Evaluation of Methane Gas Hazards and Ventilation Adequacy in Underground Coal Mines in Benue State, North Central Nigeria

Methane emission from coal seams constitutes one of the most serious safety hazards in underground mining, and its management requires systematic gas content characterisation and ventilation adequacy assessment. This study evaluates methane gas hazard profiles and ventilation system performance at underground coal mines in Otukpo and Gboko districts of Benue State, North Central Nigeria. Methane content of coal was measured by the USBM direct method using desorption canisters on core samples from five boreholes. In-situ gas monitoring using catalytic bead sensors was conducted at 12 underground measurement points during active shift operations. Ventilation quantities were measured at principal splits and auxiliary fans using vane anemometry, and a ventilation network model was constructed in VentSim software to evaluate current and alternative ventilation configurations. Results indicate coal seam methane contents of 0.8 to 3.2 cubic metres per tonne, classifying the Benue coal as gassy and requiring statutory methane management measures under Nigerian Mines Regulations. Measured face concentrations approach 1.5 percent methane in restricted areas during peak production, approaching the statutory 1.25 percent alert level. Current ventilation quantities are insufficient for the planned production expansion by a factor of 2.4. The study recommends an auxiliary fan upgrade programme, installation of fixed gas monitoring sensors at critical locations, and the adoption of a methane management plan. Keywords: methane, underground coal, ventilation, Benue State, gas hazard.