Ivanhoe Mines Ltd., developer of the Oyu Tolgoi copper and gold deposit in Mongolia, soared in Toronto on speculation that a share sale by its partner Rio Tinto Group boosts the likelihood the project will proceed

Rio, the world’s third-largest mining company, agreed in October 2006 to pay $388 million to double to its stake in Ivanhoe to 19.9 percent upon the conclusion of an agreement with Mongolia on Oyu Tolgoi.