South32 refinery workers strike as $8b Alcoa takeover looms

Maintenance staff at one of the world's biggest alumina refineries have gone on strike as they push for improved pay and conditions.

The industrial action by South32 staff at the Worsley Alumina facility, 200 kilometres south of Perth, comes ahead of a multi-billion-dollar takeover by US miner Alcoa.

Workers, alongside Electrical Trades Union (ETU) and Australian Manufacturing Workers Union (AMWU) representatives, formed a picket line along the refinery's entrance road on Tuesday morning.

In July Alcoa announced it would buy South32's major bauxite mine and alumina refinery as part of a deal worth more than $8 billion.

The strike marked the start of 48 hours of protected industrial action, coinciding with a planned shutdown at the main processing plant that refines raw bauxite into alumina at the site.

Union representatives are trying to finalise a renewed enterprise bargaining agreement before ownership changes hands in the first half of 2027.

Unions claim pay, condition gap

The dispute rests on what unions allege is a significant difference in working conditions between South32 staff and those doing similar work at Alcoa.

"What we're always open to do is negotiations," ETU WA secretary Adam Woodage said.

"However, we haven't heard from South32 since they had an overwhelming 'no' vote on their latest offer to this workforce."

The union representatives also said the potential loss of discretionary bonuses after the Alcoa takeover could cost workers up to 10 per cent of their wages.

Workers on the picket line asked for their names to be withheld due to the potential workplace impact.

One employee of 15 years said the stoppage was ultimately about standing up for newer workers, who he said were receiving inferior pay and conditions despite performing identical work.

Another said conditions had been steadily whittled away since South32 was spun out of BHP in 2015.

AMWU WA secretary Steve McCartney said the decision to strike was not made lightly.

"They're like everyone else — they're trying to pay bills, they're trying to pay houses off, they're trying to get kids through school," he said.

"They deserve to be paid the same money, doing the same job at the same end of town."

A South32 spokesperson said the company continued to engage constructively with staff and noted a range of worker benefits beyond base pay.

The spokesperson said the existing "short-term benefit policy" would continue under Alcoa's ownership, which had been communicated to staff and unions.

"We want to find ways to address issues they may have while ensuring our operation remains sustainable," the spokesperson said.

"We have plans in place to support ongoing operations at Worsley Alumina during this time and do not expect any impact on our operations."