Union members at South32's Worsley Alumina refinery in Western Australia began a 48-hour stoppage on November 10, seeking firmer protection of pay and working conditions before Alcoa's planned acquisition of the assets. The action by the Electrical Trades Union and Australian Manufacturing Workers' Union coincides with a scheduled shutdown at the refinery's main processing plant.
Around 200 union members are employed at the operation, according to AMWU state secretary Steve McCartney. He said the workforce wants existing earnings secured through the enterprise agreement rather than relying on assurances. A central issue is the future of short-term incentive payments, which have averaged 10 per cent over the past five years. The union says South32 has cited incentive pay when describing total remuneration but has not offered a binding guarantee that the payments will continue after ownership changes. McCartney said workers are not asking for higher bonuses, only continuity of benefits they have received.
Working-hour gap adds to concern
Working hours have also become contentious. ETU WA secretary Adam Woodage said Alcoa shift and day workers have a 36-hour week, while Worsley shift workers work 42 hours. South32 day workers complete 40 hours over four 10-hour days. Woodage said those differences will draw more attention as the companies combine aluminium operations, and that employees want an agreement recognising their skills and contribution.
South32 said it is engaging constructively with employees and representatives during enterprise agreement negotiations. It said Worsley employees receive benefits beyond base wages and that its existing short-term incentive policy will continue after the transaction. The company also said it has plans to keep the refinery operating during the stoppage and does not expect production to be affected.
Acquisition scope and timing
The dispute is unfolding against Alcoa's proposed acquisition of a large part of South32's aluminium value chain, with an implied enterprise value of up to USD 5.6 billion. Announced in July 2026, the deal covers South32's 86 per cent interest in Worsley Alumina, full ownership of the Hillside aluminium smelter in South Africa, a 33 per cent interest in Brazil's Mineração Rio do Norte bauxite mine, a 36 per cent interest in the Brazil Alumina refinery and a 40 per cent interest in the Brazil Aluminium smelter.
The implied value comprises USD 3.1 billion in cash, about USD 1 billion in newly issued Alcoa shares, around USD 750 million in net debt and lease liabilities assumed by Alcoa, and up to USD 750 million in contingent cash payments tied to alumina and aluminium price targets through 2030. Alcoa will also assume rehabilitation provisions estimated at about USD 1.2 billion, separate from the implied enterprise value. South32 plans to distribute roughly half of the Alcoa shares it receives, worth around USD 500 million at announcement, to eligible shareholders through a fully franked special dividend after completion. The transaction excludes Mozal Aluminium in Mozambique, which remains with South32 and on care and maintenance.
Completion is targeted for June 29, 2027, subject to regulatory and other closing conditions. South32 shareholders approved the transaction on October 15, 2026.
Why Worsley matters to the enlarged group
Worsley has annual alumina production capacity of about 4.4 million tonnes and is central to Alcoa's planned expansion in bauxite, alumina and aluminium. Wood Mackenzie estimates the acquisition would raise Alcoa's attributable bauxite production by 53.6 per cent to nearly 53 million tonnes a year and attributable alumina output by 51.6 per cent, while smelting capacity would increase by about 26 per cent. Alcoa expects about USD 900 million in net present value from operational synergies, including better integration between Worsley and its existing Western Australian operations. Once completed, the expanded portfolio is expected to produce about 14.8 million tonnes of alumina and 3.2 million tonnes of aluminium annually.
For Alcoa, retaining experienced workers and stable operations at Worsley will matter as it integrates the assets. The enterprise agreement outcome could therefore influence employment terms at a facility that forms a significant part of the proposed transaction.