Leaching of a zinc ore and concentrate using the Geocoat™ technology

In this study, the Geocoat™ technology was used for the extraction of zinc from a mineral concentrate obtained from the Kooshk mine (Yazd, Iran) by a culture dominated by the mesophilic bacterium Acidithiobacillusferrooxidans in a packed column bioreactor. A low grade sphalerite ore was used as support for the concentrate coating. During the 100 days of leaching pH, Fe3+, Fetotal, microbial population density and zinc extraction were measured. The final zinc extraction from concentrate and low grade support was 97% and 78%, respectively, and it was found that leaching from the support does not proceed significantly before leaching from the coating is completed.

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► The Geocoat™ technology exploits the advantages of bioleaching in tanks (high recovery rates of metal) with those of heaps (low capital and operating costs).
► Monitoring of pH on its optimum range has an impressive effect on the final recovery.
► The support rock phase begins leaching essentially only after concentrate leaching.
► Two-stage nature of the process has been reported in this study for the first time.