Sandfire Resources' (ASX:SFR) more attractive development opportunities besides the Black Butte project in Montana, as well as its modest scale, increase the likelihood of divestment, Jefferies said in a Monday note.

The company modeled around 25,000 tonnes per annum of copper over a 12-year life-of-mine and a net present value of AU$91 million for Black Butte. The Lowry reserve increase of 4.7 million tonnes adds around four-years to the Black Butte life-of-mine.

Jefferies reduced its capital expenditure forecast in-line with Sandfire's expectations to $475 million. Development of the Lowry deposit remains contingent on regulatory approvals with the company guiding to a six-year process commencing coincident with Johnny Lee deposit access decline development.

Sandfire seems to hold an internal preference for the Kalkaroo project, with its increased scale and expedited development timeline, Jefferies noted.

The investment firm retained its buy rating on Sandfire Resources with a price target of AU$24.

Sandfire Resources' shares slipped 1% in recent Tuesday trade.