Investigation of hydrogen sulfide neutralization technology formed in uranium ores during in-situ leaching

This study investigates the formation mechanisms of H 2 S during in-situ leaching (ISL) of sulfide-bearing uranium ores at the Zafarabad deposit (State Enterprise "Navoiyuran") and evaluates effective neutralization methods. The presence of H 2 S in pregnant leach solutions causes severe corrosion of pipelines and equipment and negatively affects process efficiency. Field sampling from MSQ-6 and MSQ-13 wells revealed significant spatial variability of H 2 S concentrations. SEM–EDS analysis confirmed that sulfide minerals, particularly pyrite (FeS 2 ), are the primary source of H 2 S formation under acidic conditions. The H 2 S concentration was determined using iodometric titration. Laboratory experiments were performed to compare the performance of oxidizing agents (NaClO, KMnO 4 , and H 2 O 2 ) at different stoichiometric ratios. All reagents effectively removed H 2 S; however, their impacts on solution chemistry differed. NaClO introduced chloride ions, while KMnO 4 generated Mn 2+ , both of which complicate downstream uranium recovery. In contrast, H 2 O 2 efficiently oxidised without forming harmful residual ions and maintained solution stability. The results demonstrate that H 2 O 2 is the most suitable reagent for H 2 S neutralisation, thereby improving process efficiency, reducing corrosion, and enhancing operational stability in the ISL of sulfide-rich uranium ores.

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