The　development　of　geothermal　resources　in　deep　mining　has　garnered　extensive　research　interest　in　recent　years.　The　present　work　studies　the　thermal　storage　backfill　materials　synthesized　by　integrating　microencapsulated　phase　change　materials　(MPCM)　into　geopolymers　prepared　with　copper　mine　tailings　(CMT)　and　blast　furnace　slag　(BFS).　With　the　increment　of　MPCM　content,　the　compressive　strength　of　the　geopolymers　declined.　Despite　this,　the　lowest　7　days　compressive　strength　of　the　geopolymers　could　still　reach　24.5　MPa.　The　results　in　microstructures　of　the　geopolymers　indicated　that　paraffin　was　successfully　encapsulated　within　the　microcapsules　and　MPCM　was　well　dispersed　in　the　geopolymer　matrix.　The　melting　temperature　of　the　MPCM　was　54.78　°C　and　the　melting　latent　heat　was　116.43　J/g.　Infrared　thermography　showed　that　the　highest　average　temperature　of　geopolymer　with　20　%　MPCM　was　5.0　°C　lower　than　that　without　MPCM,　indicating　superior　thermal　storage　capacity　of　the　geopolymers　with　MPCM.　This　study　provides　a　clue　for　the　synthesis　of　thermal　storage　backfill　materials　with　in-situ　waste　in　extracting　geothermal　resources　and　reducing　the　temperature　of　deep　mining　environments.　©　2025　Elsevier　Inc.