Hi Kranky,Haven't met yet , but a lot of people think I am you (...

Hi Kranky,
Haven't met yet , but a lot of people think I am you ( a much better looking version of course).
Not a holder but have a question for you as you state you like questions from non holders.
Not a real full bottle on the tech that Mantle is involved with CAG/Exergen but believe it involves pumping a coal slurry down and then up a what is a km or km and a half shaft in a pipe?
Having had a bit of involvement with pumping slurries in my time I found that they always block up at some stage.
Now normaly on flat land this is not a major problem, but I could see it being a bit of a drama if it happened down a shaft.
Do you have any thoughts on this?