The mine was shuttered in 2011 and Consolidated Nickel Mines (CNM) took over in 2014.
CNM says it has spent US$50 million getting the sulphide operation back in business.
The goal for production is 30,000-40,000 tonnes per annum of nickel concentrate over a seven year mine life, at 12% Ni, from a JORC resource of 6 million tonnes at 1% Ni.
"Today is the culmination of nearly four years of hard work by the team and has involved a full reassessment of the project to de-risk it both technically and economically," CNM CEO Simon Purkiss said.
The mine employs 380 people.
CNM says Munali would earn $60 million in revenue per annum from a nickel price of $15,000 per tonne running at full capacity.
The nickel price is currently at around $13,000/t, recovering from the January low of around $10,000/t in term for first concentrate production at Munali.
The company is backed by Chengtun Mining, which has three directors on the board, and private equity firm Plinian Capital, which has two board spots.