Known as "The Trio", the founding Kazakh shareholders of ENRC have been accused by one former board member, Ken Olisa, of being "more Soviet than City".
Worth an estimated £2.1bn each, Alexander Machkevich, Patokh Chodiev and Alijan Ibragimov – in their late 50s – have amassed a labyrinth of mining and metals interests over the years.
Mr Machkevich, who once spent £12.8m at a Damien Hirst auction at Sotheby's, had campaigned to become chairman.
But he agreed last month to keep his distance as his appointment would have run counter to the perception of good corporate governance.
As part of the governance review, Mehmet Dalman, an existing board member, was named as senior independent director while Terence Wilkinson, a former chief executive of AIM-listed Ridge Mining and Lonrho, also joined the board.