(Reuters) -Debt-laden Tianqi Lithium has secured a lifeline from Perth-based nickel and gold miner IGO Ltd, which will invest $1.4 billion in the unit that controls Greenbushes, the world’s largest hard-rock lithium mine. China’s Tianqi, one of the biggest producers of lithium chemicals used in electric-vehicle batteries, was due to make a$1.88 billion loan repayment by the end of November but secured a one-month extension, buying it time. On Tuesday, Tianqi said in a filing that IGO Lithium Holdings would take a 49% stake in Tianqi Lithium Energy Australia (TLEA), with Tianqi retaining control with 51%. That gives IGO 24.99% in Greenbushes plus 49% in Tianqi’s suspended Kwinana lithium processing plant, both of which are in Western Australia, a source with knowledge of the deal said. The Chinese company said it planned to use the proceeds mostly to repay $1.2 billion of the principal on a loan used to buy a stake in Chile’s SQM in 2018, as well as interest. Following the agreement with IGO, Tianqi said it planned to extend the loan repayment deadline to Nov. 25, 2022. Tianqi also said its chairman Jiang Weiping had agreed to provide a $117 million shareholder loan to the company. That loan, with a term of no more than five years and interest rate no higher than 5%, can be drawn down from Feb. 1, it added. The IGO deal, which needs approval from Australia’s Foreign Investment Review Board, will be put to Tianqi shareholders on Jan. 5, Tianqi said in a separate filing. U.S.-based Albemarle Corp, which holds 49% in the Talison Lithium joint venture that operates Greenbushes to TLEA’s 51%, said the transaction “appears to be structured in a way that would not trigger Albemarle’s right of first refusal.” “If so, we believe the structure of the Talison JV would remain unchanged,” spokeswoman Hailey Quinn said, adding that the company would evaluate further once full details are known. Albemarle previously said it was keen to take full control of Greenbushes should a Tianqi sale trigger its preemption rights.