"We are delighted to see the last of the major state permits we have applied for released as draft permits by the state, along with the draft Section 401 Certification," president and CEO Jon Cherry said.

"It has been a long and difficult road, and we look forward to receiving the agencies' final decisions on these permits."

The environmental review process spanned nearly 10 years, with the state validating the final environmental impact statement in March 2016 and PolyMet describing it as "the largest and lengthiest environmental review ever conducted in Minnesota".

The draft air emission, water permit and permit to mine will be discussed at public meetings next month held jointly with the Department of Natural Resources.

In the coming year, PolyMet expects its surface rights to cover 19,050 acres on completion of an authorised land exchange, and is in finance discussions aiming to secure the funds to start development on receipt of key permits.

In September 2007, PolyMet expanded its proven and probable mineral reserves to 274.7 million short tons grading 0.28% copper, 0.08% nickel, 0.01% cobalt, 75 parts per billion (ppb) platinum, 260 ppb palladium and 37 ppb gold; based on prices of US$1.25/lb copper, $5.60/lb nickel, $15.25/lb cobalt, $210/oz palladium, $800/oz platinum and $400/oz gold.

The company said it planned to complete a definitive cost estimate and project update prior to starting construction.

It is backed by Glencore (LN:GLEN), which held 29.1% of issued shares at the end of October.

PolyMet had $11.2 million in cash at the end of October and a working capital deficiency of $130.2 million, mainly due to a $47.7 million secured convertible debt and $89.7 million secured non-convertible debt due to Glencore on March 31.

PolyMet shares have ranged between C71c-$1.40 in the past year and closed down 1c yesterday to $1.23.