Last year we developed a two-dimensional deterministic heterogeneous matrix
diffusion model, which is capable of utilising porosity information
originating from real drill-core samples. The results of numerical
infiltration experiment we had performed with the model displayed
substantial spatial variations in the penetration depth. Because it is
practically impossible to verify experimentally those two-dimensional
penetration profiles we had computed, this time we decided to try modelling
of measured leaching curves. Unfortunately we have not succeeded in
acquiring such curves for the exact same samples, which we have used in
numerical leaching experiments. Nevertheless it can be seen, that the shape
of leaching curves computed with the heterogeneous model is clearly closer
to the shape of measured curves, than the shape of curves provided by the
standard model. These differences can be utilised as a basis for an
approximate numerical method of assessing the geometric factor, which has
traditionally been a purely empirical parameter.
The results of the new numerical experiments agree with our older results
from last year: the heterogeneity of the rock matrix has highly significant
impact on the diffusion. However, when interpreting the results, one must
not neglect numerous limitations of the model, and hence, one should not
attempt to overgeneralise the conclusions.