm, 28.01% between 37 µm and 10 µm, 10.39% between 10 µm and 5 µm, and 5.59% below 5 µm. Chemical analysis revealed low concentrations of Ag, Cu, Zn, Pb, As, Sb, and Te, alongside moderate levels of sulfur and organic carbon (CORG). These characteristics indicate moderate cyanide and oxygen consumption due to iron sulfides, as well as medium preg-robbing effects from organic carbon in cyanide solution. The presence of significant clay, mica, and chlorite in the gangue may cause viscosity issues during downstream processing, requiring proper management. Approximately 84% of gold grains are finer than 74 µm, implying that liberation will require fine to ultrafine grinding, provided slime-related challenges are addressed and economic viability is confirmed. The Okote deposit is largely composed of free-milling ores with a minor refractory component. While flotation, gravity separation, and cyanidation, or their combinations, are technically feasible, the complex chemistry of flotation demands specialized training, reagent management, and precise operational control. Given the wide gold grain size distribution, a combination of gravity separation followed by cyanidation is recommended as the more appropriate processing route for the Okote gold deposit. | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/8584 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Ababa University | |
| dc.subject | Gold | |
| dc.subject | mineralogy | |
| dc.subject | Okote gold deposit | |
| dc.subject | gold processing | |
| dc.title | Mineralogical Characterization of Okote Gold Ore Deposit, Oromia Region, Southern Ethiopia: Implication to Gold Processing | |
| dc.type | Thesis |