Aviation sl#t
The mining company can buy,lease or rent an aicraft (but not rented with pilot supplied) to use as another piece of plant to operate in the conduct of their business.
They must employ or provide their own pilot, (yes, even a private pilot) to fly the aircraft as all or part of his duties. Flight and duty times are not applicable to private operations, nor is passenger liability cover.
A charter company ( AOC holder ) must have passenger liability cover and must have a "Certificate of Compliance" issued by CASA to be displayed with all the certificates associated with an AOC.
A very good example of this type of private operations is MH Holdings in PNG.
This timber company has a C206, C208 (van) a BE58 and or a PA31. The aircraft are used to fly urgently needed parts and/ or personnel as required to various job sites, and also weekly runs for payroll and crew changes. The pilots seem to be very happy with their salary package (accom, wages, leave, bonuses etc). If you get the chance to fly for them grab it quickly before someone else does.
Another example in Oz is the likes of Stanbroke Pastoral company, similar deal, but you also live and work as a roustabout in addition to flying. Private ops again.
You can be paid to fly in private ops, even on a PPL, though most companies conducting private ops tend to stick with the more qualified CPL's. A CPL is not needed to earn money as a pilot, but the operation must have an AOC if it is going to be paid for flying freight and/or passengers.
In closing, your last post intimated that the company you mentioned is "CONTRACTED".
If that company is not the mining company, then the "contracting" company may indeed be conducting commercial operations if it is supplying an aircraft complete with pilot to fly passngers or freight for hire or reward for someone else. In that case, CASA will take an interest.
As stated earlier, the mining company can rent, lease, hire or buy an aircraft, but they must provide their own pilot and no charge must be made to anyone for transport of people or freight in that aircraft.
Yes, you can earn money in private ops, even "meat bombing" manages to qualify as private ops.