Mining there has been suspended since May 6 when a methane ignition event seriously injured five workers.
Investigations have so far failed to find a definitive cause for the ignition event.
Part of the longwall panel where the methane ignition incident occurred will be permanently sealed.
The mine will also buy additional longwall equipment.
Anglo American metallurgical coal business CEO Tyler Mitchelson said permanent sealing provided the greatest level of safety and would aid works to prepare Grosvenor mine for a safe restart of operations, which was likely to be in the second half of 2021.
"The decision to permanently seal the longwall area continues our step by step approach to working through the Grosvenor incident," he said.
"Safety comes first, and we're taking the time to ensure mining does not restart until we know it's safe to do so.
"Over the past two weeks, we have installed three temporary seals in the longwall area, which has allowed us to isolate the area of the mine where heating occurred and stabilise the environment prior to the permanent sealing work commencing.
"We are in the process of developing the detailed technical roadmap to safely restart mining next year, including a detailed risk assessment process involving internal and external experts.
"New longwall equipment will be purchased, providing us with the opportunity to assess the best available technology to further expedite our automation and technology journey at Grosvenor.
"As we communicated to our workforce including key contractors recently, we are continuing to review our controls to prevent a methane ignition occurring again.
"The pilot study to assess the use of pressure sensors to cut power to the longwall at Moranbah North is under way and we will be reviewing all technology options to improve our controls at Grosvenor.
"This work will continue as more information becomes available from investigations.
"As we develop our technical roadmap to restarting longwall mining next year, we will work through the resourcing impacts and will be engaging further with our workforce over coming weeks.
"Surface activities will continue and underground development work will resume when it is safe to do so.
"It's unacceptable that our colleagues were seriously injured on May 6.
"Mining operations at Grosvenor will restart with the benefit of learnings from our investigation and the Board of Inquiry's recommendations, and with additional safety measures in place.
"Where appropriate, these learnings will be applied across our business and may have implications across the industry.
"Our injured colleagues are continuing their medical treatment on the road to recovery and we continue to offer support to our colleagues and their families."