(Sharecast News) - BHP said it was returning $10.4bn to shareholders via a share buy back and special dividend using the proceeds from the sale of its US shale business.The mining giant promised to return all of the net proceeds from the $10.8bn sale in July. BP bought most of the business in a deal completed this week.BHP will target an off-market buy-back of $5.2bn starting on November 19 and closing on December 14. It added that it reserved the right to buy back its Australian BHP Billiton Limited shares at up to a 14% discount.