The legislators’ resolution brings an 18-month review on the deals governing the copper-gold mine to a close, allowing the company to continue with an ongoing $7 billion expansion of the operation.

The news is something of a relief for Rio Tinto, which feared the government might try to completely renegotiate the agreements on the asset’s development — a 2009 investment agreement, a 2011 amended and restated shareholder agreement and a 2015 underground mine development and financing plan.

The resolution, however, recommends to explore options to improve the deal, including looking at the Mongolian government’s equity share in Oyu Tolgoi, a re-definition of the reserve report and updated feasibility report, and a renewal of environmental and water assessments.

“Adherence to these agreements by all parties has underpinned a total in-country spend of around $10 billion since 2010,” Rio Tinto’s chief executive copper and diamonds, Arnaud Soirat, said in the statement.

Soirat acknowledged there was still “a lot of work to do” to ensure Oyu Tolgoi reaches its full potential.

Oyu Tolgoi was discovered in 2001 and Rio gained control of it in 2012. The ongoing mine expansion is expected to lift production from 125–150kt this year to 560kt at full tilt from 2025, making it the biggest new copper mine to come on stream in several years.

The giant operation is one-third owned by Mongolia’s government and two-third held by Canada’s Turquoise Hill Resources (TSX, NYSE:TRQ). Out of Turquoise’s 66% share, Rio owns 51%.