chart, page-7

dott,

"what doesn't stack up for me IS this big problem they are having with the partly processed material, which is afterall ,surly, just the material at the last stage of the process that would have to be put through the system in the normal course of procedures"

They are not having a big problem with the partly processed material. That has been resolved.

It is also a mistake to assume that the partly processed material is the same as the material that would have to be put through the system in the normal course of procedures.
i.e The partly processed material may have originally been subject to slightly different processes thereby causing a gas problem in the slurry pumps which necessitated the changeover to screw conveyors.