The feasibility study design for the Mine Life Extension project is expected to be complete by midyear for approval by the board of Ok Tedi Mining Limited.
"An opportunity exists to extend the life of mine to 2025 beyond the previously stated MLE of 2021," OTML told PNGIndustryNews.net.
"However, OTML will only do so when studies confirm that MLE is environmentally and socially acceptable and technically and financially feasible."
The mine aims to deliver a mine extension plan which is environmentally and socially acceptable and has already made tough decisions in this regard.
"OTML has chosen to pursue a plan that has lower environment impact and is feasible over one that is best in terms of commercial terms," the miner said.
Under the extension project, OTML plans to continue existing open cut mining, starting with developing an open pit cutback which is subject to government and community approval.
But the extension project is also likely to involve underground mining, especially around the Gold Coast zone of the pit boundary.
Several key changes to earlier MLE project designs have caused some delays.
Of the significant changes, OTML said pit water would be drained into a tunnel which bypassed the Harvey Creek waste dump to the south and this dump in the creek valley was planned to hold up to 500 million tonnes of waste rock.
The dump will also be engineered to withstand most earthquake conditions, according to independent experts.
Production under the extended mining plans is expected to vary by either matching the current rate - which amounted to 130,456 tonnes of copper and 419,249 ounces of gold in 2011 - or to reach 60% of this output, according to OTML estimates.
"In the years 2016-2020, OTML expects only modest revenues compared with revenues generated under current operations," OTML said.
There have been four revisions on the modelling for the MLE project so far and OTML is working on a subsequent revised mining plan which will go through more environmental scrutiny.
"Further studies are required to confirm the erosion rate results and silt loads to the river," OTML said.
OTML has received government feedback for its mine closure plan which needs approvals from Papua New Guinea's mining and environment departments.
The next update to the mine closure plan is expected to be submitted around the end of 2013.
The PNG government has a 36.6% stake of the Ok Tedi mine and it is a major source of government revenue.