Just had a quick google. The below link shows that company tax...

Just had a quick google. The below link shows that company tax rate it Botswana is 22% however mining profits are taxed differently using the formula of 70% minus (1500/x) where x is equal to pre-tax profit margin. The calculated rate cannot be below the 22% company tax rate.

So if your pre-tax profit margin is 40%, the income tax rate will be 70 - (1500/40) = 32.5%.

Also it appears Botswana has no repatriation tax so if the want to pay dividends back to Australian based shareholders it shouldn’t incur further taxes (but it will not be franked). Please correct me if wrong as it was just a quick google search.

http://taxsummaries.pwc.com/ID/Botswana-Corporate-Taxes-on-corporate-income