In a statement, the local stock exchange said the minimum bid would be set at $65 per share, for a total package price of $4.066 billion.

China's Tianqi has agreed to purchase the shares. The company struck a deal earlier this year to buy nearly a fourth of SQM from Nutrien, which must offload the stake to meet regulatory commitments after it was formed in January by the merger of Agrium and Potash Corp of Saskatchewan.

Tianqi's interest in the Chilean lithium producer comes as Beijing is aggressively promoting electric vehicles to combat air pollution and help China's domestic carmakers leapfrog the combustion engine to build global brands.

Lithium is a key ingredient in the batteries that power everything from cellphones to electric vehicles.

The deal to purchase the shares from Nutrien has overcome repeated legal challenges in Chile.

Chilean authorities initially expressed concerns that a tie-up between Tianqi and SQM would give the Chinese company control of 70 percent of the global lithium market and unprecedented pricing power.

Tianqi, through Talison Lithium which it controls, is also in a joint venture with SQM´s top competitor, No. 1 lithium producer Albemarle Corp in Australia, where they own the world's biggest lithium mine, Greenbushes.

But a Chilean antitrust court blessed the transaction, placing conditions on the sale that limit Tianqi´s access to SQM business secrets and sensitive information.

Several groups, including SQM itself, filed appeals against the antitrust court's decision to authorize the deal, but each was struck down, allowing the sale to proceed.

The country´s Constitutional Court in late October also rejected a last-ditch lawsuit by SQM majority shareholder Julio Ponce Lerou to overturn the antitrust court´s decision.

Nutrien has said it plans to use proceeds from the sale of stakes in SQM and two other companies in part to expand its network of farm retail stores in the United States, and to establish a network in Brazil.

(Reporting by Dave Sherwood; Editing by Bill Trott and Jonathan Oatis)

By Dave Sherwood