Can anyone enlighten me on the dangers of cat fines, possible causes and how we can reduce or eliminate them. We run slow speed (100 rpm) diesel engines - 8RLBF90 sulzer.

Cat finers are a source of considerable wear to piston rings and cylinders and need to be eliminated.(shown as alluminium and silicon in the FO)Many marine engines suffer in this way.
Our previous correspondence relates and fuel oil analysis is required to ascertain if Cat fines are present.
Routine cylinder drain oil analysis can be of benefit and show the depth of the problem.
If cat fines are present in the fuel oil then they should be removed as in marine applications by centrifuge.

Aluminium and Silicon oxides a.k.a. cat fines originate from the refining process, and can cause severe abrasive wear mainly of the injection pump and nozzles, but also of cylinder liners and piston rings.

Better efficiency concerning removal of high Aluminium and Silicon content can be achieved by using lower flow rate of fuel separator.

Aluminium and Silicon:
Good < 15 [mg/kg]
Moderate 5 - 15
Poor > 15
Limit in Bunker C fuel <= 80
Limit before engine = 15