The 4th MINRESCUE meeting was held on the 30th September and 1st of October 2021. Due to the pandemic situation, the meeting was held hybrid at a distance via the online platform of MS Teams and at GIG premises. General project progress and specific deliverables were summed up. The research results obtained were discussed as well as future testing plans. At 1st October the project partners visited coal processing plant at Mine “Piast-Ziemowit” of PGG SA to investigate the coal production process and waste flow and storage facilities.