Sphalerite bioleaching comparison in shake flasks and percolators

摘要

Bioleaching experiments with a mixed Acidithiobacillus-culture were carried out in shake flasks as well as in column percolators with crushed and sieved sphalerite-rich ore from a former mine in the German Harz Mountains. An efficient sphalerite dissolution in the bioleaching assays was observed in contrast to the chemical leaching experiments. Up to 6 g/L zinc were measured in the pregnant leach solution. Total cell counting and most-probable-number cultivation congruently exhibited high cell numbers at the end of the bioleaching experiments of about one month. The redox potential was higher in the bioleaching than in the chemical control assays. The pH was adjusted to values about 2.5 to be able to compare the leaching kinetics at a similar pH for bioleaching and chemical leaching assays. The kinetics of sphalerite bioleaching showed a linear increase of the zinc concentration in solution and exhibited similar sphalerite surface related reaction rates for percolators and shake flasks. Besides zinc, up to 1 mg/L gallium as trace element was extracted.