leaching of malecite and azurite from sedimentary copper deposits: a case study of sorkheh copper mine

The sorkheh copper mine, a sedimentary deposit, presents unique challenges for copper extraction due to the high carbonate content in its oxide ores. this study investigates the mineralogical composition, flotation efficiency, and leaching performance to develop a sustainable processing strategy. mineralogical analyses reveal significant concentrations of calcite and quartz as gangue minerals, along with copper oxides such as malachite and azurite. calcite, which accounts for approximately 24.1% of the ore, is a major consumer of acids, complicating leaching operations. flotation tests using sodium oleate and oleic acid removed over 90% of calcite but incurred copper losses, demonstrating limitations in selectivity. acidic leaching with sulfuric acid achieved a recovery rate of 85.55%, albeit with high acid consumption due to carbonate reactions. conversely, alkaline leaching using ammonium hydroxide and ammonium carbonate avoided calcite dissolution and achieved a copper recovery of 66.64%. while acidic leaching proved more efficient, its environmental and economic costs necessitate alternative approaches. an integrated strategy combining flotation pre-treatment and sequential leaching is proposed to enhance recovery rates. flotation reduces carbonate content, improving the efficiency of subsequent leaching processes. alkaline leaching serves as a complementary method to address residual copper oxides. future work should focus on optimizing reagent use, improving the selectivity of flotation collectors, and minimizing environmental impacts of ammonia-based leaching. this study demonstrates the potential for tailored approaches to process complex carbonate-rich ores, providing valuable insights into advancing sustainable copper extraction methods.