The report compares leaching results obtained by two one-step batch leaching tests (en 12457 part 1 and 2) with leaching results obtained by a two-steps batch-leaching test (EN 12457 part 3). The effect of the used contact time and the effect of using different number of leaching steps were evaluated. The comparison made in the report was partly based on statistical evaluations and partly based on the authors profound knowledge of leaching test and hereby obtained data.
With respect to the contact time it was found that for two of the three test materials the contact time had no major influence on the leached amount. For the third tested materials the contact time significantly influenced the leaching of some elements. All in all it was concluded that a contact time of 24 hours might be preferable in a one-stage leaching test both with respect to fulfilling the equilibrium assumption and from a practical point of view.
With respect to different number of leaching steps (1 or 2 steps, respectively) it is concluded, that the number of leaching steps had no major influence on the leached amount.
Nevertheless, when using a relatively high accumulated L/S-ratio as for instance 10 l/kg, it is still recommended to use a two-stage leaching test, especially for materials which have not been tested earlier.