Preparation and performance characterization of a molasses-based composite inhibitor for coal spontaneous combustion in steeply inclined goafs

Coal spontaneous combustion (CSC) in goafs is a serious hazard to underground mine safety. Traditional inhibitors usually have weak bonding strength and high fluidity. Therefore , they adhere poorly to coal surfaces in steeply inclined goafs and show limited suppression efficiency. To address this issue, this study developed a novel composite inhibitor with enhanced bonding strength and adhesion properties for CSC mitigation in steeply inclined goafs. The bonding, adhesion, antioxidant characteristics, and CSC suppression performances of molasses solution (MS) and its composites with CaCl 2 and MgCl 2 were systematically evaluated through laboratory and field tests. Results showed that 30 % MS exhibited strong coal adhesion, with a bonding strength of 132.21 N and an adhesion rate of 6.65 %, representing 140 and 41.5 times increases, respectively, compared to pure water. When combined with 15 % CaCl 2 and 10 % MgCl 2 , the composite inhibitor significantly suppressed coal oxidation at low temperatures, reducing oxygen consumption rates by 72.9 % (90 °C), 84.3 % (170 °C), and 62.2 % (250 °C), with corresponding inhibition rates of 73.4 %, 87.1 %, and 77.9 %. Field tests in a steeply inclined goaf showed CO concentrations decreased by 47.5 % (intake side) and 35.2 % (return side), effectively controlling CSC. Furthermore, the inhibition mechanisms of the molasses-based composite were elucidated. This study demonstrates that molasses-based composite inhibitors provide an effective and practical approach for preventing CSC in steeply inclined goafs.