The head of the Tiwai Point aluminium smelter has resigned to join one of the country's big power companies.
Stew Hamilton has been with the smelter's majority owner Rio Tinto for 22 years, and took over as chief executive of NZ Aluminium Smelters in 2018.
He will leave in July to become general manager of generation at Mercury Energy.
"The smelter has been going through a very public period of transition, and Stew's commitment and leadership has been hugely valued throughout this time," said Rio Tinto acting managing director of Pacific operations Daniel van der Westhuizen.
The smelter was due to shut this year, but was given a lifeline until at least 2024 after it reached a new power deal with its power suppliers.
Hamilton has had to contend with pressure to tackle the disposal of toxic waste by-product, and the clean-up of the smelter site when it eventually shuts.
"The last few years have been very challenging and I am proud of what the team has achieved over that time," Hamilton said.
The smelter consumes about 13 percent of the country's power, but has long complained about high power costs, especially for transmission, which it has said undermined its viability at a time when world aluminium prices have been depressed.
Mercury chief executive Vince Hawksworth said Hamilton's broad experience and commitment to workplace safety were key reasons for his appointment.
"A core part of the role is ensuring the long-term sustainability, resilience and productivity of our hydro, geothermal and wind assets."