While DSTP is banned for environmental reasons in many countries around the world, high rainfall in PNG can quickly overflow the biggest tailings dams conceived by engineers and the country is also susceptible to earthquakes.
In a landmark judgement, the National Court of Madang not only removed the existing injunction over the project's crucial DSTP, but also refused to grant a permanent injunction over it.
There could be an appeal to PNG's High Court by lawyers representing landowners in the project area, but joint venture partner Highlands Pacific (8.56%) is confident such a case will get the same favourable outcome.
In a further boon to the completed nickel laterite mine, a work order restriction by PNG's chief inspector of mines has also been lifted.
Highlands Pacific managing director John Gooding said both decisions were "right".
"Given the significant delays posed by the environmental legal actions of the past 18 months and the loss of revenue to the project, landowners and the PNG economy it would be extremely disappointing and counterproductive to seek to tie up this project in further legal actions through appeals by the plaintiffs," he said.
"Contrary to public commentary, the PNG government has statutory regulatory authorities which use rigorous processes to review or action issues of concern at operations like Ramu. The recent review by the chief inspector of mines is a case in point.
"Like any project there may be some initial teething problems, and it is only fair that the operators, Ramu NiCo Management, be given a fair opportunity to explain those issues and its approach and actions so that the project's modern facilities can be made fully operational."
Located 75 kilometres west of the provincial capital of Madang, the Ramu mine is expected to produce 31,150 tonnes of nickel and 3300t of cobalt per annum in a high-grade concentrate over a 20-year mine life.
The resources could also potentially support mining for a further 15-20 years.
China Metallurgical Construction Company subsidiary MCC Ramu NiCo owns 85% of the project, but Highlands' stake will increase to 11.3% once the project development debt is paid off, which could be in 8 years.
The PNG explorer also has an option to acquire a 9.25% stake of the emerging mine at a fair market value, providing the potential for Highlands to increase its total stake to 20.55%.
Shares in Highlands, which also has an 18.8% stake in the Xstrata-led $5.3 billion Frieda River copper-gold project in PNG, were down 2.5c to 31.5c by 1.30pm AEST.