Sewa bay - can't really make out why for all the reasons you have already outlined.
Thinking Ramu -
dual source for security of supply?
slurry pipe capacity?
cheaper ore feed?
Thinking not Ramu -
sell out of Ramu and do it all over again?
find a deposit and flick it off?
What is the chromite likely to be worth? Four or five hundred ton per day on local roads would be interesting