July 31 (Reuters) - Ivanhoe Mines Ltd IVN.TO
* Ivanhoe Mines releases positive results of an independent definitive feasibility study for the planned first phase of its Platreef PGMS, nickel, copper and gold mine in south africa
* Ivanhoe Mines Ltd - estimated pre-production capital requirement of approximately us$1.5 billion for Platreef dfs
* Ivanhoe Mines says results of financial analysis show an after-tax npv of $916 million, an after-tax irr of about 14% and a payback period of about 5 yrs