The Hidden Valley site is focusing on safely operating at a free cash flow neutral or better position. The partners are considering all options in relation to the site's future.

Also in PNG, Newcrest's board has considered the stage one and stage two pre-feasibility studies for the Wafi-Golpu copper-gold project.

Wafi-Golpu is another project owned 50-50 by Newcrest and Harmony Gold.

There are key elements of the studies that need more work done on them at full feasibility level. These are geotechnical, hydrology, tailings, port and power. Confirmation of the geotechnical and hydrology aspects will require further drilling from an exploration platform accessed via a decline.

One of the next steps in the project is to sign a pre-mine development agreement with the PNG government. Once that is signed approval will have to be sought by the JV partners' boards to proceed with the advanced exploration work and earthworks.

Part of that approval will involve deciding whether to proceed with the exploration decline or not.

Should it go ahead, Wafi-Golpu is likely to be developed as a block cave.

Stage One is an initial development of a higher grade resource to maximise early production and free cash flow.

The stage-two study focused on expanding and optimising the deeper block cave, BC2, and establishing a third block cave, BC3.

The first step of stage two will be to debottleneck the stage one processing plant to increase production capacity of the 6 million tonne per annum stage one facility to 7Mtpa.

The second stage will involve expanding processing capacity to 14Mtpa and increasing the mine's production rate.

Of course, stage one is still up in the air pending boards' approval of the exploration decline.

The Newcrest board also approved the progression of the Lihir Pit Optimisation Pre-feasibility Study through to feasibility study stage.

The purpose of that project is to optimise the integrated life-of-mine plan for Lihir including different mine scheduling and ore scheduling options, the most appropriate mining methods and civil engineering options.

Newcrest managing director and CEO Sandeep Biswas said the Lihir project was a testament to a team challenging existing thinking and developing a better solution.

"A potential capital saving of $1 billion for the future seepage barrier is a great outcome for Lihir and shareholders," he said.

One of the issues at that operation was dealing with sulphide ores. Ore at Lihir gets crushed, ground and then either put through a flotation circuit or injected directly into autoclaves before being sent for leaching.

Installing modern oxygen flow meters on the three autoclaves helped increase the capacity and flexibility in the autoclave circuit.

This allowed more sulphur rich ore to be mined, meaning the company had more time to compact the inner harbour and construct a cut-off wall rather than take a more costly cofferdam option.