The restart marked exactly a century since the mine first went into production.
The company changed its board of directors and plans to spin out non-core assets La Verde, Capricho, and Paco Orco into a new company.
The miner may cut its labor costs by 10%, which could involve layoffs among its 35,000 staff.
Case centres on a 2018 toxic spill at the Badila oilfield, equivalent in volume to 34 Olympic-sized swimming pools.
