This helped me understand so am sharing it as maybe someone else...

This helped me understand so am sharing it as maybe someone else could benefit too:

"The NIMCIX system is essentially a series of cylindrical towers or columns, each divided into a number of stages holding contacting trays for distributing liquid. Each stage contains resin, the volume of which is determined by the requirements of the process. The feed solution is pumped into the bottom of the first tower and flows upwards, fluidising the resin in each stage. Plant design is discussed under the headings: physical model; kinetic model; simulation of the loading column; number of stages in the elution column."