Around 200 union members at South32's Worsley Alumina refinery in Western Australia began a 48-hour stoppage on 10 November, seeking firmer protection for their pay and conditions before Alcoa's planned acquisition of the company's aluminium assets. The action involves members of the Electrical Trades Union (ETU) and the Australian Manufacturing Workers' Union (AMWU), and coincides with a scheduled shutdown at the refinery's main processing plant.
AMWU state secretary Steve McCartney said the workforce wanted existing earnings protected ahead of the ownership change. The unions are negotiating a new enterprise agreement with South32 while the company prepares to transfer a large part of its aluminium business to Alcoa.
Incentive payments become the sticking point
Short-term incentive payments are the central issue. According to McCartney, Worsley workers have received an average bonus of 10 per cent over the past five years and want those payments secured in the enterprise agreement. The union argues that South32 has cited incentive payments when describing total remuneration but has not given a binding guarantee that they will continue under new ownership.
McCartney said the claim is not for higher pay, but for continuation of benefits employees have consistently received.
Working hours add a second point of friction
ETU WA secretary Adam Woodage pointed to differences in hours between the two workforces in comparable roles. Alcoa's shift and day workers operate a 36-hour week, compared with 42 hours for shift workers at Worsley, while South32's day workers complete 40 hours across four 10-hour days.
Woodage said those gaps would attract closer scrutiny as the two companies move to combine their aluminium operations, and that employees wanted an agreement recognising their skills, contributions and role in the business.
South32 says talks are constructive
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 added that it had plans in place to maintain operations at the refinery during the industrial action and did not expect the stoppage to affect production.
The transaction behind the dispute
The stoppage is unfolding alongside Alcoa's acquisition of a substantial 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 in Western Australia, 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, which sit outside that enterprise value.
South32 intends to distribute roughly 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. Mozal Aluminium in Mozambique is excluded and remains under South32's ownership on care and maintenance. Completion is targeted for 29 June 2027, subject to regulatory and other closing conditions; South32 shareholders approved the transaction on 15 October 2026.
Why Worsley matters to the enlarged group
Worsley has annual alumina production capacity of approximately 4.4 million tonnes, making it a significant asset in Western Australia's alumina industry. Wood Mackenzie estimates the transaction will increase Alcoa's attributable bauxite production by 53.6 per cent to nearly 53 million tonnes a year and attributable alumina production by 51.6 per cent, while aluminium smelting capacity rises by around 26 per cent.
Alcoa expects the deal to generate approximately USD 900 million in net present value through operational synergies, including improved 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 once the transaction is completed.
Against that backdrop, securing experienced employees and keeping Worsley stable 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 included in the proposed acquisition.