About 200 union members at South32's Worsley Alumina refinery in Western Australia began a 48-hour stoppage on November 10, seeking stronger guarantees on pay and working conditions before Alcoa's planned acquisition of South32's aluminium assets.
The action involves members of the Electrical Trades Union and the Australian Manufacturing Workers' Union. It coincides with a scheduled shutdown at the refinery's main processing plant. AMWU state secretary Steve McCartney said the workforce wants existing earnings protected before the ownership change.
Bonus guarantees at issue
Short-term incentive payments are a central concern. McCartney said Worsley workers have received an average bonus of 10% over the past five years and want the payments secured in their enterprise agreement. The union says South32 has cited incentive payments when discussing overall remuneration but has not offered a binding guarantee. McCartney said the request is not for higher payments but for continuation of benefits workers have consistently received.
Working hours compared
Differences in hours and employment conditions between South32 and Alcoa employees in comparable roles have also become contentious. ETU WA secretary Adam Woodage said Alcoa's shift and day workers have a 36-hour week, compared with 42 hours for shift workers at Worsley. South32 day workers complete 40 hours over four 10-hour days. Woodage said those differences would face greater scrutiny as the companies move toward combining aluminium operations, and that employees want an agreement recognising their skills, contributions and role.
Company position
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 would continue after the transaction is completed. The company also said it has plans to maintain operations during the industrial action and does not expect the stoppage to affect production.
Alcoa's acquisition
The dispute comes as Alcoa prepares to acquire a substantial part of South32's aluminium value chain in a transaction with an implied enterprise value of up to USD 5.6 billion. Announced in July 2026, the deal covers South32's 86% interest in Worsley Alumina, full ownership of the Hillside Aluminium smelter in South Africa, a 33% interest in Brazil's Mineração Rio do Norte bauxite mine, a 36% interest in the Brazil Alumina refinery and a 40% interest in the Brazil Aluminium smelter.
The implied enterprise 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 agreed alumina and aluminium price targets through 2030. Alcoa will also assume rehabilitation provisions linked to the acquired assets, estimated at about USD 1.2 billion, separate from the enterprise value. South32 intends to distribute about 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 owned by South32 and on care and maintenance.
The acquisition is targeted for completion by June 29, 2027, subject to regulatory and other closing conditions. South32 shareholders approved it on October 15, 2026.
Worsley in the expanded portfolio
Worsley has annual alumina production capacity of about 4.4 million tonnes and is a significant part of Alcoa's planned expansion. Wood Mackenzie estimates the acquisition will raise Alcoa's attributable bauxite production by 53.6% to nearly 53 million tonnes a year and attributable alumina production by 51.6%, while increasing aluminium smelting capacity by around 26%. Alcoa expects about USD 900 million in net present value from operational synergies, including better integration between Worsley and its existing Western Australian operations. The expanded portfolio is expected to produce about 14.8 million tonnes of alumina and 3.2 million tonnes of aluminium annually after completion.
Securing experienced employees and maintaining stable operations at Worsley will remain important as Alcoa prepares to integrate the assets. The outcome of the enterprise agreement negotiations could shape employment conditions at a key facility in the proposed acquisition.