By The Associated PressBY THE NUMBERS: Freeport-McMoRan Copper & Gold Inc. plans to buy Plains Exploration & Production Co. and McMoRan Exploration Co. for a combined $9 billion. The Phoenix mining company also will assume $11 billion in debt. The deal is expected to close next year. BROADER PICTURE: The addition of the two companies will help Freeport-McMoRan diversify into the global market for natural gas without losing focus on its mining operations. WHAT'S NEXT: Analysts say there could be some backlash from shareholders. The deal requires approval from shareholders at Plains Exploration and McMoRan but not from those at Freeport-McMoRan.