"If the weather events have resulted in significant disruption...

"If the weather events have resulted in significant disruption to mine production at Ravenswood then the company should really announce as much and give the market some revised guidance based on the impacts of the weather events."

Yes, they definitely should have said something.  Perhaps they are too busy dealing with the problems rather than worrying about announcements?

"Clearly they haven't, as yet, so it should be safe to assume any impact will be limited and not a threat to current guidance."

See comment above, and look at recent news for the region.  It is NOT safe to assume any impact will be limited.  Rail lines in and out are shut down and will take significant times to repair.  The workforce (and local management) is in a state of shock.  Half of the nearest city was totally destroyed, the other half was heavily damaged.  There are over 300,000 rotting carcasses of cattle nearby.  And more severe weather is moving in, so the disaster is in no way over. 

If this happened in North America or Europe it would be 1st, 2nd, and 3rd page news.  Just because the "mass media" is ignoring the effects of catastrophic global warming on other continents does not mean it is not happening.