Windalco's parent company Russian aluminium producer Rusal says its first-half net profit rose to US$ 2 billion from a loss of US$124 million a year ago.
The turnaround was due to higher sales and stronger prices for the metal.
Hong-Kong listed Rusal, the world's third largest aluminium producer, increased its January-June sales by 6% year on year, while the average price for a ton of aluminium rose by 30%.
Rusal sells the metal, used in construction and electronics among other industries, to Europe, the United States and Asia.
It has been hit by Russia's government decision to raise export taxes for the country's metals producers for August to December.
Rusal said in June the 15% export tax on aluminium exports, or a minimum of $254 a tonne, would cost it several hundred million dollars this year and may lead to lower 2021 sales.
Meanwhile - problems have developed with wage and fringe benefits negotiations for workers employed to Rusal's operations in Jamaica.
The Union of Clerical, Administrative and Supervisory Employees, (UCASE) says nearly a year ago it served a 24 point claim on Windalco on behalf of more than 600 production workers at the company's Ewarton, Port Esquivel, Kirkvine Works and Swallenburg locations.