Leaching reactors have been described using three different approaches
. These models are the overall mass balance, the population-balance mo
del and the segregated-flow model. Each of these models has been used
extensively without the relationship between them being either underst
ood or quantified. These models do not only differ in their conceptual
basis, but also yield different results for the same reaction conditi
ons. The conceptual relationship between the various approaches to the
mathematical modelling of continuous leaching reactors is discussed,
and it is suggested that the population-balance model is the most appr
opriate approach for the modelling of leaching reactors. The populatio
n-balance method of the mathematical modelling of leaching reactors is
discussed. The population balance incorporates the kinetic parameters
obtained from the analysis of the batch experiments. The model is use
d to analyse the batch laboratory experiments and to predict the opera
tion of the continuous plant. The model accounts for the particle-size
distribution of the feed, the residence-time distribution of the reac
tor, the leaching kinetics, and the solution mass balance. The model i
s used to obtain predictions of the operation of the zinc pressure lea
ching reactor at Trail, B.C., and the bacterial leaching of a refracto
ry gold ore at Fairview, South Africa. The predictions of the continuo
us operation are shown to be in excellent agreement with the data from
the plant operation.