* EMG to sell down about one-third of Coronado
* Coronado is big independent producer of coking coal
* Set to be biggest coal float in Australia since 2012 (Adds details of IPO plan and background on Coronado)
MELBOURNE/SYDNEY, Aug 28 (Reuters) - U.S. private equity firm Energy and Minerals Group (EMG) is planning an A$1 billion ($732 million) initial public offering (IPO) of Connecticut-based Coronado Coal in Australia, two people with knowledge of the plan said on Tuesday.
The IPO, which is expected to value the whole company at around A$3 billion, is likely to be the biggest coal mining float in Australia since Yancoal Australia listed in 2012 at the peak of the country's mining boom.
Coronado aims to issue a prospectus in October, targeting a listing in late November, one person said.
Analysts working for the joint lead managers - Goldman Sachs, UBS, Credit Suisse and Bell Potter - are set to release research next week, two sources said.
Coronado mainly produces metallurgical coal used in steelmaking, with annual output of 8.2 million tonnes from three U.S. mines and 8.5 million tonnes from the Curragh mine in Australia, which it bought from Wesfarmers Ltd in December for A$700 million.
That makes it one of the biggest metallurgical coal producers outside the big diversified miners, competing with U.S. firm Warrior Met Coal Inc.
It also produces 3.5 million tonnes a year of steaming coal at Curragh which it sells to the Queensland state government's power producer Stanwell Corp.
Coronado's spokeswoman in Connecticut declined to comment on the planned IPO, which was first reported by the Australian Financial Review. ($1 = 1.3669 Australian dollars) (Reporting by Sonali Paul and Paulina Duran; Editing by Muralikumar Anantharaman)