Glencore Plc agreed to a $960 million deal that will boost ownership of two giant Congolese cobalt and copper mines, and sever its ties with controversial Israeli billionaire Dan Gertler. For Glencore, the deal achieves two things: greater control of key assets at a time of booming copper and cobalt prices and a parting of ways from Gertler after his business in the Democratic Republic of Congo and relationship with President Joseph Kabila attracted scrutiny from the U.S. Department of Justice.