FIG. 8.

Plot of 1 − (1 − X)^1/3 versus time for the bacterial and chemical leaching data. (A) Plot of the bacterial leaching data from Fig. 2A, confirming that the shrinking-particle model with surface reaction control describes the leaching of sphalerite in the presence of bacteria at high concentrations of ferrous ions. (B) Plot of chemical leaching data from Fig. 2B showing that the shrinking-particle model with surface reaction control does not describe the leaching of sphalerite in the absence of bacteria at high concentrations of ferrous ions, except for the first 8 to 10 h.