Queensland and, to a lesser extent, NSW are both predominantly coal exporters.
The slowdown in China means less steaming coal but more significantly, it means less steel production so less premium coking coal, softer prices etc.
Coal prices have dropped massively from their peak.
Marginal pits that looked ok at $140/tonne are looking decidedly shakey at $70/tonne.
I think Cactus Jack has shared his "secret" insight and it's the same thing Alan Kohler and several other economic commentators have been saying for about 12 months.
The Boom's over, everyone can go back to sleep for 3-4 years