The Salina Cruz refinery, damaged by fire and floods earlier this month, will be up and running again by July 30.
The US$2.5bn deal involves the acquisition of Brazilian miner Vale's fertilizer assets by US-based Mosaic.
The local subsidiary of Canadian company International Frontier Resources (IFR) has been given the go-ahead to begin work on its onshore Tecolutla block.
Peru's President Pedro Pablo Kuczynski is battling political rivals in addition to bad weather and corruption scandals that are blocking plans to accelerate infrastructure projects and create jobs.
The legislation mandates a six-member, independent board for Chile's state oil company, as well as a US$400mn capital injection from the government.