Rio Tinto Group (ASX:RIO) completed its acquisition of Sumitomo Chemical's 20.64% interest in New Zealand Aluminium Smelters, which operates the Tiwai Point aluminum smelter, the company said in a Nov. 1 statement.

Following the acquisition, Rio Tinto now wholly owns New Zealand Aluminium Smelters.

Separately, the mining and metals giant said it completed the purchase of Sumitomo Chemical's 2.46% stake in Boyne Smelters, bringing its total interest in the Australian aluminum smelter to 73.5%.