From Kalbar’s Fingerboards Project (Glenaladale) website:
Kalbar proposes to extract 170Mt of ore to produce around 8Mt of heavy mineral concentrate (HMC) over 15-20 years.
giving an average of ~500,000 tonnes per annum.
Looking closely at the map Fernback seems 1/2 way between Sale and Bairnsdale. When you look at the distance between Fernbank and the mine site area at Glenaladale is only around 15kms from the Fernback rail line,. If the mine site has a lift of 15 to 20 years in Queensland and with 170m Tonnes to 500,000 tonnes of traffic to leave the area a spur would be a good alternative to trucks and other movements to the rail head.
15km of rail spur to the mine area (not familiar with the area) would be around $18m once off and some maintenance (which would need to be done on the raods anyway and more expensive) would say be $2m over the period is $20m of investment over 15 years is approximately $750k per annum over 500,000 tonnes is around $1.20 per ton for the use of the spur. That is going to be a lot cheaper than trucks and roads.
Its not that far, the postulated "road" from mine to required new siding is 9km. Making that a 9km spur line is not a huge deal.