A Review of the Geochemistry and Processing Pathways for Sulphur Recovery from Ethiopian Volcanic Deposits

The geological architecture of the East African Rift System, specifically within the Afar Triple Junction and the Main Ethiopian Rift, provides a unique tectono-magmatic environment for the formation of extensive volcanogenic sulphur deposits. This review synthesizes the geochemical characteristics and potential processing pathways for Ethiopia’s dormant sulphur resources, which are becoming strategically vital as the nation seeks to mitigate its 100% dependency on mineral imports for its agricultural and industrial sectors. Current assessments identify significant native sulphur reserves at Dallol (7 million tons) and Dofan/Chebrit Ale (6 million tons), alongside over 2.5 billion tons of inferred mixed sulphates in the Danakil Basin. Geochemical investigations, supported by stable sulphur isotope systematics (δ<sup>34</sup>S), reveal a polygenetic origin for these deposits: primary magmatic degassing of H<sub>2</sub>S and SO<sub>2</sub> at centers like Erta Ale (δ<sup>34</sup>S) of -0.5‰ to +0.9‰) contrasts with complex hydrothermal recycling and bacterial sulphate reduction in evaporitic sequences. While the study evaluates the technical feasibility of extraction methods including the Frasch process, froth flotation, and solvent extraction it notes that these pathways, despite recovery efficiencies exceeding 90%, must be meticulously adapted to the hyper-arid, high-enthalpy conditions of the Ethiopian Rift. Ultimately, the integration of domestic sulphur recovery with existing geothermal energy projects is proposed as a critical step toward establishing a self-sustaining industrial ecosystem. By addressing existing knowledge gaps in pilot-scale validation and environmental lifecycle assessments, Ethiopia can leverage its volcanic heritage to ensure national food security and regional economic influence.