Rio Tinto to delay Quebec lithium plant build

Rio Tinto (ASX, LSE: RIO) will slow the construction of its Nemaska lithium processing plant in Quebec due to rising costs, which could see its commissioning delayed, Bloomberg reported.

In the coming weeks, the company is expected to withdraw many of its contractors and leave only a minimal number of workers on site, Bloomberg said on Friday, citing sources.

The report comes just weeks after the Australian miner gained control over Nemaska — which includes the proposed lithium hydroxide conversion plant in Bécancour — in a bid to expand its battery materials business.

The facility was about 60% complete at the end of last year and is projected to have an annual production capacity of 32,000 tonnes.

In mid-February, Rio Tinto increased its ownership of Nemaska to 53.9% — thus becoming its majority owner — and said it plans to invest $300 million on the Quebec lithium operation. The Quebec government, which holds the remaining 46.1%, also pledged to invest $200 million in Nemaska.

Commissioning of the Bécancour plant was initially planned for this year, with first production expected two years later.

Timeline unclear

It remains unclear whether the slowdown of construction would impact the project’s timeline. One source cited by Bloomberg said that building of the lithium facility is expected to fully restart in 2027. 

The Bécancour site is part of Nemaska’s fully integrated spodumene-to-lithium project in Québec, anchored by the Whabouchi deposit in the James Bay region. It is designed to be a 26-year, open-pit and underground operation producing 200,000 tonnes of concentrates annually.

Rio Tinto, which entered the project through its acquisition of Arcadium a year ago, is currently reviewing whether the Whabouchi deposit presents the optimal spodumene supply strategy for Bécancour in comparison to its Galaxy hard rock lithium project, also in James Bay.

The evaluation is expected to be completed in the first half of 2026, according to Bloomberg, whose source said the company is at the moment leaning towards the Galaxy project.