Some numbers(that could be completely wrong here) .....from...

Some numbers(that could be completely wrong here) .....from rough memory MKO MD stated to me BZW should have operating costs of round $18 per ton

so if BZW can be run at full tilt 3mtpa =54mill AUD basic running costs

now say we get low grade ore of only 1 gram per ton of ore X 3mtpa = 96,000oz Gold p.a ...=153mill AUD

now of course there is many extra costs -admin -freight - toll treatment cut etc ...but we can see even if BZW is feed even higher ore their should well be a good amount of FAT left over

Now of course the history is BZW has bankrupted many an operator ....last one NAV produced 100koz of gold but it took them a year and a half ...over that time NAV would have be lucky to average 1500oz AUD
fuel price would have been much high AUD crude oil price has halved since then ..partial collapse of a pit wall ....etc
of course the NAVs high interest cost 11mill+ debt they had on the books wouldn't have helped...

personal I don't think BZW failed in the past just from lower grade ore .....