A logo for mining company BHP Billiton adorns a sign outside the Perth Convention Centre where their annual general meeting was being held in Perth, Western Australia, November 19, 2015. REUTERS/David Gray/File Photo

A logo for mining company BHP Billiton adorns a sign outside the Perth Convention Centre where their annual general meeting was being held in Perth, Western Australia, November 19, 2015. REUTERS/David Gray/File Photo

A logo for mining company BHP Billiton adorns a sign outside the Perth Convention Centre where their annual general meeting was being held in Perth, Western Australia, November 19, 2015. REUTERS/David Gray/File Photo

September 21, 2016 12:46 AM (UTC+8)