Workers 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 proposed acquisition of South32's aluminium assets. The action involves members of the Electrical Trades Union and the Australian Manufacturing Workers' Union, with around 200 union members employed at the operation, according to AMWU state secretary Steve McCartney.
The stoppage coincides with a scheduled shutdown at the refinery's main processing plant. McCartney said workers want their existing earnings protected before the ownership change, rather than an increase in pay.
Bonus payments at the centre
Short-term incentive payments are a central issue. McCartney said Worsley workers had received an average bonus of 10 per cent over the past five years and want the payments secured through their enterprise agreement. The union argues that South32 has referred to incentive payments when discussing overall remuneration but has not provided a binding guarantee to protect those earnings.
Working hours have also emerged as a point of contention. ETU WA secretary Adam Woodage said Alcoa's shift and day workers have a 36-hour working week, compared with 42 hours for shift workers at Worsley. South32's day workers complete 40 hours across four 10-hour days. Woodage argued that those differences would face greater scrutiny as the companies move towards combining their aluminium operations, and that employees want an agreement recognising their skills and contributions.
Company position
South32 said it was engaging constructively with employees and their representatives during enterprise agreement negotiations. The company said Worsley employees receive benefits beyond base wages and that its existing short-term incentive policy would continue after the transaction is completed. It also said it had plans to maintain operations during the industrial action and did not expect the stoppage to affect production.
Transaction scope
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 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 enterprise value comprises USD 3.1 billion in cash, approximately USD 1 billion in newly issued Alcoa shares, around USD 750 million in net debt and lease liabilities to be assumed by Alcoa, and up to USD 750 million in contingent cash payments linked to agreed alumina and aluminium price targets through 2030. Alcoa will also assume rehabilitation provisions associated with the acquired assets, estimated at about USD 1.2 billion, separate from the implied enterprise value.
South32 intends to distribute approximately half of the Alcoa shares it receives, worth around USD 500 million at the time of the announcement, to eligible shareholders through a fully franked special dividend after completion. The transaction excludes Mozal Aluminium in Mozambique. Completion is targeted for June 29, 2027, subject to regulatory and other closing conditions; South32 shareholders approved the transaction on October 15, 2026.
Worsley's role in expanded portfolio
Worsley has an annual alumina production capacity of approximately 4.4 million tonnes. According to Wood Mackenzie, the acquisition will increase Alcoa's attributable bauxite production by 53.6 per cent to nearly 53 million tonnes annually, while attributable alumina production is expected to rise by 51.6 per cent and aluminium smelting capacity by around 26 per cent. Alcoa expects the acquisition to generate approximately USD 900 million in net present value through operational synergies, including better integration between Worsley and its existing Western Australian operations.
Once completed, the expanded portfolio is expected to produce approximately 14.8 million tonnes of alumina and 3.2 million tonnes of aluminium annually. Against that backdrop, securing experienced employees and maintaining stable operations at Worsley will remain important as Alcoa prepares to integrate the acquired assets. The outcome of the enterprise agreement negotiations could therefore shape employment conditions at one of the key facilities in the proposed acquisition.