1. Modeling a liquid-liquid extraction stage

1.1 Introduction

We've just seen that "modeling a device" is an expression that covers two different notions.

• One is hydrodynamic. We need to account for the circulation of fluids in the device. This part does not fall within the scope of material transfer theory, so we won't deal with it here. Readers interested in the subject should refer either to the general articles on fluid mechanics and its applications, or to those on the various unit operations in this treatise.

• The other is the art of calculating material transfer, given fluid flow. The remainder of 1