UK investigators raided home of former investment banker to look for evidence connected with a bribery investigation into mining giant Rio Tinto Group.
The changes to the mining code in Congo, which supplies some 60 percent of the world's cobalt, could have repercussions for consumers around the world.
Last year, a more than month-long strike at Escondida ended with workers opting to extend their previous contract through July 31 of this year instead of replacing it.