Update: Rival challenges expected as Rio’s $3.9 bid agreed by Riversdale

A new report details subpar investor returns in the mining industry over the last decade, particularly big cap diversified companies which have not adapted to new realities.

Chemaf agreed to sell its assets to Chinese defence and industrial giant, China North Industries Corp, or Norinco in June.

The restart marked exactly a century since the mine first went into production.

Most mining firms rely on their own diesel supplies to extract iron ore, diamonds, rutile and bauxite in the resource-rich country.