Business Rio Tinto to shutter New Zealand aluminium smelter, putting jobs and economy in peril Updated : July 09, 2020 10:21 AM IST The smelter is a joint venture, with Rio holding a 79.4 percent stake and Japan's Sumitomo Chemical Co holding 20.6 percent. Finance Minister Grant Robertson said the decision by Rio Tinto, the world's biggest iron ore miner, was "disappointing" and the timing could not be worse. Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.