ANALISIS HUBUNGAN NILAI HGI (HARDGROVE GRINDABILITY INDEX) ASH CONTENT INHERENT MOISTURE DAN TOTAL SULFUR TERHADAP NILAI KALORI BATUBARA DI PT. GEOSERVICES SAMARINDA KALIMANTAN TIMUR. geo. sci. kut. bas. 2022, 5 (1), 31-37. https://doi.org/10.30872/geofisunmul.v5i1.789.