Rio Tinto is in the process of lifting its ownership stake in the Canadian miner to 42.3 percent and currently has the right to buy up to 49 percent of the company. Rio and Ivanhoe have a standstill agreement that expires in January 2012 that keeps the Anglo-Australian mining company from taking majority control of Ivanhoe. A spokesman for Ivanhoe declined to comment. Rio Tinto was not immediately able to comment. Ivanhoe opened the door to other buyers in July by terminating a clause in their agreement that restricted sales to other strategic investors.