announcement says nothing, page-5

Sorry Lonhro344 the answer is not mining but infrastructure. Most of the work done by "South Spur Rail" and "Southern and Silverton", the divisions that operate the locos, is for ARTC and other rail maintainers. The other source of work is port shuttles of containers to inland yards. They are all fully occupied as there is still a major motive power shortage on standard guage.
With the feds pushing rail infrastructure and NSW trying to unclog the roads near the port this work will not reduce.