Abstract:

In HPAL (High-Pressure Acid Leach) autoclaves, the mechanical process of stirring and mixing is primarily facilitated by the agitator. These agitators are crucial for achieving rapid and uniform mixing of the ore suspension with sulfuric acid, thereby preventing acid hotspots and ensuring a high leaching rate. Additionally, they play a vital role in maintaining the ore particles in suspension, allowing for their efficient transfer over compartment walls into subsequent compartments. Existing impeller designs, including those specifically developed for this application like the EPAL impeller, effectively address these tasks. However, the formation of deposits on impellers and autoclave walls remains a challenge, influenced by the type of ore processed. Chemical solutions to mitigate these deposits are not feasible in HPAL applications, necessitating alternative approaches. One such solution, presented this year, involves the development of an energy-efficient impeller designed to minimize deposit formation on its surfaces through a specially engineered shape. This design was optimized using advanced simulation techniques across multiple iterations to enhance flow dynamics. Various prototypes of the new impeller were tested and evaluated on a 70-liter, a 1 m³ and a 7 m³ scale. The final version has been successfully accomplished and is now ready for large-scale implementation.

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Mr. Wolfgang Keller