The logo of Sumitomo Metal Mining Co is pictured at the company's headquarters in Tokyo, Japan, September 13, 2018. REUTERS/Ritsuko Shimizu/Files Japan's Sumitomo Metal Mining and Sumitomo Corp agreed to sell their stakes in the Sierra Gorda copper mine in Chile to Australian miner South32 Ltd for around US$1.5 billion, the companies said on Thursday. The Japanese sellers, who together hold a 45per cent stake, had said last year that they were considering exiting the venture, which they own with Polish state-owned miner KGHM, after years of losses.