la trobe lignite developements - rio sponsored, page-18

Two perspectives – technological and commercial

Technologically, both ESI and Pac processes use shear in the force cone of an extruder to separate the hydroxyl bound water and seal up the micro-crevices so that material is no longer hydroscopic (water absorbing). (Albeit one extruder does paste tubes and the other pellets)

Exogen (lambasted here at times) is trying to use smart fluid engineering to eliminate the cost of shear implicit in ESI and Pac (IMO, shear is not cheap at commercial sizes paste extruders – i.e. brick plants).

This compression is energy intensive, but once commenced does release the energy in the bond, making the process (generally) exothermic. However, if that exothermic energy is lost due to mechanical or flow arrangements the overall process becomes endothermic. This is (still) the problem (IMO) at ESI, Pac and Exogen, all of whom absorb energy.

Commercially, ESI plans to use process heat to remove the unbound water which (should be) cost effective, and its pellets are designed to be capable of moving thru their drier without crushing. Again, IMO, this is an issue that has to be shown on scale up – it seems to work fine in the pilot.

Pac use intermediate processes to commercialise the compacted material. Their idea is that this is less risky than drying it, and they have a neat series of off take processes to maximize the utility of their feedstocks. Again, seems to work well in pilot plants.

Exogen are looking at a different strategy.

IN summary, Pac and ESI, IMO, have very very similar front end technologies (and therefore costs). The have different back end flow streams that may lead to different commercial outcomes.

Key issue must be, and management focus on, delivering an operating scaled commercial demo plant, of 50+tph at 70-90% utilisation for a cost of product that their buyers will pay.

Key buyer, IMO, power station, not coal export.