Gas environment

The most important factors associated with the gas environment in an outburst prone region are the seam gas pressure, gas permeability and the gas content and composition. Mining operations promote the change of methane into a fully gas state and the resultant increase in gas pressure triggers the outburst. Therefore, mines take the position of monitoring gas pressure to avoid build-up. However, it is easier to monitor the gas content of the coal and use this value to obtain gas pressure (see following graph). In Australia, the critical value of gas content for outbursting with carbon dioxide is 6 – 7 m3/t.