ST. PAUL— A highly anticipated environmental analysis on the proposed PolyMet mining project was set for release Friday, laying out the effects of a mine and how the company hopes to prevent damage at what would be the state’s first copper-nickel extraction and processing operation.

The release of the report by the Department of Natural Resources would initiate a 30-day public comment period. By early next year, the DNR would have to determine if the study is adequate. From there, the company would need to apply for about two dozen local, state and federal permits.

The 3,000-page report was compiled by the DNR, the U.S. Forest Service and the U.S. Army Corps of Engineers to survey the effects if it allows the copper and nickel mining that differs from the taconite mining Minnesota is known for. Because of the complexity involved, the state agency was also planning to put out guide sheets to help the public decode scientific jargon.

Gov. Mark Dayton has said the ultimate call his administration will make on a “permit to mine” will be the most monumental and difficult decision of his two-term tenure. The project has caused divisions within his Democratic Party, splitting those who see its job potential and those who worry about environmental damage.

In advance of the final environmental impact statement release, Dayton traveled to mines in South Dakota and Michigan to assess how those were undertaken and where they succeeded or fell short.

PolyMet has proposed extracting the minerals from an open-pit mine and reusing a former LTV Steel Mining Co. processing plant in Hoyt Lakes that it bought from Cleveland Cliffs. PolyMet predicts it would extract 553 million tons of rock over the 20-year life of the mine.

One question is whether PolyMet can provide sufficient financial assurances for a proper cleanup when it eventually closes. The state can force the company to pledge millions in guarantees, but so far officials have not said precisely what such a package would entail.