The sale, for a consideration of $A8.5 million, is expected to be completed in May, subject to the satisfaction of certain conditions.
Resource Portfolio Partners holds interests in coking and thermal coal and uranium.
The put-and-call option agreement made last year with Resource Portfolio Partners to divest Eastern’s 90% interest in the Broughton Coal Joint Venture ends in March.
The permit holds a 30 million tonne coal resource contained in two seams.
In June 2005, Eastern entered a joint venture agreement with Mitsui Coal Holdings worth $4 million to complete a feasibility study into the development of the resource.
In early 2007, Eastern announced it would not develop Broughton as a stand-alone project.
Eastern has been looking to offload its stake for some time, with Rio Tinto twice pulling out of buying Broughton last year. Both times Rio offered $10 million.
Last year, Indian coke manufacturer Ennore Coke was rumoured to be interested in Eastern’s stake in the project.