Ann: Media Release Net Profit $106.4 Million for the Half Year, page-40

Once the $8 million is spent on the plant it should only be the cost of doing the beneficiation through the plant as well as transport as the cost of digging it out of the ground has already been accounted for.
An extra 250,000 tonnes of 36% Mn at current price of AUD$293.5/tonne. ( From the report $91.6 million / 312,029 tonnes sold)
The extra 250,000 tonnes sold = $73.3 million, you'd have to assume that profit would be more but as a minimum using the report ($37 million profit /312,029 tonnes) = $118.50/tonne profit.
On 250,000 tonnes annually = $29.6 million PROFIT
Its definitely worth the exercise.